Import tools: 6d96590e1e51042af8d3fb42ff6b06e1ae8c7a59 from branch v3.6r3.6.23-rc0r3.6.23

ref: 27c04a6448..6d96590e1e
for: 3.6.18

TOOLS-2803    [v3.6] Add --config option for password values

43 files changed, 14742 insertions, 7 deletions

diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/Godeps b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/Godeps
index b7dd17d007d..67a9dfd0bd5 100644
--- a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/Godeps
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/Godeps
@@ -1,5 +1,7 @@
 gopkg.in/mgo.v2                         39b4000d99037e917f3a3b9d2dcab667a9ef284a    github.com/10gen/mgo
 gopkg.in/tomb.v2                        14b3d72120e8d10ea6e6b7f87f7175734b1faab8
+gopkg.in/yaml.v2                        0b1645d91e851e735d3e23330303ce81f70adbe3
+github.com/pkg/errors                   614d223910a179a466c1767a985424175c39b465
 github.com/jtolds/gls                   8ddce2a84170772b95dd5d576c48d517b22cac63
 github.com/jacobsa/oglematchers         3ecefc49db07722beca986d9bb71ddd026b133f0
 github.com/smartystreets/assertions     287b4346dc4e71a038c346375a9d572453bc469b
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options.go
index 96622109e96..1e8ab118a0a 100644
--- a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options.go
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options.go
@@ -10,6 +10,7 @@ package options
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"regexp"
 	"runtime"
@@ -22,6 +23,8 @@ import (
 	"github.com/mongodb/mongo-tools/common/failpoint"
 	"github.com/mongodb/mongo-tools/common/log"
 	"github.com/mongodb/mongo-tools/common/util"
+	"github.com/pkg/errors"
+	"gopkg.in/yaml.v2"
 )
 
 // Gitspec that the tool was built with. Needs to be set using -ldflags
@@ -95,8 +98,9 @@ type Namespace struct {
 
 // Struct holding generic options
 type General struct {
-	Help    bool `long:"help" description:"print usage"`
-	Version bool `long:"version" description:"print the tool version and exit"`
+	Help       bool   `long:"help" description:"print usage"`
+	Version    bool   `long:"version" description:"print the tool version and exit"`
+	ConfigPath string `long:"config" value-name:"<filename>" description:"path to a configuration file"`
 
 	MaxProcs   int    `long:"numThreads" hidden:"true"`
 	Failpoints string `long:"failpoints" hidden:"true"`
@@ -421,9 +425,16 @@ func (o *ToolOptions) AddOptions(opts ExtraOptions) {
 	}
 }
 
-// Parse the command line args.  Returns any extra args not accounted for by
-// parsing, as well as an error if the parsing returns an error.
+// ParseArgs parses a potential config file followed by the command line args, overriding
+// any values in the config file. Returns any extra args not accounted for by parsing,
+// as well as an error if the parsing returns an error.
 func (o *ToolOptions) ParseArgs(args []string) ([]string, error) {
+	LogSensitiveOptionWarnings(args)
+
+	if err := o.ParseConfigFile(args); err != nil {
+		return []string{}, err
+	}
+
 	args, err := o.parser.ParseArgs(args)
 	if err != nil {
 		return []string{}, err
@@ -455,6 +466,91 @@ func (o *ToolOptions) ParseArgs(args []string) ([]string, error) {
 	return args, err
 }
 
+// LogSensitiveOptionWarnings logs a warning for any sensitive information (i.e. passwords)
+// that appear on the command line for the --password, --uri and --sslPEMKeyPassword options.
+// This also applies to a connection string that appears as a positional argument.
+func LogSensitiveOptionWarnings(args []string) {
+	passwordMsg := "WARNING: On some systems, a password provided directly using " +
+		"--password may be visible to system status programs such as `ps` that may be " +
+		"invoked by other users. Consider omitting the password to provide it via stdin, " +
+		"or using the --config option to specify a configuration file with the password."
+
+	uriMsg := "WARNING: On some systems, a password provided directly in a connection string " +
+		"or using --uri may be visible to system status programs such as `ps` that may be " +
+		"invoked by other users. Consider omitting the password to provide it via stdin, " +
+		"or using the --config option to specify a configuration file with the password."
+
+	sslMsg := "WARNING: On some systems, a password provided directly using --sslPEMKeyPassword " +
+		"may be visible to system status programs such as `ps` that may be invoked by other users. " +
+		"Consider using the --config option to specify a configuration file with the password."
+
+	// Create temporary options for parsing command line args.
+	tempOpts := New("", "", EnabledOptions{Auth: true, Connection: true, URI: true})
+	_, err := tempOpts.parser.ParseArgs(args)
+	if err != nil {
+		return
+	}
+
+	// Log a message for --password, if specified.
+	if tempOpts.Auth.Password != "" {
+		log.Logvf(log.Always, passwordMsg)
+	}
+
+	// Log a message for --uri or a positional connection string, if either is specified.
+	uri := tempOpts.URI.ConnectionString
+	if uri != "" {
+		if cs, err := connstring.ParseURIConnectionString(uri); err == nil && cs.Password != "" {
+			log.Logvf(log.Always, uriMsg)
+		}
+	}
+
+	// Log a message for --sslPEMKeyPassword, if specified.
+	if tempOpts.SSL.SSLPEMKeyPassword != "" {
+		log.Logvf(log.Always, sslMsg)
+	}
+}
+
+// ParseConfigFile iterates over args to find a --config option. If not found, we return.
+// If found, we read the contents of the specified config file in YAML format. We parse
+// any values corresponding to --password, --uri and --sslPEMKeyPassword, and store them
+// in the opts.
+func (opts *ToolOptions) ParseConfigFile(args []string) error {
+	// Get config file path from the arguments, if specified.
+	_, err := opts.parser.ParseArgs(args)
+	if err != nil {
+		return err
+	}
+
+	// No --config option was specified.
+	if opts.General.ConfigPath == "" {
+		return nil
+	}
+
+	// --config option specifies a file path.
+	configBytes, err := ioutil.ReadFile(opts.General.ConfigPath)
+	if err != nil {
+		return errors.Wrapf(err, "error opening file with --config")
+	}
+
+	// Unmarshal the config file as a top-level YAML file.
+	var config struct {
+		Password          string `yaml:"password"`
+		ConnectionString  string `yaml:"uri"`
+		SSLPEMKeyPassword string `yaml:"sslPEMKeyPassword"`
+	}
+	err = yaml.UnmarshalStrict(configBytes, &config)
+	if err != nil {
+		return errors.Wrapf(err, "error parsing config file %s", opts.General.ConfigPath)
+	}
+
+	// Assign each parsed value to its respective ToolOptions field.
+	opts.Auth.Password = config.Password
+	opts.URI.ConnectionString = config.ConnectionString
+	opts.SSL.SSLPEMKeyPassword = config.SSLPEMKeyPassword
+
+	return nil
+}
+
 func (opts *ToolOptions) handleUnknownOption(option string, arg flags.SplitArgument, args []string) ([]string, error) {
 	if option == "dbpath" || option == "directoryperdb" || option == "journal" {
 		return args, fmt.Errorf("--dbpath and related flags are not supported in 3.0 tools.\n" +
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options_test.go
index 6d2150df9fc..54aeaf3cdea 100644
--- a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options_test.go
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/common/options/options_test.go
@@ -8,17 +8,24 @@ package options
 
 import (
 	"bytes"
+	"io/ioutil"
+	"os"
+
 	"github.com/mongodb/mongo-tools/common/connstring"
 	"github.com/mongodb/mongo-tools/common/log"
 	"github.com/mongodb/mongo-tools/common/testtype"
 	. "github.com/smartystreets/goconvey/convey"
-	"os"
 
 	"runtime"
 	"testing"
 	"time"
 )
 
+const (
+	ShouldSucceed = iota
+	ShouldFail
+)
+
 func TestVerbosityFlag(t *testing.T) {
 	Convey("With a new ToolOptions", t, func() {
 		enabled := EnabledOptions{false, false, false, false}
@@ -468,4 +475,158 @@ func TestDeprecationWarning(t *testing.T) {
 			So(result, ShouldNotContainSubstring, deprecationWarningSSLAllow)
 		})
 	})
-}
\ No newline at end of file
+}
+
+type configTester struct {
+	description  string
+	yamlBytes    []byte
+	expectedOpts *ToolOptions
+	outcome      int
+}
+
+func runConfigFileTestCases(testCases []configTester) {
+	configFilePath := "./test-config.yaml"
+	args := []string{"--config", configFilePath}
+	defer os.Remove(configFilePath)
+
+	for _, testCase := range testCases {
+		if err := ioutil.WriteFile(configFilePath, testCase.yamlBytes, 0644); err != nil {
+			So(err, ShouldBeNil)
+		}
+		opts := New("test", "", EnabledOptions{true, true, true, true})
+		err := opts.ParseConfigFile(args)
+
+		var assertion func()
+		if testCase.outcome == ShouldSucceed {
+			assertion = func() {
+				So(err, ShouldBeNil)
+				So(opts.Auth.Password, ShouldEqual, testCase.expectedOpts.Auth.Password)
+				So(opts.URI.ConnectionString, ShouldEqual, testCase.expectedOpts.URI.ConnectionString)
+				So(opts.SSL.SSLPEMKeyPassword, ShouldEqual, testCase.expectedOpts.SSL.SSLPEMKeyPassword)
+			}
+		} else {
+			assertion = func() {
+				So(err, ShouldNotBeNil)
+			}
+		}
+
+		Convey(testCase.description, assertion)
+	}
+}
+
+func createExpectedOpts(pw string, uri string, ssl string) *ToolOptions {
+	opts := New("test", "", EnabledOptions{true, true, true, true})
+	opts.Auth.Password = pw
+	opts.URI.ConnectionString = uri
+	opts.SSL.SSLPEMKeyPassword = ssl
+	return opts
+}
+
+func TestParseConfigFile(t *testing.T) {
+	if !testtype.HasTestType(testtype.UnitTestType) {
+		t.SkipNow()
+	}
+
+	Convey("should error with no config file specified", t, func() {
+		opts := New("test", "", EnabledOptions{})
+
+		// --config at beginning of args list
+		args := []string{"--config", "--database", "myDB"}
+		So(opts.ParseConfigFile(args), ShouldNotBeNil)
+
+		// --config at end of args list
+		args = []string{"--database", "myDB", "--config"}
+		So(opts.ParseConfigFile(args), ShouldNotBeNil)
+
+		// --config= at beginning of args list
+		args = []string{"--config=", "--database", "myDB"}
+		So(opts.ParseConfigFile(args), ShouldNotBeNil)
+
+		// --config= at end of args list
+		args = []string{"--database", "myDB", "--config="}
+		So(opts.ParseConfigFile(args), ShouldNotBeNil)
+	})
+
+	Convey("should error with non-existent config file specified", t, func() {
+		opts := New("test", "", EnabledOptions{})
+
+		// --config with non-existent file
+		args := []string{"--config", "DoesNotExist.yaml", "--database", "myDB"}
+		So(opts.ParseConfigFile(args), ShouldNotBeNil)
+
+		// --config= with non-existent file
+		args = []string{"--config=DoesNotExist.yaml", "--database", "myDB"}
+		So(opts.ParseConfigFile(args), ShouldNotBeNil)
+	})
+
+	Convey("with an existing config file specified", t, func() {
+		runConfigFileTestCases([]configTester{
+			{
+				"containing nothing (empty file)",
+				[]byte(""),
+				createExpectedOpts("", "", ""),
+				ShouldSucceed,
+			},
+			{
+				"containing only password field",
+				[]byte("password: abc123"),
+				createExpectedOpts("abc123", "", ""),
+				ShouldSucceed,
+			},
+			{
+				"containing only uri field",
+				[]byte("uri: abc123"),
+				createExpectedOpts("", "abc123", ""),
+				ShouldSucceed,
+			},
+			{
+				"containing only sslPEMKeyPassword field",
+				[]byte("sslPEMKeyPassword: abc123"),
+				createExpectedOpts("", "", "abc123"),
+				ShouldSucceed,
+			},
+			{
+				"containing all of password, uri and sslPEMKeyPassword fields",
+				[]byte("password: abc123\nuri: def456\nsslPEMKeyPassword: ghi789"),
+				createExpectedOpts("abc123", "def456", "ghi789"),
+				ShouldSucceed,
+			},
+			{
+				"containing a duplicate field",
+				[]byte("password: abc123\npassword: def456"),
+				nil,
+				ShouldFail,
+			},
+			{
+				"containing an unsupported or misspelled field",
+				[]byte("pasword: abc123"),
+				nil,
+				ShouldFail,
+			},
+		})
+	})
+
+	Convey("with command line args that override config file values", t, func() {
+		configFilePath := "./test-config.yaml"
+		defer os.Remove(configFilePath)
+		if err := ioutil.WriteFile(configFilePath, []byte("password: abc123"), 0644); err != nil {
+			So(err, ShouldBeNil)
+		}
+
+		Convey("with --config followed by --password", func() {
+			args := []string{"--config=" + configFilePath, "--password=def456"}
+			opts := New("test", "", EnabledOptions{Auth: true})
+			_, err := opts.ParseArgs(args)
+			So(err, ShouldBeNil)
+			So(opts.Auth.Password, ShouldEqual, "def456")
+		})
+
+		Convey("with --password followed by --config", func() {
+			args := []string{"--password=ghi789", "--config=" + configFilePath}
+			opts := New("test", "", EnabledOptions{Auth: true})
+			_, err := opts.ParseArgs(args)
+			So(err, ShouldBeNil)
+			So(opts.Auth.Password, ShouldEqual, "ghi789")
+		})
+	})
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/import.data b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/import.data
index ce1ad9da21b..32e97eb4292 100644
--- a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/import.data
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/import.data
@@ -2,5 +2,5 @@
     "vendor": "tools",
     "github": "mongodb/mongo-tools.git",
     "branch": "v3.6",
-    "commit": "27c04a6448462549a61aa1403ad3a09dde2ec9b5"
+    "commit": "6d96590e1e51042af8d3fb42ff6b06e1ae8c7a59"
 }
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/.travis.yml b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/.travis.yml
new file mode 100644
index 00000000000..9159de03e03
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/.travis.yml
@@ -0,0 +1,10 @@
+language: go
+go_import_path: github.com/pkg/errors
+go:
+  - 1.11.x
+  - 1.12.x
+  - 1.13.x
+  - tip
+
+script:
+  - make check
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/LICENSE b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/LICENSE
new file mode 100644
index 00000000000..835ba3e755c
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/LICENSE
@@ -0,0 +1,23 @@
+Copyright (c) 2015, Dave Cheney <dave@cheney.net>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/Makefile b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/Makefile
new file mode 100644
index 00000000000..ce9d7cded64
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/Makefile
@@ -0,0 +1,44 @@
+PKGS := github.com/pkg/errors
+SRCDIRS := $(shell go list -f '{{.Dir}}' $(PKGS))
+GO := go
+
+check: test vet gofmt misspell unconvert staticcheck ineffassign unparam
+
+test: 
+	$(GO) test $(PKGS)
+
+vet: | test
+	$(GO) vet $(PKGS)
+
+staticcheck:
+	$(GO) get honnef.co/go/tools/cmd/staticcheck
+	staticcheck -checks all $(PKGS)
+
+misspell:
+	$(GO) get github.com/client9/misspell/cmd/misspell
+	misspell \
+		-locale GB \
+		-error \
+		*.md *.go
+
+unconvert:
+	$(GO) get github.com/mdempsky/unconvert
+	unconvert -v $(PKGS)
+
+ineffassign:
+	$(GO) get github.com/gordonklaus/ineffassign
+	find $(SRCDIRS) -name '*.go' | xargs ineffassign
+
+pedantic: check errcheck
+
+unparam:
+	$(GO) get mvdan.cc/unparam
+	unparam ./...
+
+errcheck:
+	$(GO) get github.com/kisielk/errcheck
+	errcheck $(PKGS)
+
+gofmt:  
+	@echo Checking code is gofmted
+	@test -z "$(shell gofmt -s -l -d -e $(SRCDIRS) | tee /dev/stderr)"
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/README.md b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/README.md
new file mode 100644
index 00000000000..54dfdcb12ea
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/README.md
@@ -0,0 +1,59 @@
+# errors [![Travis-CI](https://travis-ci.org/pkg/errors.svg)](https://travis-ci.org/pkg/errors) [![AppVeyor](https://ci.appveyor.com/api/projects/status/b98mptawhudj53ep/branch/master?svg=true)](https://ci.appveyor.com/project/davecheney/errors/branch/master) [![GoDoc](https://godoc.org/github.com/pkg/errors?status.svg)](http://godoc.org/github.com/pkg/errors) [![Report card](https://goreportcard.com/badge/github.com/pkg/errors)](https://goreportcard.com/report/github.com/pkg/errors) [![Sourcegraph](https://sourcegraph.com/github.com/pkg/errors/-/badge.svg)](https://sourcegraph.com/github.com/pkg/errors?badge)
+
+Package errors provides simple error handling primitives.
+
+`go get github.com/pkg/errors`
+
+The traditional error handling idiom in Go is roughly akin to
+```go
+if err != nil {
+        return err
+}
+```
+which applied recursively up the call stack results in error reports without context or debugging information. The errors package allows programmers to add context to the failure path in their code in a way that does not destroy the original value of the error.
+
+## Adding context to an error
+
+The errors.Wrap function returns a new error that adds context to the original error. For example
+```go
+_, err := ioutil.ReadAll(r)
+if err != nil {
+        return errors.Wrap(err, "read failed")
+}
+```
+## Retrieving the cause of an error
+
+Using `errors.Wrap` constructs a stack of errors, adding context to the preceding error. Depending on the nature of the error it may be necessary to reverse the operation of errors.Wrap to retrieve the original error for inspection. Any error value which implements this interface can be inspected by `errors.Cause`.
+```go
+type causer interface {
+        Cause() error
+}
+```
+`errors.Cause` will recursively retrieve the topmost error which does not implement `causer`, which is assumed to be the original cause. For example:
+```go
+switch err := errors.Cause(err).(type) {
+case *MyError:
+        // handle specifically
+default:
+        // unknown error
+}
+```
+
+[Read the package documentation for more information](https://godoc.org/github.com/pkg/errors).
+
+## Roadmap
+
+With the upcoming [Go2 error proposals](https://go.googlesource.com/proposal/+/master/design/go2draft.md) this package is moving into maintenance mode. The roadmap for a 1.0 release is as follows:
+
+- 0.9. Remove pre Go 1.9 and Go 1.10 support, address outstanding pull requests (if possible)
+- 1.0. Final release.
+
+## Contributing
+
+Because of the Go2 errors changes, this package is not accepting proposals for new functionality. With that said, we welcome pull requests, bug fixes and issue reports. 
+
+Before sending a PR, please discuss your change by raising an issue.
+
+## License
+
+BSD-2-Clause
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/appveyor.yml b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/appveyor.yml
new file mode 100644
index 00000000000..a932eade024
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/appveyor.yml
@@ -0,0 +1,32 @@
+version: build-{build}.{branch}
+
+clone_folder: C:\gopath\src\github.com\pkg\errors
+shallow_clone: true # for startup speed
+
+environment:
+  GOPATH: C:\gopath
+
+platform:
+  - x64
+
+# http://www.appveyor.com/docs/installed-software
+install:
+  # some helpful output for debugging builds
+  - go version
+  - go env
+  # pre-installed MinGW at C:\MinGW is 32bit only
+  # but MSYS2 at C:\msys64 has mingw64
+  - set PATH=C:\msys64\mingw64\bin;%PATH%
+  - gcc --version
+  - g++ --version
+
+build_script:
+  - go install -v ./...
+
+test_script:
+  - set PATH=C:\gopath\bin;%PATH%
+  - go test -v ./...
+
+#artifacts:
+#  - path: '%GOPATH%\bin\*.exe'
+deploy: off
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/bench_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/bench_test.go
new file mode 100644
index 00000000000..c906870e0c2
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/bench_test.go
@@ -0,0 +1,110 @@
+// +build go1.7
+
+package errors
+
+import (
+	"fmt"
+	"testing"
+
+	stderrors "errors"
+)
+
+func noErrors(at, depth int) error {
+	if at >= depth {
+		return stderrors.New("no error")
+	}
+	return noErrors(at+1, depth)
+}
+
+func yesErrors(at, depth int) error {
+	if at >= depth {
+		return New("ye error")
+	}
+	return yesErrors(at+1, depth)
+}
+
+// GlobalE is an exported global to store the result of benchmark results,
+// preventing the compiler from optimising the benchmark functions away.
+var GlobalE interface{}
+
+func BenchmarkErrors(b *testing.B) {
+	type run struct {
+		stack int
+		std   bool
+	}
+	runs := []run{
+		{10, false},
+		{10, true},
+		{100, false},
+		{100, true},
+		{1000, false},
+		{1000, true},
+	}
+	for _, r := range runs {
+		part := "pkg/errors"
+		if r.std {
+			part = "errors"
+		}
+		name := fmt.Sprintf("%s-stack-%d", part, r.stack)
+		b.Run(name, func(b *testing.B) {
+			var err error
+			f := yesErrors
+			if r.std {
+				f = noErrors
+			}
+			b.ReportAllocs()
+			for i := 0; i < b.N; i++ {
+				err = f(0, r.stack)
+			}
+			b.StopTimer()
+			GlobalE = err
+		})
+	}
+}
+
+func BenchmarkStackFormatting(b *testing.B) {
+	type run struct {
+		stack  int
+		format string
+	}
+	runs := []run{
+		{10, "%s"},
+		{10, "%v"},
+		{10, "%+v"},
+		{30, "%s"},
+		{30, "%v"},
+		{30, "%+v"},
+		{60, "%s"},
+		{60, "%v"},
+		{60, "%+v"},
+	}
+
+	var stackStr string
+	for _, r := range runs {
+		name := fmt.Sprintf("%s-stack-%d", r.format, r.stack)
+		b.Run(name, func(b *testing.B) {
+			err := yesErrors(0, r.stack)
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				stackStr = fmt.Sprintf(r.format, err)
+			}
+			b.StopTimer()
+		})
+	}
+
+	for _, r := range runs {
+		name := fmt.Sprintf("%s-stacktrace-%d", r.format, r.stack)
+		b.Run(name, func(b *testing.B) {
+			err := yesErrors(0, r.stack)
+			st := err.(*fundamental).stack.StackTrace()
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				stackStr = fmt.Sprintf(r.format, st)
+			}
+			b.StopTimer()
+		})
+	}
+	GlobalE = stackStr
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/errors.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/errors.go
new file mode 100644
index 00000000000..161aea25829
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/errors.go
@@ -0,0 +1,288 @@
+// Package errors provides simple error handling primitives.
+//
+// The traditional error handling idiom in Go is roughly akin to
+//
+//     if err != nil {
+//             return err
+//     }
+//
+// which when applied recursively up the call stack results in error reports
+// without context or debugging information. The errors package allows
+// programmers to add context to the failure path in their code in a way
+// that does not destroy the original value of the error.
+//
+// Adding context to an error
+//
+// The errors.Wrap function returns a new error that adds context to the
+// original error by recording a stack trace at the point Wrap is called,
+// together with the supplied message. For example
+//
+//     _, err := ioutil.ReadAll(r)
+//     if err != nil {
+//             return errors.Wrap(err, "read failed")
+//     }
+//
+// If additional control is required, the errors.WithStack and
+// errors.WithMessage functions destructure errors.Wrap into its component
+// operations: annotating an error with a stack trace and with a message,
+// respectively.
+//
+// Retrieving the cause of an error
+//
+// Using errors.Wrap constructs a stack of errors, adding context to the
+// preceding error. Depending on the nature of the error it may be necessary
+// to reverse the operation of errors.Wrap to retrieve the original error
+// for inspection. Any error value which implements this interface
+//
+//     type causer interface {
+//             Cause() error
+//     }
+//
+// can be inspected by errors.Cause. errors.Cause will recursively retrieve
+// the topmost error that does not implement causer, which is assumed to be
+// the original cause. For example:
+//
+//     switch err := errors.Cause(err).(type) {
+//     case *MyError:
+//             // handle specifically
+//     default:
+//             // unknown error
+//     }
+//
+// Although the causer interface is not exported by this package, it is
+// considered a part of its stable public interface.
+//
+// Formatted printing of errors
+//
+// All error values returned from this package implement fmt.Formatter and can
+// be formatted by the fmt package. The following verbs are supported:
+//
+//     %s    print the error. If the error has a Cause it will be
+//           printed recursively.
+//     %v    see %s
+//     %+v   extended format. Each Frame of the error's StackTrace will
+//           be printed in detail.
+//
+// Retrieving the stack trace of an error or wrapper
+//
+// New, Errorf, Wrap, and Wrapf record a stack trace at the point they are
+// invoked. This information can be retrieved with the following interface:
+//
+//     type stackTracer interface {
+//             StackTrace() errors.StackTrace
+//     }
+//
+// The returned errors.StackTrace type is defined as
+//
+//     type StackTrace []Frame
+//
+// The Frame type represents a call site in the stack trace. Frame supports
+// the fmt.Formatter interface that can be used for printing information about
+// the stack trace of this error. For example:
+//
+//     if err, ok := err.(stackTracer); ok {
+//             for _, f := range err.StackTrace() {
+//                     fmt.Printf("%+s:%d\n", f, f)
+//             }
+//     }
+//
+// Although the stackTracer interface is not exported by this package, it is
+// considered a part of its stable public interface.
+//
+// See the documentation for Frame.Format for more details.
+package errors
+
+import (
+	"fmt"
+	"io"
+)
+
+// New returns an error with the supplied message.
+// New also records the stack trace at the point it was called.
+func New(message string) error {
+	return &fundamental{
+		msg:   message,
+		stack: callers(),
+	}
+}
+
+// Errorf formats according to a format specifier and returns the string
+// as a value that satisfies error.
+// Errorf also records the stack trace at the point it was called.
+func Errorf(format string, args ...interface{}) error {
+	return &fundamental{
+		msg:   fmt.Sprintf(format, args...),
+		stack: callers(),
+	}
+}
+
+// fundamental is an error that has a message and a stack, but no caller.
+type fundamental struct {
+	msg string
+	*stack
+}
+
+func (f *fundamental) Error() string { return f.msg }
+
+func (f *fundamental) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		if s.Flag('+') {
+			io.WriteString(s, f.msg)
+			f.stack.Format(s, verb)
+			return
+		}
+		fallthrough
+	case 's':
+		io.WriteString(s, f.msg)
+	case 'q':
+		fmt.Fprintf(s, "%q", f.msg)
+	}
+}
+
+// WithStack annotates err with a stack trace at the point WithStack was called.
+// If err is nil, WithStack returns nil.
+func WithStack(err error) error {
+	if err == nil {
+		return nil
+	}
+	return &withStack{
+		err,
+		callers(),
+	}
+}
+
+type withStack struct {
+	error
+	*stack
+}
+
+func (w *withStack) Cause() error { return w.error }
+
+// Unwrap provides compatibility for Go 1.13 error chains.
+func (w *withStack) Unwrap() error { return w.error }
+
+func (w *withStack) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		if s.Flag('+') {
+			fmt.Fprintf(s, "%+v", w.Cause())
+			w.stack.Format(s, verb)
+			return
+		}
+		fallthrough
+	case 's':
+		io.WriteString(s, w.Error())
+	case 'q':
+		fmt.Fprintf(s, "%q", w.Error())
+	}
+}
+
+// Wrap returns an error annotating err with a stack trace
+// at the point Wrap is called, and the supplied message.
+// If err is nil, Wrap returns nil.
+func Wrap(err error, message string) error {
+	if err == nil {
+		return nil
+	}
+	err = &withMessage{
+		cause: err,
+		msg:   message,
+	}
+	return &withStack{
+		err,
+		callers(),
+	}
+}
+
+// Wrapf returns an error annotating err with a stack trace
+// at the point Wrapf is called, and the format specifier.
+// If err is nil, Wrapf returns nil.
+func Wrapf(err error, format string, args ...interface{}) error {
+	if err == nil {
+		return nil
+	}
+	err = &withMessage{
+		cause: err,
+		msg:   fmt.Sprintf(format, args...),
+	}
+	return &withStack{
+		err,
+		callers(),
+	}
+}
+
+// WithMessage annotates err with a new message.
+// If err is nil, WithMessage returns nil.
+func WithMessage(err error, message string) error {
+	if err == nil {
+		return nil
+	}
+	return &withMessage{
+		cause: err,
+		msg:   message,
+	}
+}
+
+// WithMessagef annotates err with the format specifier.
+// If err is nil, WithMessagef returns nil.
+func WithMessagef(err error, format string, args ...interface{}) error {
+	if err == nil {
+		return nil
+	}
+	return &withMessage{
+		cause: err,
+		msg:   fmt.Sprintf(format, args...),
+	}
+}
+
+type withMessage struct {
+	cause error
+	msg   string
+}
+
+func (w *withMessage) Error() string { return w.msg + ": " + w.cause.Error() }
+func (w *withMessage) Cause() error  { return w.cause }
+
+// Unwrap provides compatibility for Go 1.13 error chains.
+func (w *withMessage) Unwrap() error { return w.cause }
+
+func (w *withMessage) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		if s.Flag('+') {
+			fmt.Fprintf(s, "%+v\n", w.Cause())
+			io.WriteString(s, w.msg)
+			return
+		}
+		fallthrough
+	case 's', 'q':
+		io.WriteString(s, w.Error())
+	}
+}
+
+// Cause returns the underlying cause of the error, if possible.
+// An error value has a cause if it implements the following
+// interface:
+//
+//     type causer interface {
+//            Cause() error
+//     }
+//
+// If the error does not implement Cause, the original error will
+// be returned. If the error is nil, nil will be returned without further
+// investigation.
+func Cause(err error) error {
+	type causer interface {
+		Cause() error
+	}
+
+	for err != nil {
+		cause, ok := err.(causer)
+		if !ok {
+			break
+		}
+		err = cause.Cause()
+	}
+	return err
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/errors_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/errors_test.go
new file mode 100644
index 00000000000..2089b2f762d
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/errors_test.go
@@ -0,0 +1,251 @@
+package errors
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+	"testing"
+)
+
+func TestNew(t *testing.T) {
+	tests := []struct {
+		err  string
+		want error
+	}{
+		{"", fmt.Errorf("")},
+		{"foo", fmt.Errorf("foo")},
+		{"foo", New("foo")},
+		{"string with format specifiers: %v", errors.New("string with format specifiers: %v")},
+	}
+
+	for _, tt := range tests {
+		got := New(tt.err)
+		if got.Error() != tt.want.Error() {
+			t.Errorf("New.Error(): got: %q, want %q", got, tt.want)
+		}
+	}
+}
+
+func TestWrapNil(t *testing.T) {
+	got := Wrap(nil, "no error")
+	if got != nil {
+		t.Errorf("Wrap(nil, \"no error\"): got %#v, expected nil", got)
+	}
+}
+
+func TestWrap(t *testing.T) {
+	tests := []struct {
+		err     error
+		message string
+		want    string
+	}{
+		{io.EOF, "read error", "read error: EOF"},
+		{Wrap(io.EOF, "read error"), "client error", "client error: read error: EOF"},
+	}
+
+	for _, tt := range tests {
+		got := Wrap(tt.err, tt.message).Error()
+		if got != tt.want {
+			t.Errorf("Wrap(%v, %q): got: %v, want %v", tt.err, tt.message, got, tt.want)
+		}
+	}
+}
+
+type nilError struct{}
+
+func (nilError) Error() string { return "nil error" }
+
+func TestCause(t *testing.T) {
+	x := New("error")
+	tests := []struct {
+		err  error
+		want error
+	}{{
+		// nil error is nil
+		err:  nil,
+		want: nil,
+	}, {
+		// explicit nil error is nil
+		err:  (error)(nil),
+		want: nil,
+	}, {
+		// typed nil is nil
+		err:  (*nilError)(nil),
+		want: (*nilError)(nil),
+	}, {
+		// uncaused error is unaffected
+		err:  io.EOF,
+		want: io.EOF,
+	}, {
+		// caused error returns cause
+		err:  Wrap(io.EOF, "ignored"),
+		want: io.EOF,
+	}, {
+		err:  x, // return from errors.New
+		want: x,
+	}, {
+		WithMessage(nil, "whoops"),
+		nil,
+	}, {
+		WithMessage(io.EOF, "whoops"),
+		io.EOF,
+	}, {
+		WithStack(nil),
+		nil,
+	}, {
+		WithStack(io.EOF),
+		io.EOF,
+	}}
+
+	for i, tt := range tests {
+		got := Cause(tt.err)
+		if !reflect.DeepEqual(got, tt.want) {
+			t.Errorf("test %d: got %#v, want %#v", i+1, got, tt.want)
+		}
+	}
+}
+
+func TestWrapfNil(t *testing.T) {
+	got := Wrapf(nil, "no error")
+	if got != nil {
+		t.Errorf("Wrapf(nil, \"no error\"): got %#v, expected nil", got)
+	}
+}
+
+func TestWrapf(t *testing.T) {
+	tests := []struct {
+		err     error
+		message string
+		want    string
+	}{
+		{io.EOF, "read error", "read error: EOF"},
+		{Wrapf(io.EOF, "read error without format specifiers"), "client error", "client error: read error without format specifiers: EOF"},
+		{Wrapf(io.EOF, "read error with %d format specifier", 1), "client error", "client error: read error with 1 format specifier: EOF"},
+	}
+
+	for _, tt := range tests {
+		got := Wrapf(tt.err, tt.message).Error()
+		if got != tt.want {
+			t.Errorf("Wrapf(%v, %q): got: %v, want %v", tt.err, tt.message, got, tt.want)
+		}
+	}
+}
+
+func TestErrorf(t *testing.T) {
+	tests := []struct {
+		err  error
+		want string
+	}{
+		{Errorf("read error without format specifiers"), "read error without format specifiers"},
+		{Errorf("read error with %d format specifier", 1), "read error with 1 format specifier"},
+	}
+
+	for _, tt := range tests {
+		got := tt.err.Error()
+		if got != tt.want {
+			t.Errorf("Errorf(%v): got: %q, want %q", tt.err, got, tt.want)
+		}
+	}
+}
+
+func TestWithStackNil(t *testing.T) {
+	got := WithStack(nil)
+	if got != nil {
+		t.Errorf("WithStack(nil): got %#v, expected nil", got)
+	}
+}
+
+func TestWithStack(t *testing.T) {
+	tests := []struct {
+		err  error
+		want string
+	}{
+		{io.EOF, "EOF"},
+		{WithStack(io.EOF), "EOF"},
+	}
+
+	for _, tt := range tests {
+		got := WithStack(tt.err).Error()
+		if got != tt.want {
+			t.Errorf("WithStack(%v): got: %v, want %v", tt.err, got, tt.want)
+		}
+	}
+}
+
+func TestWithMessageNil(t *testing.T) {
+	got := WithMessage(nil, "no error")
+	if got != nil {
+		t.Errorf("WithMessage(nil, \"no error\"): got %#v, expected nil", got)
+	}
+}
+
+func TestWithMessage(t *testing.T) {
+	tests := []struct {
+		err     error
+		message string
+		want    string
+	}{
+		{io.EOF, "read error", "read error: EOF"},
+		{WithMessage(io.EOF, "read error"), "client error", "client error: read error: EOF"},
+	}
+
+	for _, tt := range tests {
+		got := WithMessage(tt.err, tt.message).Error()
+		if got != tt.want {
+			t.Errorf("WithMessage(%v, %q): got: %q, want %q", tt.err, tt.message, got, tt.want)
+		}
+	}
+}
+
+func TestWithMessagefNil(t *testing.T) {
+	got := WithMessagef(nil, "no error")
+	if got != nil {
+		t.Errorf("WithMessage(nil, \"no error\"): got %#v, expected nil", got)
+	}
+}
+
+func TestWithMessagef(t *testing.T) {
+	tests := []struct {
+		err     error
+		message string
+		want    string
+	}{
+		{io.EOF, "read error", "read error: EOF"},
+		{WithMessagef(io.EOF, "read error without format specifier"), "client error", "client error: read error without format specifier: EOF"},
+		{WithMessagef(io.EOF, "read error with %d format specifier", 1), "client error", "client error: read error with 1 format specifier: EOF"},
+	}
+
+	for _, tt := range tests {
+		got := WithMessagef(tt.err, tt.message).Error()
+		if got != tt.want {
+			t.Errorf("WithMessage(%v, %q): got: %q, want %q", tt.err, tt.message, got, tt.want)
+		}
+	}
+}
+
+// errors.New, etc values are not expected to be compared by value
+// but the change in errors#27 made them incomparable. Assert that
+// various kinds of errors have a functional equality operator, even
+// if the result of that equality is always false.
+func TestErrorEquality(t *testing.T) {
+	vals := []error{
+		nil,
+		io.EOF,
+		errors.New("EOF"),
+		New("EOF"),
+		Errorf("EOF"),
+		Wrap(io.EOF, "EOF"),
+		Wrapf(io.EOF, "EOF%d", 2),
+		WithMessage(nil, "whoops"),
+		WithMessage(io.EOF, "whoops"),
+		WithStack(io.EOF),
+		WithStack(nil),
+	}
+
+	for i := range vals {
+		for j := range vals {
+			_ = vals[i] == vals[j] // mustn't panic
+		}
+	}
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/example_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/example_test.go
new file mode 100644
index 00000000000..7d0e286f4bb
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/example_test.go
@@ -0,0 +1,205 @@
+package errors_test
+
+import (
+	"fmt"
+
+	"github.com/pkg/errors"
+)
+
+func ExampleNew() {
+	err := errors.New("whoops")
+	fmt.Println(err)
+
+	// Output: whoops
+}
+
+func ExampleNew_printf() {
+	err := errors.New("whoops")
+	fmt.Printf("%+v", err)
+
+	// Example output:
+	// whoops
+	// github.com/pkg/errors_test.ExampleNew_printf
+	//         /home/dfc/src/github.com/pkg/errors/example_test.go:17
+	// testing.runExample
+	//         /home/dfc/go/src/testing/example.go:114
+	// testing.RunExamples
+	//         /home/dfc/go/src/testing/example.go:38
+	// testing.(*M).Run
+	//         /home/dfc/go/src/testing/testing.go:744
+	// main.main
+	//         /github.com/pkg/errors/_test/_testmain.go:106
+	// runtime.main
+	//         /home/dfc/go/src/runtime/proc.go:183
+	// runtime.goexit
+	//         /home/dfc/go/src/runtime/asm_amd64.s:2059
+}
+
+func ExampleWithMessage() {
+	cause := errors.New("whoops")
+	err := errors.WithMessage(cause, "oh noes")
+	fmt.Println(err)
+
+	// Output: oh noes: whoops
+}
+
+func ExampleWithStack() {
+	cause := errors.New("whoops")
+	err := errors.WithStack(cause)
+	fmt.Println(err)
+
+	// Output: whoops
+}
+
+func ExampleWithStack_printf() {
+	cause := errors.New("whoops")
+	err := errors.WithStack(cause)
+	fmt.Printf("%+v", err)
+
+	// Example Output:
+	// whoops
+	// github.com/pkg/errors_test.ExampleWithStack_printf
+	//         /home/fabstu/go/src/github.com/pkg/errors/example_test.go:55
+	// testing.runExample
+	//         /usr/lib/go/src/testing/example.go:114
+	// testing.RunExamples
+	//         /usr/lib/go/src/testing/example.go:38
+	// testing.(*M).Run
+	//         /usr/lib/go/src/testing/testing.go:744
+	// main.main
+	//         github.com/pkg/errors/_test/_testmain.go:106
+	// runtime.main
+	//         /usr/lib/go/src/runtime/proc.go:183
+	// runtime.goexit
+	//         /usr/lib/go/src/runtime/asm_amd64.s:2086
+	// github.com/pkg/errors_test.ExampleWithStack_printf
+	//         /home/fabstu/go/src/github.com/pkg/errors/example_test.go:56
+	// testing.runExample
+	//         /usr/lib/go/src/testing/example.go:114
+	// testing.RunExamples
+	//         /usr/lib/go/src/testing/example.go:38
+	// testing.(*M).Run
+	//         /usr/lib/go/src/testing/testing.go:744
+	// main.main
+	//         github.com/pkg/errors/_test/_testmain.go:106
+	// runtime.main
+	//         /usr/lib/go/src/runtime/proc.go:183
+	// runtime.goexit
+	//         /usr/lib/go/src/runtime/asm_amd64.s:2086
+}
+
+func ExampleWrap() {
+	cause := errors.New("whoops")
+	err := errors.Wrap(cause, "oh noes")
+	fmt.Println(err)
+
+	// Output: oh noes: whoops
+}
+
+func fn() error {
+	e1 := errors.New("error")
+	e2 := errors.Wrap(e1, "inner")
+	e3 := errors.Wrap(e2, "middle")
+	return errors.Wrap(e3, "outer")
+}
+
+func ExampleCause() {
+	err := fn()
+	fmt.Println(err)
+	fmt.Println(errors.Cause(err))
+
+	// Output: outer: middle: inner: error
+	// error
+}
+
+func ExampleWrap_extended() {
+	err := fn()
+	fmt.Printf("%+v\n", err)
+
+	// Example output:
+	// error
+	// github.com/pkg/errors_test.fn
+	//         /home/dfc/src/github.com/pkg/errors/example_test.go:47
+	// github.com/pkg/errors_test.ExampleCause_printf
+	//         /home/dfc/src/github.com/pkg/errors/example_test.go:63
+	// testing.runExample
+	//         /home/dfc/go/src/testing/example.go:114
+	// testing.RunExamples
+	//         /home/dfc/go/src/testing/example.go:38
+	// testing.(*M).Run
+	//         /home/dfc/go/src/testing/testing.go:744
+	// main.main
+	//         /github.com/pkg/errors/_test/_testmain.go:104
+	// runtime.main
+	//         /home/dfc/go/src/runtime/proc.go:183
+	// runtime.goexit
+	//         /home/dfc/go/src/runtime/asm_amd64.s:2059
+	// github.com/pkg/errors_test.fn
+	// 	  /home/dfc/src/github.com/pkg/errors/example_test.go:48: inner
+	// github.com/pkg/errors_test.fn
+	//        /home/dfc/src/github.com/pkg/errors/example_test.go:49: middle
+	// github.com/pkg/errors_test.fn
+	//      /home/dfc/src/github.com/pkg/errors/example_test.go:50: outer
+}
+
+func ExampleWrapf() {
+	cause := errors.New("whoops")
+	err := errors.Wrapf(cause, "oh noes #%d", 2)
+	fmt.Println(err)
+
+	// Output: oh noes #2: whoops
+}
+
+func ExampleErrorf_extended() {
+	err := errors.Errorf("whoops: %s", "foo")
+	fmt.Printf("%+v", err)
+
+	// Example output:
+	// whoops: foo
+	// github.com/pkg/errors_test.ExampleErrorf
+	//         /home/dfc/src/github.com/pkg/errors/example_test.go:101
+	// testing.runExample
+	//         /home/dfc/go/src/testing/example.go:114
+	// testing.RunExamples
+	//         /home/dfc/go/src/testing/example.go:38
+	// testing.(*M).Run
+	//         /home/dfc/go/src/testing/testing.go:744
+	// main.main
+	//         /github.com/pkg/errors/_test/_testmain.go:102
+	// runtime.main
+	//         /home/dfc/go/src/runtime/proc.go:183
+	// runtime.goexit
+	//         /home/dfc/go/src/runtime/asm_amd64.s:2059
+}
+
+func Example_stackTrace() {
+	type stackTracer interface {
+		StackTrace() errors.StackTrace
+	}
+
+	err, ok := errors.Cause(fn()).(stackTracer)
+	if !ok {
+		panic("oops, err does not implement stackTracer")
+	}
+
+	st := err.StackTrace()
+	fmt.Printf("%+v", st[0:2]) // top two frames
+
+	// Example output:
+	// github.com/pkg/errors_test.fn
+	//	/home/dfc/src/github.com/pkg/errors/example_test.go:47
+	// github.com/pkg/errors_test.Example_stackTrace
+	//	/home/dfc/src/github.com/pkg/errors/example_test.go:127
+}
+
+func ExampleCause_printf() {
+	err := errors.Wrap(func() error {
+		return func() error {
+			return errors.New("hello world")
+		}()
+	}(), "failed")
+
+	fmt.Printf("%v", err)
+
+	// Output: failed: hello world
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/format_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/format_test.go
new file mode 100644
index 00000000000..cb1df821fcf
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/format_test.go
@@ -0,0 +1,560 @@
+package errors
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+func TestFormatNew(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   string
+	}{{
+		New("error"),
+		"%s",
+		"error",
+	}, {
+		New("error"),
+		"%v",
+		"error",
+	}, {
+		New("error"),
+		"%+v",
+		"error\n" +
+			"github.com/pkg/errors.TestFormatNew\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:26",
+	}, {
+		New("error"),
+		"%q",
+		`"error"`,
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.error, tt.format, tt.want)
+	}
+}
+
+func TestFormatErrorf(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   string
+	}{{
+		Errorf("%s", "error"),
+		"%s",
+		"error",
+	}, {
+		Errorf("%s", "error"),
+		"%v",
+		"error",
+	}, {
+		Errorf("%s", "error"),
+		"%+v",
+		"error\n" +
+			"github.com/pkg/errors.TestFormatErrorf\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:56",
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.error, tt.format, tt.want)
+	}
+}
+
+func TestFormatWrap(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   string
+	}{{
+		Wrap(New("error"), "error2"),
+		"%s",
+		"error2: error",
+	}, {
+		Wrap(New("error"), "error2"),
+		"%v",
+		"error2: error",
+	}, {
+		Wrap(New("error"), "error2"),
+		"%+v",
+		"error\n" +
+			"github.com/pkg/errors.TestFormatWrap\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:82",
+	}, {
+		Wrap(io.EOF, "error"),
+		"%s",
+		"error: EOF",
+	}, {
+		Wrap(io.EOF, "error"),
+		"%v",
+		"error: EOF",
+	}, {
+		Wrap(io.EOF, "error"),
+		"%+v",
+		"EOF\n" +
+			"error\n" +
+			"github.com/pkg/errors.TestFormatWrap\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:96",
+	}, {
+		Wrap(Wrap(io.EOF, "error1"), "error2"),
+		"%+v",
+		"EOF\n" +
+			"error1\n" +
+			"github.com/pkg/errors.TestFormatWrap\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:103\n",
+	}, {
+		Wrap(New("error with space"), "context"),
+		"%q",
+		`"context: error with space"`,
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.error, tt.format, tt.want)
+	}
+}
+
+func TestFormatWrapf(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   string
+	}{{
+		Wrapf(io.EOF, "error%d", 2),
+		"%s",
+		"error2: EOF",
+	}, {
+		Wrapf(io.EOF, "error%d", 2),
+		"%v",
+		"error2: EOF",
+	}, {
+		Wrapf(io.EOF, "error%d", 2),
+		"%+v",
+		"EOF\n" +
+			"error2\n" +
+			"github.com/pkg/errors.TestFormatWrapf\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:134",
+	}, {
+		Wrapf(New("error"), "error%d", 2),
+		"%s",
+		"error2: error",
+	}, {
+		Wrapf(New("error"), "error%d", 2),
+		"%v",
+		"error2: error",
+	}, {
+		Wrapf(New("error"), "error%d", 2),
+		"%+v",
+		"error\n" +
+			"github.com/pkg/errors.TestFormatWrapf\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:149",
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.error, tt.format, tt.want)
+	}
+}
+
+func TestFormatWithStack(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   []string
+	}{{
+		WithStack(io.EOF),
+		"%s",
+		[]string{"EOF"},
+	}, {
+		WithStack(io.EOF),
+		"%v",
+		[]string{"EOF"},
+	}, {
+		WithStack(io.EOF),
+		"%+v",
+		[]string{"EOF",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:175"},
+	}, {
+		WithStack(New("error")),
+		"%s",
+		[]string{"error"},
+	}, {
+		WithStack(New("error")),
+		"%v",
+		[]string{"error"},
+	}, {
+		WithStack(New("error")),
+		"%+v",
+		[]string{"error",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:189",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:189"},
+	}, {
+		WithStack(WithStack(io.EOF)),
+		"%+v",
+		[]string{"EOF",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:197",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:197"},
+	}, {
+		WithStack(WithStack(Wrapf(io.EOF, "message"))),
+		"%+v",
+		[]string{"EOF",
+			"message",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:205",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:205",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:205"},
+	}, {
+		WithStack(Errorf("error%d", 1)),
+		"%+v",
+		[]string{"error1",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:216",
+			"github.com/pkg/errors.TestFormatWithStack\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:216"},
+	}}
+
+	for i, tt := range tests {
+		testFormatCompleteCompare(t, i, tt.error, tt.format, tt.want, true)
+	}
+}
+
+func TestFormatWithMessage(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   []string
+	}{{
+		WithMessage(New("error"), "error2"),
+		"%s",
+		[]string{"error2: error"},
+	}, {
+		WithMessage(New("error"), "error2"),
+		"%v",
+		[]string{"error2: error"},
+	}, {
+		WithMessage(New("error"), "error2"),
+		"%+v",
+		[]string{
+			"error",
+			"github.com/pkg/errors.TestFormatWithMessage\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:244",
+			"error2"},
+	}, {
+		WithMessage(io.EOF, "addition1"),
+		"%s",
+		[]string{"addition1: EOF"},
+	}, {
+		WithMessage(io.EOF, "addition1"),
+		"%v",
+		[]string{"addition1: EOF"},
+	}, {
+		WithMessage(io.EOF, "addition1"),
+		"%+v",
+		[]string{"EOF", "addition1"},
+	}, {
+		WithMessage(WithMessage(io.EOF, "addition1"), "addition2"),
+		"%v",
+		[]string{"addition2: addition1: EOF"},
+	}, {
+		WithMessage(WithMessage(io.EOF, "addition1"), "addition2"),
+		"%+v",
+		[]string{"EOF", "addition1", "addition2"},
+	}, {
+		Wrap(WithMessage(io.EOF, "error1"), "error2"),
+		"%+v",
+		[]string{"EOF", "error1", "error2",
+			"github.com/pkg/errors.TestFormatWithMessage\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:272"},
+	}, {
+		WithMessage(Errorf("error%d", 1), "error2"),
+		"%+v",
+		[]string{"error1",
+			"github.com/pkg/errors.TestFormatWithMessage\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:278",
+			"error2"},
+	}, {
+		WithMessage(WithStack(io.EOF), "error"),
+		"%+v",
+		[]string{
+			"EOF",
+			"github.com/pkg/errors.TestFormatWithMessage\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:285",
+			"error"},
+	}, {
+		WithMessage(Wrap(WithStack(io.EOF), "inside-error"), "outside-error"),
+		"%+v",
+		[]string{
+			"EOF",
+			"github.com/pkg/errors.TestFormatWithMessage\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:293",
+			"inside-error",
+			"github.com/pkg/errors.TestFormatWithMessage\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:293",
+			"outside-error"},
+	}}
+
+	for i, tt := range tests {
+		testFormatCompleteCompare(t, i, tt.error, tt.format, tt.want, true)
+	}
+}
+
+func TestFormatGeneric(t *testing.T) {
+	starts := []struct {
+		err  error
+		want []string
+	}{
+		{New("new-error"), []string{
+			"new-error",
+			"github.com/pkg/errors.TestFormatGeneric\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:315"},
+		}, {Errorf("errorf-error"), []string{
+			"errorf-error",
+			"github.com/pkg/errors.TestFormatGeneric\n" +
+				"\t.+/github.com/pkg/errors/format_test.go:319"},
+		}, {errors.New("errors-new-error"), []string{
+			"errors-new-error"},
+		},
+	}
+
+	wrappers := []wrapper{
+		{
+			func(err error) error { return WithMessage(err, "with-message") },
+			[]string{"with-message"},
+		}, {
+			func(err error) error { return WithStack(err) },
+			[]string{
+				"github.com/pkg/errors.(func·002|TestFormatGeneric.func2)\n\t" +
+					".+/github.com/pkg/errors/format_test.go:333",
+			},
+		}, {
+			func(err error) error { return Wrap(err, "wrap-error") },
+			[]string{
+				"wrap-error",
+				"github.com/pkg/errors.(func·003|TestFormatGeneric.func3)\n\t" +
+					".+/github.com/pkg/errors/format_test.go:339",
+			},
+		}, {
+			func(err error) error { return Wrapf(err, "wrapf-error%d", 1) },
+			[]string{
+				"wrapf-error1",
+				"github.com/pkg/errors.(func·004|TestFormatGeneric.func4)\n\t" +
+					".+/github.com/pkg/errors/format_test.go:346",
+			},
+		},
+	}
+
+	for s := range starts {
+		err := starts[s].err
+		want := starts[s].want
+		testFormatCompleteCompare(t, s, err, "%+v", want, false)
+		testGenericRecursive(t, err, want, wrappers, 3)
+	}
+}
+
+func wrappedNew(message string) error { // This function will be mid-stack inlined in go 1.12+
+	return New(message)
+}
+
+func TestFormatWrappedNew(t *testing.T) {
+	tests := []struct {
+		error
+		format string
+		want   string
+	}{{
+		wrappedNew("error"),
+		"%+v",
+		"error\n" +
+			"github.com/pkg/errors.wrappedNew\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:364\n" +
+			"github.com/pkg/errors.TestFormatWrappedNew\n" +
+			"\t.+/github.com/pkg/errors/format_test.go:373",
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.error, tt.format, tt.want)
+	}
+}
+
+func testFormatRegexp(t *testing.T, n int, arg interface{}, format, want string) {
+	t.Helper()
+	got := fmt.Sprintf(format, arg)
+	gotLines := strings.SplitN(got, "\n", -1)
+	wantLines := strings.SplitN(want, "\n", -1)
+
+	if len(wantLines) > len(gotLines) {
+		t.Errorf("test %d: wantLines(%d) > gotLines(%d):\n got: %q\nwant: %q", n+1, len(wantLines), len(gotLines), got, want)
+		return
+	}
+
+	for i, w := range wantLines {
+		match, err := regexp.MatchString(w, gotLines[i])
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !match {
+			t.Errorf("test %d: line %d: fmt.Sprintf(%q, err):\n got: %q\nwant: %q", n+1, i+1, format, got, want)
+		}
+	}
+}
+
+var stackLineR = regexp.MustCompile(`\.`)
+
+// parseBlocks parses input into a slice, where:
+//  - incase entry contains a newline, its a stacktrace
+//  - incase entry contains no newline, its a solo line.
+//
+// Detecting stack boundaries only works incase the WithStack-calls are
+// to be found on the same line, thats why it is optionally here.
+//
+// Example use:
+//
+// for _, e := range blocks {
+//   if strings.ContainsAny(e, "\n") {
+//     // Match as stack
+//   } else {
+//     // Match as line
+//   }
+// }
+//
+func parseBlocks(input string, detectStackboundaries bool) ([]string, error) {
+	var blocks []string
+
+	stack := ""
+	wasStack := false
+	lines := map[string]bool{} // already found lines
+
+	for _, l := range strings.Split(input, "\n") {
+		isStackLine := stackLineR.MatchString(l)
+
+		switch {
+		case !isStackLine && wasStack:
+			blocks = append(blocks, stack, l)
+			stack = ""
+			lines = map[string]bool{}
+		case isStackLine:
+			if wasStack {
+				// Detecting two stacks after another, possible cause lines match in
+				// our tests due to WithStack(WithStack(io.EOF)) on same line.
+				if detectStackboundaries {
+					if lines[l] {
+						if len(stack) == 0 {
+							return nil, errors.New("len of block must not be zero here")
+						}
+
+						blocks = append(blocks, stack)
+						stack = l
+						lines = map[string]bool{l: true}
+						continue
+					}
+				}
+
+				stack = stack + "\n" + l
+			} else {
+				stack = l
+			}
+			lines[l] = true
+		case !isStackLine && !wasStack:
+			blocks = append(blocks, l)
+		default:
+			return nil, errors.New("must not happen")
+		}
+
+		wasStack = isStackLine
+	}
+
+	// Use up stack
+	if stack != "" {
+		blocks = append(blocks, stack)
+	}
+	return blocks, nil
+}
+
+func testFormatCompleteCompare(t *testing.T, n int, arg interface{}, format string, want []string, detectStackBoundaries bool) {
+	gotStr := fmt.Sprintf(format, arg)
+
+	got, err := parseBlocks(gotStr, detectStackBoundaries)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(got) != len(want) {
+		t.Fatalf("test %d: fmt.Sprintf(%s, err) -> wrong number of blocks: got(%d) want(%d)\n got: %s\nwant: %s\ngotStr: %q",
+			n+1, format, len(got), len(want), prettyBlocks(got), prettyBlocks(want), gotStr)
+	}
+
+	for i := range got {
+		if strings.ContainsAny(want[i], "\n") {
+			// Match as stack
+			match, err := regexp.MatchString(want[i], got[i])
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !match {
+				t.Fatalf("test %d: block %d: fmt.Sprintf(%q, err):\ngot:\n%q\nwant:\n%q\nall-got:\n%s\nall-want:\n%s\n",
+					n+1, i+1, format, got[i], want[i], prettyBlocks(got), prettyBlocks(want))
+			}
+		} else {
+			// Match as message
+			if got[i] != want[i] {
+				t.Fatalf("test %d: fmt.Sprintf(%s, err) at block %d got != want:\n got: %q\nwant: %q", n+1, format, i+1, got[i], want[i])
+			}
+		}
+	}
+}
+
+type wrapper struct {
+	wrap func(err error) error
+	want []string
+}
+
+func prettyBlocks(blocks []string) string {
+	var out []string
+
+	for _, b := range blocks {
+		out = append(out, fmt.Sprintf("%v", b))
+	}
+
+	return "   " + strings.Join(out, "\n   ")
+}
+
+func testGenericRecursive(t *testing.T, beforeErr error, beforeWant []string, list []wrapper, maxDepth int) {
+	if len(beforeWant) == 0 {
+		panic("beforeWant must not be empty")
+	}
+	for _, w := range list {
+		if len(w.want) == 0 {
+			panic("want must not be empty")
+		}
+
+		err := w.wrap(beforeErr)
+
+		// Copy required cause append(beforeWant, ..) modified beforeWant subtly.
+		beforeCopy := make([]string, len(beforeWant))
+		copy(beforeCopy, beforeWant)
+
+		beforeWant := beforeCopy
+		last := len(beforeWant) - 1
+		var want []string
+
+		// Merge two stacks behind each other.
+		if strings.ContainsAny(beforeWant[last], "\n") && strings.ContainsAny(w.want[0], "\n") {
+			want = append(beforeWant[:last], append([]string{beforeWant[last] + "((?s).*)" + w.want[0]}, w.want[1:]...)...)
+		} else {
+			want = append(beforeWant, w.want...)
+		}
+
+		testFormatCompleteCompare(t, maxDepth, err, "%+v", want, false)
+		if maxDepth > 0 {
+			testGenericRecursive(t, err, want, list, maxDepth-1)
+		}
+	}
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/go113.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/go113.go
new file mode 100644
index 00000000000..be0d10d0c79
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/go113.go
@@ -0,0 +1,38 @@
+// +build go1.13
+
+package errors
+
+import (
+	stderrors "errors"
+)
+
+// Is reports whether any error in err's chain matches target.
+//
+// The chain consists of err itself followed by the sequence of errors obtained by
+// repeatedly calling Unwrap.
+//
+// An error is considered to match a target if it is equal to that target or if
+// it implements a method Is(error) bool such that Is(target) returns true.
+func Is(err, target error) bool { return stderrors.Is(err, target) }
+
+// As finds the first error in err's chain that matches target, and if so, sets
+// target to that error value and returns true.
+//
+// The chain consists of err itself followed by the sequence of errors obtained by
+// repeatedly calling Unwrap.
+//
+// An error matches target if the error's concrete value is assignable to the value
+// pointed to by target, or if the error has a method As(interface{}) bool such that
+// As(target) returns true. In the latter case, the As method is responsible for
+// setting target.
+//
+// As will panic if target is not a non-nil pointer to either a type that implements
+// error, or to any interface type. As returns false if err is nil.
+func As(err error, target interface{}) bool { return stderrors.As(err, target) }
+
+// Unwrap returns the result of calling the Unwrap method on err, if err's
+// type contains an Unwrap method returning error.
+// Otherwise, Unwrap returns nil.
+func Unwrap(err error) error {
+	return stderrors.Unwrap(err)
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/go113_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/go113_test.go
new file mode 100644
index 00000000000..4ea37e61975
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/go113_test.go
@@ -0,0 +1,178 @@
+// +build go1.13
+
+package errors
+
+import (
+	stderrors "errors"
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+func TestErrorChainCompat(t *testing.T) {
+	err := stderrors.New("error that gets wrapped")
+	wrapped := Wrap(err, "wrapped up")
+	if !stderrors.Is(wrapped, err) {
+		t.Errorf("Wrap does not support Go 1.13 error chains")
+	}
+}
+
+func TestIs(t *testing.T) {
+	err := New("test")
+
+	type args struct {
+		err    error
+		target error
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			name: "with stack",
+			args: args{
+				err:    WithStack(err),
+				target: err,
+			},
+			want: true,
+		},
+		{
+			name: "with message",
+			args: args{
+				err:    WithMessage(err, "test"),
+				target: err,
+			},
+			want: true,
+		},
+		{
+			name: "with message format",
+			args: args{
+				err:    WithMessagef(err, "%s", "test"),
+				target: err,
+			},
+			want: true,
+		},
+		{
+			name: "std errors compatibility",
+			args: args{
+				err:    fmt.Errorf("wrap it: %w", err),
+				target: err,
+			},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Is(tt.args.err, tt.args.target); got != tt.want {
+				t.Errorf("Is() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+type customErr struct {
+	msg string
+}
+
+func (c customErr) Error() string { return c.msg }
+
+func TestAs(t *testing.T) {
+	var err = customErr{msg: "test message"}
+
+	type args struct {
+		err    error
+		target interface{}
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			name: "with stack",
+			args: args{
+				err:    WithStack(err),
+				target: new(customErr),
+			},
+			want: true,
+		},
+		{
+			name: "with message",
+			args: args{
+				err:    WithMessage(err, "test"),
+				target: new(customErr),
+			},
+			want: true,
+		},
+		{
+			name: "with message format",
+			args: args{
+				err:    WithMessagef(err, "%s", "test"),
+				target: new(customErr),
+			},
+			want: true,
+		},
+		{
+			name: "std errors compatibility",
+			args: args{
+				err:    fmt.Errorf("wrap it: %w", err),
+				target: new(customErr),
+			},
+			want: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := As(tt.args.err, tt.args.target); got != tt.want {
+				t.Errorf("As() = %v, want %v", got, tt.want)
+			}
+
+			ce := tt.args.target.(*customErr)
+			if !reflect.DeepEqual(err, *ce) {
+				t.Errorf("set target error failed, target error is %v", *ce)
+			}
+		})
+	}
+}
+
+func TestUnwrap(t *testing.T) {
+	err := New("test")
+
+	type args struct {
+		err error
+	}
+	tests := []struct {
+		name string
+		args args
+		want error
+	}{
+		{
+			name: "with stack",
+			args: args{err: WithStack(err)},
+			want: err,
+		},
+		{
+			name: "with message",
+			args: args{err: WithMessage(err, "test")},
+			want: err,
+		},
+		{
+			name: "with message format",
+			args: args{err: WithMessagef(err, "%s", "test")},
+			want: err,
+		},
+		{
+			name: "std errors compatibility",
+			args: args{err: fmt.Errorf("wrap: %w", err)},
+			want: err,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := Unwrap(tt.args.err); !reflect.DeepEqual(err, tt.want) {
+				t.Errorf("Unwrap() error = %v, want %v", err, tt.want)
+			}
+		})
+	}
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/json_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/json_test.go
new file mode 100644
index 00000000000..ad1adec9c81
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/json_test.go
@@ -0,0 +1,51 @@
+package errors
+
+import (
+	"encoding/json"
+	"regexp"
+	"testing"
+)
+
+func TestFrameMarshalText(t *testing.T) {
+	var tests = []struct {
+		Frame
+		want string
+	}{{
+		initpc,
+		`^github.com/pkg/errors\.init(\.ializers)? .+/github\.com/pkg/errors/stack_test.go:\d+$`,
+	}, {
+		0,
+		`^unknown$`,
+	}}
+	for i, tt := range tests {
+		got, err := tt.Frame.MarshalText()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !regexp.MustCompile(tt.want).Match(got) {
+			t.Errorf("test %d: MarshalJSON:\n got %q\n want %q", i+1, string(got), tt.want)
+		}
+	}
+}
+
+func TestFrameMarshalJSON(t *testing.T) {
+	var tests = []struct {
+		Frame
+		want string
+	}{{
+		initpc,
+		`^"github\.com/pkg/errors\.init(\.ializers)? .+/github\.com/pkg/errors/stack_test.go:\d+"$`,
+	}, {
+		0,
+		`^"unknown"$`,
+	}}
+	for i, tt := range tests {
+		got, err := json.Marshal(tt.Frame)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !regexp.MustCompile(tt.want).Match(got) {
+			t.Errorf("test %d: MarshalJSON:\n got %q\n want %q", i+1, string(got), tt.want)
+		}
+	}
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/stack.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/stack.go
new file mode 100644
index 00000000000..779a8348fb9
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/stack.go
@@ -0,0 +1,177 @@
+package errors
+
+import (
+	"fmt"
+	"io"
+	"path"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+// Frame represents a program counter inside a stack frame.
+// For historical reasons if Frame is interpreted as a uintptr
+// its value represents the program counter + 1.
+type Frame uintptr
+
+// pc returns the program counter for this frame;
+// multiple frames may have the same PC value.
+func (f Frame) pc() uintptr { return uintptr(f) - 1 }
+
+// file returns the full path to the file that contains the
+// function for this Frame's pc.
+func (f Frame) file() string {
+	fn := runtime.FuncForPC(f.pc())
+	if fn == nil {
+		return "unknown"
+	}
+	file, _ := fn.FileLine(f.pc())
+	return file
+}
+
+// line returns the line number of source code of the
+// function for this Frame's pc.
+func (f Frame) line() int {
+	fn := runtime.FuncForPC(f.pc())
+	if fn == nil {
+		return 0
+	}
+	_, line := fn.FileLine(f.pc())
+	return line
+}
+
+// name returns the name of this function, if known.
+func (f Frame) name() string {
+	fn := runtime.FuncForPC(f.pc())
+	if fn == nil {
+		return "unknown"
+	}
+	return fn.Name()
+}
+
+// Format formats the frame according to the fmt.Formatter interface.
+//
+//    %s    source file
+//    %d    source line
+//    %n    function name
+//    %v    equivalent to %s:%d
+//
+// Format accepts flags that alter the printing of some verbs, as follows:
+//
+//    %+s   function name and path of source file relative to the compile time
+//          GOPATH separated by \n\t (<funcname>\n\t<path>)
+//    %+v   equivalent to %+s:%d
+func (f Frame) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 's':
+		switch {
+		case s.Flag('+'):
+			io.WriteString(s, f.name())
+			io.WriteString(s, "\n\t")
+			io.WriteString(s, f.file())
+		default:
+			io.WriteString(s, path.Base(f.file()))
+		}
+	case 'd':
+		io.WriteString(s, strconv.Itoa(f.line()))
+	case 'n':
+		io.WriteString(s, funcname(f.name()))
+	case 'v':
+		f.Format(s, 's')
+		io.WriteString(s, ":")
+		f.Format(s, 'd')
+	}
+}
+
+// MarshalText formats a stacktrace Frame as a text string. The output is the
+// same as that of fmt.Sprintf("%+v", f), but without newlines or tabs.
+func (f Frame) MarshalText() ([]byte, error) {
+	name := f.name()
+	if name == "unknown" {
+		return []byte(name), nil
+	}
+	return []byte(fmt.Sprintf("%s %s:%d", name, f.file(), f.line())), nil
+}
+
+// StackTrace is stack of Frames from innermost (newest) to outermost (oldest).
+type StackTrace []Frame
+
+// Format formats the stack of Frames according to the fmt.Formatter interface.
+//
+//    %s	lists source files for each Frame in the stack
+//    %v	lists the source file and line number for each Frame in the stack
+//
+// Format accepts flags that alter the printing of some verbs, as follows:
+//
+//    %+v   Prints filename, function, and line number for each Frame in the stack.
+func (st StackTrace) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		switch {
+		case s.Flag('+'):
+			for _, f := range st {
+				io.WriteString(s, "\n")
+				f.Format(s, verb)
+			}
+		case s.Flag('#'):
+			fmt.Fprintf(s, "%#v", []Frame(st))
+		default:
+			st.formatSlice(s, verb)
+		}
+	case 's':
+		st.formatSlice(s, verb)
+	}
+}
+
+// formatSlice will format this StackTrace into the given buffer as a slice of
+// Frame, only valid when called with '%s' or '%v'.
+func (st StackTrace) formatSlice(s fmt.State, verb rune) {
+	io.WriteString(s, "[")
+	for i, f := range st {
+		if i > 0 {
+			io.WriteString(s, " ")
+		}
+		f.Format(s, verb)
+	}
+	io.WriteString(s, "]")
+}
+
+// stack represents a stack of program counters.
+type stack []uintptr
+
+func (s *stack) Format(st fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		switch {
+		case st.Flag('+'):
+			for _, pc := range *s {
+				f := Frame(pc)
+				fmt.Fprintf(st, "\n%+v", f)
+			}
+		}
+	}
+}
+
+func (s *stack) StackTrace() StackTrace {
+	f := make([]Frame, len(*s))
+	for i := 0; i < len(f); i++ {
+		f[i] = Frame((*s)[i])
+	}
+	return f
+}
+
+func callers() *stack {
+	const depth = 32
+	var pcs [depth]uintptr
+	n := runtime.Callers(3, pcs[:])
+	var st stack = pcs[0:n]
+	return &st
+}
+
+// funcname removes the path prefix component of a function's name reported by func.Name().
+func funcname(name string) string {
+	i := strings.LastIndex(name, "/")
+	name = name[i+1:]
+	i = strings.Index(name, ".")
+	return name[i+1:]
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/stack_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/stack_test.go
new file mode 100644
index 00000000000..aa10a72e487
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/github.com/pkg/errors/stack_test.go
@@ -0,0 +1,250 @@
+package errors
+
+import (
+	"fmt"
+	"runtime"
+	"testing"
+)
+
+var initpc = caller()
+
+type X struct{}
+
+// val returns a Frame pointing to itself.
+func (x X) val() Frame {
+	return caller()
+}
+
+// ptr returns a Frame pointing to itself.
+func (x *X) ptr() Frame {
+	return caller()
+}
+
+func TestFrameFormat(t *testing.T) {
+	var tests = []struct {
+		Frame
+		format string
+		want   string
+	}{{
+		initpc,
+		"%s",
+		"stack_test.go",
+	}, {
+		initpc,
+		"%+s",
+		"github.com/pkg/errors.init\n" +
+			"\t.+/github.com/pkg/errors/stack_test.go",
+	}, {
+		0,
+		"%s",
+		"unknown",
+	}, {
+		0,
+		"%+s",
+		"unknown",
+	}, {
+		initpc,
+		"%d",
+		"9",
+	}, {
+		0,
+		"%d",
+		"0",
+	}, {
+		initpc,
+		"%n",
+		"init",
+	}, {
+		func() Frame {
+			var x X
+			return x.ptr()
+		}(),
+		"%n",
+		`\(\*X\).ptr`,
+	}, {
+		func() Frame {
+			var x X
+			return x.val()
+		}(),
+		"%n",
+		"X.val",
+	}, {
+		0,
+		"%n",
+		"",
+	}, {
+		initpc,
+		"%v",
+		"stack_test.go:9",
+	}, {
+		initpc,
+		"%+v",
+		"github.com/pkg/errors.init\n" +
+			"\t.+/github.com/pkg/errors/stack_test.go:9",
+	}, {
+		0,
+		"%v",
+		"unknown:0",
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.Frame, tt.format, tt.want)
+	}
+}
+
+func TestFuncname(t *testing.T) {
+	tests := []struct {
+		name, want string
+	}{
+		{"", ""},
+		{"runtime.main", "main"},
+		{"github.com/pkg/errors.funcname", "funcname"},
+		{"funcname", "funcname"},
+		{"io.copyBuffer", "copyBuffer"},
+		{"main.(*R).Write", "(*R).Write"},
+	}
+
+	for _, tt := range tests {
+		got := funcname(tt.name)
+		want := tt.want
+		if got != want {
+			t.Errorf("funcname(%q): want: %q, got %q", tt.name, want, got)
+		}
+	}
+}
+
+func TestStackTrace(t *testing.T) {
+	tests := []struct {
+		err  error
+		want []string
+	}{{
+		New("ooh"), []string{
+			"github.com/pkg/errors.TestStackTrace\n" +
+				"\t.+/github.com/pkg/errors/stack_test.go:121",
+		},
+	}, {
+		Wrap(New("ooh"), "ahh"), []string{
+			"github.com/pkg/errors.TestStackTrace\n" +
+				"\t.+/github.com/pkg/errors/stack_test.go:126", // this is the stack of Wrap, not New
+		},
+	}, {
+		Cause(Wrap(New("ooh"), "ahh")), []string{
+			"github.com/pkg/errors.TestStackTrace\n" +
+				"\t.+/github.com/pkg/errors/stack_test.go:131", // this is the stack of New
+		},
+	}, {
+		func() error { return New("ooh") }(), []string{
+			`github.com/pkg/errors.TestStackTrace.func1` +
+				"\n\t.+/github.com/pkg/errors/stack_test.go:136", // this is the stack of New
+			"github.com/pkg/errors.TestStackTrace\n" +
+				"\t.+/github.com/pkg/errors/stack_test.go:136", // this is the stack of New's caller
+		},
+	}, {
+		Cause(func() error {
+			return func() error {
+				return Errorf("hello %s", fmt.Sprintf("world: %s", "ooh"))
+			}()
+		}()), []string{
+			`github.com/pkg/errors.TestStackTrace.func2.1` +
+				"\n\t.+/github.com/pkg/errors/stack_test.go:145", // this is the stack of Errorf
+			`github.com/pkg/errors.TestStackTrace.func2` +
+				"\n\t.+/github.com/pkg/errors/stack_test.go:146", // this is the stack of Errorf's caller
+			"github.com/pkg/errors.TestStackTrace\n" +
+				"\t.+/github.com/pkg/errors/stack_test.go:147", // this is the stack of Errorf's caller's caller
+		},
+	}}
+	for i, tt := range tests {
+		x, ok := tt.err.(interface {
+			StackTrace() StackTrace
+		})
+		if !ok {
+			t.Errorf("expected %#v to implement StackTrace() StackTrace", tt.err)
+			continue
+		}
+		st := x.StackTrace()
+		for j, want := range tt.want {
+			testFormatRegexp(t, i, st[j], "%+v", want)
+		}
+	}
+}
+
+func stackTrace() StackTrace {
+	const depth = 8
+	var pcs [depth]uintptr
+	n := runtime.Callers(1, pcs[:])
+	var st stack = pcs[0:n]
+	return st.StackTrace()
+}
+
+func TestStackTraceFormat(t *testing.T) {
+	tests := []struct {
+		StackTrace
+		format string
+		want   string
+	}{{
+		nil,
+		"%s",
+		`\[\]`,
+	}, {
+		nil,
+		"%v",
+		`\[\]`,
+	}, {
+		nil,
+		"%+v",
+		"",
+	}, {
+		nil,
+		"%#v",
+		`\[\]errors.Frame\(nil\)`,
+	}, {
+		make(StackTrace, 0),
+		"%s",
+		`\[\]`,
+	}, {
+		make(StackTrace, 0),
+		"%v",
+		`\[\]`,
+	}, {
+		make(StackTrace, 0),
+		"%+v",
+		"",
+	}, {
+		make(StackTrace, 0),
+		"%#v",
+		`\[\]errors.Frame{}`,
+	}, {
+		stackTrace()[:2],
+		"%s",
+		`\[stack_test.go stack_test.go\]`,
+	}, {
+		stackTrace()[:2],
+		"%v",
+		`\[stack_test.go:174 stack_test.go:221\]`,
+	}, {
+		stackTrace()[:2],
+		"%+v",
+		"\n" +
+			"github.com/pkg/errors.stackTrace\n" +
+			"\t.+/github.com/pkg/errors/stack_test.go:174\n" +
+			"github.com/pkg/errors.TestStackTraceFormat\n" +
+			"\t.+/github.com/pkg/errors/stack_test.go:225",
+	}, {
+		stackTrace()[:2],
+		"%#v",
+		`\[\]errors.Frame{stack_test.go:174, stack_test.go:233}`,
+	}}
+
+	for i, tt := range tests {
+		testFormatRegexp(t, i, tt.StackTrace, tt.format, tt.want)
+	}
+}
+
+// a version of runtime.Caller that returns a Frame, not a uintptr.
+func caller() Frame {
+	var pcs [3]uintptr
+	n := runtime.Callers(2, pcs[:])
+	frames := runtime.CallersFrames(pcs[:n])
+	frame, _ := frames.Next()
+	return Frame(frame.PC)
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/.travis.yml b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/.travis.yml
new file mode 100644
index 00000000000..055480b9ef8
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/.travis.yml
@@ -0,0 +1,16 @@
+language: go
+
+go:
+    - "1.4.x"
+    - "1.5.x"
+    - "1.6.x"
+    - "1.7.x"
+    - "1.8.x"
+    - "1.9.x"
+    - "1.10.x"
+    - "1.11.x"
+    - "1.12.x"
+    - "1.13.x"
+    - "tip"
+
+go_import_path: gopkg.in/yaml.v2
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/LICENSE b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/LICENSE
new file mode 100644
index 00000000000..8dada3edaf5
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/LICENSE
@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright {yyyy} {name of copyright owner}
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/LICENSE.libyaml b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/LICENSE.libyaml
new file mode 100644
index 00000000000..8da58fbf6f8
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/LICENSE.libyaml
@@ -0,0 +1,31 @@
+The following files were ported to Go from C files of libyaml, and thus
+are still covered by their original copyright and license:
+
+    apic.go
+    emitterc.go
+    parserc.go
+    readerc.go
+    scannerc.go
+    writerc.go
+    yamlh.go
+    yamlprivateh.go
+
+Copyright (c) 2006 Kirill Simonov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/NOTICE b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/NOTICE
new file mode 100644
index 00000000000..866d74a7ad7
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/NOTICE
@@ -0,0 +1,13 @@
+Copyright 2011-2016 Canonical Ltd.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/README.md b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/README.md
new file mode 100644
index 00000000000..b50c6e87755
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/README.md
@@ -0,0 +1,133 @@
+# YAML support for the Go language
+
+Introduction
+------------
+
+The yaml package enables Go programs to comfortably encode and decode YAML
+values. It was developed within [Canonical](https://www.canonical.com) as
+part of the [juju](https://juju.ubuntu.com) project, and is based on a
+pure Go port of the well-known [libyaml](http://pyyaml.org/wiki/LibYAML)
+C library to parse and generate YAML data quickly and reliably.
+
+Compatibility
+-------------
+
+The yaml package supports most of YAML 1.1 and 1.2, including support for
+anchors, tags, map merging, etc. Multi-document unmarshalling is not yet
+implemented, and base-60 floats from YAML 1.1 are purposefully not
+supported since they're a poor design and are gone in YAML 1.2.
+
+Installation and usage
+----------------------
+
+The import path for the package is *gopkg.in/yaml.v2*.
+
+To install it, run:
+
+    go get gopkg.in/yaml.v2
+
+API documentation
+-----------------
+
+If opened in a browser, the import path itself leads to the API documentation:
+
+  * [https://gopkg.in/yaml.v2](https://gopkg.in/yaml.v2)
+
+API stability
+-------------
+
+The package API for yaml v2 will remain stable as described in [gopkg.in](https://gopkg.in).
+
+
+License
+-------
+
+The yaml package is licensed under the Apache License 2.0. Please see the LICENSE file for details.
+
+
+Example
+-------
+
+```Go
+package main
+
+import (
+        "fmt"
+        "log"
+
+        "gopkg.in/yaml.v2"
+)
+
+var data = `
+a: Easy!
+b:
+  c: 2
+  d: [3, 4]
+`
+
+// Note: struct fields must be public in order for unmarshal to
+// correctly populate the data.
+type T struct {
+        A string
+        B struct {
+                RenamedC int   `yaml:"c"`
+                D        []int `yaml:",flow"`
+        }
+}
+
+func main() {
+        t := T{}
+    
+        err := yaml.Unmarshal([]byte(data), &t)
+        if err != nil {
+                log.Fatalf("error: %v", err)
+        }
+        fmt.Printf("--- t:\n%v\n\n", t)
+    
+        d, err := yaml.Marshal(&t)
+        if err != nil {
+                log.Fatalf("error: %v", err)
+        }
+        fmt.Printf("--- t dump:\n%s\n\n", string(d))
+    
+        m := make(map[interface{}]interface{})
+    
+        err = yaml.Unmarshal([]byte(data), &m)
+        if err != nil {
+                log.Fatalf("error: %v", err)
+        }
+        fmt.Printf("--- m:\n%v\n\n", m)
+    
+        d, err = yaml.Marshal(&m)
+        if err != nil {
+                log.Fatalf("error: %v", err)
+        }
+        fmt.Printf("--- m dump:\n%s\n\n", string(d))
+}
+```
+
+This example will generate the following output:
+
+```
+--- t:
+{Easy! {2 [3 4]}}
+
+--- t dump:
+a: Easy!
+b:
+  c: 2
+  d: [3, 4]
+
+
+--- m:
+map[a:Easy! b:map[c:2 d:[3 4]]]
+
+--- m dump:
+a: Easy!
+b:
+  c: 2
+  d:
+  - 3
+  - 4
+```
+
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/apic.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/apic.go
new file mode 100644
index 00000000000..d2c2308f1f4
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/apic.go
@@ -0,0 +1,740 @@
+package yaml
+
+import (
+	"io"
+)
+
+func yaml_insert_token(parser *yaml_parser_t, pos int, token *yaml_token_t) {
+	//fmt.Println("yaml_insert_token", "pos:", pos, "typ:", token.typ, "head:", parser.tokens_head, "len:", len(parser.tokens))
+
+	// Check if we can move the queue at the beginning of the buffer.
+	if parser.tokens_head > 0 && len(parser.tokens) == cap(parser.tokens) {
+		if parser.tokens_head != len(parser.tokens) {
+			copy(parser.tokens, parser.tokens[parser.tokens_head:])
+		}
+		parser.tokens = parser.tokens[:len(parser.tokens)-parser.tokens_head]
+		parser.tokens_head = 0
+	}
+	parser.tokens = append(parser.tokens, *token)
+	if pos < 0 {
+		return
+	}
+	copy(parser.tokens[parser.tokens_head+pos+1:], parser.tokens[parser.tokens_head+pos:])
+	parser.tokens[parser.tokens_head+pos] = *token
+}
+
+// Create a new parser object.
+func yaml_parser_initialize(parser *yaml_parser_t) bool {
+	*parser = yaml_parser_t{
+		raw_buffer: make([]byte, 0, input_raw_buffer_size),
+		buffer:     make([]byte, 0, input_buffer_size),
+	}
+	return true
+}
+
+// Destroy a parser object.
+func yaml_parser_delete(parser *yaml_parser_t) {
+	*parser = yaml_parser_t{}
+}
+
+// String read handler.
+func yaml_string_read_handler(parser *yaml_parser_t, buffer []byte) (n int, err error) {
+	if parser.input_pos == len(parser.input) {
+		return 0, io.EOF
+	}
+	n = copy(buffer, parser.input[parser.input_pos:])
+	parser.input_pos += n
+	return n, nil
+}
+
+// Reader read handler.
+func yaml_reader_read_handler(parser *yaml_parser_t, buffer []byte) (n int, err error) {
+	return parser.input_reader.Read(buffer)
+}
+
+// Set a string input.
+func yaml_parser_set_input_string(parser *yaml_parser_t, input []byte) {
+	if parser.read_handler != nil {
+		panic("must set the input source only once")
+	}
+	parser.read_handler = yaml_string_read_handler
+	parser.input = input
+	parser.input_pos = 0
+}
+
+// Set a file input.
+func yaml_parser_set_input_reader(parser *yaml_parser_t, r io.Reader) {
+	if parser.read_handler != nil {
+		panic("must set the input source only once")
+	}
+	parser.read_handler = yaml_reader_read_handler
+	parser.input_reader = r
+}
+
+// Set the source encoding.
+func yaml_parser_set_encoding(parser *yaml_parser_t, encoding yaml_encoding_t) {
+	if parser.encoding != yaml_ANY_ENCODING {
+		panic("must set the encoding only once")
+	}
+	parser.encoding = encoding
+}
+
+// Create a new emitter object.
+func yaml_emitter_initialize(emitter *yaml_emitter_t) {
+	*emitter = yaml_emitter_t{
+		buffer:     make([]byte, output_buffer_size),
+		raw_buffer: make([]byte, 0, output_raw_buffer_size),
+		states:     make([]yaml_emitter_state_t, 0, initial_stack_size),
+		events:     make([]yaml_event_t, 0, initial_queue_size),
+		best_width: -1,
+	}
+}
+
+// Destroy an emitter object.
+func yaml_emitter_delete(emitter *yaml_emitter_t) {
+	*emitter = yaml_emitter_t{}
+}
+
+// String write handler.
+func yaml_string_write_handler(emitter *yaml_emitter_t, buffer []byte) error {
+	*emitter.output_buffer = append(*emitter.output_buffer, buffer...)
+	return nil
+}
+
+// yaml_writer_write_handler uses emitter.output_writer to write the
+// emitted text.
+func yaml_writer_write_handler(emitter *yaml_emitter_t, buffer []byte) error {
+	_, err := emitter.output_writer.Write(buffer)
+	return err
+}
+
+// Set a string output.
+func yaml_emitter_set_output_string(emitter *yaml_emitter_t, output_buffer *[]byte) {
+	if emitter.write_handler != nil {
+		panic("must set the output target only once")
+	}
+	emitter.write_handler = yaml_string_write_handler
+	emitter.output_buffer = output_buffer
+}
+
+// Set a file output.
+func yaml_emitter_set_output_writer(emitter *yaml_emitter_t, w io.Writer) {
+	if emitter.write_handler != nil {
+		panic("must set the output target only once")
+	}
+	emitter.write_handler = yaml_writer_write_handler
+	emitter.output_writer = w
+}
+
+// Set the output encoding.
+func yaml_emitter_set_encoding(emitter *yaml_emitter_t, encoding yaml_encoding_t) {
+	if emitter.encoding != yaml_ANY_ENCODING {
+		panic("must set the output encoding only once")
+	}
+	emitter.encoding = encoding
+}
+
+// Set the canonical output style.
+func yaml_emitter_set_canonical(emitter *yaml_emitter_t, canonical bool) {
+	emitter.canonical = canonical
+}
+
+//// Set the indentation increment.
+func yaml_emitter_set_indent(emitter *yaml_emitter_t, indent int) {
+	if indent < 2 || indent > 9 {
+		indent = 2
+	}
+	emitter.best_indent = indent
+}
+
+// Set the preferred line width.
+func yaml_emitter_set_width(emitter *yaml_emitter_t, width int) {
+	if width < 0 {
+		width = -1
+	}
+	emitter.best_width = width
+}
+
+// Set if unescaped non-ASCII characters are allowed.
+func yaml_emitter_set_unicode(emitter *yaml_emitter_t, unicode bool) {
+	emitter.unicode = unicode
+}
+
+// Set the preferred line break character.
+func yaml_emitter_set_break(emitter *yaml_emitter_t, line_break yaml_break_t) {
+	emitter.line_break = line_break
+}
+
+///*
+// * Destroy a token object.
+// */
+//
+//YAML_DECLARE(void)
+//yaml_token_delete(yaml_token_t *token)
+//{
+//    assert(token);  // Non-NULL token object expected.
+//
+//    switch (token.type)
+//    {
+//        case YAML_TAG_DIRECTIVE_TOKEN:
+//            yaml_free(token.data.tag_directive.handle);
+//            yaml_free(token.data.tag_directive.prefix);
+//            break;
+//
+//        case YAML_ALIAS_TOKEN:
+//            yaml_free(token.data.alias.value);
+//            break;
+//
+//        case YAML_ANCHOR_TOKEN:
+//            yaml_free(token.data.anchor.value);
+//            break;
+//
+//        case YAML_TAG_TOKEN:
+//            yaml_free(token.data.tag.handle);
+//            yaml_free(token.data.tag.suffix);
+//            break;
+//
+//        case YAML_SCALAR_TOKEN:
+//            yaml_free(token.data.scalar.value);
+//            break;
+//
+//        default:
+//            break;
+//    }
+//
+//    memset(token, 0, sizeof(yaml_token_t));
+//}
+//
+///*
+// * Check if a string is a valid UTF-8 sequence.
+// *
+// * Check 'reader.c' for more details on UTF-8 encoding.
+// */
+//
+//static int
+//yaml_check_utf8(yaml_char_t *start, size_t length)
+//{
+//    yaml_char_t *end = start+length;
+//    yaml_char_t *pointer = start;
+//
+//    while (pointer < end) {
+//        unsigned char octet;
+//        unsigned int width;
+//        unsigned int value;
+//        size_t k;
+//
+//        octet = pointer[0];
+//        width = (octet & 0x80) == 0x00 ? 1 :
+//                (octet & 0xE0) == 0xC0 ? 2 :
+//                (octet & 0xF0) == 0xE0 ? 3 :
+//                (octet & 0xF8) == 0xF0 ? 4 : 0;
+//        value = (octet & 0x80) == 0x00 ? octet & 0x7F :
+//                (octet & 0xE0) == 0xC0 ? octet & 0x1F :
+//                (octet & 0xF0) == 0xE0 ? octet & 0x0F :
+//                (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
+//        if (!width) return 0;
+//        if (pointer+width > end) return 0;
+//        for (k = 1; k < width; k ++) {
+//            octet = pointer[k];
+//            if ((octet & 0xC0) != 0x80) return 0;
+//            value = (value << 6) + (octet & 0x3F);
+//        }
+//        if (!((width == 1) ||
+//            (width == 2 && value >= 0x80) ||
+//            (width == 3 && value >= 0x800) ||
+//            (width == 4 && value >= 0x10000))) return 0;
+//
+//        pointer += width;
+//    }
+//
+//    return 1;
+//}
+//
+
+// Create STREAM-START.
+func yaml_stream_start_event_initialize(event *yaml_event_t, encoding yaml_encoding_t) {
+	*event = yaml_event_t{
+		typ:      yaml_STREAM_START_EVENT,
+		encoding: encoding,
+	}
+}
+
+// Create STREAM-END.
+func yaml_stream_end_event_initialize(event *yaml_event_t) {
+	*event = yaml_event_t{
+		typ: yaml_STREAM_END_EVENT,
+	}
+}
+
+// Create DOCUMENT-START.
+func yaml_document_start_event_initialize(
+	event *yaml_event_t,
+	version_directive *yaml_version_directive_t,
+	tag_directives []yaml_tag_directive_t,
+	implicit bool,
+) {
+	*event = yaml_event_t{
+		typ:               yaml_DOCUMENT_START_EVENT,
+		version_directive: version_directive,
+		tag_directives:    tag_directives,
+		implicit:          implicit,
+	}
+}
+
+// Create DOCUMENT-END.
+func yaml_document_end_event_initialize(event *yaml_event_t, implicit bool) {
+	*event = yaml_event_t{
+		typ:      yaml_DOCUMENT_END_EVENT,
+		implicit: implicit,
+	}
+}
+
+///*
+// * Create ALIAS.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_alias_event_initialize(event *yaml_event_t, anchor *yaml_char_t)
+//{
+//    mark yaml_mark_t = { 0, 0, 0 }
+//    anchor_copy *yaml_char_t = NULL
+//
+//    assert(event) // Non-NULL event object is expected.
+//    assert(anchor) // Non-NULL anchor is expected.
+//
+//    if (!yaml_check_utf8(anchor, strlen((char *)anchor))) return 0
+//
+//    anchor_copy = yaml_strdup(anchor)
+//    if (!anchor_copy)
+//        return 0
+//
+//    ALIAS_EVENT_INIT(*event, anchor_copy, mark, mark)
+//
+//    return 1
+//}
+
+// Create SCALAR.
+func yaml_scalar_event_initialize(event *yaml_event_t, anchor, tag, value []byte, plain_implicit, quoted_implicit bool, style yaml_scalar_style_t) bool {
+	*event = yaml_event_t{
+		typ:             yaml_SCALAR_EVENT,
+		anchor:          anchor,
+		tag:             tag,
+		value:           value,
+		implicit:        plain_implicit,
+		quoted_implicit: quoted_implicit,
+		style:           yaml_style_t(style),
+	}
+	return true
+}
+
+// Create SEQUENCE-START.
+func yaml_sequence_start_event_initialize(event *yaml_event_t, anchor, tag []byte, implicit bool, style yaml_sequence_style_t) bool {
+	*event = yaml_event_t{
+		typ:      yaml_SEQUENCE_START_EVENT,
+		anchor:   anchor,
+		tag:      tag,
+		implicit: implicit,
+		style:    yaml_style_t(style),
+	}
+	return true
+}
+
+// Create SEQUENCE-END.
+func yaml_sequence_end_event_initialize(event *yaml_event_t) bool {
+	*event = yaml_event_t{
+		typ: yaml_SEQUENCE_END_EVENT,
+	}
+	return true
+}
+
+// Create MAPPING-START.
+func yaml_mapping_start_event_initialize(event *yaml_event_t, anchor, tag []byte, implicit bool, style yaml_mapping_style_t) {
+	*event = yaml_event_t{
+		typ:      yaml_MAPPING_START_EVENT,
+		anchor:   anchor,
+		tag:      tag,
+		implicit: implicit,
+		style:    yaml_style_t(style),
+	}
+}
+
+// Create MAPPING-END.
+func yaml_mapping_end_event_initialize(event *yaml_event_t) {
+	*event = yaml_event_t{
+		typ: yaml_MAPPING_END_EVENT,
+	}
+}
+
+// Destroy an event object.
+func yaml_event_delete(event *yaml_event_t) {
+	*event = yaml_event_t{}
+}
+
+///*
+// * Create a document object.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_document_initialize(document *yaml_document_t,
+//        version_directive *yaml_version_directive_t,
+//        tag_directives_start *yaml_tag_directive_t,
+//        tag_directives_end *yaml_tag_directive_t,
+//        start_implicit int, end_implicit int)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//    struct {
+//        start *yaml_node_t
+//        end *yaml_node_t
+//        top *yaml_node_t
+//    } nodes = { NULL, NULL, NULL }
+//    version_directive_copy *yaml_version_directive_t = NULL
+//    struct {
+//        start *yaml_tag_directive_t
+//        end *yaml_tag_directive_t
+//        top *yaml_tag_directive_t
+//    } tag_directives_copy = { NULL, NULL, NULL }
+//    value yaml_tag_directive_t = { NULL, NULL }
+//    mark yaml_mark_t = { 0, 0, 0 }
+//
+//    assert(document) // Non-NULL document object is expected.
+//    assert((tag_directives_start && tag_directives_end) ||
+//            (tag_directives_start == tag_directives_end))
+//                            // Valid tag directives are expected.
+//
+//    if (!STACK_INIT(&context, nodes, INITIAL_STACK_SIZE)) goto error
+//
+//    if (version_directive) {
+//        version_directive_copy = yaml_malloc(sizeof(yaml_version_directive_t))
+//        if (!version_directive_copy) goto error
+//        version_directive_copy.major = version_directive.major
+//        version_directive_copy.minor = version_directive.minor
+//    }
+//
+//    if (tag_directives_start != tag_directives_end) {
+//        tag_directive *yaml_tag_directive_t
+//        if (!STACK_INIT(&context, tag_directives_copy, INITIAL_STACK_SIZE))
+//            goto error
+//        for (tag_directive = tag_directives_start
+//                tag_directive != tag_directives_end; tag_directive ++) {
+//            assert(tag_directive.handle)
+//            assert(tag_directive.prefix)
+//            if (!yaml_check_utf8(tag_directive.handle,
+//                        strlen((char *)tag_directive.handle)))
+//                goto error
+//            if (!yaml_check_utf8(tag_directive.prefix,
+//                        strlen((char *)tag_directive.prefix)))
+//                goto error
+//            value.handle = yaml_strdup(tag_directive.handle)
+//            value.prefix = yaml_strdup(tag_directive.prefix)
+//            if (!value.handle || !value.prefix) goto error
+//            if (!PUSH(&context, tag_directives_copy, value))
+//                goto error
+//            value.handle = NULL
+//            value.prefix = NULL
+//        }
+//    }
+//
+//    DOCUMENT_INIT(*document, nodes.start, nodes.end, version_directive_copy,
+//            tag_directives_copy.start, tag_directives_copy.top,
+//            start_implicit, end_implicit, mark, mark)
+//
+//    return 1
+//
+//error:
+//    STACK_DEL(&context, nodes)
+//    yaml_free(version_directive_copy)
+//    while (!STACK_EMPTY(&context, tag_directives_copy)) {
+//        value yaml_tag_directive_t = POP(&context, tag_directives_copy)
+//        yaml_free(value.handle)
+//        yaml_free(value.prefix)
+//    }
+//    STACK_DEL(&context, tag_directives_copy)
+//    yaml_free(value.handle)
+//    yaml_free(value.prefix)
+//
+//    return 0
+//}
+//
+///*
+// * Destroy a document object.
+// */
+//
+//YAML_DECLARE(void)
+//yaml_document_delete(document *yaml_document_t)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//    tag_directive *yaml_tag_directive_t
+//
+//    context.error = YAML_NO_ERROR // Eliminate a compiler warning.
+//
+//    assert(document) // Non-NULL document object is expected.
+//
+//    while (!STACK_EMPTY(&context, document.nodes)) {
+//        node yaml_node_t = POP(&context, document.nodes)
+//        yaml_free(node.tag)
+//        switch (node.type) {
+//            case YAML_SCALAR_NODE:
+//                yaml_free(node.data.scalar.value)
+//                break
+//            case YAML_SEQUENCE_NODE:
+//                STACK_DEL(&context, node.data.sequence.items)
+//                break
+//            case YAML_MAPPING_NODE:
+//                STACK_DEL(&context, node.data.mapping.pairs)
+//                break
+//            default:
+//                assert(0) // Should not happen.
+//        }
+//    }
+//    STACK_DEL(&context, document.nodes)
+//
+//    yaml_free(document.version_directive)
+//    for (tag_directive = document.tag_directives.start
+//            tag_directive != document.tag_directives.end
+//            tag_directive++) {
+//        yaml_free(tag_directive.handle)
+//        yaml_free(tag_directive.prefix)
+//    }
+//    yaml_free(document.tag_directives.start)
+//
+//    memset(document, 0, sizeof(yaml_document_t))
+//}
+//
+///**
+// * Get a document node.
+// */
+//
+//YAML_DECLARE(yaml_node_t *)
+//yaml_document_get_node(document *yaml_document_t, index int)
+//{
+//    assert(document) // Non-NULL document object is expected.
+//
+//    if (index > 0 && document.nodes.start + index <= document.nodes.top) {
+//        return document.nodes.start + index - 1
+//    }
+//    return NULL
+//}
+//
+///**
+// * Get the root object.
+// */
+//
+//YAML_DECLARE(yaml_node_t *)
+//yaml_document_get_root_node(document *yaml_document_t)
+//{
+//    assert(document) // Non-NULL document object is expected.
+//
+//    if (document.nodes.top != document.nodes.start) {
+//        return document.nodes.start
+//    }
+//    return NULL
+//}
+//
+///*
+// * Add a scalar node to a document.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_document_add_scalar(document *yaml_document_t,
+//        tag *yaml_char_t, value *yaml_char_t, length int,
+//        style yaml_scalar_style_t)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//    mark yaml_mark_t = { 0, 0, 0 }
+//    tag_copy *yaml_char_t = NULL
+//    value_copy *yaml_char_t = NULL
+//    node yaml_node_t
+//
+//    assert(document) // Non-NULL document object is expected.
+//    assert(value) // Non-NULL value is expected.
+//
+//    if (!tag) {
+//        tag = (yaml_char_t *)YAML_DEFAULT_SCALAR_TAG
+//    }
+//
+//    if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error
+//    tag_copy = yaml_strdup(tag)
+//    if (!tag_copy) goto error
+//
+//    if (length < 0) {
+//        length = strlen((char *)value)
+//    }
+//
+//    if (!yaml_check_utf8(value, length)) goto error
+//    value_copy = yaml_malloc(length+1)
+//    if (!value_copy) goto error
+//    memcpy(value_copy, value, length)
+//    value_copy[length] = '\0'
+//
+//    SCALAR_NODE_INIT(node, tag_copy, value_copy, length, style, mark, mark)
+//    if (!PUSH(&context, document.nodes, node)) goto error
+//
+//    return document.nodes.top - document.nodes.start
+//
+//error:
+//    yaml_free(tag_copy)
+//    yaml_free(value_copy)
+//
+//    return 0
+//}
+//
+///*
+// * Add a sequence node to a document.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_document_add_sequence(document *yaml_document_t,
+//        tag *yaml_char_t, style yaml_sequence_style_t)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//    mark yaml_mark_t = { 0, 0, 0 }
+//    tag_copy *yaml_char_t = NULL
+//    struct {
+//        start *yaml_node_item_t
+//        end *yaml_node_item_t
+//        top *yaml_node_item_t
+//    } items = { NULL, NULL, NULL }
+//    node yaml_node_t
+//
+//    assert(document) // Non-NULL document object is expected.
+//
+//    if (!tag) {
+//        tag = (yaml_char_t *)YAML_DEFAULT_SEQUENCE_TAG
+//    }
+//
+//    if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error
+//    tag_copy = yaml_strdup(tag)
+//    if (!tag_copy) goto error
+//
+//    if (!STACK_INIT(&context, items, INITIAL_STACK_SIZE)) goto error
+//
+//    SEQUENCE_NODE_INIT(node, tag_copy, items.start, items.end,
+//            style, mark, mark)
+//    if (!PUSH(&context, document.nodes, node)) goto error
+//
+//    return document.nodes.top - document.nodes.start
+//
+//error:
+//    STACK_DEL(&context, items)
+//    yaml_free(tag_copy)
+//
+//    return 0
+//}
+//
+///*
+// * Add a mapping node to a document.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_document_add_mapping(document *yaml_document_t,
+//        tag *yaml_char_t, style yaml_mapping_style_t)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//    mark yaml_mark_t = { 0, 0, 0 }
+//    tag_copy *yaml_char_t = NULL
+//    struct {
+//        start *yaml_node_pair_t
+//        end *yaml_node_pair_t
+//        top *yaml_node_pair_t
+//    } pairs = { NULL, NULL, NULL }
+//    node yaml_node_t
+//
+//    assert(document) // Non-NULL document object is expected.
+//
+//    if (!tag) {
+//        tag = (yaml_char_t *)YAML_DEFAULT_MAPPING_TAG
+//    }
+//
+//    if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error
+//    tag_copy = yaml_strdup(tag)
+//    if (!tag_copy) goto error
+//
+//    if (!STACK_INIT(&context, pairs, INITIAL_STACK_SIZE)) goto error
+//
+//    MAPPING_NODE_INIT(node, tag_copy, pairs.start, pairs.end,
+//            style, mark, mark)
+//    if (!PUSH(&context, document.nodes, node)) goto error
+//
+//    return document.nodes.top - document.nodes.start
+//
+//error:
+//    STACK_DEL(&context, pairs)
+//    yaml_free(tag_copy)
+//
+//    return 0
+//}
+//
+///*
+// * Append an item to a sequence node.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_document_append_sequence_item(document *yaml_document_t,
+//        sequence int, item int)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//
+//    assert(document) // Non-NULL document is required.
+//    assert(sequence > 0
+//            && document.nodes.start + sequence <= document.nodes.top)
+//                            // Valid sequence id is required.
+//    assert(document.nodes.start[sequence-1].type == YAML_SEQUENCE_NODE)
+//                            // A sequence node is required.
+//    assert(item > 0 && document.nodes.start + item <= document.nodes.top)
+//                            // Valid item id is required.
+//
+//    if (!PUSH(&context,
+//                document.nodes.start[sequence-1].data.sequence.items, item))
+//        return 0
+//
+//    return 1
+//}
+//
+///*
+// * Append a pair of a key and a value to a mapping node.
+// */
+//
+//YAML_DECLARE(int)
+//yaml_document_append_mapping_pair(document *yaml_document_t,
+//        mapping int, key int, value int)
+//{
+//    struct {
+//        error yaml_error_type_t
+//    } context
+//
+//    pair yaml_node_pair_t
+//
+//    assert(document) // Non-NULL document is required.
+//    assert(mapping > 0
+//            && document.nodes.start + mapping <= document.nodes.top)
+//                            // Valid mapping id is required.
+//    assert(document.nodes.start[mapping-1].type == YAML_MAPPING_NODE)
+//                            // A mapping node is required.
+//    assert(key > 0 && document.nodes.start + key <= document.nodes.top)
+//                            // Valid key id is required.
+//    assert(value > 0 && document.nodes.start + value <= document.nodes.top)
+//                            // Valid value id is required.
+//
+//    pair.key = key
+//    pair.value = value
+//
+//    if (!PUSH(&context,
+//                document.nodes.start[mapping-1].data.mapping.pairs, pair))
+//        return 0
+//
+//    return 1
+//}
+//
+//
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/decode.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/decode.go
new file mode 100644
index 00000000000..129bc2a97d3
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/decode.go
@@ -0,0 +1,815 @@
+package yaml
+
+import (
+	"encoding"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"math"
+	"reflect"
+	"strconv"
+	"time"
+)
+
+const (
+	documentNode = 1 << iota
+	mappingNode
+	sequenceNode
+	scalarNode
+	aliasNode
+)
+
+type node struct {
+	kind         int
+	line, column int
+	tag          string
+	// For an alias node, alias holds the resolved alias.
+	alias    *node
+	value    string
+	implicit bool
+	children []*node
+	anchors  map[string]*node
+}
+
+// ----------------------------------------------------------------------------
+// Parser, produces a node tree out of a libyaml event stream.
+
+type parser struct {
+	parser   yaml_parser_t
+	event    yaml_event_t
+	doc      *node
+	doneInit bool
+}
+
+func newParser(b []byte) *parser {
+	p := parser{}
+	if !yaml_parser_initialize(&p.parser) {
+		panic("failed to initialize YAML emitter")
+	}
+	if len(b) == 0 {
+		b = []byte{'\n'}
+	}
+	yaml_parser_set_input_string(&p.parser, b)
+	return &p
+}
+
+func newParserFromReader(r io.Reader) *parser {
+	p := parser{}
+	if !yaml_parser_initialize(&p.parser) {
+		panic("failed to initialize YAML emitter")
+	}
+	yaml_parser_set_input_reader(&p.parser, r)
+	return &p
+}
+
+func (p *parser) init() {
+	if p.doneInit {
+		return
+	}
+	p.expect(yaml_STREAM_START_EVENT)
+	p.doneInit = true
+}
+
+func (p *parser) destroy() {
+	if p.event.typ != yaml_NO_EVENT {
+		yaml_event_delete(&p.event)
+	}
+	yaml_parser_delete(&p.parser)
+}
+
+// expect consumes an event from the event stream and
+// checks that it's of the expected type.
+func (p *parser) expect(e yaml_event_type_t) {
+	if p.event.typ == yaml_NO_EVENT {
+		if !yaml_parser_parse(&p.parser, &p.event) {
+			p.fail()
+		}
+	}
+	if p.event.typ == yaml_STREAM_END_EVENT {
+		failf("attempted to go past the end of stream; corrupted value?")
+	}
+	if p.event.typ != e {
+		p.parser.problem = fmt.Sprintf("expected %s event but got %s", e, p.event.typ)
+		p.fail()
+	}
+	yaml_event_delete(&p.event)
+	p.event.typ = yaml_NO_EVENT
+}
+
+// peek peeks at the next event in the event stream,
+// puts the results into p.event and returns the event type.
+func (p *parser) peek() yaml_event_type_t {
+	if p.event.typ != yaml_NO_EVENT {
+		return p.event.typ
+	}
+	if !yaml_parser_parse(&p.parser, &p.event) {
+		p.fail()
+	}
+	return p.event.typ
+}
+
+func (p *parser) fail() {
+	var where string
+	var line int
+	if p.parser.problem_mark.line != 0 {
+		line = p.parser.problem_mark.line
+		// Scanner errors don't iterate line before returning error
+		if p.parser.error == yaml_SCANNER_ERROR {
+			line++
+		}
+	} else if p.parser.context_mark.line != 0 {
+		line = p.parser.context_mark.line
+	}
+	if line != 0 {
+		where = "line " + strconv.Itoa(line) + ": "
+	}
+	var msg string
+	if len(p.parser.problem) > 0 {
+		msg = p.parser.problem
+	} else {
+		msg = "unknown problem parsing YAML content"
+	}
+	failf("%s%s", where, msg)
+}
+
+func (p *parser) anchor(n *node, anchor []byte) {
+	if anchor != nil {
+		p.doc.anchors[string(anchor)] = n
+	}
+}
+
+func (p *parser) parse() *node {
+	p.init()
+	switch p.peek() {
+	case yaml_SCALAR_EVENT:
+		return p.scalar()
+	case yaml_ALIAS_EVENT:
+		return p.alias()
+	case yaml_MAPPING_START_EVENT:
+		return p.mapping()
+	case yaml_SEQUENCE_START_EVENT:
+		return p.sequence()
+	case yaml_DOCUMENT_START_EVENT:
+		return p.document()
+	case yaml_STREAM_END_EVENT:
+		// Happens when attempting to decode an empty buffer.
+		return nil
+	default:
+		panic("attempted to parse unknown event: " + p.event.typ.String())
+	}
+}
+
+func (p *parser) node(kind int) *node {
+	return &node{
+		kind:   kind,
+		line:   p.event.start_mark.line,
+		column: p.event.start_mark.column,
+	}
+}
+
+func (p *parser) document() *node {
+	n := p.node(documentNode)
+	n.anchors = make(map[string]*node)
+	p.doc = n
+	p.expect(yaml_DOCUMENT_START_EVENT)
+	n.children = append(n.children, p.parse())
+	p.expect(yaml_DOCUMENT_END_EVENT)
+	return n
+}
+
+func (p *parser) alias() *node {
+	n := p.node(aliasNode)
+	n.value = string(p.event.anchor)
+	n.alias = p.doc.anchors[n.value]
+	if n.alias == nil {
+		failf("unknown anchor '%s' referenced", n.value)
+	}
+	p.expect(yaml_ALIAS_EVENT)
+	return n
+}
+
+func (p *parser) scalar() *node {
+	n := p.node(scalarNode)
+	n.value = string(p.event.value)
+	n.tag = string(p.event.tag)
+	n.implicit = p.event.implicit
+	p.anchor(n, p.event.anchor)
+	p.expect(yaml_SCALAR_EVENT)
+	return n
+}
+
+func (p *parser) sequence() *node {
+	n := p.node(sequenceNode)
+	p.anchor(n, p.event.anchor)
+	p.expect(yaml_SEQUENCE_START_EVENT)
+	for p.peek() != yaml_SEQUENCE_END_EVENT {
+		n.children = append(n.children, p.parse())
+	}
+	p.expect(yaml_SEQUENCE_END_EVENT)
+	return n
+}
+
+func (p *parser) mapping() *node {
+	n := p.node(mappingNode)
+	p.anchor(n, p.event.anchor)
+	p.expect(yaml_MAPPING_START_EVENT)
+	for p.peek() != yaml_MAPPING_END_EVENT {
+		n.children = append(n.children, p.parse(), p.parse())
+	}
+	p.expect(yaml_MAPPING_END_EVENT)
+	return n
+}
+
+// ----------------------------------------------------------------------------
+// Decoder, unmarshals a node into a provided value.
+
+type decoder struct {
+	doc     *node
+	aliases map[*node]bool
+	mapType reflect.Type
+	terrors []string
+	strict  bool
+
+	decodeCount int
+	aliasCount  int
+	aliasDepth  int
+}
+
+var (
+	mapItemType    = reflect.TypeOf(MapItem{})
+	durationType   = reflect.TypeOf(time.Duration(0))
+	defaultMapType = reflect.TypeOf(map[interface{}]interface{}{})
+	ifaceType      = defaultMapType.Elem()
+	timeType       = reflect.TypeOf(time.Time{})
+	ptrTimeType    = reflect.TypeOf(&time.Time{})
+)
+
+func newDecoder(strict bool) *decoder {
+	d := &decoder{mapType: defaultMapType, strict: strict}
+	d.aliases = make(map[*node]bool)
+	return d
+}
+
+func (d *decoder) terror(n *node, tag string, out reflect.Value) {
+	if n.tag != "" {
+		tag = n.tag
+	}
+	value := n.value
+	if tag != yaml_SEQ_TAG && tag != yaml_MAP_TAG {
+		if len(value) > 10 {
+			value = " `" + value[:7] + "...`"
+		} else {
+			value = " `" + value + "`"
+		}
+	}
+	d.terrors = append(d.terrors, fmt.Sprintf("line %d: cannot unmarshal %s%s into %s", n.line+1, shortTag(tag), value, out.Type()))
+}
+
+func (d *decoder) callUnmarshaler(n *node, u Unmarshaler) (good bool) {
+	terrlen := len(d.terrors)
+	err := u.UnmarshalYAML(func(v interface{}) (err error) {
+		defer handleErr(&err)
+		d.unmarshal(n, reflect.ValueOf(v))
+		if len(d.terrors) > terrlen {
+			issues := d.terrors[terrlen:]
+			d.terrors = d.terrors[:terrlen]
+			return &TypeError{issues}
+		}
+		return nil
+	})
+	if e, ok := err.(*TypeError); ok {
+		d.terrors = append(d.terrors, e.Errors...)
+		return false
+	}
+	if err != nil {
+		fail(err)
+	}
+	return true
+}
+
+// d.prepare initializes and dereferences pointers and calls UnmarshalYAML
+// if a value is found to implement it.
+// It returns the initialized and dereferenced out value, whether
+// unmarshalling was already done by UnmarshalYAML, and if so whether
+// its types unmarshalled appropriately.
+//
+// If n holds a null value, prepare returns before doing anything.
+func (d *decoder) prepare(n *node, out reflect.Value) (newout reflect.Value, unmarshaled, good bool) {
+	if n.tag == yaml_NULL_TAG || n.kind == scalarNode && n.tag == "" && (n.value == "null" || n.value == "~" || n.value == "" && n.implicit) {
+		return out, false, false
+	}
+	again := true
+	for again {
+		again = false
+		if out.Kind() == reflect.Ptr {
+			if out.IsNil() {
+				out.Set(reflect.New(out.Type().Elem()))
+			}
+			out = out.Elem()
+			again = true
+		}
+		if out.CanAddr() {
+			if u, ok := out.Addr().Interface().(Unmarshaler); ok {
+				good = d.callUnmarshaler(n, u)
+				return out, true, good
+			}
+		}
+	}
+	return out, false, false
+}
+
+const (
+	// 400,000 decode operations is ~500kb of dense object declarations, or
+	// ~5kb of dense object declarations with 10000% alias expansion
+	alias_ratio_range_low = 400000
+
+	// 4,000,000 decode operations is ~5MB of dense object declarations, or
+	// ~4.5MB of dense object declarations with 10% alias expansion
+	alias_ratio_range_high = 4000000
+
+	// alias_ratio_range is the range over which we scale allowed alias ratios
+	alias_ratio_range = float64(alias_ratio_range_high - alias_ratio_range_low)
+)
+
+func allowedAliasRatio(decodeCount int) float64 {
+	switch {
+	case decodeCount <= alias_ratio_range_low:
+		// allow 99% to come from alias expansion for small-to-medium documents
+		return 0.99
+	case decodeCount >= alias_ratio_range_high:
+		// allow 10% to come from alias expansion for very large documents
+		return 0.10
+	default:
+		// scale smoothly from 99% down to 10% over the range.
+		// this maps to 396,000 - 400,000 allowed alias-driven decodes over the range.
+		// 400,000 decode operations is ~100MB of allocations in worst-case scenarios (single-item maps).
+		return 0.99 - 0.89*(float64(decodeCount-alias_ratio_range_low)/alias_ratio_range)
+	}
+}
+
+func (d *decoder) unmarshal(n *node, out reflect.Value) (good bool) {
+	d.decodeCount++
+	if d.aliasDepth > 0 {
+		d.aliasCount++
+	}
+	if d.aliasCount > 100 && d.decodeCount > 1000 && float64(d.aliasCount)/float64(d.decodeCount) > allowedAliasRatio(d.decodeCount) {
+		failf("document contains excessive aliasing")
+	}
+	switch n.kind {
+	case documentNode:
+		return d.document(n, out)
+	case aliasNode:
+		return d.alias(n, out)
+	}
+	out, unmarshaled, good := d.prepare(n, out)
+	if unmarshaled {
+		return good
+	}
+	switch n.kind {
+	case scalarNode:
+		good = d.scalar(n, out)
+	case mappingNode:
+		good = d.mapping(n, out)
+	case sequenceNode:
+		good = d.sequence(n, out)
+	default:
+		panic("internal error: unknown node kind: " + strconv.Itoa(n.kind))
+	}
+	return good
+}
+
+func (d *decoder) document(n *node, out reflect.Value) (good bool) {
+	if len(n.children) == 1 {
+		d.doc = n
+		d.unmarshal(n.children[0], out)
+		return true
+	}
+	return false
+}
+
+func (d *decoder) alias(n *node, out reflect.Value) (good bool) {
+	if d.aliases[n] {
+		// TODO this could actually be allowed in some circumstances.
+		failf("anchor '%s' value contains itself", n.value)
+	}
+	d.aliases[n] = true
+	d.aliasDepth++
+	good = d.unmarshal(n.alias, out)
+	d.aliasDepth--
+	delete(d.aliases, n)
+	return good
+}
+
+var zeroValue reflect.Value
+
+func resetMap(out reflect.Value) {
+	for _, k := range out.MapKeys() {
+		out.SetMapIndex(k, zeroValue)
+	}
+}
+
+func (d *decoder) scalar(n *node, out reflect.Value) bool {
+	var tag string
+	var resolved interface{}
+	if n.tag == "" && !n.implicit {
+		tag = yaml_STR_TAG
+		resolved = n.value
+	} else {
+		tag, resolved = resolve(n.tag, n.value)
+		if tag == yaml_BINARY_TAG {
+			data, err := base64.StdEncoding.DecodeString(resolved.(string))
+			if err != nil {
+				failf("!!binary value contains invalid base64 data")
+			}
+			resolved = string(data)
+		}
+	}
+	if resolved == nil {
+		if out.Kind() == reflect.Map && !out.CanAddr() {
+			resetMap(out)
+		} else {
+			out.Set(reflect.Zero(out.Type()))
+		}
+		return true
+	}
+	if resolvedv := reflect.ValueOf(resolved); out.Type() == resolvedv.Type() {
+		// We've resolved to exactly the type we want, so use that.
+		out.Set(resolvedv)
+		return true
+	}
+	// Perhaps we can use the value as a TextUnmarshaler to
+	// set its value.
+	if out.CanAddr() {
+		u, ok := out.Addr().Interface().(encoding.TextUnmarshaler)
+		if ok {
+			var text []byte
+			if tag == yaml_BINARY_TAG {
+				text = []byte(resolved.(string))
+			} else {
+				// We let any value be unmarshaled into TextUnmarshaler.
+				// That might be more lax than we'd like, but the
+				// TextUnmarshaler itself should bowl out any dubious values.
+				text = []byte(n.value)
+			}
+			err := u.UnmarshalText(text)
+			if err != nil {
+				fail(err)
+			}
+			return true
+		}
+	}
+	switch out.Kind() {
+	case reflect.String:
+		if tag == yaml_BINARY_TAG {
+			out.SetString(resolved.(string))
+			return true
+		}
+		if resolved != nil {
+			out.SetString(n.value)
+			return true
+		}
+	case reflect.Interface:
+		if resolved == nil {
+			out.Set(reflect.Zero(out.Type()))
+		} else if tag == yaml_TIMESTAMP_TAG {
+			// It looks like a timestamp but for backward compatibility
+			// reasons we set it as a string, so that code that unmarshals
+			// timestamp-like values into interface{} will continue to
+			// see a string and not a time.Time.
+			// TODO(v3) Drop this.
+			out.Set(reflect.ValueOf(n.value))
+		} else {
+			out.Set(reflect.ValueOf(resolved))
+		}
+		return true
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		switch resolved := resolved.(type) {
+		case int:
+			if !out.OverflowInt(int64(resolved)) {
+				out.SetInt(int64(resolved))
+				return true
+			}
+		case int64:
+			if !out.OverflowInt(resolved) {
+				out.SetInt(resolved)
+				return true
+			}
+		case uint64:
+			if resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
+				out.SetInt(int64(resolved))
+				return true
+			}
+		case float64:
+			if resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
+				out.SetInt(int64(resolved))
+				return true
+			}
+		case string:
+			if out.Type() == durationType {
+				d, err := time.ParseDuration(resolved)
+				if err == nil {
+					out.SetInt(int64(d))
+					return true
+				}
+			}
+		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		switch resolved := resolved.(type) {
+		case int:
+			if resolved >= 0 && !out.OverflowUint(uint64(resolved)) {
+				out.SetUint(uint64(resolved))
+				return true
+			}
+		case int64:
+			if resolved >= 0 && !out.OverflowUint(uint64(resolved)) {
+				out.SetUint(uint64(resolved))
+				return true
+			}
+		case uint64:
+			if !out.OverflowUint(uint64(resolved)) {
+				out.SetUint(uint64(resolved))
+				return true
+			}
+		case float64:
+			if resolved <= math.MaxUint64 && !out.OverflowUint(uint64(resolved)) {
+				out.SetUint(uint64(resolved))
+				return true
+			}
+		}
+	case reflect.Bool:
+		switch resolved := resolved.(type) {
+		case bool:
+			out.SetBool(resolved)
+			return true
+		}
+	case reflect.Float32, reflect.Float64:
+		switch resolved := resolved.(type) {
+		case int:
+			out.SetFloat(float64(resolved))
+			return true
+		case int64:
+			out.SetFloat(float64(resolved))
+			return true
+		case uint64:
+			out.SetFloat(float64(resolved))
+			return true
+		case float64:
+			out.SetFloat(resolved)
+			return true
+		}
+	case reflect.Struct:
+		if resolvedv := reflect.ValueOf(resolved); out.Type() == resolvedv.Type() {
+			out.Set(resolvedv)
+			return true
+		}
+	case reflect.Ptr:
+		if out.Type().Elem() == reflect.TypeOf(resolved) {
+			// TODO DOes this make sense? When is out a Ptr except when decoding a nil value?
+			elem := reflect.New(out.Type().Elem())
+			elem.Elem().Set(reflect.ValueOf(resolved))
+			out.Set(elem)
+			return true
+		}
+	}
+	d.terror(n, tag, out)
+	return false
+}
+
+func settableValueOf(i interface{}) reflect.Value {
+	v := reflect.ValueOf(i)
+	sv := reflect.New(v.Type()).Elem()
+	sv.Set(v)
+	return sv
+}
+
+func (d *decoder) sequence(n *node, out reflect.Value) (good bool) {
+	l := len(n.children)
+
+	var iface reflect.Value
+	switch out.Kind() {
+	case reflect.Slice:
+		out.Set(reflect.MakeSlice(out.Type(), l, l))
+	case reflect.Array:
+		if l != out.Len() {
+			failf("invalid array: want %d elements but got %d", out.Len(), l)
+		}
+	case reflect.Interface:
+		// No type hints. Will have to use a generic sequence.
+		iface = out
+		out = settableValueOf(make([]interface{}, l))
+	default:
+		d.terror(n, yaml_SEQ_TAG, out)
+		return false
+	}
+	et := out.Type().Elem()
+
+	j := 0
+	for i := 0; i < l; i++ {
+		e := reflect.New(et).Elem()
+		if ok := d.unmarshal(n.children[i], e); ok {
+			out.Index(j).Set(e)
+			j++
+		}
+	}
+	if out.Kind() != reflect.Array {
+		out.Set(out.Slice(0, j))
+	}
+	if iface.IsValid() {
+		iface.Set(out)
+	}
+	return true
+}
+
+func (d *decoder) mapping(n *node, out reflect.Value) (good bool) {
+	switch out.Kind() {
+	case reflect.Struct:
+		return d.mappingStruct(n, out)
+	case reflect.Slice:
+		return d.mappingSlice(n, out)
+	case reflect.Map:
+		// okay
+	case reflect.Interface:
+		if d.mapType.Kind() == reflect.Map {
+			iface := out
+			out = reflect.MakeMap(d.mapType)
+			iface.Set(out)
+		} else {
+			slicev := reflect.New(d.mapType).Elem()
+			if !d.mappingSlice(n, slicev) {
+				return false
+			}
+			out.Set(slicev)
+			return true
+		}
+	default:
+		d.terror(n, yaml_MAP_TAG, out)
+		return false
+	}
+	outt := out.Type()
+	kt := outt.Key()
+	et := outt.Elem()
+
+	mapType := d.mapType
+	if outt.Key() == ifaceType && outt.Elem() == ifaceType {
+		d.mapType = outt
+	}
+
+	if out.IsNil() {
+		out.Set(reflect.MakeMap(outt))
+	}
+	l := len(n.children)
+	for i := 0; i < l; i += 2 {
+		if isMerge(n.children[i]) {
+			d.merge(n.children[i+1], out)
+			continue
+		}
+		k := reflect.New(kt).Elem()
+		if d.unmarshal(n.children[i], k) {
+			kkind := k.Kind()
+			if kkind == reflect.Interface {
+				kkind = k.Elem().Kind()
+			}
+			if kkind == reflect.Map || kkind == reflect.Slice {
+				failf("invalid map key: %#v", k.Interface())
+			}
+			e := reflect.New(et).Elem()
+			if d.unmarshal(n.children[i+1], e) {
+				d.setMapIndex(n.children[i+1], out, k, e)
+			}
+		}
+	}
+	d.mapType = mapType
+	return true
+}
+
+func (d *decoder) setMapIndex(n *node, out, k, v reflect.Value) {
+	if d.strict && out.MapIndex(k) != zeroValue {
+		d.terrors = append(d.terrors, fmt.Sprintf("line %d: key %#v already set in map", n.line+1, k.Interface()))
+		return
+	}
+	out.SetMapIndex(k, v)
+}
+
+func (d *decoder) mappingSlice(n *node, out reflect.Value) (good bool) {
+	outt := out.Type()
+	if outt.Elem() != mapItemType {
+		d.terror(n, yaml_MAP_TAG, out)
+		return false
+	}
+
+	mapType := d.mapType
+	d.mapType = outt
+
+	var slice []MapItem
+	var l = len(n.children)
+	for i := 0; i < l; i += 2 {
+		if isMerge(n.children[i]) {
+			d.merge(n.children[i+1], out)
+			continue
+		}
+		item := MapItem{}
+		k := reflect.ValueOf(&item.Key).Elem()
+		if d.unmarshal(n.children[i], k) {
+			v := reflect.ValueOf(&item.Value).Elem()
+			if d.unmarshal(n.children[i+1], v) {
+				slice = append(slice, item)
+			}
+		}
+	}
+	out.Set(reflect.ValueOf(slice))
+	d.mapType = mapType
+	return true
+}
+
+func (d *decoder) mappingStruct(n *node, out reflect.Value) (good bool) {
+	sinfo, err := getStructInfo(out.Type())
+	if err != nil {
+		panic(err)
+	}
+	name := settableValueOf("")
+	l := len(n.children)
+
+	var inlineMap reflect.Value
+	var elemType reflect.Type
+	if sinfo.InlineMap != -1 {
+		inlineMap = out.Field(sinfo.InlineMap)
+		inlineMap.Set(reflect.New(inlineMap.Type()).Elem())
+		elemType = inlineMap.Type().Elem()
+	}
+
+	var doneFields []bool
+	if d.strict {
+		doneFields = make([]bool, len(sinfo.FieldsList))
+	}
+	for i := 0; i < l; i += 2 {
+		ni := n.children[i]
+		if isMerge(ni) {
+			d.merge(n.children[i+1], out)
+			continue
+		}
+		if !d.unmarshal(ni, name) {
+			continue
+		}
+		if info, ok := sinfo.FieldsMap[name.String()]; ok {
+			if d.strict {
+				if doneFields[info.Id] {
+					d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s already set in type %s", ni.line+1, name.String(), out.Type()))
+					continue
+				}
+				doneFields[info.Id] = true
+			}
+			var field reflect.Value
+			if info.Inline == nil {
+				field = out.Field(info.Num)
+			} else {
+				field = out.FieldByIndex(info.Inline)
+			}
+			d.unmarshal(n.children[i+1], field)
+		} else if sinfo.InlineMap != -1 {
+			if inlineMap.IsNil() {
+				inlineMap.Set(reflect.MakeMap(inlineMap.Type()))
+			}
+			value := reflect.New(elemType).Elem()
+			d.unmarshal(n.children[i+1], value)
+			d.setMapIndex(n.children[i+1], inlineMap, name, value)
+		} else if d.strict {
+			d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s not found in type %s", ni.line+1, name.String(), out.Type()))
+		}
+	}
+	return true
+}
+
+func failWantMap() {
+	failf("map merge requires map or sequence of maps as the value")
+}
+
+func (d *decoder) merge(n *node, out reflect.Value) {
+	switch n.kind {
+	case mappingNode:
+		d.unmarshal(n, out)
+	case aliasNode:
+		if n.alias != nil && n.alias.kind != mappingNode {
+			failWantMap()
+		}
+		d.unmarshal(n, out)
+	case sequenceNode:
+		// Step backwards as earlier nodes take precedence.
+		for i := len(n.children) - 1; i >= 0; i-- {
+			ni := n.children[i]
+			if ni.kind == aliasNode {
+				if ni.alias != nil && ni.alias.kind != mappingNode {
+					failWantMap()
+				}
+			} else if ni.kind != mappingNode {
+				failWantMap()
+			}
+			d.unmarshal(ni, out)
+		}
+	default:
+		failWantMap()
+	}
+}
+
+func isMerge(n *node) bool {
+	return n.kind == scalarNode && n.value == "<<" && (n.implicit == true || n.tag == yaml_MERGE_TAG)
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/decode_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/decode_test.go
new file mode 100644
index 00000000000..c7d104e9082
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/decode_test.go
@@ -0,0 +1,1367 @@
+package yaml_test
+
+import (
+	"errors"
+	"io"
+	"math"
+	"reflect"
+	"strings"
+	"time"
+
+	. "gopkg.in/check.v1"
+	"gopkg.in/yaml.v2"
+)
+
+var unmarshalIntTest = 123
+
+var unmarshalTests = []struct {
+	data  string
+	value interface{}
+}{
+	{
+		"",
+		(*struct{})(nil),
+	},
+	{
+		"{}", &struct{}{},
+	}, {
+		"v: hi",
+		map[string]string{"v": "hi"},
+	}, {
+		"v: hi", map[string]interface{}{"v": "hi"},
+	}, {
+		"v: true",
+		map[string]string{"v": "true"},
+	}, {
+		"v: true",
+		map[string]interface{}{"v": true},
+	}, {
+		"v: 10",
+		map[string]interface{}{"v": 10},
+	}, {
+		"v: 0b10",
+		map[string]interface{}{"v": 2},
+	}, {
+		"v: 0xA",
+		map[string]interface{}{"v": 10},
+	}, {
+		"v: 4294967296",
+		map[string]int64{"v": 4294967296},
+	}, {
+		"v: 0.1",
+		map[string]interface{}{"v": 0.1},
+	}, {
+		"v: .1",
+		map[string]interface{}{"v": 0.1},
+	}, {
+		"v: .Inf",
+		map[string]interface{}{"v": math.Inf(+1)},
+	}, {
+		"v: -.Inf",
+		map[string]interface{}{"v": math.Inf(-1)},
+	}, {
+		"v: -10",
+		map[string]interface{}{"v": -10},
+	}, {
+		"v: -.1",
+		map[string]interface{}{"v": -0.1},
+	},
+
+	// Simple values.
+	{
+		"123",
+		&unmarshalIntTest,
+	},
+
+	// Floats from spec
+	{
+		"canonical: 6.8523e+5",
+		map[string]interface{}{"canonical": 6.8523e+5},
+	}, {
+		"expo: 685.230_15e+03",
+		map[string]interface{}{"expo": 685.23015e+03},
+	}, {
+		"fixed: 685_230.15",
+		map[string]interface{}{"fixed": 685230.15},
+	}, {
+		"neginf: -.inf",
+		map[string]interface{}{"neginf": math.Inf(-1)},
+	}, {
+		"fixed: 685_230.15",
+		map[string]float64{"fixed": 685230.15},
+	},
+	//{"sexa: 190:20:30.15", map[string]interface{}{"sexa": 0}}, // Unsupported
+	//{"notanum: .NaN", map[string]interface{}{"notanum": math.NaN()}}, // Equality of NaN fails.
+
+	// Bools from spec
+	{
+		"canonical: y",
+		map[string]interface{}{"canonical": true},
+	}, {
+		"answer: NO",
+		map[string]interface{}{"answer": false},
+	}, {
+		"logical: True",
+		map[string]interface{}{"logical": true},
+	}, {
+		"option: on",
+		map[string]interface{}{"option": true},
+	}, {
+		"option: on",
+		map[string]bool{"option": true},
+	},
+	// Ints from spec
+	{
+		"canonical: 685230",
+		map[string]interface{}{"canonical": 685230},
+	}, {
+		"decimal: +685_230",
+		map[string]interface{}{"decimal": 685230},
+	}, {
+		"octal: 02472256",
+		map[string]interface{}{"octal": 685230},
+	}, {
+		"hexa: 0x_0A_74_AE",
+		map[string]interface{}{"hexa": 685230},
+	}, {
+		"bin: 0b1010_0111_0100_1010_1110",
+		map[string]interface{}{"bin": 685230},
+	}, {
+		"bin: -0b101010",
+		map[string]interface{}{"bin": -42},
+	}, {
+		"bin: -0b1000000000000000000000000000000000000000000000000000000000000000",
+		map[string]interface{}{"bin": -9223372036854775808},
+	}, {
+		"decimal: +685_230",
+		map[string]int{"decimal": 685230},
+	},
+
+	//{"sexa: 190:20:30", map[string]interface{}{"sexa": 0}}, // Unsupported
+
+	// Nulls from spec
+	{
+		"empty:",
+		map[string]interface{}{"empty": nil},
+	}, {
+		"canonical: ~",
+		map[string]interface{}{"canonical": nil},
+	}, {
+		"english: null",
+		map[string]interface{}{"english": nil},
+	}, {
+		"~: null key",
+		map[interface{}]string{nil: "null key"},
+	}, {
+		"empty:",
+		map[string]*bool{"empty": nil},
+	},
+
+	// Flow sequence
+	{
+		"seq: [A,B]",
+		map[string]interface{}{"seq": []interface{}{"A", "B"}},
+	}, {
+		"seq: [A,B,C,]",
+		map[string][]string{"seq": []string{"A", "B", "C"}},
+	}, {
+		"seq: [A,1,C]",
+		map[string][]string{"seq": []string{"A", "1", "C"}},
+	}, {
+		"seq: [A,1,C]",
+		map[string][]int{"seq": []int{1}},
+	}, {
+		"seq: [A,1,C]",
+		map[string]interface{}{"seq": []interface{}{"A", 1, "C"}},
+	},
+	// Block sequence
+	{
+		"seq:\n - A\n - B",
+		map[string]interface{}{"seq": []interface{}{"A", "B"}},
+	}, {
+		"seq:\n - A\n - B\n - C",
+		map[string][]string{"seq": []string{"A", "B", "C"}},
+	}, {
+		"seq:\n - A\n - 1\n - C",
+		map[string][]string{"seq": []string{"A", "1", "C"}},
+	}, {
+		"seq:\n - A\n - 1\n - C",
+		map[string][]int{"seq": []int{1}},
+	}, {
+		"seq:\n - A\n - 1\n - C",
+		map[string]interface{}{"seq": []interface{}{"A", 1, "C"}},
+	},
+
+	// Literal block scalar
+	{
+		"scalar: | # Comment\n\n literal\n\n \ttext\n\n",
+		map[string]string{"scalar": "\nliteral\n\n\ttext\n"},
+	},
+
+	// Folded block scalar
+	{
+		"scalar: > # Comment\n\n folded\n line\n \n next\n line\n  * one\n  * two\n\n last\n line\n\n",
+		map[string]string{"scalar": "\nfolded line\nnext line\n * one\n * two\n\nlast line\n"},
+	},
+
+	// Map inside interface with no type hints.
+	{
+		"a: {b: c}",
+		map[interface{}]interface{}{"a": map[interface{}]interface{}{"b": "c"}},
+	},
+
+	// Structs and type conversions.
+	{
+		"hello: world",
+		&struct{ Hello string }{"world"},
+	}, {
+		"a: {b: c}",
+		&struct{ A struct{ B string } }{struct{ B string }{"c"}},
+	}, {
+		"a: {b: c}",
+		&struct{ A *struct{ B string } }{&struct{ B string }{"c"}},
+	}, {
+		"a: {b: c}",
+		&struct{ A map[string]string }{map[string]string{"b": "c"}},
+	}, {
+		"a: {b: c}",
+		&struct{ A *map[string]string }{&map[string]string{"b": "c"}},
+	}, {
+		"a:",
+		&struct{ A map[string]string }{},
+	}, {
+		"a: 1",
+		&struct{ A int }{1},
+	}, {
+		"a: 1",
+		&struct{ A float64 }{1},
+	}, {
+		"a: 1.0",
+		&struct{ A int }{1},
+	}, {
+		"a: 1.0",
+		&struct{ A uint }{1},
+	}, {
+		"a: [1, 2]",
+		&struct{ A []int }{[]int{1, 2}},
+	}, {
+		"a: [1, 2]",
+		&struct{ A [2]int }{[2]int{1, 2}},
+	}, {
+		"a: 1",
+		&struct{ B int }{0},
+	}, {
+		"a: 1",
+		&struct {
+			B int "a"
+		}{1},
+	}, {
+		"a: y",
+		&struct{ A bool }{true},
+	},
+
+	// Some cross type conversions
+	{
+		"v: 42",
+		map[string]uint{"v": 42},
+	}, {
+		"v: -42",
+		map[string]uint{},
+	}, {
+		"v: 4294967296",
+		map[string]uint64{"v": 4294967296},
+	}, {
+		"v: -4294967296",
+		map[string]uint64{},
+	},
+
+	// int
+	{
+		"int_max: 2147483647",
+		map[string]int{"int_max": math.MaxInt32},
+	},
+	{
+		"int_min: -2147483648",
+		map[string]int{"int_min": math.MinInt32},
+	},
+	{
+		"int_overflow: 9223372036854775808", // math.MaxInt64 + 1
+		map[string]int{},
+	},
+
+	// int64
+	{
+		"int64_max: 9223372036854775807",
+		map[string]int64{"int64_max": math.MaxInt64},
+	},
+	{
+		"int64_max_base2: 0b111111111111111111111111111111111111111111111111111111111111111",
+		map[string]int64{"int64_max_base2": math.MaxInt64},
+	},
+	{
+		"int64_min: -9223372036854775808",
+		map[string]int64{"int64_min": math.MinInt64},
+	},
+	{
+		"int64_neg_base2: -0b111111111111111111111111111111111111111111111111111111111111111",
+		map[string]int64{"int64_neg_base2": -math.MaxInt64},
+	},
+	{
+		"int64_overflow: 9223372036854775808", // math.MaxInt64 + 1
+		map[string]int64{},
+	},
+
+	// uint
+	{
+		"uint_min: 0",
+		map[string]uint{"uint_min": 0},
+	},
+	{
+		"uint_max: 4294967295",
+		map[string]uint{"uint_max": math.MaxUint32},
+	},
+	{
+		"uint_underflow: -1",
+		map[string]uint{},
+	},
+
+	// uint64
+	{
+		"uint64_min: 0",
+		map[string]uint{"uint64_min": 0},
+	},
+	{
+		"uint64_max: 18446744073709551615",
+		map[string]uint64{"uint64_max": math.MaxUint64},
+	},
+	{
+		"uint64_max_base2: 0b1111111111111111111111111111111111111111111111111111111111111111",
+		map[string]uint64{"uint64_max_base2": math.MaxUint64},
+	},
+	{
+		"uint64_maxint64: 9223372036854775807",
+		map[string]uint64{"uint64_maxint64": math.MaxInt64},
+	},
+	{
+		"uint64_underflow: -1",
+		map[string]uint64{},
+	},
+
+	// float32
+	{
+		"float32_max: 3.40282346638528859811704183484516925440e+38",
+		map[string]float32{"float32_max": math.MaxFloat32},
+	},
+	{
+		"float32_nonzero: 1.401298464324817070923729583289916131280e-45",
+		map[string]float32{"float32_nonzero": math.SmallestNonzeroFloat32},
+	},
+	{
+		"float32_maxuint64: 18446744073709551615",
+		map[string]float32{"float32_maxuint64": float32(math.MaxUint64)},
+	},
+	{
+		"float32_maxuint64+1: 18446744073709551616",
+		map[string]float32{"float32_maxuint64+1": float32(math.MaxUint64 + 1)},
+	},
+
+	// float64
+	{
+		"float64_max: 1.797693134862315708145274237317043567981e+308",
+		map[string]float64{"float64_max": math.MaxFloat64},
+	},
+	{
+		"float64_nonzero: 4.940656458412465441765687928682213723651e-324",
+		map[string]float64{"float64_nonzero": math.SmallestNonzeroFloat64},
+	},
+	{
+		"float64_maxuint64: 18446744073709551615",
+		map[string]float64{"float64_maxuint64": float64(math.MaxUint64)},
+	},
+	{
+		"float64_maxuint64+1: 18446744073709551616",
+		map[string]float64{"float64_maxuint64+1": float64(math.MaxUint64 + 1)},
+	},
+
+	// Overflow cases.
+	{
+		"v: 4294967297",
+		map[string]int32{},
+	}, {
+		"v: 128",
+		map[string]int8{},
+	},
+
+	// Quoted values.
+	{
+		"'1': '\"2\"'",
+		map[interface{}]interface{}{"1": "\"2\""},
+	}, {
+		"v:\n- A\n- 'B\n\n  C'\n",
+		map[string][]string{"v": []string{"A", "B\nC"}},
+	},
+
+	// Explicit tags.
+	{
+		"v: !!float '1.1'",
+		map[string]interface{}{"v": 1.1},
+	}, {
+		"v: !!float 0",
+		map[string]interface{}{"v": float64(0)},
+	}, {
+		"v: !!float -1",
+		map[string]interface{}{"v": float64(-1)},
+	}, {
+		"v: !!null ''",
+		map[string]interface{}{"v": nil},
+	}, {
+		"%TAG !y! tag:yaml.org,2002:\n---\nv: !y!int '1'",
+		map[string]interface{}{"v": 1},
+	},
+
+	// Non-specific tag (Issue #75)
+	{
+		"v: ! test",
+		map[string]interface{}{"v": "test"},
+	},
+
+	// Anchors and aliases.
+	{
+		"a: &x 1\nb: &y 2\nc: *x\nd: *y\n",
+		&struct{ A, B, C, D int }{1, 2, 1, 2},
+	}, {
+		"a: &a {c: 1}\nb: *a",
+		&struct {
+			A, B struct {
+				C int
+			}
+		}{struct{ C int }{1}, struct{ C int }{1}},
+	}, {
+		"a: &a [1, 2]\nb: *a",
+		&struct{ B []int }{[]int{1, 2}},
+	},
+
+	// Bug #1133337
+	{
+		"foo: ''",
+		map[string]*string{"foo": new(string)},
+	}, {
+		"foo: null",
+		map[string]*string{"foo": nil},
+	}, {
+		"foo: null",
+		map[string]string{"foo": ""},
+	}, {
+		"foo: null",
+		map[string]interface{}{"foo": nil},
+	},
+
+	// Support for ~
+	{
+		"foo: ~",
+		map[string]*string{"foo": nil},
+	}, {
+		"foo: ~",
+		map[string]string{"foo": ""},
+	}, {
+		"foo: ~",
+		map[string]interface{}{"foo": nil},
+	},
+
+	// Ignored field
+	{
+		"a: 1\nb: 2\n",
+		&struct {
+			A int
+			B int "-"
+		}{1, 0},
+	},
+
+	// Bug #1191981
+	{
+		"" +
+			"%YAML 1.1\n" +
+			"--- !!str\n" +
+			`"Generic line break (no glyph)\n\` + "\n" +
+			` Generic line break (glyphed)\n\` + "\n" +
+			` Line separator\u2028\` + "\n" +
+			` Paragraph separator\u2029"` + "\n",
+		"" +
+			"Generic line break (no glyph)\n" +
+			"Generic line break (glyphed)\n" +
+			"Line separator\u2028Paragraph separator\u2029",
+	},
+
+	// Struct inlining
+	{
+		"a: 1\nb: 2\nc: 3\n",
+		&struct {
+			A int
+			C inlineB `yaml:",inline"`
+		}{1, inlineB{2, inlineC{3}}},
+	},
+
+	// Map inlining
+	{
+		"a: 1\nb: 2\nc: 3\n",
+		&struct {
+			A int
+			C map[string]int `yaml:",inline"`
+		}{1, map[string]int{"b": 2, "c": 3}},
+	},
+
+	// bug 1243827
+	{
+		"a: -b_c",
+		map[string]interface{}{"a": "-b_c"},
+	},
+	{
+		"a: +b_c",
+		map[string]interface{}{"a": "+b_c"},
+	},
+	{
+		"a: 50cent_of_dollar",
+		map[string]interface{}{"a": "50cent_of_dollar"},
+	},
+
+	// issue #295 (allow scalars with colons in flow mappings and sequences)
+	{
+		"a: {b: https://github.com/go-yaml/yaml}",
+		map[string]interface{}{"a": map[interface{}]interface{}{
+			"b": "https://github.com/go-yaml/yaml",
+		}},
+	},
+	{
+		"a: [https://github.com/go-yaml/yaml]",
+		map[string]interface{}{"a": []interface{}{"https://github.com/go-yaml/yaml"}},
+	},
+
+	// Duration
+	{
+		"a: 3s",
+		map[string]time.Duration{"a": 3 * time.Second},
+	},
+
+	// Issue #24.
+	{
+		"a: <foo>",
+		map[string]string{"a": "<foo>"},
+	},
+
+	// Base 60 floats are obsolete and unsupported.
+	{
+		"a: 1:1\n",
+		map[string]string{"a": "1:1"},
+	},
+
+	// Binary data.
+	{
+		"a: !!binary gIGC\n",
+		map[string]string{"a": "\x80\x81\x82"},
+	}, {
+		"a: !!binary |\n  " + strings.Repeat("kJCQ", 17) + "kJ\n  CQ\n",
+		map[string]string{"a": strings.Repeat("\x90", 54)},
+	}, {
+		"a: !!binary |\n  " + strings.Repeat("A", 70) + "\n  ==\n",
+		map[string]string{"a": strings.Repeat("\x00", 52)},
+	},
+
+	// Ordered maps.
+	{
+		"{b: 2, a: 1, d: 4, c: 3, sub: {e: 5}}",
+		&yaml.MapSlice{{"b", 2}, {"a", 1}, {"d", 4}, {"c", 3}, {"sub", yaml.MapSlice{{"e", 5}}}},
+	},
+
+	// Issue #39.
+	{
+		"a:\n b:\n  c: d\n",
+		map[string]struct{ B interface{} }{"a": {map[interface{}]interface{}{"c": "d"}}},
+	},
+
+	// Custom map type.
+	{
+		"a: {b: c}",
+		M{"a": M{"b": "c"}},
+	},
+
+	// Support encoding.TextUnmarshaler.
+	{
+		"a: 1.2.3.4\n",
+		map[string]textUnmarshaler{"a": textUnmarshaler{S: "1.2.3.4"}},
+	},
+	{
+		"a: 2015-02-24T18:19:39Z\n",
+		map[string]textUnmarshaler{"a": textUnmarshaler{"2015-02-24T18:19:39Z"}},
+	},
+
+	// Timestamps
+	{
+		// Date only.
+		"a: 2015-01-01\n",
+		map[string]time.Time{"a": time.Date(2015, 1, 1, 0, 0, 0, 0, time.UTC)},
+	},
+	{
+		// RFC3339
+		"a: 2015-02-24T18:19:39.12Z\n",
+		map[string]time.Time{"a": time.Date(2015, 2, 24, 18, 19, 39, .12e9, time.UTC)},
+	},
+	{
+		// RFC3339 with short dates.
+		"a: 2015-2-3T3:4:5Z",
+		map[string]time.Time{"a": time.Date(2015, 2, 3, 3, 4, 5, 0, time.UTC)},
+	},
+	{
+		// ISO8601 lower case t
+		"a: 2015-02-24t18:19:39Z\n",
+		map[string]time.Time{"a": time.Date(2015, 2, 24, 18, 19, 39, 0, time.UTC)},
+	},
+	{
+		// space separate, no time zone
+		"a: 2015-02-24 18:19:39\n",
+		map[string]time.Time{"a": time.Date(2015, 2, 24, 18, 19, 39, 0, time.UTC)},
+	},
+	// Some cases not currently handled. Uncomment these when
+	// the code is fixed.
+	//	{
+	//		// space separated with time zone
+	//		"a: 2001-12-14 21:59:43.10 -5",
+	//		map[string]interface{}{"a": time.Date(2001, 12, 14, 21, 59, 43, .1e9, time.UTC)},
+	//	},
+	//	{
+	//		// arbitrary whitespace between fields
+	//		"a: 2001-12-14 \t\t \t21:59:43.10 \t Z",
+	//		map[string]interface{}{"a": time.Date(2001, 12, 14, 21, 59, 43, .1e9, time.UTC)},
+	//	},
+	{
+		// explicit string tag
+		"a: !!str 2015-01-01",
+		map[string]interface{}{"a": "2015-01-01"},
+	},
+	{
+		// explicit timestamp tag on quoted string
+		"a: !!timestamp \"2015-01-01\"",
+		map[string]time.Time{"a": time.Date(2015, 1, 1, 0, 0, 0, 0, time.UTC)},
+	},
+	{
+		// explicit timestamp tag on unquoted string
+		"a: !!timestamp 2015-01-01",
+		map[string]time.Time{"a": time.Date(2015, 1, 1, 0, 0, 0, 0, time.UTC)},
+	},
+	{
+		// quoted string that's a valid timestamp
+		"a: \"2015-01-01\"",
+		map[string]interface{}{"a": "2015-01-01"},
+	},
+	{
+		// explicit timestamp tag into interface.
+		"a: !!timestamp \"2015-01-01\"",
+		map[string]interface{}{"a": "2015-01-01"},
+	},
+	{
+		// implicit timestamp tag into interface.
+		"a: 2015-01-01",
+		map[string]interface{}{"a": "2015-01-01"},
+	},
+
+	// Encode empty lists as zero-length slices.
+	{
+		"a: []",
+		&struct{ A []int }{[]int{}},
+	},
+
+	// UTF-16-LE
+	{
+		"\xff\xfe\xf1\x00o\x00\xf1\x00o\x00:\x00 \x00v\x00e\x00r\x00y\x00 \x00y\x00e\x00s\x00\n\x00",
+		M{"ñoño": "very yes"},
+	},
+	// UTF-16-LE with surrogate.
+	{
+		"\xff\xfe\xf1\x00o\x00\xf1\x00o\x00:\x00 \x00v\x00e\x00r\x00y\x00 \x00y\x00e\x00s\x00 \x00=\xd8\xd4\xdf\n\x00",
+		M{"ñoño": "very yes 🟔"},
+	},
+
+	// UTF-16-BE
+	{
+		"\xfe\xff\x00\xf1\x00o\x00\xf1\x00o\x00:\x00 \x00v\x00e\x00r\x00y\x00 \x00y\x00e\x00s\x00\n",
+		M{"ñoño": "very yes"},
+	},
+	// UTF-16-BE with surrogate.
+	{
+		"\xfe\xff\x00\xf1\x00o\x00\xf1\x00o\x00:\x00 \x00v\x00e\x00r\x00y\x00 \x00y\x00e\x00s\x00 \xd8=\xdf\xd4\x00\n",
+		M{"ñoño": "very yes 🟔"},
+	},
+
+	// This *is* in fact a float number, per the spec. #171 was a mistake.
+	{
+		"a: 123456e1\n",
+		M{"a": 123456e1},
+	}, {
+		"a: 123456E1\n",
+		M{"a": 123456E1},
+	},
+	// yaml-test-suite 3GZX: Spec Example 7.1. Alias Nodes
+	{
+		"First occurrence: &anchor Foo\nSecond occurrence: *anchor\nOverride anchor: &anchor Bar\nReuse anchor: *anchor\n",
+		map[interface{}]interface{}{
+			"Reuse anchor":      "Bar",
+			"First occurrence":  "Foo",
+			"Second occurrence": "Foo",
+			"Override anchor":   "Bar",
+		},
+	},
+	// Single document with garbage following it.
+	{
+		"---\nhello\n...\n}not yaml",
+		"hello",
+	},
+	{
+		"a: 5\n",
+		&struct{ A jsonNumberT }{"5"},
+	},
+	{
+		"a: 5.5\n",
+		&struct{ A jsonNumberT }{"5.5"},
+	},
+	{
+		`
+a:
+  b
+b:
+  ? a
+  : a`,
+		&M{"a": "b",
+			"b": M{
+				"a": "a",
+			}},
+	},
+}
+
+type M map[interface{}]interface{}
+
+type inlineB struct {
+	B       int
+	inlineC `yaml:",inline"`
+}
+
+type inlineC struct {
+	C int
+}
+
+func (s *S) TestUnmarshal(c *C) {
+	for i, item := range unmarshalTests {
+		c.Logf("test %d: %q", i, item.data)
+		t := reflect.ValueOf(item.value).Type()
+		value := reflect.New(t)
+		err := yaml.Unmarshal([]byte(item.data), value.Interface())
+		if _, ok := err.(*yaml.TypeError); !ok {
+			c.Assert(err, IsNil)
+		}
+		c.Assert(value.Elem().Interface(), DeepEquals, item.value, Commentf("error: %v", err))
+	}
+}
+
+// TODO(v3): This test should also work when unmarshaling onto an interface{}.
+func (s *S) TestUnmarshalFullTimestamp(c *C) {
+	// Full timestamp in same format as encoded. This is confirmed to be
+	// properly decoded by Python as a timestamp as well.
+	var str = "2015-02-24T18:19:39.123456789-03:00"
+	var t time.Time
+	err := yaml.Unmarshal([]byte(str), &t)
+	c.Assert(err, IsNil)
+	c.Assert(t, Equals, time.Date(2015, 2, 24, 18, 19, 39, 123456789, t.Location()))
+	c.Assert(t.In(time.UTC), Equals, time.Date(2015, 2, 24, 21, 19, 39, 123456789, time.UTC))
+}
+
+func (s *S) TestDecoderSingleDocument(c *C) {
+	// Test that Decoder.Decode works as expected on
+	// all the unmarshal tests.
+	for i, item := range unmarshalTests {
+		c.Logf("test %d: %q", i, item.data)
+		if item.data == "" {
+			// Behaviour differs when there's no YAML.
+			continue
+		}
+		t := reflect.ValueOf(item.value).Type()
+		value := reflect.New(t)
+		err := yaml.NewDecoder(strings.NewReader(item.data)).Decode(value.Interface())
+		if _, ok := err.(*yaml.TypeError); !ok {
+			c.Assert(err, IsNil)
+		}
+		c.Assert(value.Elem().Interface(), DeepEquals, item.value)
+	}
+}
+
+var decoderTests = []struct {
+	data   string
+	values []interface{}
+}{{
+	"",
+	nil,
+}, {
+	"a: b",
+	[]interface{}{
+		map[interface{}]interface{}{"a": "b"},
+	},
+}, {
+	"---\na: b\n...\n",
+	[]interface{}{
+		map[interface{}]interface{}{"a": "b"},
+	},
+}, {
+	"---\n'hello'\n...\n---\ngoodbye\n...\n",
+	[]interface{}{
+		"hello",
+		"goodbye",
+	},
+}}
+
+func (s *S) TestDecoder(c *C) {
+	for i, item := range decoderTests {
+		c.Logf("test %d: %q", i, item.data)
+		var values []interface{}
+		dec := yaml.NewDecoder(strings.NewReader(item.data))
+		for {
+			var value interface{}
+			err := dec.Decode(&value)
+			if err == io.EOF {
+				break
+			}
+			c.Assert(err, IsNil)
+			values = append(values, value)
+		}
+		c.Assert(values, DeepEquals, item.values)
+	}
+}
+
+type errReader struct{}
+
+func (errReader) Read([]byte) (int, error) {
+	return 0, errors.New("some read error")
+}
+
+func (s *S) TestDecoderReadError(c *C) {
+	err := yaml.NewDecoder(errReader{}).Decode(&struct{}{})
+	c.Assert(err, ErrorMatches, `yaml: input error: some read error`)
+}
+
+func (s *S) TestUnmarshalNaN(c *C) {
+	value := map[string]interface{}{}
+	err := yaml.Unmarshal([]byte("notanum: .NaN"), &value)
+	c.Assert(err, IsNil)
+	c.Assert(math.IsNaN(value["notanum"].(float64)), Equals, true)
+}
+
+var unmarshalErrorTests = []struct {
+	data, error string
+}{
+	{"v: !!float 'error'", "yaml: cannot decode !!str `error` as a !!float"},
+	{"v: [A,", "yaml: line 1: did not find expected node content"},
+	{"v:\n- [A,", "yaml: line 2: did not find expected node content"},
+	{"a:\n- b: *,", "yaml: line 2: did not find expected alphabetic or numeric character"},
+	{"a: *b\n", "yaml: unknown anchor 'b' referenced"},
+	{"a: &a\n  b: *a\n", "yaml: anchor 'a' value contains itself"},
+	{"a: &x null\n<<:\n- *x\nb: &x {}\n", `yaml: map merge requires map or sequence of maps as the value`}, // Issue #529.
+	{"value: -", "yaml: block sequence entries are not allowed in this context"},
+	{"a: !!binary ==", "yaml: !!binary value contains invalid base64 data"},
+	{"{[.]}", `yaml: invalid map key: \[\]interface \{\}\{"\."\}`},
+	{"{{.}}", `yaml: invalid map key: map\[interface\ \{\}\]interface \{\}\{".":interface \{\}\(nil\)\}`},
+	{"b: *a\na: &a {c: 1}", `yaml: unknown anchor 'a' referenced`},
+	{"%TAG !%79! tag:yaml.org,2002:\n---\nv: !%79!int '1'", "yaml: did not find expected whitespace"},
+	{"a:\n  1:\nb\n  2:", ".*could not find expected ':'"},
+	{
+		"a: &a [00,00,00,00,00,00,00,00,00]\n" +
+		"b: &b [*a,*a,*a,*a,*a,*a,*a,*a,*a]\n" +
+		"c: &c [*b,*b,*b,*b,*b,*b,*b,*b,*b]\n" +
+		"d: &d [*c,*c,*c,*c,*c,*c,*c,*c,*c]\n" +
+		"e: &e [*d,*d,*d,*d,*d,*d,*d,*d,*d]\n" +
+		"f: &f [*e,*e,*e,*e,*e,*e,*e,*e,*e]\n" +
+		"g: &g [*f,*f,*f,*f,*f,*f,*f,*f,*f]\n" +
+		"h: &h [*g,*g,*g,*g,*g,*g,*g,*g,*g]\n" +
+		"i: &i [*h,*h,*h,*h,*h,*h,*h,*h,*h]\n",
+		"yaml: document contains excessive aliasing",
+	},
+}
+
+func (s *S) TestUnmarshalErrors(c *C) {
+	for i, item := range unmarshalErrorTests {
+		c.Logf("test %d: %q", i, item.data)
+		var value interface{}
+		err := yaml.Unmarshal([]byte(item.data), &value)
+		c.Assert(err, ErrorMatches, item.error, Commentf("Partial unmarshal: %#v", value))
+
+		if strings.Contains(item.data, ":") {
+			// Repeat test with typed value.
+			var value map[string]interface{}
+			err := yaml.Unmarshal([]byte(item.data), &value)
+			c.Assert(err, ErrorMatches, item.error, Commentf("Partial unmarshal: %#v", value))
+		}
+	}
+}
+
+func (s *S) TestDecoderErrors(c *C) {
+	for _, item := range unmarshalErrorTests {
+		var value interface{}
+		err := yaml.NewDecoder(strings.NewReader(item.data)).Decode(&value)
+		c.Assert(err, ErrorMatches, item.error, Commentf("Partial unmarshal: %#v", value))
+	}
+}
+
+var unmarshalerTests = []struct {
+	data, tag string
+	value     interface{}
+}{
+	{"_: {hi: there}", "!!map", map[interface{}]interface{}{"hi": "there"}},
+	{"_: [1,A]", "!!seq", []interface{}{1, "A"}},
+	{"_: 10", "!!int", 10},
+	{"_: null", "!!null", nil},
+	{`_: BAR!`, "!!str", "BAR!"},
+	{`_: "BAR!"`, "!!str", "BAR!"},
+	{"_: !!foo 'BAR!'", "!!foo", "BAR!"},
+	{`_: ""`, "!!str", ""},
+}
+
+var unmarshalerResult = map[int]error{}
+
+type unmarshalerType struct {
+	value interface{}
+}
+
+func (o *unmarshalerType) UnmarshalYAML(unmarshal func(v interface{}) error) error {
+	if err := unmarshal(&o.value); err != nil {
+		return err
+	}
+	if i, ok := o.value.(int); ok {
+		if result, ok := unmarshalerResult[i]; ok {
+			return result
+		}
+	}
+	return nil
+}
+
+type unmarshalerPointer struct {
+	Field *unmarshalerType "_"
+}
+
+type unmarshalerValue struct {
+	Field unmarshalerType "_"
+}
+
+func (s *S) TestUnmarshalerPointerField(c *C) {
+	for _, item := range unmarshalerTests {
+		obj := &unmarshalerPointer{}
+		err := yaml.Unmarshal([]byte(item.data), obj)
+		c.Assert(err, IsNil)
+		if item.value == nil {
+			c.Assert(obj.Field, IsNil)
+		} else {
+			c.Assert(obj.Field, NotNil, Commentf("Pointer not initialized (%#v)", item.value))
+			c.Assert(obj.Field.value, DeepEquals, item.value)
+		}
+	}
+}
+
+func (s *S) TestUnmarshalerValueField(c *C) {
+	for _, item := range unmarshalerTests {
+		obj := &unmarshalerValue{}
+		err := yaml.Unmarshal([]byte(item.data), obj)
+		c.Assert(err, IsNil)
+		c.Assert(obj.Field, NotNil, Commentf("Pointer not initialized (%#v)", item.value))
+		c.Assert(obj.Field.value, DeepEquals, item.value)
+	}
+}
+
+func (s *S) TestUnmarshalerWholeDocument(c *C) {
+	obj := &unmarshalerType{}
+	err := yaml.Unmarshal([]byte(unmarshalerTests[0].data), obj)
+	c.Assert(err, IsNil)
+	value, ok := obj.value.(map[interface{}]interface{})
+	c.Assert(ok, Equals, true, Commentf("value: %#v", obj.value))
+	c.Assert(value["_"], DeepEquals, unmarshalerTests[0].value)
+}
+
+func (s *S) TestUnmarshalerTypeError(c *C) {
+	unmarshalerResult[2] = &yaml.TypeError{[]string{"foo"}}
+	unmarshalerResult[4] = &yaml.TypeError{[]string{"bar"}}
+	defer func() {
+		delete(unmarshalerResult, 2)
+		delete(unmarshalerResult, 4)
+	}()
+
+	type T struct {
+		Before int
+		After  int
+		M      map[string]*unmarshalerType
+	}
+	var v T
+	data := `{before: A, m: {abc: 1, def: 2, ghi: 3, jkl: 4}, after: B}`
+	err := yaml.Unmarshal([]byte(data), &v)
+	c.Assert(err, ErrorMatches, ""+
+		"yaml: unmarshal errors:\n"+
+		"  line 1: cannot unmarshal !!str `A` into int\n"+
+		"  foo\n"+
+		"  bar\n"+
+		"  line 1: cannot unmarshal !!str `B` into int")
+	c.Assert(v.M["abc"], NotNil)
+	c.Assert(v.M["def"], IsNil)
+	c.Assert(v.M["ghi"], NotNil)
+	c.Assert(v.M["jkl"], IsNil)
+
+	c.Assert(v.M["abc"].value, Equals, 1)
+	c.Assert(v.M["ghi"].value, Equals, 3)
+}
+
+type proxyTypeError struct{}
+
+func (v *proxyTypeError) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	var a int32
+	var b int64
+	if err := unmarshal(&s); err != nil {
+		panic(err)
+	}
+	if s == "a" {
+		if err := unmarshal(&b); err == nil {
+			panic("should have failed")
+		}
+		return unmarshal(&a)
+	}
+	if err := unmarshal(&a); err == nil {
+		panic("should have failed")
+	}
+	return unmarshal(&b)
+}
+
+func (s *S) TestUnmarshalerTypeErrorProxying(c *C) {
+	type T struct {
+		Before int
+		After  int
+		M      map[string]*proxyTypeError
+	}
+	var v T
+	data := `{before: A, m: {abc: a, def: b}, after: B}`
+	err := yaml.Unmarshal([]byte(data), &v)
+	c.Assert(err, ErrorMatches, ""+
+		"yaml: unmarshal errors:\n"+
+		"  line 1: cannot unmarshal !!str `A` into int\n"+
+		"  line 1: cannot unmarshal !!str `a` into int32\n"+
+		"  line 1: cannot unmarshal !!str `b` into int64\n"+
+		"  line 1: cannot unmarshal !!str `B` into int")
+}
+
+type failingUnmarshaler struct{}
+
+var failingErr = errors.New("failingErr")
+
+func (ft *failingUnmarshaler) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	return failingErr
+}
+
+func (s *S) TestUnmarshalerError(c *C) {
+	err := yaml.Unmarshal([]byte("a: b"), &failingUnmarshaler{})
+	c.Assert(err, Equals, failingErr)
+}
+
+type sliceUnmarshaler []int
+
+func (su *sliceUnmarshaler) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var slice []int
+	err := unmarshal(&slice)
+	if err == nil {
+		*su = slice
+		return nil
+	}
+
+	var intVal int
+	err = unmarshal(&intVal)
+	if err == nil {
+		*su = []int{intVal}
+		return nil
+	}
+
+	return err
+}
+
+func (s *S) TestUnmarshalerRetry(c *C) {
+	var su sliceUnmarshaler
+	err := yaml.Unmarshal([]byte("[1, 2, 3]"), &su)
+	c.Assert(err, IsNil)
+	c.Assert(su, DeepEquals, sliceUnmarshaler([]int{1, 2, 3}))
+
+	err = yaml.Unmarshal([]byte("1"), &su)
+	c.Assert(err, IsNil)
+	c.Assert(su, DeepEquals, sliceUnmarshaler([]int{1}))
+}
+
+// From http://yaml.org/type/merge.html
+var mergeTests = `
+anchors:
+  list:
+    - &CENTER { "x": 1, "y": 2 }
+    - &LEFT   { "x": 0, "y": 2 }
+    - &BIG    { "r": 10 }
+    - &SMALL  { "r": 1 }
+
+# All the following maps are equal:
+
+plain:
+  # Explicit keys
+  "x": 1
+  "y": 2
+  "r": 10
+  label: center/big
+
+mergeOne:
+  # Merge one map
+  << : *CENTER
+  "r": 10
+  label: center/big
+
+mergeMultiple:
+  # Merge multiple maps
+  << : [ *CENTER, *BIG ]
+  label: center/big
+
+override:
+  # Override
+  << : [ *BIG, *LEFT, *SMALL ]
+  "x": 1
+  label: center/big
+
+shortTag:
+  # Explicit short merge tag
+  !!merge "<<" : [ *CENTER, *BIG ]
+  label: center/big
+
+longTag:
+  # Explicit merge long tag
+  !<tag:yaml.org,2002:merge> "<<" : [ *CENTER, *BIG ]
+  label: center/big
+
+inlineMap:
+  # Inlined map 
+  << : {"x": 1, "y": 2, "r": 10}
+  label: center/big
+
+inlineSequenceMap:
+  # Inlined map in sequence
+  << : [ *CENTER, {"r": 10} ]
+  label: center/big
+`
+
+func (s *S) TestMerge(c *C) {
+	var want = map[interface{}]interface{}{
+		"x":     1,
+		"y":     2,
+		"r":     10,
+		"label": "center/big",
+	}
+
+	var m map[interface{}]interface{}
+	err := yaml.Unmarshal([]byte(mergeTests), &m)
+	c.Assert(err, IsNil)
+	for name, test := range m {
+		if name == "anchors" {
+			continue
+		}
+		c.Assert(test, DeepEquals, want, Commentf("test %q failed", name))
+	}
+}
+
+func (s *S) TestMergeStruct(c *C) {
+	type Data struct {
+		X, Y, R int
+		Label   string
+	}
+	want := Data{1, 2, 10, "center/big"}
+
+	var m map[string]Data
+	err := yaml.Unmarshal([]byte(mergeTests), &m)
+	c.Assert(err, IsNil)
+	for name, test := range m {
+		if name == "anchors" {
+			continue
+		}
+		c.Assert(test, Equals, want, Commentf("test %q failed", name))
+	}
+}
+
+var unmarshalNullTests = []func() interface{}{
+	func() interface{} { var v interface{}; v = "v"; return &v },
+	func() interface{} { var s = "s"; return &s },
+	func() interface{} { var s = "s"; sptr := &s; return &sptr },
+	func() interface{} { var i = 1; return &i },
+	func() interface{} { var i = 1; iptr := &i; return &iptr },
+	func() interface{} { m := map[string]int{"s": 1}; return &m },
+	func() interface{} { m := map[string]int{"s": 1}; return m },
+}
+
+func (s *S) TestUnmarshalNull(c *C) {
+	for _, test := range unmarshalNullTests {
+		item := test()
+		zero := reflect.Zero(reflect.TypeOf(item).Elem()).Interface()
+		err := yaml.Unmarshal([]byte("null"), item)
+		c.Assert(err, IsNil)
+		if reflect.TypeOf(item).Kind() == reflect.Map {
+			c.Assert(reflect.ValueOf(item).Interface(), DeepEquals, reflect.MakeMap(reflect.TypeOf(item)).Interface())
+		} else {
+			c.Assert(reflect.ValueOf(item).Elem().Interface(), DeepEquals, zero)
+		}
+	}
+}
+
+func (s *S) TestUnmarshalSliceOnPreset(c *C) {
+	// Issue #48.
+	v := struct{ A []int }{[]int{1}}
+	yaml.Unmarshal([]byte("a: [2]"), &v)
+	c.Assert(v.A, DeepEquals, []int{2})
+}
+
+var unmarshalStrictTests = []struct {
+	data  string
+	value interface{}
+	error string
+}{{
+	data:  "a: 1\nc: 2\n",
+	value: struct{ A, B int }{A: 1},
+	error: `yaml: unmarshal errors:\n  line 2: field c not found in type struct { A int; B int }`,
+}, {
+	data:  "a: 1\nb: 2\na: 3\n",
+	value: struct{ A, B int }{A: 3, B: 2},
+	error: `yaml: unmarshal errors:\n  line 3: field a already set in type struct { A int; B int }`,
+}, {
+	data: "c: 3\na: 1\nb: 2\nc: 4\n",
+	value: struct {
+		A       int
+		inlineB `yaml:",inline"`
+	}{
+		A: 1,
+		inlineB: inlineB{
+			B: 2,
+			inlineC: inlineC{
+				C: 4,
+			},
+		},
+	},
+	error: `yaml: unmarshal errors:\n  line 4: field c already set in type struct { A int; yaml_test.inlineB "yaml:\\",inline\\"" }`,
+}, {
+	data: "c: 0\na: 1\nb: 2\nc: 1\n",
+	value: struct {
+		A       int
+		inlineB `yaml:",inline"`
+	}{
+		A: 1,
+		inlineB: inlineB{
+			B: 2,
+			inlineC: inlineC{
+				C: 1,
+			},
+		},
+	},
+	error: `yaml: unmarshal errors:\n  line 4: field c already set in type struct { A int; yaml_test.inlineB "yaml:\\",inline\\"" }`,
+}, {
+	data: "c: 1\na: 1\nb: 2\nc: 3\n",
+	value: struct {
+		A int
+		M map[string]interface{} `yaml:",inline"`
+	}{
+		A: 1,
+		M: map[string]interface{}{
+			"b": 2,
+			"c": 3,
+		},
+	},
+	error: `yaml: unmarshal errors:\n  line 4: key "c" already set in map`,
+}, {
+	data: "a: 1\n9: 2\nnull: 3\n9: 4",
+	value: map[interface{}]interface{}{
+		"a": 1,
+		nil: 3,
+		9:   4,
+	},
+	error: `yaml: unmarshal errors:\n  line 4: key 9 already set in map`,
+}}
+
+func (s *S) TestUnmarshalStrict(c *C) {
+	for i, item := range unmarshalStrictTests {
+		c.Logf("test %d: %q", i, item.data)
+		// First test that normal Unmarshal unmarshals to the expected value.
+		t := reflect.ValueOf(item.value).Type()
+		value := reflect.New(t)
+		err := yaml.Unmarshal([]byte(item.data), value.Interface())
+		c.Assert(err, Equals, nil)
+		c.Assert(value.Elem().Interface(), DeepEquals, item.value)
+
+		// Then test that UnmarshalStrict fails on the same thing.
+		t = reflect.ValueOf(item.value).Type()
+		value = reflect.New(t)
+		err = yaml.UnmarshalStrict([]byte(item.data), value.Interface())
+		c.Assert(err, ErrorMatches, item.error)
+	}
+}
+
+type textUnmarshaler struct {
+	S string
+}
+
+func (t *textUnmarshaler) UnmarshalText(s []byte) error {
+	t.S = string(s)
+	return nil
+}
+
+func (s *S) TestFuzzCrashers(c *C) {
+	cases := []string{
+		// runtime error: index out of range
+		"\"\\0\\\r\n",
+
+		// should not happen
+		"  0: [\n] 0",
+		"? ? \"\n\" 0",
+		"    - {\n000}0",
+		"0:\n  0: [0\n] 0",
+		"    - \"\n000\"0",
+		"    - \"\n000\"\"",
+		"0:\n    - {\n000}0",
+		"0:\n    - \"\n000\"0",
+		"0:\n    - \"\n000\"\"",
+
+		// runtime error: index out of range
+		" \ufeff\n",
+		"? \ufeff\n",
+		"? \ufeff:\n",
+		"0: \ufeff\n",
+		"? \ufeff: \ufeff\n",
+	}
+	for _, data := range cases {
+		var v interface{}
+		_ = yaml.Unmarshal([]byte(data), &v)
+	}
+}
+
+//var data []byte
+//func init() {
+//	var err error
+//	data, err = ioutil.ReadFile("/tmp/file.yaml")
+//	if err != nil {
+//		panic(err)
+//	}
+//}
+//
+//func (s *S) BenchmarkUnmarshal(c *C) {
+//	var err error
+//	for i := 0; i < c.N; i++ {
+//		var v map[string]interface{}
+//		err = yaml.Unmarshal(data, &v)
+//	}
+//	if err != nil {
+//		panic(err)
+//	}
+//}
+//
+//func (s *S) BenchmarkMarshal(c *C) {
+//	var v map[string]interface{}
+//	yaml.Unmarshal(data, &v)
+//	c.ResetTimer()
+//	for i := 0; i < c.N; i++ {
+//		yaml.Marshal(&v)
+//	}
+//}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/emitterc.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/emitterc.go
new file mode 100644
index 00000000000..a1c2cc52627
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/emitterc.go
@@ -0,0 +1,1685 @@
+package yaml
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// Flush the buffer if needed.
+func flush(emitter *yaml_emitter_t) bool {
+	if emitter.buffer_pos+5 >= len(emitter.buffer) {
+		return yaml_emitter_flush(emitter)
+	}
+	return true
+}
+
+// Put a character to the output buffer.
+func put(emitter *yaml_emitter_t, value byte) bool {
+	if emitter.buffer_pos+5 >= len(emitter.buffer) && !yaml_emitter_flush(emitter) {
+		return false
+	}
+	emitter.buffer[emitter.buffer_pos] = value
+	emitter.buffer_pos++
+	emitter.column++
+	return true
+}
+
+// Put a line break to the output buffer.
+func put_break(emitter *yaml_emitter_t) bool {
+	if emitter.buffer_pos+5 >= len(emitter.buffer) && !yaml_emitter_flush(emitter) {
+		return false
+	}
+	switch emitter.line_break {
+	case yaml_CR_BREAK:
+		emitter.buffer[emitter.buffer_pos] = '\r'
+		emitter.buffer_pos += 1
+	case yaml_LN_BREAK:
+		emitter.buffer[emitter.buffer_pos] = '\n'
+		emitter.buffer_pos += 1
+	case yaml_CRLN_BREAK:
+		emitter.buffer[emitter.buffer_pos+0] = '\r'
+		emitter.buffer[emitter.buffer_pos+1] = '\n'
+		emitter.buffer_pos += 2
+	default:
+		panic("unknown line break setting")
+	}
+	emitter.column = 0
+	emitter.line++
+	return true
+}
+
+// Copy a character from a string into buffer.
+func write(emitter *yaml_emitter_t, s []byte, i *int) bool {
+	if emitter.buffer_pos+5 >= len(emitter.buffer) && !yaml_emitter_flush(emitter) {
+		return false
+	}
+	p := emitter.buffer_pos
+	w := width(s[*i])
+	switch w {
+	case 4:
+		emitter.buffer[p+3] = s[*i+3]
+		fallthrough
+	case 3:
+		emitter.buffer[p+2] = s[*i+2]
+		fallthrough
+	case 2:
+		emitter.buffer[p+1] = s[*i+1]
+		fallthrough
+	case 1:
+		emitter.buffer[p+0] = s[*i+0]
+	default:
+		panic("unknown character width")
+	}
+	emitter.column++
+	emitter.buffer_pos += w
+	*i += w
+	return true
+}
+
+// Write a whole string into buffer.
+func write_all(emitter *yaml_emitter_t, s []byte) bool {
+	for i := 0; i < len(s); {
+		if !write(emitter, s, &i) {
+			return false
+		}
+	}
+	return true
+}
+
+// Copy a line break character from a string into buffer.
+func write_break(emitter *yaml_emitter_t, s []byte, i *int) bool {
+	if s[*i] == '\n' {
+		if !put_break(emitter) {
+			return false
+		}
+		*i++
+	} else {
+		if !write(emitter, s, i) {
+			return false
+		}
+		emitter.column = 0
+		emitter.line++
+	}
+	return true
+}
+
+// Set an emitter error and return false.
+func yaml_emitter_set_emitter_error(emitter *yaml_emitter_t, problem string) bool {
+	emitter.error = yaml_EMITTER_ERROR
+	emitter.problem = problem
+	return false
+}
+
+// Emit an event.
+func yaml_emitter_emit(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	emitter.events = append(emitter.events, *event)
+	for !yaml_emitter_need_more_events(emitter) {
+		event := &emitter.events[emitter.events_head]
+		if !yaml_emitter_analyze_event(emitter, event) {
+			return false
+		}
+		if !yaml_emitter_state_machine(emitter, event) {
+			return false
+		}
+		yaml_event_delete(event)
+		emitter.events_head++
+	}
+	return true
+}
+
+// Check if we need to accumulate more events before emitting.
+//
+// We accumulate extra
+//  - 1 event for DOCUMENT-START
+//  - 2 events for SEQUENCE-START
+//  - 3 events for MAPPING-START
+//
+func yaml_emitter_need_more_events(emitter *yaml_emitter_t) bool {
+	if emitter.events_head == len(emitter.events) {
+		return true
+	}
+	var accumulate int
+	switch emitter.events[emitter.events_head].typ {
+	case yaml_DOCUMENT_START_EVENT:
+		accumulate = 1
+		break
+	case yaml_SEQUENCE_START_EVENT:
+		accumulate = 2
+		break
+	case yaml_MAPPING_START_EVENT:
+		accumulate = 3
+		break
+	default:
+		return false
+	}
+	if len(emitter.events)-emitter.events_head > accumulate {
+		return false
+	}
+	var level int
+	for i := emitter.events_head; i < len(emitter.events); i++ {
+		switch emitter.events[i].typ {
+		case yaml_STREAM_START_EVENT, yaml_DOCUMENT_START_EVENT, yaml_SEQUENCE_START_EVENT, yaml_MAPPING_START_EVENT:
+			level++
+		case yaml_STREAM_END_EVENT, yaml_DOCUMENT_END_EVENT, yaml_SEQUENCE_END_EVENT, yaml_MAPPING_END_EVENT:
+			level--
+		}
+		if level == 0 {
+			return false
+		}
+	}
+	return true
+}
+
+// Append a directive to the directives stack.
+func yaml_emitter_append_tag_directive(emitter *yaml_emitter_t, value *yaml_tag_directive_t, allow_duplicates bool) bool {
+	for i := 0; i < len(emitter.tag_directives); i++ {
+		if bytes.Equal(value.handle, emitter.tag_directives[i].handle) {
+			if allow_duplicates {
+				return true
+			}
+			return yaml_emitter_set_emitter_error(emitter, "duplicate %TAG directive")
+		}
+	}
+
+	// [Go] Do we actually need to copy this given garbage collection
+	// and the lack of deallocating destructors?
+	tag_copy := yaml_tag_directive_t{
+		handle: make([]byte, len(value.handle)),
+		prefix: make([]byte, len(value.prefix)),
+	}
+	copy(tag_copy.handle, value.handle)
+	copy(tag_copy.prefix, value.prefix)
+	emitter.tag_directives = append(emitter.tag_directives, tag_copy)
+	return true
+}
+
+// Increase the indentation level.
+func yaml_emitter_increase_indent(emitter *yaml_emitter_t, flow, indentless bool) bool {
+	emitter.indents = append(emitter.indents, emitter.indent)
+	if emitter.indent < 0 {
+		if flow {
+			emitter.indent = emitter.best_indent
+		} else {
+			emitter.indent = 0
+		}
+	} else if !indentless {
+		emitter.indent += emitter.best_indent
+	}
+	return true
+}
+
+// State dispatcher.
+func yaml_emitter_state_machine(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	switch emitter.state {
+	default:
+	case yaml_EMIT_STREAM_START_STATE:
+		return yaml_emitter_emit_stream_start(emitter, event)
+
+	case yaml_EMIT_FIRST_DOCUMENT_START_STATE:
+		return yaml_emitter_emit_document_start(emitter, event, true)
+
+	case yaml_EMIT_DOCUMENT_START_STATE:
+		return yaml_emitter_emit_document_start(emitter, event, false)
+
+	case yaml_EMIT_DOCUMENT_CONTENT_STATE:
+		return yaml_emitter_emit_document_content(emitter, event)
+
+	case yaml_EMIT_DOCUMENT_END_STATE:
+		return yaml_emitter_emit_document_end(emitter, event)
+
+	case yaml_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE:
+		return yaml_emitter_emit_flow_sequence_item(emitter, event, true)
+
+	case yaml_EMIT_FLOW_SEQUENCE_ITEM_STATE:
+		return yaml_emitter_emit_flow_sequence_item(emitter, event, false)
+
+	case yaml_EMIT_FLOW_MAPPING_FIRST_KEY_STATE:
+		return yaml_emitter_emit_flow_mapping_key(emitter, event, true)
+
+	case yaml_EMIT_FLOW_MAPPING_KEY_STATE:
+		return yaml_emitter_emit_flow_mapping_key(emitter, event, false)
+
+	case yaml_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE:
+		return yaml_emitter_emit_flow_mapping_value(emitter, event, true)
+
+	case yaml_EMIT_FLOW_MAPPING_VALUE_STATE:
+		return yaml_emitter_emit_flow_mapping_value(emitter, event, false)
+
+	case yaml_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE:
+		return yaml_emitter_emit_block_sequence_item(emitter, event, true)
+
+	case yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE:
+		return yaml_emitter_emit_block_sequence_item(emitter, event, false)
+
+	case yaml_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE:
+		return yaml_emitter_emit_block_mapping_key(emitter, event, true)
+
+	case yaml_EMIT_BLOCK_MAPPING_KEY_STATE:
+		return yaml_emitter_emit_block_mapping_key(emitter, event, false)
+
+	case yaml_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE:
+		return yaml_emitter_emit_block_mapping_value(emitter, event, true)
+
+	case yaml_EMIT_BLOCK_MAPPING_VALUE_STATE:
+		return yaml_emitter_emit_block_mapping_value(emitter, event, false)
+
+	case yaml_EMIT_END_STATE:
+		return yaml_emitter_set_emitter_error(emitter, "expected nothing after STREAM-END")
+	}
+	panic("invalid emitter state")
+}
+
+// Expect STREAM-START.
+func yaml_emitter_emit_stream_start(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	if event.typ != yaml_STREAM_START_EVENT {
+		return yaml_emitter_set_emitter_error(emitter, "expected STREAM-START")
+	}
+	if emitter.encoding == yaml_ANY_ENCODING {
+		emitter.encoding = event.encoding
+		if emitter.encoding == yaml_ANY_ENCODING {
+			emitter.encoding = yaml_UTF8_ENCODING
+		}
+	}
+	if emitter.best_indent < 2 || emitter.best_indent > 9 {
+		emitter.best_indent = 2
+	}
+	if emitter.best_width >= 0 && emitter.best_width <= emitter.best_indent*2 {
+		emitter.best_width = 80
+	}
+	if emitter.best_width < 0 {
+		emitter.best_width = 1<<31 - 1
+	}
+	if emitter.line_break == yaml_ANY_BREAK {
+		emitter.line_break = yaml_LN_BREAK
+	}
+
+	emitter.indent = -1
+	emitter.line = 0
+	emitter.column = 0
+	emitter.whitespace = true
+	emitter.indention = true
+
+	if emitter.encoding != yaml_UTF8_ENCODING {
+		if !yaml_emitter_write_bom(emitter) {
+			return false
+		}
+	}
+	emitter.state = yaml_EMIT_FIRST_DOCUMENT_START_STATE
+	return true
+}
+
+// Expect DOCUMENT-START or STREAM-END.
+func yaml_emitter_emit_document_start(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
+
+	if event.typ == yaml_DOCUMENT_START_EVENT {
+
+		if event.version_directive != nil {
+			if !yaml_emitter_analyze_version_directive(emitter, event.version_directive) {
+				return false
+			}
+		}
+
+		for i := 0; i < len(event.tag_directives); i++ {
+			tag_directive := &event.tag_directives[i]
+			if !yaml_emitter_analyze_tag_directive(emitter, tag_directive) {
+				return false
+			}
+			if !yaml_emitter_append_tag_directive(emitter, tag_directive, false) {
+				return false
+			}
+		}
+
+		for i := 0; i < len(default_tag_directives); i++ {
+			tag_directive := &default_tag_directives[i]
+			if !yaml_emitter_append_tag_directive(emitter, tag_directive, true) {
+				return false
+			}
+		}
+
+		implicit := event.implicit
+		if !first || emitter.canonical {
+			implicit = false
+		}
+
+		if emitter.open_ended && (event.version_directive != nil || len(event.tag_directives) > 0) {
+			if !yaml_emitter_write_indicator(emitter, []byte("..."), true, false, false) {
+				return false
+			}
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+		}
+
+		if event.version_directive != nil {
+			implicit = false
+			if !yaml_emitter_write_indicator(emitter, []byte("%YAML"), true, false, false) {
+				return false
+			}
+			if !yaml_emitter_write_indicator(emitter, []byte("1.1"), true, false, false) {
+				return false
+			}
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+		}
+
+		if len(event.tag_directives) > 0 {
+			implicit = false
+			for i := 0; i < len(event.tag_directives); i++ {
+				tag_directive := &event.tag_directives[i]
+				if !yaml_emitter_write_indicator(emitter, []byte("%TAG"), true, false, false) {
+					return false
+				}
+				if !yaml_emitter_write_tag_handle(emitter, tag_directive.handle) {
+					return false
+				}
+				if !yaml_emitter_write_tag_content(emitter, tag_directive.prefix, true) {
+					return false
+				}
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+			}
+		}
+
+		if yaml_emitter_check_empty_document(emitter) {
+			implicit = false
+		}
+		if !implicit {
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+			if !yaml_emitter_write_indicator(emitter, []byte("---"), true, false, false) {
+				return false
+			}
+			if emitter.canonical {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+			}
+		}
+
+		emitter.state = yaml_EMIT_DOCUMENT_CONTENT_STATE
+		return true
+	}
+
+	if event.typ == yaml_STREAM_END_EVENT {
+		if emitter.open_ended {
+			if !yaml_emitter_write_indicator(emitter, []byte("..."), true, false, false) {
+				return false
+			}
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+		}
+		if !yaml_emitter_flush(emitter) {
+			return false
+		}
+		emitter.state = yaml_EMIT_END_STATE
+		return true
+	}
+
+	return yaml_emitter_set_emitter_error(emitter, "expected DOCUMENT-START or STREAM-END")
+}
+
+// Expect the root node.
+func yaml_emitter_emit_document_content(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	emitter.states = append(emitter.states, yaml_EMIT_DOCUMENT_END_STATE)
+	return yaml_emitter_emit_node(emitter, event, true, false, false, false)
+}
+
+// Expect DOCUMENT-END.
+func yaml_emitter_emit_document_end(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	if event.typ != yaml_DOCUMENT_END_EVENT {
+		return yaml_emitter_set_emitter_error(emitter, "expected DOCUMENT-END")
+	}
+	if !yaml_emitter_write_indent(emitter) {
+		return false
+	}
+	if !event.implicit {
+		// [Go] Allocate the slice elsewhere.
+		if !yaml_emitter_write_indicator(emitter, []byte("..."), true, false, false) {
+			return false
+		}
+		if !yaml_emitter_write_indent(emitter) {
+			return false
+		}
+	}
+	if !yaml_emitter_flush(emitter) {
+		return false
+	}
+	emitter.state = yaml_EMIT_DOCUMENT_START_STATE
+	emitter.tag_directives = emitter.tag_directives[:0]
+	return true
+}
+
+// Expect a flow item node.
+func yaml_emitter_emit_flow_sequence_item(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
+	if first {
+		if !yaml_emitter_write_indicator(emitter, []byte{'['}, true, true, false) {
+			return false
+		}
+		if !yaml_emitter_increase_indent(emitter, true, false) {
+			return false
+		}
+		emitter.flow_level++
+	}
+
+	if event.typ == yaml_SEQUENCE_END_EVENT {
+		emitter.flow_level--
+		emitter.indent = emitter.indents[len(emitter.indents)-1]
+		emitter.indents = emitter.indents[:len(emitter.indents)-1]
+		if emitter.canonical && !first {
+			if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
+				return false
+			}
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+		}
+		if !yaml_emitter_write_indicator(emitter, []byte{']'}, false, false, false) {
+			return false
+		}
+		emitter.state = emitter.states[len(emitter.states)-1]
+		emitter.states = emitter.states[:len(emitter.states)-1]
+
+		return true
+	}
+
+	if !first {
+		if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
+			return false
+		}
+	}
+
+	if emitter.canonical || emitter.column > emitter.best_width {
+		if !yaml_emitter_write_indent(emitter) {
+			return false
+		}
+	}
+	emitter.states = append(emitter.states, yaml_EMIT_FLOW_SEQUENCE_ITEM_STATE)
+	return yaml_emitter_emit_node(emitter, event, false, true, false, false)
+}
+
+// Expect a flow key node.
+func yaml_emitter_emit_flow_mapping_key(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
+	if first {
+		if !yaml_emitter_write_indicator(emitter, []byte{'{'}, true, true, false) {
+			return false
+		}
+		if !yaml_emitter_increase_indent(emitter, true, false) {
+			return false
+		}
+		emitter.flow_level++
+	}
+
+	if event.typ == yaml_MAPPING_END_EVENT {
+		emitter.flow_level--
+		emitter.indent = emitter.indents[len(emitter.indents)-1]
+		emitter.indents = emitter.indents[:len(emitter.indents)-1]
+		if emitter.canonical && !first {
+			if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
+				return false
+			}
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+		}
+		if !yaml_emitter_write_indicator(emitter, []byte{'}'}, false, false, false) {
+			return false
+		}
+		emitter.state = emitter.states[len(emitter.states)-1]
+		emitter.states = emitter.states[:len(emitter.states)-1]
+		return true
+	}
+
+	if !first {
+		if !yaml_emitter_write_indicator(emitter, []byte{','}, false, false, false) {
+			return false
+		}
+	}
+	if emitter.canonical || emitter.column > emitter.best_width {
+		if !yaml_emitter_write_indent(emitter) {
+			return false
+		}
+	}
+
+	if !emitter.canonical && yaml_emitter_check_simple_key(emitter) {
+		emitter.states = append(emitter.states, yaml_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE)
+		return yaml_emitter_emit_node(emitter, event, false, false, true, true)
+	}
+	if !yaml_emitter_write_indicator(emitter, []byte{'?'}, true, false, false) {
+		return false
+	}
+	emitter.states = append(emitter.states, yaml_EMIT_FLOW_MAPPING_VALUE_STATE)
+	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
+}
+
+// Expect a flow value node.
+func yaml_emitter_emit_flow_mapping_value(emitter *yaml_emitter_t, event *yaml_event_t, simple bool) bool {
+	if simple {
+		if !yaml_emitter_write_indicator(emitter, []byte{':'}, false, false, false) {
+			return false
+		}
+	} else {
+		if emitter.canonical || emitter.column > emitter.best_width {
+			if !yaml_emitter_write_indent(emitter) {
+				return false
+			}
+		}
+		if !yaml_emitter_write_indicator(emitter, []byte{':'}, true, false, false) {
+			return false
+		}
+	}
+	emitter.states = append(emitter.states, yaml_EMIT_FLOW_MAPPING_KEY_STATE)
+	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
+}
+
+// Expect a block item node.
+func yaml_emitter_emit_block_sequence_item(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
+	if first {
+		if !yaml_emitter_increase_indent(emitter, false, emitter.mapping_context && !emitter.indention) {
+			return false
+		}
+	}
+	if event.typ == yaml_SEQUENCE_END_EVENT {
+		emitter.indent = emitter.indents[len(emitter.indents)-1]
+		emitter.indents = emitter.indents[:len(emitter.indents)-1]
+		emitter.state = emitter.states[len(emitter.states)-1]
+		emitter.states = emitter.states[:len(emitter.states)-1]
+		return true
+	}
+	if !yaml_emitter_write_indent(emitter) {
+		return false
+	}
+	if !yaml_emitter_write_indicator(emitter, []byte{'-'}, true, false, true) {
+		return false
+	}
+	emitter.states = append(emitter.states, yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE)
+	return yaml_emitter_emit_node(emitter, event, false, true, false, false)
+}
+
+// Expect a block key node.
+func yaml_emitter_emit_block_mapping_key(emitter *yaml_emitter_t, event *yaml_event_t, first bool) bool {
+	if first {
+		if !yaml_emitter_increase_indent(emitter, false, false) {
+			return false
+		}
+	}
+	if event.typ == yaml_MAPPING_END_EVENT {
+		emitter.indent = emitter.indents[len(emitter.indents)-1]
+		emitter.indents = emitter.indents[:len(emitter.indents)-1]
+		emitter.state = emitter.states[len(emitter.states)-1]
+		emitter.states = emitter.states[:len(emitter.states)-1]
+		return true
+	}
+	if !yaml_emitter_write_indent(emitter) {
+		return false
+	}
+	if yaml_emitter_check_simple_key(emitter) {
+		emitter.states = append(emitter.states, yaml_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE)
+		return yaml_emitter_emit_node(emitter, event, false, false, true, true)
+	}
+	if !yaml_emitter_write_indicator(emitter, []byte{'?'}, true, false, true) {
+		return false
+	}
+	emitter.states = append(emitter.states, yaml_EMIT_BLOCK_MAPPING_VALUE_STATE)
+	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
+}
+
+// Expect a block value node.
+func yaml_emitter_emit_block_mapping_value(emitter *yaml_emitter_t, event *yaml_event_t, simple bool) bool {
+	if simple {
+		if !yaml_emitter_write_indicator(emitter, []byte{':'}, false, false, false) {
+			return false
+		}
+	} else {
+		if !yaml_emitter_write_indent(emitter) {
+			return false
+		}
+		if !yaml_emitter_write_indicator(emitter, []byte{':'}, true, false, true) {
+			return false
+		}
+	}
+	emitter.states = append(emitter.states, yaml_EMIT_BLOCK_MAPPING_KEY_STATE)
+	return yaml_emitter_emit_node(emitter, event, false, false, true, false)
+}
+
+// Expect a node.
+func yaml_emitter_emit_node(emitter *yaml_emitter_t, event *yaml_event_t,
+	root bool, sequence bool, mapping bool, simple_key bool) bool {
+
+	emitter.root_context = root
+	emitter.sequence_context = sequence
+	emitter.mapping_context = mapping
+	emitter.simple_key_context = simple_key
+
+	switch event.typ {
+	case yaml_ALIAS_EVENT:
+		return yaml_emitter_emit_alias(emitter, event)
+	case yaml_SCALAR_EVENT:
+		return yaml_emitter_emit_scalar(emitter, event)
+	case yaml_SEQUENCE_START_EVENT:
+		return yaml_emitter_emit_sequence_start(emitter, event)
+	case yaml_MAPPING_START_EVENT:
+		return yaml_emitter_emit_mapping_start(emitter, event)
+	default:
+		return yaml_emitter_set_emitter_error(emitter,
+			fmt.Sprintf("expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS, but got %v", event.typ))
+	}
+}
+
+// Expect ALIAS.
+func yaml_emitter_emit_alias(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	if !yaml_emitter_process_anchor(emitter) {
+		return false
+	}
+	emitter.state = emitter.states[len(emitter.states)-1]
+	emitter.states = emitter.states[:len(emitter.states)-1]
+	return true
+}
+
+// Expect SCALAR.
+func yaml_emitter_emit_scalar(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	if !yaml_emitter_select_scalar_style(emitter, event) {
+		return false
+	}
+	if !yaml_emitter_process_anchor(emitter) {
+		return false
+	}
+	if !yaml_emitter_process_tag(emitter) {
+		return false
+	}
+	if !yaml_emitter_increase_indent(emitter, true, false) {
+		return false
+	}
+	if !yaml_emitter_process_scalar(emitter) {
+		return false
+	}
+	emitter.indent = emitter.indents[len(emitter.indents)-1]
+	emitter.indents = emitter.indents[:len(emitter.indents)-1]
+	emitter.state = emitter.states[len(emitter.states)-1]
+	emitter.states = emitter.states[:len(emitter.states)-1]
+	return true
+}
+
+// Expect SEQUENCE-START.
+func yaml_emitter_emit_sequence_start(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	if !yaml_emitter_process_anchor(emitter) {
+		return false
+	}
+	if !yaml_emitter_process_tag(emitter) {
+		return false
+	}
+	if emitter.flow_level > 0 || emitter.canonical || event.sequence_style() == yaml_FLOW_SEQUENCE_STYLE ||
+		yaml_emitter_check_empty_sequence(emitter) {
+		emitter.state = yaml_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE
+	} else {
+		emitter.state = yaml_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE
+	}
+	return true
+}
+
+// Expect MAPPING-START.
+func yaml_emitter_emit_mapping_start(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+	if !yaml_emitter_process_anchor(emitter) {
+		return false
+	}
+	if !yaml_emitter_process_tag(emitter) {
+		return false
+	}
+	if emitter.flow_level > 0 || emitter.canonical || event.mapping_style() == yaml_FLOW_MAPPING_STYLE ||
+		yaml_emitter_check_empty_mapping(emitter) {
+		emitter.state = yaml_EMIT_FLOW_MAPPING_FIRST_KEY_STATE
+	} else {
+		emitter.state = yaml_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE
+	}
+	return true
+}
+
+// Check if the document content is an empty scalar.
+func yaml_emitter_check_empty_document(emitter *yaml_emitter_t) bool {
+	return false // [Go] Huh?
+}
+
+// Check if the next events represent an empty sequence.
+func yaml_emitter_check_empty_sequence(emitter *yaml_emitter_t) bool {
+	if len(emitter.events)-emitter.events_head < 2 {
+		return false
+	}
+	return emitter.events[emitter.events_head].typ == yaml_SEQUENCE_START_EVENT &&
+		emitter.events[emitter.events_head+1].typ == yaml_SEQUENCE_END_EVENT
+}
+
+// Check if the next events represent an empty mapping.
+func yaml_emitter_check_empty_mapping(emitter *yaml_emitter_t) bool {
+	if len(emitter.events)-emitter.events_head < 2 {
+		return false
+	}
+	return emitter.events[emitter.events_head].typ == yaml_MAPPING_START_EVENT &&
+		emitter.events[emitter.events_head+1].typ == yaml_MAPPING_END_EVENT
+}
+
+// Check if the next node can be expressed as a simple key.
+func yaml_emitter_check_simple_key(emitter *yaml_emitter_t) bool {
+	length := 0
+	switch emitter.events[emitter.events_head].typ {
+	case yaml_ALIAS_EVENT:
+		length += len(emitter.anchor_data.anchor)
+	case yaml_SCALAR_EVENT:
+		if emitter.scalar_data.multiline {
+			return false
+		}
+		length += len(emitter.anchor_data.anchor) +
+			len(emitter.tag_data.handle) +
+			len(emitter.tag_data.suffix) +
+			len(emitter.scalar_data.value)
+	case yaml_SEQUENCE_START_EVENT:
+		if !yaml_emitter_check_empty_sequence(emitter) {
+			return false
+		}
+		length += len(emitter.anchor_data.anchor) +
+			len(emitter.tag_data.handle) +
+			len(emitter.tag_data.suffix)
+	case yaml_MAPPING_START_EVENT:
+		if !yaml_emitter_check_empty_mapping(emitter) {
+			return false
+		}
+		length += len(emitter.anchor_data.anchor) +
+			len(emitter.tag_data.handle) +
+			len(emitter.tag_data.suffix)
+	default:
+		return false
+	}
+	return length <= 128
+}
+
+// Determine an acceptable scalar style.
+func yaml_emitter_select_scalar_style(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+
+	no_tag := len(emitter.tag_data.handle) == 0 && len(emitter.tag_data.suffix) == 0
+	if no_tag && !event.implicit && !event.quoted_implicit {
+		return yaml_emitter_set_emitter_error(emitter, "neither tag nor implicit flags are specified")
+	}
+
+	style := event.scalar_style()
+	if style == yaml_ANY_SCALAR_STYLE {
+		style = yaml_PLAIN_SCALAR_STYLE
+	}
+	if emitter.canonical {
+		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+	}
+	if emitter.simple_key_context && emitter.scalar_data.multiline {
+		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+	}
+
+	if style == yaml_PLAIN_SCALAR_STYLE {
+		if emitter.flow_level > 0 && !emitter.scalar_data.flow_plain_allowed ||
+			emitter.flow_level == 0 && !emitter.scalar_data.block_plain_allowed {
+			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
+		}
+		if len(emitter.scalar_data.value) == 0 && (emitter.flow_level > 0 || emitter.simple_key_context) {
+			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
+		}
+		if no_tag && !event.implicit {
+			style = yaml_SINGLE_QUOTED_SCALAR_STYLE
+		}
+	}
+	if style == yaml_SINGLE_QUOTED_SCALAR_STYLE {
+		if !emitter.scalar_data.single_quoted_allowed {
+			style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+		}
+	}
+	if style == yaml_LITERAL_SCALAR_STYLE || style == yaml_FOLDED_SCALAR_STYLE {
+		if !emitter.scalar_data.block_allowed || emitter.flow_level > 0 || emitter.simple_key_context {
+			style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+		}
+	}
+
+	if no_tag && !event.quoted_implicit && style != yaml_PLAIN_SCALAR_STYLE {
+		emitter.tag_data.handle = []byte{'!'}
+	}
+	emitter.scalar_data.style = style
+	return true
+}
+
+// Write an anchor.
+func yaml_emitter_process_anchor(emitter *yaml_emitter_t) bool {
+	if emitter.anchor_data.anchor == nil {
+		return true
+	}
+	c := []byte{'&'}
+	if emitter.anchor_data.alias {
+		c[0] = '*'
+	}
+	if !yaml_emitter_write_indicator(emitter, c, true, false, false) {
+		return false
+	}
+	return yaml_emitter_write_anchor(emitter, emitter.anchor_data.anchor)
+}
+
+// Write a tag.
+func yaml_emitter_process_tag(emitter *yaml_emitter_t) bool {
+	if len(emitter.tag_data.handle) == 0 && len(emitter.tag_data.suffix) == 0 {
+		return true
+	}
+	if len(emitter.tag_data.handle) > 0 {
+		if !yaml_emitter_write_tag_handle(emitter, emitter.tag_data.handle) {
+			return false
+		}
+		if len(emitter.tag_data.suffix) > 0 {
+			if !yaml_emitter_write_tag_content(emitter, emitter.tag_data.suffix, false) {
+				return false
+			}
+		}
+	} else {
+		// [Go] Allocate these slices elsewhere.
+		if !yaml_emitter_write_indicator(emitter, []byte("!<"), true, false, false) {
+			return false
+		}
+		if !yaml_emitter_write_tag_content(emitter, emitter.tag_data.suffix, false) {
+			return false
+		}
+		if !yaml_emitter_write_indicator(emitter, []byte{'>'}, false, false, false) {
+			return false
+		}
+	}
+	return true
+}
+
+// Write a scalar.
+func yaml_emitter_process_scalar(emitter *yaml_emitter_t) bool {
+	switch emitter.scalar_data.style {
+	case yaml_PLAIN_SCALAR_STYLE:
+		return yaml_emitter_write_plain_scalar(emitter, emitter.scalar_data.value, !emitter.simple_key_context)
+
+	case yaml_SINGLE_QUOTED_SCALAR_STYLE:
+		return yaml_emitter_write_single_quoted_scalar(emitter, emitter.scalar_data.value, !emitter.simple_key_context)
+
+	case yaml_DOUBLE_QUOTED_SCALAR_STYLE:
+		return yaml_emitter_write_double_quoted_scalar(emitter, emitter.scalar_data.value, !emitter.simple_key_context)
+
+	case yaml_LITERAL_SCALAR_STYLE:
+		return yaml_emitter_write_literal_scalar(emitter, emitter.scalar_data.value)
+
+	case yaml_FOLDED_SCALAR_STYLE:
+		return yaml_emitter_write_folded_scalar(emitter, emitter.scalar_data.value)
+	}
+	panic("unknown scalar style")
+}
+
+// Check if a %YAML directive is valid.
+func yaml_emitter_analyze_version_directive(emitter *yaml_emitter_t, version_directive *yaml_version_directive_t) bool {
+	if version_directive.major != 1 || version_directive.minor != 1 {
+		return yaml_emitter_set_emitter_error(emitter, "incompatible %YAML directive")
+	}
+	return true
+}
+
+// Check if a %TAG directive is valid.
+func yaml_emitter_analyze_tag_directive(emitter *yaml_emitter_t, tag_directive *yaml_tag_directive_t) bool {
+	handle := tag_directive.handle
+	prefix := tag_directive.prefix
+	if len(handle) == 0 {
+		return yaml_emitter_set_emitter_error(emitter, "tag handle must not be empty")
+	}
+	if handle[0] != '!' {
+		return yaml_emitter_set_emitter_error(emitter, "tag handle must start with '!'")
+	}
+	if handle[len(handle)-1] != '!' {
+		return yaml_emitter_set_emitter_error(emitter, "tag handle must end with '!'")
+	}
+	for i := 1; i < len(handle)-1; i += width(handle[i]) {
+		if !is_alpha(handle, i) {
+			return yaml_emitter_set_emitter_error(emitter, "tag handle must contain alphanumerical characters only")
+		}
+	}
+	if len(prefix) == 0 {
+		return yaml_emitter_set_emitter_error(emitter, "tag prefix must not be empty")
+	}
+	return true
+}
+
+// Check if an anchor is valid.
+func yaml_emitter_analyze_anchor(emitter *yaml_emitter_t, anchor []byte, alias bool) bool {
+	if len(anchor) == 0 {
+		problem := "anchor value must not be empty"
+		if alias {
+			problem = "alias value must not be empty"
+		}
+		return yaml_emitter_set_emitter_error(emitter, problem)
+	}
+	for i := 0; i < len(anchor); i += width(anchor[i]) {
+		if !is_alpha(anchor, i) {
+			problem := "anchor value must contain alphanumerical characters only"
+			if alias {
+				problem = "alias value must contain alphanumerical characters only"
+			}
+			return yaml_emitter_set_emitter_error(emitter, problem)
+		}
+	}
+	emitter.anchor_data.anchor = anchor
+	emitter.anchor_data.alias = alias
+	return true
+}
+
+// Check if a tag is valid.
+func yaml_emitter_analyze_tag(emitter *yaml_emitter_t, tag []byte) bool {
+	if len(tag) == 0 {
+		return yaml_emitter_set_emitter_error(emitter, "tag value must not be empty")
+	}
+	for i := 0; i < len(emitter.tag_directives); i++ {
+		tag_directive := &emitter.tag_directives[i]
+		if bytes.HasPrefix(tag, tag_directive.prefix) {
+			emitter.tag_data.handle = tag_directive.handle
+			emitter.tag_data.suffix = tag[len(tag_directive.prefix):]
+			return true
+		}
+	}
+	emitter.tag_data.suffix = tag
+	return true
+}
+
+// Check if a scalar is valid.
+func yaml_emitter_analyze_scalar(emitter *yaml_emitter_t, value []byte) bool {
+	var (
+		block_indicators   = false
+		flow_indicators    = false
+		line_breaks        = false
+		special_characters = false
+
+		leading_space  = false
+		leading_break  = false
+		trailing_space = false
+		trailing_break = false
+		break_space    = false
+		space_break    = false
+
+		preceded_by_whitespace = false
+		followed_by_whitespace = false
+		previous_space         = false
+		previous_break         = false
+	)
+
+	emitter.scalar_data.value = value
+
+	if len(value) == 0 {
+		emitter.scalar_data.multiline = false
+		emitter.scalar_data.flow_plain_allowed = false
+		emitter.scalar_data.block_plain_allowed = true
+		emitter.scalar_data.single_quoted_allowed = true
+		emitter.scalar_data.block_allowed = false
+		return true
+	}
+
+	if len(value) >= 3 && ((value[0] == '-' && value[1] == '-' && value[2] == '-') || (value[0] == '.' && value[1] == '.' && value[2] == '.')) {
+		block_indicators = true
+		flow_indicators = true
+	}
+
+	preceded_by_whitespace = true
+	for i, w := 0, 0; i < len(value); i += w {
+		w = width(value[i])
+		followed_by_whitespace = i+w >= len(value) || is_blank(value, i+w)
+
+		if i == 0 {
+			switch value[i] {
+			case '#', ',', '[', ']', '{', '}', '&', '*', '!', '|', '>', '\'', '"', '%', '@', '`':
+				flow_indicators = true
+				block_indicators = true
+			case '?', ':':
+				flow_indicators = true
+				if followed_by_whitespace {
+					block_indicators = true
+				}
+			case '-':
+				if followed_by_whitespace {
+					flow_indicators = true
+					block_indicators = true
+				}
+			}
+		} else {
+			switch value[i] {
+			case ',', '?', '[', ']', '{', '}':
+				flow_indicators = true
+			case ':':
+				flow_indicators = true
+				if followed_by_whitespace {
+					block_indicators = true
+				}
+			case '#':
+				if preceded_by_whitespace {
+					flow_indicators = true
+					block_indicators = true
+				}
+			}
+		}
+
+		if !is_printable(value, i) || !is_ascii(value, i) && !emitter.unicode {
+			special_characters = true
+		}
+		if is_space(value, i) {
+			if i == 0 {
+				leading_space = true
+			}
+			if i+width(value[i]) == len(value) {
+				trailing_space = true
+			}
+			if previous_break {
+				break_space = true
+			}
+			previous_space = true
+			previous_break = false
+		} else if is_break(value, i) {
+			line_breaks = true
+			if i == 0 {
+				leading_break = true
+			}
+			if i+width(value[i]) == len(value) {
+				trailing_break = true
+			}
+			if previous_space {
+				space_break = true
+			}
+			previous_space = false
+			previous_break = true
+		} else {
+			previous_space = false
+			previous_break = false
+		}
+
+		// [Go]: Why 'z'? Couldn't be the end of the string as that's the loop condition.
+		preceded_by_whitespace = is_blankz(value, i)
+	}
+
+	emitter.scalar_data.multiline = line_breaks
+	emitter.scalar_data.flow_plain_allowed = true
+	emitter.scalar_data.block_plain_allowed = true
+	emitter.scalar_data.single_quoted_allowed = true
+	emitter.scalar_data.block_allowed = true
+
+	if leading_space || leading_break || trailing_space || trailing_break {
+		emitter.scalar_data.flow_plain_allowed = false
+		emitter.scalar_data.block_plain_allowed = false
+	}
+	if trailing_space {
+		emitter.scalar_data.block_allowed = false
+	}
+	if break_space {
+		emitter.scalar_data.flow_plain_allowed = false
+		emitter.scalar_data.block_plain_allowed = false
+		emitter.scalar_data.single_quoted_allowed = false
+	}
+	if space_break || special_characters {
+		emitter.scalar_data.flow_plain_allowed = false
+		emitter.scalar_data.block_plain_allowed = false
+		emitter.scalar_data.single_quoted_allowed = false
+		emitter.scalar_data.block_allowed = false
+	}
+	if line_breaks {
+		emitter.scalar_data.flow_plain_allowed = false
+		emitter.scalar_data.block_plain_allowed = false
+	}
+	if flow_indicators {
+		emitter.scalar_data.flow_plain_allowed = false
+	}
+	if block_indicators {
+		emitter.scalar_data.block_plain_allowed = false
+	}
+	return true
+}
+
+// Check if the event data is valid.
+func yaml_emitter_analyze_event(emitter *yaml_emitter_t, event *yaml_event_t) bool {
+
+	emitter.anchor_data.anchor = nil
+	emitter.tag_data.handle = nil
+	emitter.tag_data.suffix = nil
+	emitter.scalar_data.value = nil
+
+	switch event.typ {
+	case yaml_ALIAS_EVENT:
+		if !yaml_emitter_analyze_anchor(emitter, event.anchor, true) {
+			return false
+		}
+
+	case yaml_SCALAR_EVENT:
+		if len(event.anchor) > 0 {
+			if !yaml_emitter_analyze_anchor(emitter, event.anchor, false) {
+				return false
+			}
+		}
+		if len(event.tag) > 0 && (emitter.canonical || (!event.implicit && !event.quoted_implicit)) {
+			if !yaml_emitter_analyze_tag(emitter, event.tag) {
+				return false
+			}
+		}
+		if !yaml_emitter_analyze_scalar(emitter, event.value) {
+			return false
+		}
+
+	case yaml_SEQUENCE_START_EVENT:
+		if len(event.anchor) > 0 {
+			if !yaml_emitter_analyze_anchor(emitter, event.anchor, false) {
+				return false
+			}
+		}
+		if len(event.tag) > 0 && (emitter.canonical || !event.implicit) {
+			if !yaml_emitter_analyze_tag(emitter, event.tag) {
+				return false
+			}
+		}
+
+	case yaml_MAPPING_START_EVENT:
+		if len(event.anchor) > 0 {
+			if !yaml_emitter_analyze_anchor(emitter, event.anchor, false) {
+				return false
+			}
+		}
+		if len(event.tag) > 0 && (emitter.canonical || !event.implicit) {
+			if !yaml_emitter_analyze_tag(emitter, event.tag) {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+// Write the BOM character.
+func yaml_emitter_write_bom(emitter *yaml_emitter_t) bool {
+	if !flush(emitter) {
+		return false
+	}
+	pos := emitter.buffer_pos
+	emitter.buffer[pos+0] = '\xEF'
+	emitter.buffer[pos+1] = '\xBB'
+	emitter.buffer[pos+2] = '\xBF'
+	emitter.buffer_pos += 3
+	return true
+}
+
+func yaml_emitter_write_indent(emitter *yaml_emitter_t) bool {
+	indent := emitter.indent
+	if indent < 0 {
+		indent = 0
+	}
+	if !emitter.indention || emitter.column > indent || (emitter.column == indent && !emitter.whitespace) {
+		if !put_break(emitter) {
+			return false
+		}
+	}
+	for emitter.column < indent {
+		if !put(emitter, ' ') {
+			return false
+		}
+	}
+	emitter.whitespace = true
+	emitter.indention = true
+	return true
+}
+
+func yaml_emitter_write_indicator(emitter *yaml_emitter_t, indicator []byte, need_whitespace, is_whitespace, is_indention bool) bool {
+	if need_whitespace && !emitter.whitespace {
+		if !put(emitter, ' ') {
+			return false
+		}
+	}
+	if !write_all(emitter, indicator) {
+		return false
+	}
+	emitter.whitespace = is_whitespace
+	emitter.indention = (emitter.indention && is_indention)
+	emitter.open_ended = false
+	return true
+}
+
+func yaml_emitter_write_anchor(emitter *yaml_emitter_t, value []byte) bool {
+	if !write_all(emitter, value) {
+		return false
+	}
+	emitter.whitespace = false
+	emitter.indention = false
+	return true
+}
+
+func yaml_emitter_write_tag_handle(emitter *yaml_emitter_t, value []byte) bool {
+	if !emitter.whitespace {
+		if !put(emitter, ' ') {
+			return false
+		}
+	}
+	if !write_all(emitter, value) {
+		return false
+	}
+	emitter.whitespace = false
+	emitter.indention = false
+	return true
+}
+
+func yaml_emitter_write_tag_content(emitter *yaml_emitter_t, value []byte, need_whitespace bool) bool {
+	if need_whitespace && !emitter.whitespace {
+		if !put(emitter, ' ') {
+			return false
+		}
+	}
+	for i := 0; i < len(value); {
+		var must_write bool
+		switch value[i] {
+		case ';', '/', '?', ':', '@', '&', '=', '+', '$', ',', '_', '.', '~', '*', '\'', '(', ')', '[', ']':
+			must_write = true
+		default:
+			must_write = is_alpha(value, i)
+		}
+		if must_write {
+			if !write(emitter, value, &i) {
+				return false
+			}
+		} else {
+			w := width(value[i])
+			for k := 0; k < w; k++ {
+				octet := value[i]
+				i++
+				if !put(emitter, '%') {
+					return false
+				}
+
+				c := octet >> 4
+				if c < 10 {
+					c += '0'
+				} else {
+					c += 'A' - 10
+				}
+				if !put(emitter, c) {
+					return false
+				}
+
+				c = octet & 0x0f
+				if c < 10 {
+					c += '0'
+				} else {
+					c += 'A' - 10
+				}
+				if !put(emitter, c) {
+					return false
+				}
+			}
+		}
+	}
+	emitter.whitespace = false
+	emitter.indention = false
+	return true
+}
+
+func yaml_emitter_write_plain_scalar(emitter *yaml_emitter_t, value []byte, allow_breaks bool) bool {
+	if !emitter.whitespace {
+		if !put(emitter, ' ') {
+			return false
+		}
+	}
+
+	spaces := false
+	breaks := false
+	for i := 0; i < len(value); {
+		if is_space(value, i) {
+			if allow_breaks && !spaces && emitter.column > emitter.best_width && !is_space(value, i+1) {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+				i += width(value[i])
+			} else {
+				if !write(emitter, value, &i) {
+					return false
+				}
+			}
+			spaces = true
+		} else if is_break(value, i) {
+			if !breaks && value[i] == '\n' {
+				if !put_break(emitter) {
+					return false
+				}
+			}
+			if !write_break(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = true
+			breaks = true
+		} else {
+			if breaks {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+			}
+			if !write(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = false
+			spaces = false
+			breaks = false
+		}
+	}
+
+	emitter.whitespace = false
+	emitter.indention = false
+	if emitter.root_context {
+		emitter.open_ended = true
+	}
+
+	return true
+}
+
+func yaml_emitter_write_single_quoted_scalar(emitter *yaml_emitter_t, value []byte, allow_breaks bool) bool {
+
+	if !yaml_emitter_write_indicator(emitter, []byte{'\''}, true, false, false) {
+		return false
+	}
+
+	spaces := false
+	breaks := false
+	for i := 0; i < len(value); {
+		if is_space(value, i) {
+			if allow_breaks && !spaces && emitter.column > emitter.best_width && i > 0 && i < len(value)-1 && !is_space(value, i+1) {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+				i += width(value[i])
+			} else {
+				if !write(emitter, value, &i) {
+					return false
+				}
+			}
+			spaces = true
+		} else if is_break(value, i) {
+			if !breaks && value[i] == '\n' {
+				if !put_break(emitter) {
+					return false
+				}
+			}
+			if !write_break(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = true
+			breaks = true
+		} else {
+			if breaks {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+			}
+			if value[i] == '\'' {
+				if !put(emitter, '\'') {
+					return false
+				}
+			}
+			if !write(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = false
+			spaces = false
+			breaks = false
+		}
+	}
+	if !yaml_emitter_write_indicator(emitter, []byte{'\''}, false, false, false) {
+		return false
+	}
+	emitter.whitespace = false
+	emitter.indention = false
+	return true
+}
+
+func yaml_emitter_write_double_quoted_scalar(emitter *yaml_emitter_t, value []byte, allow_breaks bool) bool {
+	spaces := false
+	if !yaml_emitter_write_indicator(emitter, []byte{'"'}, true, false, false) {
+		return false
+	}
+
+	for i := 0; i < len(value); {
+		if !is_printable(value, i) || (!emitter.unicode && !is_ascii(value, i)) ||
+			is_bom(value, i) || is_break(value, i) ||
+			value[i] == '"' || value[i] == '\\' {
+
+			octet := value[i]
+
+			var w int
+			var v rune
+			switch {
+			case octet&0x80 == 0x00:
+				w, v = 1, rune(octet&0x7F)
+			case octet&0xE0 == 0xC0:
+				w, v = 2, rune(octet&0x1F)
+			case octet&0xF0 == 0xE0:
+				w, v = 3, rune(octet&0x0F)
+			case octet&0xF8 == 0xF0:
+				w, v = 4, rune(octet&0x07)
+			}
+			for k := 1; k < w; k++ {
+				octet = value[i+k]
+				v = (v << 6) + (rune(octet) & 0x3F)
+			}
+			i += w
+
+			if !put(emitter, '\\') {
+				return false
+			}
+
+			var ok bool
+			switch v {
+			case 0x00:
+				ok = put(emitter, '0')
+			case 0x07:
+				ok = put(emitter, 'a')
+			case 0x08:
+				ok = put(emitter, 'b')
+			case 0x09:
+				ok = put(emitter, 't')
+			case 0x0A:
+				ok = put(emitter, 'n')
+			case 0x0b:
+				ok = put(emitter, 'v')
+			case 0x0c:
+				ok = put(emitter, 'f')
+			case 0x0d:
+				ok = put(emitter, 'r')
+			case 0x1b:
+				ok = put(emitter, 'e')
+			case 0x22:
+				ok = put(emitter, '"')
+			case 0x5c:
+				ok = put(emitter, '\\')
+			case 0x85:
+				ok = put(emitter, 'N')
+			case 0xA0:
+				ok = put(emitter, '_')
+			case 0x2028:
+				ok = put(emitter, 'L')
+			case 0x2029:
+				ok = put(emitter, 'P')
+			default:
+				if v <= 0xFF {
+					ok = put(emitter, 'x')
+					w = 2
+				} else if v <= 0xFFFF {
+					ok = put(emitter, 'u')
+					w = 4
+				} else {
+					ok = put(emitter, 'U')
+					w = 8
+				}
+				for k := (w - 1) * 4; ok && k >= 0; k -= 4 {
+					digit := byte((v >> uint(k)) & 0x0F)
+					if digit < 10 {
+						ok = put(emitter, digit+'0')
+					} else {
+						ok = put(emitter, digit+'A'-10)
+					}
+				}
+			}
+			if !ok {
+				return false
+			}
+			spaces = false
+		} else if is_space(value, i) {
+			if allow_breaks && !spaces && emitter.column > emitter.best_width && i > 0 && i < len(value)-1 {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+				if is_space(value, i+1) {
+					if !put(emitter, '\\') {
+						return false
+					}
+				}
+				i += width(value[i])
+			} else if !write(emitter, value, &i) {
+				return false
+			}
+			spaces = true
+		} else {
+			if !write(emitter, value, &i) {
+				return false
+			}
+			spaces = false
+		}
+	}
+	if !yaml_emitter_write_indicator(emitter, []byte{'"'}, false, false, false) {
+		return false
+	}
+	emitter.whitespace = false
+	emitter.indention = false
+	return true
+}
+
+func yaml_emitter_write_block_scalar_hints(emitter *yaml_emitter_t, value []byte) bool {
+	if is_space(value, 0) || is_break(value, 0) {
+		indent_hint := []byte{'0' + byte(emitter.best_indent)}
+		if !yaml_emitter_write_indicator(emitter, indent_hint, false, false, false) {
+			return false
+		}
+	}
+
+	emitter.open_ended = false
+
+	var chomp_hint [1]byte
+	if len(value) == 0 {
+		chomp_hint[0] = '-'
+	} else {
+		i := len(value) - 1
+		for value[i]&0xC0 == 0x80 {
+			i--
+		}
+		if !is_break(value, i) {
+			chomp_hint[0] = '-'
+		} else if i == 0 {
+			chomp_hint[0] = '+'
+			emitter.open_ended = true
+		} else {
+			i--
+			for value[i]&0xC0 == 0x80 {
+				i--
+			}
+			if is_break(value, i) {
+				chomp_hint[0] = '+'
+				emitter.open_ended = true
+			}
+		}
+	}
+	if chomp_hint[0] != 0 {
+		if !yaml_emitter_write_indicator(emitter, chomp_hint[:], false, false, false) {
+			return false
+		}
+	}
+	return true
+}
+
+func yaml_emitter_write_literal_scalar(emitter *yaml_emitter_t, value []byte) bool {
+	if !yaml_emitter_write_indicator(emitter, []byte{'|'}, true, false, false) {
+		return false
+	}
+	if !yaml_emitter_write_block_scalar_hints(emitter, value) {
+		return false
+	}
+	if !put_break(emitter) {
+		return false
+	}
+	emitter.indention = true
+	emitter.whitespace = true
+	breaks := true
+	for i := 0; i < len(value); {
+		if is_break(value, i) {
+			if !write_break(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = true
+			breaks = true
+		} else {
+			if breaks {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+			}
+			if !write(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = false
+			breaks = false
+		}
+	}
+
+	return true
+}
+
+func yaml_emitter_write_folded_scalar(emitter *yaml_emitter_t, value []byte) bool {
+	if !yaml_emitter_write_indicator(emitter, []byte{'>'}, true, false, false) {
+		return false
+	}
+	if !yaml_emitter_write_block_scalar_hints(emitter, value) {
+		return false
+	}
+
+	if !put_break(emitter) {
+		return false
+	}
+	emitter.indention = true
+	emitter.whitespace = true
+
+	breaks := true
+	leading_spaces := true
+	for i := 0; i < len(value); {
+		if is_break(value, i) {
+			if !breaks && !leading_spaces && value[i] == '\n' {
+				k := 0
+				for is_break(value, k) {
+					k += width(value[k])
+				}
+				if !is_blankz(value, k) {
+					if !put_break(emitter) {
+						return false
+					}
+				}
+			}
+			if !write_break(emitter, value, &i) {
+				return false
+			}
+			emitter.indention = true
+			breaks = true
+		} else {
+			if breaks {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+				leading_spaces = is_blank(value, i)
+			}
+			if !breaks && is_space(value, i) && !is_space(value, i+1) && emitter.column > emitter.best_width {
+				if !yaml_emitter_write_indent(emitter) {
+					return false
+				}
+				i += width(value[i])
+			} else {
+				if !write(emitter, value, &i) {
+					return false
+				}
+			}
+			emitter.indention = false
+			breaks = false
+		}
+	}
+	return true
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/encode.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/encode.go
new file mode 100644
index 00000000000..0ee738e11b6
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/encode.go
@@ -0,0 +1,390 @@
+package yaml
+
+import (
+	"encoding"
+	"fmt"
+	"io"
+	"reflect"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+	"unicode/utf8"
+)
+
+// jsonNumber is the interface of the encoding/json.Number datatype.
+// Repeating the interface here avoids a dependency on encoding/json, and also
+// supports other libraries like jsoniter, which use a similar datatype with
+// the same interface. Detecting this interface is useful when dealing with
+// structures containing json.Number, which is a string under the hood. The
+// encoder should prefer the use of Int64(), Float64() and string(), in that
+// order, when encoding this type.
+type jsonNumber interface {
+	Float64() (float64, error)
+	Int64() (int64, error)
+	String() string
+}
+
+type encoder struct {
+	emitter yaml_emitter_t
+	event   yaml_event_t
+	out     []byte
+	flow    bool
+	// doneInit holds whether the initial stream_start_event has been
+	// emitted.
+	doneInit bool
+}
+
+func newEncoder() *encoder {
+	e := &encoder{}
+	yaml_emitter_initialize(&e.emitter)
+	yaml_emitter_set_output_string(&e.emitter, &e.out)
+	yaml_emitter_set_unicode(&e.emitter, true)
+	return e
+}
+
+func newEncoderWithWriter(w io.Writer) *encoder {
+	e := &encoder{}
+	yaml_emitter_initialize(&e.emitter)
+	yaml_emitter_set_output_writer(&e.emitter, w)
+	yaml_emitter_set_unicode(&e.emitter, true)
+	return e
+}
+
+func (e *encoder) init() {
+	if e.doneInit {
+		return
+	}
+	yaml_stream_start_event_initialize(&e.event, yaml_UTF8_ENCODING)
+	e.emit()
+	e.doneInit = true
+}
+
+func (e *encoder) finish() {
+	e.emitter.open_ended = false
+	yaml_stream_end_event_initialize(&e.event)
+	e.emit()
+}
+
+func (e *encoder) destroy() {
+	yaml_emitter_delete(&e.emitter)
+}
+
+func (e *encoder) emit() {
+	// This will internally delete the e.event value.
+	e.must(yaml_emitter_emit(&e.emitter, &e.event))
+}
+
+func (e *encoder) must(ok bool) {
+	if !ok {
+		msg := e.emitter.problem
+		if msg == "" {
+			msg = "unknown problem generating YAML content"
+		}
+		failf("%s", msg)
+	}
+}
+
+func (e *encoder) marshalDoc(tag string, in reflect.Value) {
+	e.init()
+	yaml_document_start_event_initialize(&e.event, nil, nil, true)
+	e.emit()
+	e.marshal(tag, in)
+	yaml_document_end_event_initialize(&e.event, true)
+	e.emit()
+}
+
+func (e *encoder) marshal(tag string, in reflect.Value) {
+	if !in.IsValid() || in.Kind() == reflect.Ptr && in.IsNil() {
+		e.nilv()
+		return
+	}
+	iface := in.Interface()
+	switch m := iface.(type) {
+	case jsonNumber:
+		integer, err := m.Int64()
+		if err == nil {
+			// In this case the json.Number is a valid int64
+			in = reflect.ValueOf(integer)
+			break
+		}
+		float, err := m.Float64()
+		if err == nil {
+			// In this case the json.Number is a valid float64
+			in = reflect.ValueOf(float)
+			break
+		}
+		// fallback case - no number could be obtained
+		in = reflect.ValueOf(m.String())
+	case time.Time, *time.Time:
+		// Although time.Time implements TextMarshaler,
+		// we don't want to treat it as a string for YAML
+		// purposes because YAML has special support for
+		// timestamps.
+	case Marshaler:
+		v, err := m.MarshalYAML()
+		if err != nil {
+			fail(err)
+		}
+		if v == nil {
+			e.nilv()
+			return
+		}
+		in = reflect.ValueOf(v)
+	case encoding.TextMarshaler:
+		text, err := m.MarshalText()
+		if err != nil {
+			fail(err)
+		}
+		in = reflect.ValueOf(string(text))
+	case nil:
+		e.nilv()
+		return
+	}
+	switch in.Kind() {
+	case reflect.Interface:
+		e.marshal(tag, in.Elem())
+	case reflect.Map:
+		e.mapv(tag, in)
+	case reflect.Ptr:
+		if in.Type() == ptrTimeType {
+			e.timev(tag, in.Elem())
+		} else {
+			e.marshal(tag, in.Elem())
+		}
+	case reflect.Struct:
+		if in.Type() == timeType {
+			e.timev(tag, in)
+		} else {
+			e.structv(tag, in)
+		}
+	case reflect.Slice, reflect.Array:
+		if in.Type().Elem() == mapItemType {
+			e.itemsv(tag, in)
+		} else {
+			e.slicev(tag, in)
+		}
+	case reflect.String:
+		e.stringv(tag, in)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		if in.Type() == durationType {
+			e.stringv(tag, reflect.ValueOf(iface.(time.Duration).String()))
+		} else {
+			e.intv(tag, in)
+		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		e.uintv(tag, in)
+	case reflect.Float32, reflect.Float64:
+		e.floatv(tag, in)
+	case reflect.Bool:
+		e.boolv(tag, in)
+	default:
+		panic("cannot marshal type: " + in.Type().String())
+	}
+}
+
+func (e *encoder) mapv(tag string, in reflect.Value) {
+	e.mappingv(tag, func() {
+		keys := keyList(in.MapKeys())
+		sort.Sort(keys)
+		for _, k := range keys {
+			e.marshal("", k)
+			e.marshal("", in.MapIndex(k))
+		}
+	})
+}
+
+func (e *encoder) itemsv(tag string, in reflect.Value) {
+	e.mappingv(tag, func() {
+		slice := in.Convert(reflect.TypeOf([]MapItem{})).Interface().([]MapItem)
+		for _, item := range slice {
+			e.marshal("", reflect.ValueOf(item.Key))
+			e.marshal("", reflect.ValueOf(item.Value))
+		}
+	})
+}
+
+func (e *encoder) structv(tag string, in reflect.Value) {
+	sinfo, err := getStructInfo(in.Type())
+	if err != nil {
+		panic(err)
+	}
+	e.mappingv(tag, func() {
+		for _, info := range sinfo.FieldsList {
+			var value reflect.Value
+			if info.Inline == nil {
+				value = in.Field(info.Num)
+			} else {
+				value = in.FieldByIndex(info.Inline)
+			}
+			if info.OmitEmpty && isZero(value) {
+				continue
+			}
+			e.marshal("", reflect.ValueOf(info.Key))
+			e.flow = info.Flow
+			e.marshal("", value)
+		}
+		if sinfo.InlineMap >= 0 {
+			m := in.Field(sinfo.InlineMap)
+			if m.Len() > 0 {
+				e.flow = false
+				keys := keyList(m.MapKeys())
+				sort.Sort(keys)
+				for _, k := range keys {
+					if _, found := sinfo.FieldsMap[k.String()]; found {
+						panic(fmt.Sprintf("Can't have key %q in inlined map; conflicts with struct field", k.String()))
+					}
+					e.marshal("", k)
+					e.flow = false
+					e.marshal("", m.MapIndex(k))
+				}
+			}
+		}
+	})
+}
+
+func (e *encoder) mappingv(tag string, f func()) {
+	implicit := tag == ""
+	style := yaml_BLOCK_MAPPING_STYLE
+	if e.flow {
+		e.flow = false
+		style = yaml_FLOW_MAPPING_STYLE
+	}
+	yaml_mapping_start_event_initialize(&e.event, nil, []byte(tag), implicit, style)
+	e.emit()
+	f()
+	yaml_mapping_end_event_initialize(&e.event)
+	e.emit()
+}
+
+func (e *encoder) slicev(tag string, in reflect.Value) {
+	implicit := tag == ""
+	style := yaml_BLOCK_SEQUENCE_STYLE
+	if e.flow {
+		e.flow = false
+		style = yaml_FLOW_SEQUENCE_STYLE
+	}
+	e.must(yaml_sequence_start_event_initialize(&e.event, nil, []byte(tag), implicit, style))
+	e.emit()
+	n := in.Len()
+	for i := 0; i < n; i++ {
+		e.marshal("", in.Index(i))
+	}
+	e.must(yaml_sequence_end_event_initialize(&e.event))
+	e.emit()
+}
+
+// isBase60 returns whether s is in base 60 notation as defined in YAML 1.1.
+//
+// The base 60 float notation in YAML 1.1 is a terrible idea and is unsupported
+// in YAML 1.2 and by this package, but these should be marshalled quoted for
+// the time being for compatibility with other parsers.
+func isBase60Float(s string) (result bool) {
+	// Fast path.
+	if s == "" {
+		return false
+	}
+	c := s[0]
+	if !(c == '+' || c == '-' || c >= '0' && c <= '9') || strings.IndexByte(s, ':') < 0 {
+		return false
+	}
+	// Do the full match.
+	return base60float.MatchString(s)
+}
+
+// From http://yaml.org/type/float.html, except the regular expression there
+// is bogus. In practice parsers do not enforce the "\.[0-9_]*" suffix.
+var base60float = regexp.MustCompile(`^[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+(?:\.[0-9_]*)?$`)
+
+func (e *encoder) stringv(tag string, in reflect.Value) {
+	var style yaml_scalar_style_t
+	s := in.String()
+	canUsePlain := true
+	switch {
+	case !utf8.ValidString(s):
+		if tag == yaml_BINARY_TAG {
+			failf("explicitly tagged !!binary data must be base64-encoded")
+		}
+		if tag != "" {
+			failf("cannot marshal invalid UTF-8 data as %s", shortTag(tag))
+		}
+		// It can't be encoded directly as YAML so use a binary tag
+		// and encode it as base64.
+		tag = yaml_BINARY_TAG
+		s = encodeBase64(s)
+	case tag == "":
+		// Check to see if it would resolve to a specific
+		// tag when encoded unquoted. If it doesn't,
+		// there's no need to quote it.
+		rtag, _ := resolve("", s)
+		canUsePlain = rtag == yaml_STR_TAG && !isBase60Float(s)
+	}
+	// Note: it's possible for user code to emit invalid YAML
+	// if they explicitly specify a tag and a string containing
+	// text that's incompatible with that tag.
+	switch {
+	case strings.Contains(s, "\n"):
+		style = yaml_LITERAL_SCALAR_STYLE
+	case canUsePlain:
+		style = yaml_PLAIN_SCALAR_STYLE
+	default:
+		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+	}
+	e.emitScalar(s, "", tag, style)
+}
+
+func (e *encoder) boolv(tag string, in reflect.Value) {
+	var s string
+	if in.Bool() {
+		s = "true"
+	} else {
+		s = "false"
+	}
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) intv(tag string, in reflect.Value) {
+	s := strconv.FormatInt(in.Int(), 10)
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) uintv(tag string, in reflect.Value) {
+	s := strconv.FormatUint(in.Uint(), 10)
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) timev(tag string, in reflect.Value) {
+	t := in.Interface().(time.Time)
+	s := t.Format(time.RFC3339Nano)
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) floatv(tag string, in reflect.Value) {
+	// Issue #352: When formatting, use the precision of the underlying value
+	precision := 64
+	if in.Kind() == reflect.Float32 {
+		precision = 32
+	}
+
+	s := strconv.FormatFloat(in.Float(), 'g', -1, precision)
+	switch s {
+	case "+Inf":
+		s = ".inf"
+	case "-Inf":
+		s = "-.inf"
+	case "NaN":
+		s = ".nan"
+	}
+	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) nilv() {
+	e.emitScalar("null", "", "", yaml_PLAIN_SCALAR_STYLE)
+}
+
+func (e *encoder) emitScalar(value, anchor, tag string, style yaml_scalar_style_t) {
+	implicit := tag == ""
+	e.must(yaml_scalar_event_initialize(&e.event, []byte(anchor), []byte(tag), []byte(value), implicit, implicit, style))
+	e.emit()
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/encode_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/encode_test.go
new file mode 100644
index 00000000000..f7c91ff0020
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/encode_test.go
@@ -0,0 +1,630 @@
+package yaml_test
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+	"time"
+
+	"net"
+	"os"
+
+	. "gopkg.in/check.v1"
+	"gopkg.in/yaml.v2"
+)
+
+type jsonNumberT string
+
+func (j jsonNumberT) Int64() (int64, error) {
+	val, err := strconv.Atoi(string(j))
+	if err != nil {
+		return 0, err
+	}
+	return int64(val), nil
+}
+
+func (j jsonNumberT) Float64() (float64, error) {
+	return strconv.ParseFloat(string(j), 64)
+}
+
+func (j jsonNumberT) String() string {
+	return string(j)
+}
+
+var marshalIntTest = 123
+
+var marshalTests = []struct {
+	value interface{}
+	data  string
+}{
+	{
+		nil,
+		"null\n",
+	}, {
+		(*marshalerType)(nil),
+		"null\n",
+	}, {
+		&struct{}{},
+		"{}\n",
+	}, {
+		map[string]string{"v": "hi"},
+		"v: hi\n",
+	}, {
+		map[string]interface{}{"v": "hi"},
+		"v: hi\n",
+	}, {
+		map[string]string{"v": "true"},
+		"v: \"true\"\n",
+	}, {
+		map[string]string{"v": "false"},
+		"v: \"false\"\n",
+	}, {
+		map[string]interface{}{"v": true},
+		"v: true\n",
+	}, {
+		map[string]interface{}{"v": false},
+		"v: false\n",
+	}, {
+		map[string]interface{}{"v": 10},
+		"v: 10\n",
+	}, {
+		map[string]interface{}{"v": -10},
+		"v: -10\n",
+	}, {
+		map[string]uint{"v": 42},
+		"v: 42\n",
+	}, {
+		map[string]interface{}{"v": int64(4294967296)},
+		"v: 4294967296\n",
+	}, {
+		map[string]int64{"v": int64(4294967296)},
+		"v: 4294967296\n",
+	}, {
+		map[string]uint64{"v": 4294967296},
+		"v: 4294967296\n",
+	}, {
+		map[string]interface{}{"v": "10"},
+		"v: \"10\"\n",
+	}, {
+		map[string]interface{}{"v": 0.1},
+		"v: 0.1\n",
+	}, {
+		map[string]interface{}{"v": float64(0.1)},
+		"v: 0.1\n",
+	}, {
+		map[string]interface{}{"v": float32(0.99)},
+		"v: 0.99\n",
+	}, {
+		map[string]interface{}{"v": -0.1},
+		"v: -0.1\n",
+	}, {
+		map[string]interface{}{"v": math.Inf(+1)},
+		"v: .inf\n",
+	}, {
+		map[string]interface{}{"v": math.Inf(-1)},
+		"v: -.inf\n",
+	}, {
+		map[string]interface{}{"v": math.NaN()},
+		"v: .nan\n",
+	}, {
+		map[string]interface{}{"v": nil},
+		"v: null\n",
+	}, {
+		map[string]interface{}{"v": ""},
+		"v: \"\"\n",
+	}, {
+		map[string][]string{"v": []string{"A", "B"}},
+		"v:\n- A\n- B\n",
+	}, {
+		map[string][]string{"v": []string{"A", "B\nC"}},
+		"v:\n- A\n- |-\n  B\n  C\n",
+	}, {
+		map[string][]interface{}{"v": []interface{}{"A", 1, map[string][]int{"B": []int{2, 3}}}},
+		"v:\n- A\n- 1\n- B:\n  - 2\n  - 3\n",
+	}, {
+		map[string]interface{}{"a": map[interface{}]interface{}{"b": "c"}},
+		"a:\n  b: c\n",
+	}, {
+		map[string]interface{}{"a": "-"},
+		"a: '-'\n",
+	},
+
+	// Simple values.
+	{
+		&marshalIntTest,
+		"123\n",
+	},
+
+	// Structures
+	{
+		&struct{ Hello string }{"world"},
+		"hello: world\n",
+	}, {
+		&struct {
+			A struct {
+				B string
+			}
+		}{struct{ B string }{"c"}},
+		"a:\n  b: c\n",
+	}, {
+		&struct {
+			A *struct {
+				B string
+			}
+		}{&struct{ B string }{"c"}},
+		"a:\n  b: c\n",
+	}, {
+		&struct {
+			A *struct {
+				B string
+			}
+		}{},
+		"a: null\n",
+	}, {
+		&struct{ A int }{1},
+		"a: 1\n",
+	}, {
+		&struct{ A []int }{[]int{1, 2}},
+		"a:\n- 1\n- 2\n",
+	}, {
+		&struct{ A [2]int }{[2]int{1, 2}},
+		"a:\n- 1\n- 2\n",
+	}, {
+		&struct {
+			B int "a"
+		}{1},
+		"a: 1\n",
+	}, {
+		&struct{ A bool }{true},
+		"a: true\n",
+	},
+
+	// Conditional flag
+	{
+		&struct {
+			A int "a,omitempty"
+			B int "b,omitempty"
+		}{1, 0},
+		"a: 1\n",
+	}, {
+		&struct {
+			A int "a,omitempty"
+			B int "b,omitempty"
+		}{0, 0},
+		"{}\n",
+	}, {
+		&struct {
+			A *struct{ X, y int } "a,omitempty,flow"
+		}{&struct{ X, y int }{1, 2}},
+		"a: {x: 1}\n",
+	}, {
+		&struct {
+			A *struct{ X, y int } "a,omitempty,flow"
+		}{nil},
+		"{}\n",
+	}, {
+		&struct {
+			A *struct{ X, y int } "a,omitempty,flow"
+		}{&struct{ X, y int }{}},
+		"a: {x: 0}\n",
+	}, {
+		&struct {
+			A struct{ X, y int } "a,omitempty,flow"
+		}{struct{ X, y int }{1, 2}},
+		"a: {x: 1}\n",
+	}, {
+		&struct {
+			A struct{ X, y int } "a,omitempty,flow"
+		}{struct{ X, y int }{0, 1}},
+		"{}\n",
+	}, {
+		&struct {
+			A float64 "a,omitempty"
+			B float64 "b,omitempty"
+		}{1, 0},
+		"a: 1\n",
+	},
+	{
+		&struct {
+			T1 time.Time  "t1,omitempty"
+			T2 time.Time  "t2,omitempty"
+			T3 *time.Time "t3,omitempty"
+			T4 *time.Time "t4,omitempty"
+		}{
+			T2: time.Date(2018, 1, 9, 10, 40, 47, 0, time.UTC),
+			T4: newTime(time.Date(2098, 1, 9, 10, 40, 47, 0, time.UTC)),
+		},
+		"t2: 2018-01-09T10:40:47Z\nt4: 2098-01-09T10:40:47Z\n",
+	},
+	// Nil interface that implements Marshaler.
+	{
+		map[string]yaml.Marshaler{
+			"a": nil,
+		},
+		"a: null\n",
+	},
+
+	// Flow flag
+	{
+		&struct {
+			A []int "a,flow"
+		}{[]int{1, 2}},
+		"a: [1, 2]\n",
+	}, {
+		&struct {
+			A map[string]string "a,flow"
+		}{map[string]string{"b": "c", "d": "e"}},
+		"a: {b: c, d: e}\n",
+	}, {
+		&struct {
+			A struct {
+				B, D string
+			} "a,flow"
+		}{struct{ B, D string }{"c", "e"}},
+		"a: {b: c, d: e}\n",
+	},
+
+	// Unexported field
+	{
+		&struct {
+			u int
+			A int
+		}{0, 1},
+		"a: 1\n",
+	},
+
+	// Ignored field
+	{
+		&struct {
+			A int
+			B int "-"
+		}{1, 2},
+		"a: 1\n",
+	},
+
+	// Struct inlining
+	{
+		&struct {
+			A int
+			C inlineB `yaml:",inline"`
+		}{1, inlineB{2, inlineC{3}}},
+		"a: 1\nb: 2\nc: 3\n",
+	},
+
+	// Map inlining
+	{
+		&struct {
+			A int
+			C map[string]int `yaml:",inline"`
+		}{1, map[string]int{"b": 2, "c": 3}},
+		"a: 1\nb: 2\nc: 3\n",
+	},
+
+	// Duration
+	{
+		map[string]time.Duration{"a": 3 * time.Second},
+		"a: 3s\n",
+	},
+
+	// Issue #24: bug in map merging logic.
+	{
+		map[string]string{"a": "<foo>"},
+		"a: <foo>\n",
+	},
+
+	// Issue #34: marshal unsupported base 60 floats quoted for compatibility
+	// with old YAML 1.1 parsers.
+	{
+		map[string]string{"a": "1:1"},
+		"a: \"1:1\"\n",
+	},
+
+	// Binary data.
+	{
+		map[string]string{"a": "\x00"},
+		"a: \"\\0\"\n",
+	}, {
+		map[string]string{"a": "\x80\x81\x82"},
+		"a: !!binary gIGC\n",
+	}, {
+		map[string]string{"a": strings.Repeat("\x90", 54)},
+		"a: !!binary |\n  " + strings.Repeat("kJCQ", 17) + "kJ\n  CQ\n",
+	},
+
+	// Ordered maps.
+	{
+		&yaml.MapSlice{{"b", 2}, {"a", 1}, {"d", 4}, {"c", 3}, {"sub", yaml.MapSlice{{"e", 5}}}},
+		"b: 2\na: 1\nd: 4\nc: 3\nsub:\n  e: 5\n",
+	},
+
+	// Encode unicode as utf-8 rather than in escaped form.
+	{
+		map[string]string{"a": "你好"},
+		"a: 你好\n",
+	},
+
+	// Support encoding.TextMarshaler.
+	{
+		map[string]net.IP{"a": net.IPv4(1, 2, 3, 4)},
+		"a: 1.2.3.4\n",
+	},
+	// time.Time gets a timestamp tag.
+	{
+		map[string]time.Time{"a": time.Date(2015, 2, 24, 18, 19, 39, 0, time.UTC)},
+		"a: 2015-02-24T18:19:39Z\n",
+	},
+	{
+		map[string]*time.Time{"a": newTime(time.Date(2015, 2, 24, 18, 19, 39, 0, time.UTC))},
+		"a: 2015-02-24T18:19:39Z\n",
+	},
+	{
+		// This is confirmed to be properly decoded in Python (libyaml) without a timestamp tag.
+		map[string]time.Time{"a": time.Date(2015, 2, 24, 18, 19, 39, 123456789, time.FixedZone("FOO", -3*60*60))},
+		"a: 2015-02-24T18:19:39.123456789-03:00\n",
+	},
+	// Ensure timestamp-like strings are quoted.
+	{
+		map[string]string{"a": "2015-02-24T18:19:39Z"},
+		"a: \"2015-02-24T18:19:39Z\"\n",
+	},
+
+	// Ensure strings containing ": " are quoted (reported as PR #43, but not reproducible).
+	{
+		map[string]string{"a": "b: c"},
+		"a: 'b: c'\n",
+	},
+
+	// Containing hash mark ('#') in string should be quoted
+	{
+		map[string]string{"a": "Hello #comment"},
+		"a: 'Hello #comment'\n",
+	},
+	{
+		map[string]string{"a": "你好 #comment"},
+		"a: '你好 #comment'\n",
+	},
+	{
+		map[string]interface{}{"a": jsonNumberT("5")},
+		"a: 5\n",
+	},
+	{
+		map[string]interface{}{"a": jsonNumberT("100.5")},
+		"a: 100.5\n",
+	},
+	{
+		map[string]interface{}{"a": jsonNumberT("bogus")},
+		"a: bogus\n",
+	},
+	// Ensure that strings do not wrap
+	{
+		map[string]string{"a": "abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890 abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890 "},
+		"a: 'abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890 abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890 '\n",
+	},
+}
+
+func (s *S) TestMarshal(c *C) {
+	defer os.Setenv("TZ", os.Getenv("TZ"))
+	os.Setenv("TZ", "UTC")
+	for i, item := range marshalTests {
+		c.Logf("test %d: %q", i, item.data)
+		data, err := yaml.Marshal(item.value)
+		c.Assert(err, IsNil)
+		c.Assert(string(data), Equals, item.data)
+	}
+}
+
+func (s *S) TestEncoderSingleDocument(c *C) {
+	for i, item := range marshalTests {
+		c.Logf("test %d. %q", i, item.data)
+		var buf bytes.Buffer
+		enc := yaml.NewEncoder(&buf)
+		err := enc.Encode(item.value)
+		c.Assert(err, Equals, nil)
+		err = enc.Close()
+		c.Assert(err, Equals, nil)
+		c.Assert(buf.String(), Equals, item.data)
+	}
+}
+
+func (s *S) TestEncoderMultipleDocuments(c *C) {
+	var buf bytes.Buffer
+	enc := yaml.NewEncoder(&buf)
+	err := enc.Encode(map[string]string{"a": "b"})
+	c.Assert(err, Equals, nil)
+	err = enc.Encode(map[string]string{"c": "d"})
+	c.Assert(err, Equals, nil)
+	err = enc.Close()
+	c.Assert(err, Equals, nil)
+	c.Assert(buf.String(), Equals, "a: b\n---\nc: d\n")
+}
+
+func (s *S) TestEncoderWriteError(c *C) {
+	enc := yaml.NewEncoder(errorWriter{})
+	err := enc.Encode(map[string]string{"a": "b"})
+	c.Assert(err, ErrorMatches, `yaml: write error: some write error`) // Data not flushed yet
+}
+
+type errorWriter struct{}
+
+func (errorWriter) Write([]byte) (int, error) {
+	return 0, fmt.Errorf("some write error")
+}
+
+var marshalErrorTests = []struct {
+	value interface{}
+	error string
+	panic string
+}{{
+	value: &struct {
+		B       int
+		inlineB ",inline"
+	}{1, inlineB{2, inlineC{3}}},
+	panic: `Duplicated key 'b' in struct struct \{ B int; .*`,
+}, {
+	value: &struct {
+		A int
+		B map[string]int ",inline"
+	}{1, map[string]int{"a": 2}},
+	panic: `Can't have key "a" in inlined map; conflicts with struct field`,
+}}
+
+func (s *S) TestMarshalErrors(c *C) {
+	for _, item := range marshalErrorTests {
+		if item.panic != "" {
+			c.Assert(func() { yaml.Marshal(item.value) }, PanicMatches, item.panic)
+		} else {
+			_, err := yaml.Marshal(item.value)
+			c.Assert(err, ErrorMatches, item.error)
+		}
+	}
+}
+
+func (s *S) TestMarshalTypeCache(c *C) {
+	var data []byte
+	var err error
+	func() {
+		type T struct{ A int }
+		data, err = yaml.Marshal(&T{})
+		c.Assert(err, IsNil)
+	}()
+	func() {
+		type T struct{ B int }
+		data, err = yaml.Marshal(&T{})
+		c.Assert(err, IsNil)
+	}()
+	c.Assert(string(data), Equals, "b: 0\n")
+}
+
+var marshalerTests = []struct {
+	data  string
+	value interface{}
+}{
+	{"_:\n  hi: there\n", map[interface{}]interface{}{"hi": "there"}},
+	{"_:\n- 1\n- A\n", []interface{}{1, "A"}},
+	{"_: 10\n", 10},
+	{"_: null\n", nil},
+	{"_: BAR!\n", "BAR!"},
+}
+
+type marshalerType struct {
+	value interface{}
+}
+
+func (o marshalerType) MarshalText() ([]byte, error) {
+	panic("MarshalText called on type with MarshalYAML")
+}
+
+func (o marshalerType) MarshalYAML() (interface{}, error) {
+	return o.value, nil
+}
+
+type marshalerValue struct {
+	Field marshalerType "_"
+}
+
+func (s *S) TestMarshaler(c *C) {
+	for _, item := range marshalerTests {
+		obj := &marshalerValue{}
+		obj.Field.value = item.value
+		data, err := yaml.Marshal(obj)
+		c.Assert(err, IsNil)
+		c.Assert(string(data), Equals, string(item.data))
+	}
+}
+
+func (s *S) TestMarshalerWholeDocument(c *C) {
+	obj := &marshalerType{}
+	obj.value = map[string]string{"hello": "world!"}
+	data, err := yaml.Marshal(obj)
+	c.Assert(err, IsNil)
+	c.Assert(string(data), Equals, "hello: world!\n")
+}
+
+type failingMarshaler struct{}
+
+func (ft *failingMarshaler) MarshalYAML() (interface{}, error) {
+	return nil, failingErr
+}
+
+func (s *S) TestMarshalerError(c *C) {
+	_, err := yaml.Marshal(&failingMarshaler{})
+	c.Assert(err, Equals, failingErr)
+}
+
+func (s *S) TestSortedOutput(c *C) {
+	order := []interface{}{
+		false,
+		true,
+		1,
+		uint(1),
+		1.0,
+		1.1,
+		1.2,
+		2,
+		uint(2),
+		2.0,
+		2.1,
+		"",
+		".1",
+		".2",
+		".a",
+		"1",
+		"2",
+		"a!10",
+		"a/0001",
+		"a/002",
+		"a/3",
+		"a/10",
+		"a/11",
+		"a/0012",
+		"a/100",
+		"a~10",
+		"ab/1",
+		"b/1",
+		"b/01",
+		"b/2",
+		"b/02",
+		"b/3",
+		"b/03",
+		"b1",
+		"b01",
+		"b3",
+		"c2.10",
+		"c10.2",
+		"d1",
+		"d7",
+		"d7abc",
+		"d12",
+		"d12a",
+	}
+	m := make(map[interface{}]int)
+	for _, k := range order {
+		m[k] = 1
+	}
+	data, err := yaml.Marshal(m)
+	c.Assert(err, IsNil)
+	out := "\n" + string(data)
+	last := 0
+	for i, k := range order {
+		repr := fmt.Sprint(k)
+		if s, ok := k.(string); ok {
+			if _, err = strconv.ParseFloat(repr, 32); s == "" || err == nil {
+				repr = `"` + repr + `"`
+			}
+		}
+		index := strings.Index(out, "\n"+repr+":")
+		if index == -1 {
+			c.Fatalf("%#v is not in the output: %#v", k, out)
+		}
+		if index < last {
+			c.Fatalf("%#v was generated before %#v: %q", k, order[i-1], out)
+		}
+		last = index
+	}
+}
+
+func newTime(t time.Time) *time.Time {
+	return &t
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/example_embedded_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/example_embedded_test.go
new file mode 100644
index 00000000000..171c0931a19
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/example_embedded_test.go
@@ -0,0 +1,41 @@
+package yaml_test
+
+import (
+	"fmt"
+	"log"
+
+	"gopkg.in/yaml.v2"
+)
+
+// An example showing how to unmarshal embedded
+// structs from YAML.
+
+type StructA struct {
+	A string `yaml:"a"`
+}
+
+type StructB struct {
+	// Embedded structs are not treated as embedded in YAML by default. To do that,
+	// add the ",inline" annotation below
+	StructA `yaml:",inline"`
+	B       string `yaml:"b"`
+}
+
+var data = `
+a: a string from struct A
+b: a string from struct B
+`
+
+func ExampleUnmarshal_embedded() {
+	var b StructB
+
+	err := yaml.Unmarshal([]byte(data), &b)
+	if err != nil {
+		log.Fatalf("cannot unmarshal data: %v", err)
+	}
+	fmt.Println(b.A)
+	fmt.Println(b.B)
+	// Output:
+	// a string from struct A
+	// a string from struct B
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/go.mod b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/go.mod
new file mode 100644
index 00000000000..1934e876945
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/go.mod
@@ -0,0 +1,5 @@
+module "gopkg.in/yaml.v2"
+
+require (
+	"gopkg.in/check.v1" v0.0.0-20161208181325-20d25e280405
+)
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/limit_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/limit_test.go
new file mode 100644
index 00000000000..8d8ec2d2245
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/limit_test.go
@@ -0,0 +1,128 @@
+package yaml_test
+
+import (
+	"strings"
+	"testing"
+
+	. "gopkg.in/check.v1"
+	"gopkg.in/yaml.v2"
+)
+
+var limitTests = []struct {
+	name  string
+	data  []byte
+	error string
+}{
+	{
+		name:  "1000kb of maps with 100 aliases",
+		data:  []byte(`{a: &a [{a}` + strings.Repeat(`,{a}`, 1000*1024/4-100) + `], b: &b [*a` + strings.Repeat(`,*a`, 99) + `]}`),
+		error: "yaml: document contains excessive aliasing",
+	}, {
+		name:  "1000kb of deeply nested slices",
+		data:  []byte(strings.Repeat(`[`, 1000*1024)),
+		error: "yaml: exceeded max depth of 10000",
+	}, {
+		name:  "1000kb of deeply nested maps",
+		data:  []byte("x: " + strings.Repeat(`{`, 1000*1024)),
+		error: "yaml: exceeded max depth of 10000",
+	}, {
+		name:  "1000kb of deeply nested indents",
+		data:  []byte(strings.Repeat(`- `, 1000*1024)),
+		error: "yaml: exceeded max depth of 10000",
+	}, {
+		name: "1000kb of 1000-indent lines",
+		data: []byte(strings.Repeat(strings.Repeat(`- `, 1000)+"\n", 1024/2)),
+	},
+	{name: "1kb of maps", data: []byte(`a: &a [{a}` + strings.Repeat(`,{a}`, 1*1024/4-1) + `]`)},
+	{name: "10kb of maps", data: []byte(`a: &a [{a}` + strings.Repeat(`,{a}`, 10*1024/4-1) + `]`)},
+	{name: "100kb of maps", data: []byte(`a: &a [{a}` + strings.Repeat(`,{a}`, 100*1024/4-1) + `]`)},
+	{name: "1000kb of maps", data: []byte(`a: &a [{a}` + strings.Repeat(`,{a}`, 1000*1024/4-1) + `]`)},
+	{name: "1000kb slice nested at max-depth", data: []byte(strings.Repeat(`[`, 10000) + `1` + strings.Repeat(`,1`, 1000*1024/2-20000-1) + strings.Repeat(`]`, 10000))},
+	{name: "1000kb slice nested in maps at max-depth", data: []byte("{a,b:\n" + strings.Repeat(" {a,b:", 10000-2) + ` [1` + strings.Repeat(",1", 1000*1024/2-6*10000-1) + `]` + strings.Repeat(`}`, 10000-1))},
+	{name: "1000kb of 10000-nested lines", data: []byte(strings.Repeat(`- `+strings.Repeat(`[`, 10000)+strings.Repeat(`]`, 10000)+"\n", 1000*1024/20000))},
+}
+
+func (s *S) TestLimits(c *C) {
+	if testing.Short() {
+		return
+	}
+	for _, tc := range limitTests {
+		var v interface{}
+		err := yaml.Unmarshal(tc.data, &v)
+		if len(tc.error) > 0 {
+			c.Assert(err, ErrorMatches, tc.error, Commentf("testcase: %s", tc.name))
+		} else {
+			c.Assert(err, IsNil, Commentf("testcase: %s", tc.name))
+		}
+	}
+}
+
+func Benchmark1000KB100Aliases(b *testing.B) {
+	benchmark(b, "1000kb of maps with 100 aliases")
+}
+func Benchmark1000KBDeeplyNestedSlices(b *testing.B) {
+	benchmark(b, "1000kb of deeply nested slices")
+}
+func Benchmark1000KBDeeplyNestedMaps(b *testing.B) {
+	benchmark(b, "1000kb of deeply nested maps")
+}
+func Benchmark1000KBDeeplyNestedIndents(b *testing.B) {
+	benchmark(b, "1000kb of deeply nested indents")
+}
+func Benchmark1000KB1000IndentLines(b *testing.B) {
+	benchmark(b, "1000kb of 1000-indent lines")
+}
+func Benchmark1KBMaps(b *testing.B) {
+	benchmark(b, "1kb of maps")
+}
+func Benchmark10KBMaps(b *testing.B) {
+	benchmark(b, "10kb of maps")
+}
+func Benchmark100KBMaps(b *testing.B) {
+	benchmark(b, "100kb of maps")
+}
+func Benchmark1000KBMaps(b *testing.B) {
+	benchmark(b, "1000kb of maps")
+}
+
+func BenchmarkDeepSlice(b *testing.B) {
+	benchmark(b, "1000kb slice nested at max-depth")
+}
+
+func BenchmarkDeepFlow(b *testing.B) {
+	benchmark(b, "1000kb slice nested in maps at max-depth")
+}
+
+func Benchmark1000KBMaxDepthNested(b *testing.B) {
+	benchmark(b, "1000kb of 10000-nested lines")
+}
+
+func benchmark(b *testing.B, name string) {
+	for _, t := range limitTests {
+		if t.name != name {
+			continue
+		}
+
+		b.ResetTimer()
+
+		for i := 0; i < b.N; i++ {
+			var v interface{}
+			err := yaml.Unmarshal(t.data, &v)
+			if len(t.error) > 0 {
+				if err == nil {
+					b.Errorf("expected error, got none")
+				} else if err.Error() != t.error {
+					b.Errorf("expected error '%s', got '%s'", t.error, err.Error())
+				}
+			} else {
+				if err != nil {
+					b.Errorf("unexpected error: %v", err)
+				}
+			}
+		}
+
+		return
+	}
+
+	b.Errorf("testcase %q not found", name)
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/parserc.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/parserc.go
new file mode 100644
index 00000000000..81d05dfe573
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/parserc.go
@@ -0,0 +1,1095 @@
+package yaml
+
+import (
+	"bytes"
+)
+
+// The parser implements the following grammar:
+//
+// stream               ::= STREAM-START implicit_document? explicit_document* STREAM-END
+// implicit_document    ::= block_node DOCUMENT-END*
+// explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+// block_node_or_indentless_sequence    ::=
+//                          ALIAS
+//                          | properties (block_content | indentless_block_sequence)?
+//                          | block_content
+//                          | indentless_block_sequence
+// block_node           ::= ALIAS
+//                          | properties block_content?
+//                          | block_content
+// flow_node            ::= ALIAS
+//                          | properties flow_content?
+//                          | flow_content
+// properties           ::= TAG ANCHOR? | ANCHOR TAG?
+// block_content        ::= block_collection | flow_collection | SCALAR
+// flow_content         ::= flow_collection | SCALAR
+// block_collection     ::= block_sequence | block_mapping
+// flow_collection      ::= flow_sequence | flow_mapping
+// block_sequence       ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
+// indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
+// block_mapping        ::= BLOCK-MAPPING_START
+//                          ((KEY block_node_or_indentless_sequence?)?
+//                          (VALUE block_node_or_indentless_sequence?)?)*
+//                          BLOCK-END
+// flow_sequence        ::= FLOW-SEQUENCE-START
+//                          (flow_sequence_entry FLOW-ENTRY)*
+//                          flow_sequence_entry?
+//                          FLOW-SEQUENCE-END
+// flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+// flow_mapping         ::= FLOW-MAPPING-START
+//                          (flow_mapping_entry FLOW-ENTRY)*
+//                          flow_mapping_entry?
+//                          FLOW-MAPPING-END
+// flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+
+// Peek the next token in the token queue.
+func peek_token(parser *yaml_parser_t) *yaml_token_t {
+	if parser.token_available || yaml_parser_fetch_more_tokens(parser) {
+		return &parser.tokens[parser.tokens_head]
+	}
+	return nil
+}
+
+// Remove the next token from the queue (must be called after peek_token).
+func skip_token(parser *yaml_parser_t) {
+	parser.token_available = false
+	parser.tokens_parsed++
+	parser.stream_end_produced = parser.tokens[parser.tokens_head].typ == yaml_STREAM_END_TOKEN
+	parser.tokens_head++
+}
+
+// Get the next event.
+func yaml_parser_parse(parser *yaml_parser_t, event *yaml_event_t) bool {
+	// Erase the event object.
+	*event = yaml_event_t{}
+
+	// No events after the end of the stream or error.
+	if parser.stream_end_produced || parser.error != yaml_NO_ERROR || parser.state == yaml_PARSE_END_STATE {
+		return true
+	}
+
+	// Generate the next event.
+	return yaml_parser_state_machine(parser, event)
+}
+
+// Set parser error.
+func yaml_parser_set_parser_error(parser *yaml_parser_t, problem string, problem_mark yaml_mark_t) bool {
+	parser.error = yaml_PARSER_ERROR
+	parser.problem = problem
+	parser.problem_mark = problem_mark
+	return false
+}
+
+func yaml_parser_set_parser_error_context(parser *yaml_parser_t, context string, context_mark yaml_mark_t, problem string, problem_mark yaml_mark_t) bool {
+	parser.error = yaml_PARSER_ERROR
+	parser.context = context
+	parser.context_mark = context_mark
+	parser.problem = problem
+	parser.problem_mark = problem_mark
+	return false
+}
+
+// State dispatcher.
+func yaml_parser_state_machine(parser *yaml_parser_t, event *yaml_event_t) bool {
+	//trace("yaml_parser_state_machine", "state:", parser.state.String())
+
+	switch parser.state {
+	case yaml_PARSE_STREAM_START_STATE:
+		return yaml_parser_parse_stream_start(parser, event)
+
+	case yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE:
+		return yaml_parser_parse_document_start(parser, event, true)
+
+	case yaml_PARSE_DOCUMENT_START_STATE:
+		return yaml_parser_parse_document_start(parser, event, false)
+
+	case yaml_PARSE_DOCUMENT_CONTENT_STATE:
+		return yaml_parser_parse_document_content(parser, event)
+
+	case yaml_PARSE_DOCUMENT_END_STATE:
+		return yaml_parser_parse_document_end(parser, event)
+
+	case yaml_PARSE_BLOCK_NODE_STATE:
+		return yaml_parser_parse_node(parser, event, true, false)
+
+	case yaml_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE:
+		return yaml_parser_parse_node(parser, event, true, true)
+
+	case yaml_PARSE_FLOW_NODE_STATE:
+		return yaml_parser_parse_node(parser, event, false, false)
+
+	case yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE:
+		return yaml_parser_parse_block_sequence_entry(parser, event, true)
+
+	case yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE:
+		return yaml_parser_parse_block_sequence_entry(parser, event, false)
+
+	case yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE:
+		return yaml_parser_parse_indentless_sequence_entry(parser, event)
+
+	case yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE:
+		return yaml_parser_parse_block_mapping_key(parser, event, true)
+
+	case yaml_PARSE_BLOCK_MAPPING_KEY_STATE:
+		return yaml_parser_parse_block_mapping_key(parser, event, false)
+
+	case yaml_PARSE_BLOCK_MAPPING_VALUE_STATE:
+		return yaml_parser_parse_block_mapping_value(parser, event)
+
+	case yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE:
+		return yaml_parser_parse_flow_sequence_entry(parser, event, true)
+
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE:
+		return yaml_parser_parse_flow_sequence_entry(parser, event, false)
+
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE:
+		return yaml_parser_parse_flow_sequence_entry_mapping_key(parser, event)
+
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE:
+		return yaml_parser_parse_flow_sequence_entry_mapping_value(parser, event)
+
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE:
+		return yaml_parser_parse_flow_sequence_entry_mapping_end(parser, event)
+
+	case yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE:
+		return yaml_parser_parse_flow_mapping_key(parser, event, true)
+
+	case yaml_PARSE_FLOW_MAPPING_KEY_STATE:
+		return yaml_parser_parse_flow_mapping_key(parser, event, false)
+
+	case yaml_PARSE_FLOW_MAPPING_VALUE_STATE:
+		return yaml_parser_parse_flow_mapping_value(parser, event, false)
+
+	case yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE:
+		return yaml_parser_parse_flow_mapping_value(parser, event, true)
+
+	default:
+		panic("invalid parser state")
+	}
+}
+
+// Parse the production:
+// stream   ::= STREAM-START implicit_document? explicit_document* STREAM-END
+//              ************
+func yaml_parser_parse_stream_start(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if token.typ != yaml_STREAM_START_TOKEN {
+		return yaml_parser_set_parser_error(parser, "did not find expected <stream-start>", token.start_mark)
+	}
+	parser.state = yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE
+	*event = yaml_event_t{
+		typ:        yaml_STREAM_START_EVENT,
+		start_mark: token.start_mark,
+		end_mark:   token.end_mark,
+		encoding:   token.encoding,
+	}
+	skip_token(parser)
+	return true
+}
+
+// Parse the productions:
+// implicit_document    ::= block_node DOCUMENT-END*
+//                          *
+// explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+//                          *************************
+func yaml_parser_parse_document_start(parser *yaml_parser_t, event *yaml_event_t, implicit bool) bool {
+
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	// Parse extra document end indicators.
+	if !implicit {
+		for token.typ == yaml_DOCUMENT_END_TOKEN {
+			skip_token(parser)
+			token = peek_token(parser)
+			if token == nil {
+				return false
+			}
+		}
+	}
+
+	if implicit && token.typ != yaml_VERSION_DIRECTIVE_TOKEN &&
+		token.typ != yaml_TAG_DIRECTIVE_TOKEN &&
+		token.typ != yaml_DOCUMENT_START_TOKEN &&
+		token.typ != yaml_STREAM_END_TOKEN {
+		// Parse an implicit document.
+		if !yaml_parser_process_directives(parser, nil, nil) {
+			return false
+		}
+		parser.states = append(parser.states, yaml_PARSE_DOCUMENT_END_STATE)
+		parser.state = yaml_PARSE_BLOCK_NODE_STATE
+
+		*event = yaml_event_t{
+			typ:        yaml_DOCUMENT_START_EVENT,
+			start_mark: token.start_mark,
+			end_mark:   token.end_mark,
+		}
+
+	} else if token.typ != yaml_STREAM_END_TOKEN {
+		// Parse an explicit document.
+		var version_directive *yaml_version_directive_t
+		var tag_directives []yaml_tag_directive_t
+		start_mark := token.start_mark
+		if !yaml_parser_process_directives(parser, &version_directive, &tag_directives) {
+			return false
+		}
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_DOCUMENT_START_TOKEN {
+			yaml_parser_set_parser_error(parser,
+				"did not find expected <document start>", token.start_mark)
+			return false
+		}
+		parser.states = append(parser.states, yaml_PARSE_DOCUMENT_END_STATE)
+		parser.state = yaml_PARSE_DOCUMENT_CONTENT_STATE
+		end_mark := token.end_mark
+
+		*event = yaml_event_t{
+			typ:               yaml_DOCUMENT_START_EVENT,
+			start_mark:        start_mark,
+			end_mark:          end_mark,
+			version_directive: version_directive,
+			tag_directives:    tag_directives,
+			implicit:          false,
+		}
+		skip_token(parser)
+
+	} else {
+		// Parse the stream end.
+		parser.state = yaml_PARSE_END_STATE
+		*event = yaml_event_t{
+			typ:        yaml_STREAM_END_EVENT,
+			start_mark: token.start_mark,
+			end_mark:   token.end_mark,
+		}
+		skip_token(parser)
+	}
+
+	return true
+}
+
+// Parse the productions:
+// explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+//                                                    ***********
+//
+func yaml_parser_parse_document_content(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if token.typ == yaml_VERSION_DIRECTIVE_TOKEN ||
+		token.typ == yaml_TAG_DIRECTIVE_TOKEN ||
+		token.typ == yaml_DOCUMENT_START_TOKEN ||
+		token.typ == yaml_DOCUMENT_END_TOKEN ||
+		token.typ == yaml_STREAM_END_TOKEN {
+		parser.state = parser.states[len(parser.states)-1]
+		parser.states = parser.states[:len(parser.states)-1]
+		return yaml_parser_process_empty_scalar(parser, event,
+			token.start_mark)
+	}
+	return yaml_parser_parse_node(parser, event, true, false)
+}
+
+// Parse the productions:
+// implicit_document    ::= block_node DOCUMENT-END*
+//                                     *************
+// explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+//
+func yaml_parser_parse_document_end(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	start_mark := token.start_mark
+	end_mark := token.start_mark
+
+	implicit := true
+	if token.typ == yaml_DOCUMENT_END_TOKEN {
+		end_mark = token.end_mark
+		skip_token(parser)
+		implicit = false
+	}
+
+	parser.tag_directives = parser.tag_directives[:0]
+
+	parser.state = yaml_PARSE_DOCUMENT_START_STATE
+	*event = yaml_event_t{
+		typ:        yaml_DOCUMENT_END_EVENT,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		implicit:   implicit,
+	}
+	return true
+}
+
+// Parse the productions:
+// block_node_or_indentless_sequence    ::=
+//                          ALIAS
+//                          *****
+//                          | properties (block_content | indentless_block_sequence)?
+//                            **********  *
+//                          | block_content | indentless_block_sequence
+//                            *
+// block_node           ::= ALIAS
+//                          *****
+//                          | properties block_content?
+//                            ********** *
+//                          | block_content
+//                            *
+// flow_node            ::= ALIAS
+//                          *****
+//                          | properties flow_content?
+//                            ********** *
+//                          | flow_content
+//                            *
+// properties           ::= TAG ANCHOR? | ANCHOR TAG?
+//                          *************************
+// block_content        ::= block_collection | flow_collection | SCALAR
+//                                                               ******
+// flow_content         ::= flow_collection | SCALAR
+//                                            ******
+func yaml_parser_parse_node(parser *yaml_parser_t, event *yaml_event_t, block, indentless_sequence bool) bool {
+	//defer trace("yaml_parser_parse_node", "block:", block, "indentless_sequence:", indentless_sequence)()
+
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	if token.typ == yaml_ALIAS_TOKEN {
+		parser.state = parser.states[len(parser.states)-1]
+		parser.states = parser.states[:len(parser.states)-1]
+		*event = yaml_event_t{
+			typ:        yaml_ALIAS_EVENT,
+			start_mark: token.start_mark,
+			end_mark:   token.end_mark,
+			anchor:     token.value,
+		}
+		skip_token(parser)
+		return true
+	}
+
+	start_mark := token.start_mark
+	end_mark := token.start_mark
+
+	var tag_token bool
+	var tag_handle, tag_suffix, anchor []byte
+	var tag_mark yaml_mark_t
+	if token.typ == yaml_ANCHOR_TOKEN {
+		anchor = token.value
+		start_mark = token.start_mark
+		end_mark = token.end_mark
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ == yaml_TAG_TOKEN {
+			tag_token = true
+			tag_handle = token.value
+			tag_suffix = token.suffix
+			tag_mark = token.start_mark
+			end_mark = token.end_mark
+			skip_token(parser)
+			token = peek_token(parser)
+			if token == nil {
+				return false
+			}
+		}
+	} else if token.typ == yaml_TAG_TOKEN {
+		tag_token = true
+		tag_handle = token.value
+		tag_suffix = token.suffix
+		start_mark = token.start_mark
+		tag_mark = token.start_mark
+		end_mark = token.end_mark
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ == yaml_ANCHOR_TOKEN {
+			anchor = token.value
+			end_mark = token.end_mark
+			skip_token(parser)
+			token = peek_token(parser)
+			if token == nil {
+				return false
+			}
+		}
+	}
+
+	var tag []byte
+	if tag_token {
+		if len(tag_handle) == 0 {
+			tag = tag_suffix
+			tag_suffix = nil
+		} else {
+			for i := range parser.tag_directives {
+				if bytes.Equal(parser.tag_directives[i].handle, tag_handle) {
+					tag = append([]byte(nil), parser.tag_directives[i].prefix...)
+					tag = append(tag, tag_suffix...)
+					break
+				}
+			}
+			if len(tag) == 0 {
+				yaml_parser_set_parser_error_context(parser,
+					"while parsing a node", start_mark,
+					"found undefined tag handle", tag_mark)
+				return false
+			}
+		}
+	}
+
+	implicit := len(tag) == 0
+	if indentless_sequence && token.typ == yaml_BLOCK_ENTRY_TOKEN {
+		end_mark = token.end_mark
+		parser.state = yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE
+		*event = yaml_event_t{
+			typ:        yaml_SEQUENCE_START_EVENT,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			anchor:     anchor,
+			tag:        tag,
+			implicit:   implicit,
+			style:      yaml_style_t(yaml_BLOCK_SEQUENCE_STYLE),
+		}
+		return true
+	}
+	if token.typ == yaml_SCALAR_TOKEN {
+		var plain_implicit, quoted_implicit bool
+		end_mark = token.end_mark
+		if (len(tag) == 0 && token.style == yaml_PLAIN_SCALAR_STYLE) || (len(tag) == 1 && tag[0] == '!') {
+			plain_implicit = true
+		} else if len(tag) == 0 {
+			quoted_implicit = true
+		}
+		parser.state = parser.states[len(parser.states)-1]
+		parser.states = parser.states[:len(parser.states)-1]
+
+		*event = yaml_event_t{
+			typ:             yaml_SCALAR_EVENT,
+			start_mark:      start_mark,
+			end_mark:        end_mark,
+			anchor:          anchor,
+			tag:             tag,
+			value:           token.value,
+			implicit:        plain_implicit,
+			quoted_implicit: quoted_implicit,
+			style:           yaml_style_t(token.style),
+		}
+		skip_token(parser)
+		return true
+	}
+	if token.typ == yaml_FLOW_SEQUENCE_START_TOKEN {
+		// [Go] Some of the events below can be merged as they differ only on style.
+		end_mark = token.end_mark
+		parser.state = yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE
+		*event = yaml_event_t{
+			typ:        yaml_SEQUENCE_START_EVENT,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			anchor:     anchor,
+			tag:        tag,
+			implicit:   implicit,
+			style:      yaml_style_t(yaml_FLOW_SEQUENCE_STYLE),
+		}
+		return true
+	}
+	if token.typ == yaml_FLOW_MAPPING_START_TOKEN {
+		end_mark = token.end_mark
+		parser.state = yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE
+		*event = yaml_event_t{
+			typ:        yaml_MAPPING_START_EVENT,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			anchor:     anchor,
+			tag:        tag,
+			implicit:   implicit,
+			style:      yaml_style_t(yaml_FLOW_MAPPING_STYLE),
+		}
+		return true
+	}
+	if block && token.typ == yaml_BLOCK_SEQUENCE_START_TOKEN {
+		end_mark = token.end_mark
+		parser.state = yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE
+		*event = yaml_event_t{
+			typ:        yaml_SEQUENCE_START_EVENT,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			anchor:     anchor,
+			tag:        tag,
+			implicit:   implicit,
+			style:      yaml_style_t(yaml_BLOCK_SEQUENCE_STYLE),
+		}
+		return true
+	}
+	if block && token.typ == yaml_BLOCK_MAPPING_START_TOKEN {
+		end_mark = token.end_mark
+		parser.state = yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE
+		*event = yaml_event_t{
+			typ:        yaml_MAPPING_START_EVENT,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			anchor:     anchor,
+			tag:        tag,
+			implicit:   implicit,
+			style:      yaml_style_t(yaml_BLOCK_MAPPING_STYLE),
+		}
+		return true
+	}
+	if len(anchor) > 0 || len(tag) > 0 {
+		parser.state = parser.states[len(parser.states)-1]
+		parser.states = parser.states[:len(parser.states)-1]
+
+		*event = yaml_event_t{
+			typ:             yaml_SCALAR_EVENT,
+			start_mark:      start_mark,
+			end_mark:        end_mark,
+			anchor:          anchor,
+			tag:             tag,
+			implicit:        implicit,
+			quoted_implicit: false,
+			style:           yaml_style_t(yaml_PLAIN_SCALAR_STYLE),
+		}
+		return true
+	}
+
+	context := "while parsing a flow node"
+	if block {
+		context = "while parsing a block node"
+	}
+	yaml_parser_set_parser_error_context(parser, context, start_mark,
+		"did not find expected node content", token.start_mark)
+	return false
+}
+
+// Parse the productions:
+// block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
+//                    ********************  *********** *             *********
+//
+func yaml_parser_parse_block_sequence_entry(parser *yaml_parser_t, event *yaml_event_t, first bool) bool {
+	if first {
+		token := peek_token(parser)
+		parser.marks = append(parser.marks, token.start_mark)
+		skip_token(parser)
+	}
+
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	if token.typ == yaml_BLOCK_ENTRY_TOKEN {
+		mark := token.end_mark
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_BLOCK_ENTRY_TOKEN && token.typ != yaml_BLOCK_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE)
+			return yaml_parser_parse_node(parser, event, true, false)
+		} else {
+			parser.state = yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE
+			return yaml_parser_process_empty_scalar(parser, event, mark)
+		}
+	}
+	if token.typ == yaml_BLOCK_END_TOKEN {
+		parser.state = parser.states[len(parser.states)-1]
+		parser.states = parser.states[:len(parser.states)-1]
+		parser.marks = parser.marks[:len(parser.marks)-1]
+
+		*event = yaml_event_t{
+			typ:        yaml_SEQUENCE_END_EVENT,
+			start_mark: token.start_mark,
+			end_mark:   token.end_mark,
+		}
+
+		skip_token(parser)
+		return true
+	}
+
+	context_mark := parser.marks[len(parser.marks)-1]
+	parser.marks = parser.marks[:len(parser.marks)-1]
+	return yaml_parser_set_parser_error_context(parser,
+		"while parsing a block collection", context_mark,
+		"did not find expected '-' indicator", token.start_mark)
+}
+
+// Parse the productions:
+// indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
+//                           *********** *
+func yaml_parser_parse_indentless_sequence_entry(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	if token.typ == yaml_BLOCK_ENTRY_TOKEN {
+		mark := token.end_mark
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_BLOCK_ENTRY_TOKEN &&
+			token.typ != yaml_KEY_TOKEN &&
+			token.typ != yaml_VALUE_TOKEN &&
+			token.typ != yaml_BLOCK_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE)
+			return yaml_parser_parse_node(parser, event, true, false)
+		}
+		parser.state = yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE
+		return yaml_parser_process_empty_scalar(parser, event, mark)
+	}
+	parser.state = parser.states[len(parser.states)-1]
+	parser.states = parser.states[:len(parser.states)-1]
+
+	*event = yaml_event_t{
+		typ:        yaml_SEQUENCE_END_EVENT,
+		start_mark: token.start_mark,
+		end_mark:   token.start_mark, // [Go] Shouldn't this be token.end_mark?
+	}
+	return true
+}
+
+// Parse the productions:
+// block_mapping        ::= BLOCK-MAPPING_START
+//                          *******************
+//                          ((KEY block_node_or_indentless_sequence?)?
+//                            *** *
+//                          (VALUE block_node_or_indentless_sequence?)?)*
+//
+//                          BLOCK-END
+//                          *********
+//
+func yaml_parser_parse_block_mapping_key(parser *yaml_parser_t, event *yaml_event_t, first bool) bool {
+	if first {
+		token := peek_token(parser)
+		parser.marks = append(parser.marks, token.start_mark)
+		skip_token(parser)
+	}
+
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	if token.typ == yaml_KEY_TOKEN {
+		mark := token.end_mark
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_KEY_TOKEN &&
+			token.typ != yaml_VALUE_TOKEN &&
+			token.typ != yaml_BLOCK_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_BLOCK_MAPPING_VALUE_STATE)
+			return yaml_parser_parse_node(parser, event, true, true)
+		} else {
+			parser.state = yaml_PARSE_BLOCK_MAPPING_VALUE_STATE
+			return yaml_parser_process_empty_scalar(parser, event, mark)
+		}
+	} else if token.typ == yaml_BLOCK_END_TOKEN {
+		parser.state = parser.states[len(parser.states)-1]
+		parser.states = parser.states[:len(parser.states)-1]
+		parser.marks = parser.marks[:len(parser.marks)-1]
+		*event = yaml_event_t{
+			typ:        yaml_MAPPING_END_EVENT,
+			start_mark: token.start_mark,
+			end_mark:   token.end_mark,
+		}
+		skip_token(parser)
+		return true
+	}
+
+	context_mark := parser.marks[len(parser.marks)-1]
+	parser.marks = parser.marks[:len(parser.marks)-1]
+	return yaml_parser_set_parser_error_context(parser,
+		"while parsing a block mapping", context_mark,
+		"did not find expected key", token.start_mark)
+}
+
+// Parse the productions:
+// block_mapping        ::= BLOCK-MAPPING_START
+//
+//                          ((KEY block_node_or_indentless_sequence?)?
+//
+//                          (VALUE block_node_or_indentless_sequence?)?)*
+//                           ***** *
+//                          BLOCK-END
+//
+//
+func yaml_parser_parse_block_mapping_value(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if token.typ == yaml_VALUE_TOKEN {
+		mark := token.end_mark
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_KEY_TOKEN &&
+			token.typ != yaml_VALUE_TOKEN &&
+			token.typ != yaml_BLOCK_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_BLOCK_MAPPING_KEY_STATE)
+			return yaml_parser_parse_node(parser, event, true, true)
+		}
+		parser.state = yaml_PARSE_BLOCK_MAPPING_KEY_STATE
+		return yaml_parser_process_empty_scalar(parser, event, mark)
+	}
+	parser.state = yaml_PARSE_BLOCK_MAPPING_KEY_STATE
+	return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
+}
+
+// Parse the productions:
+// flow_sequence        ::= FLOW-SEQUENCE-START
+//                          *******************
+//                          (flow_sequence_entry FLOW-ENTRY)*
+//                           *                   **********
+//                          flow_sequence_entry?
+//                          *
+//                          FLOW-SEQUENCE-END
+//                          *****************
+// flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+//                          *
+//
+func yaml_parser_parse_flow_sequence_entry(parser *yaml_parser_t, event *yaml_event_t, first bool) bool {
+	if first {
+		token := peek_token(parser)
+		parser.marks = append(parser.marks, token.start_mark)
+		skip_token(parser)
+	}
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if token.typ != yaml_FLOW_SEQUENCE_END_TOKEN {
+		if !first {
+			if token.typ == yaml_FLOW_ENTRY_TOKEN {
+				skip_token(parser)
+				token = peek_token(parser)
+				if token == nil {
+					return false
+				}
+			} else {
+				context_mark := parser.marks[len(parser.marks)-1]
+				parser.marks = parser.marks[:len(parser.marks)-1]
+				return yaml_parser_set_parser_error_context(parser,
+					"while parsing a flow sequence", context_mark,
+					"did not find expected ',' or ']'", token.start_mark)
+			}
+		}
+
+		if token.typ == yaml_KEY_TOKEN {
+			parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE
+			*event = yaml_event_t{
+				typ:        yaml_MAPPING_START_EVENT,
+				start_mark: token.start_mark,
+				end_mark:   token.end_mark,
+				implicit:   true,
+				style:      yaml_style_t(yaml_FLOW_MAPPING_STYLE),
+			}
+			skip_token(parser)
+			return true
+		} else if token.typ != yaml_FLOW_SEQUENCE_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE)
+			return yaml_parser_parse_node(parser, event, false, false)
+		}
+	}
+
+	parser.state = parser.states[len(parser.states)-1]
+	parser.states = parser.states[:len(parser.states)-1]
+	parser.marks = parser.marks[:len(parser.marks)-1]
+
+	*event = yaml_event_t{
+		typ:        yaml_SEQUENCE_END_EVENT,
+		start_mark: token.start_mark,
+		end_mark:   token.end_mark,
+	}
+
+	skip_token(parser)
+	return true
+}
+
+//
+// Parse the productions:
+// flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+//                                      *** *
+//
+func yaml_parser_parse_flow_sequence_entry_mapping_key(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if token.typ != yaml_VALUE_TOKEN &&
+		token.typ != yaml_FLOW_ENTRY_TOKEN &&
+		token.typ != yaml_FLOW_SEQUENCE_END_TOKEN {
+		parser.states = append(parser.states, yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE)
+		return yaml_parser_parse_node(parser, event, false, false)
+	}
+	mark := token.end_mark
+	skip_token(parser)
+	parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE
+	return yaml_parser_process_empty_scalar(parser, event, mark)
+}
+
+// Parse the productions:
+// flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+//                                                      ***** *
+//
+func yaml_parser_parse_flow_sequence_entry_mapping_value(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if token.typ == yaml_VALUE_TOKEN {
+		skip_token(parser)
+		token := peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_FLOW_ENTRY_TOKEN && token.typ != yaml_FLOW_SEQUENCE_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE)
+			return yaml_parser_parse_node(parser, event, false, false)
+		}
+	}
+	parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE
+	return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
+}
+
+// Parse the productions:
+// flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+//                                                                      *
+//
+func yaml_parser_parse_flow_sequence_entry_mapping_end(parser *yaml_parser_t, event *yaml_event_t) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	parser.state = yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE
+	*event = yaml_event_t{
+		typ:        yaml_MAPPING_END_EVENT,
+		start_mark: token.start_mark,
+		end_mark:   token.start_mark, // [Go] Shouldn't this be end_mark?
+	}
+	return true
+}
+
+// Parse the productions:
+// flow_mapping         ::= FLOW-MAPPING-START
+//                          ******************
+//                          (flow_mapping_entry FLOW-ENTRY)*
+//                           *                  **********
+//                          flow_mapping_entry?
+//                          ******************
+//                          FLOW-MAPPING-END
+//                          ****************
+// flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+//                          *           *** *
+//
+func yaml_parser_parse_flow_mapping_key(parser *yaml_parser_t, event *yaml_event_t, first bool) bool {
+	if first {
+		token := peek_token(parser)
+		parser.marks = append(parser.marks, token.start_mark)
+		skip_token(parser)
+	}
+
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	if token.typ != yaml_FLOW_MAPPING_END_TOKEN {
+		if !first {
+			if token.typ == yaml_FLOW_ENTRY_TOKEN {
+				skip_token(parser)
+				token = peek_token(parser)
+				if token == nil {
+					return false
+				}
+			} else {
+				context_mark := parser.marks[len(parser.marks)-1]
+				parser.marks = parser.marks[:len(parser.marks)-1]
+				return yaml_parser_set_parser_error_context(parser,
+					"while parsing a flow mapping", context_mark,
+					"did not find expected ',' or '}'", token.start_mark)
+			}
+		}
+
+		if token.typ == yaml_KEY_TOKEN {
+			skip_token(parser)
+			token = peek_token(parser)
+			if token == nil {
+				return false
+			}
+			if token.typ != yaml_VALUE_TOKEN &&
+				token.typ != yaml_FLOW_ENTRY_TOKEN &&
+				token.typ != yaml_FLOW_MAPPING_END_TOKEN {
+				parser.states = append(parser.states, yaml_PARSE_FLOW_MAPPING_VALUE_STATE)
+				return yaml_parser_parse_node(parser, event, false, false)
+			} else {
+				parser.state = yaml_PARSE_FLOW_MAPPING_VALUE_STATE
+				return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
+			}
+		} else if token.typ != yaml_FLOW_MAPPING_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE)
+			return yaml_parser_parse_node(parser, event, false, false)
+		}
+	}
+
+	parser.state = parser.states[len(parser.states)-1]
+	parser.states = parser.states[:len(parser.states)-1]
+	parser.marks = parser.marks[:len(parser.marks)-1]
+	*event = yaml_event_t{
+		typ:        yaml_MAPPING_END_EVENT,
+		start_mark: token.start_mark,
+		end_mark:   token.end_mark,
+	}
+	skip_token(parser)
+	return true
+}
+
+// Parse the productions:
+// flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+//                                   *                  ***** *
+//
+func yaml_parser_parse_flow_mapping_value(parser *yaml_parser_t, event *yaml_event_t, empty bool) bool {
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+	if empty {
+		parser.state = yaml_PARSE_FLOW_MAPPING_KEY_STATE
+		return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
+	}
+	if token.typ == yaml_VALUE_TOKEN {
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+		if token.typ != yaml_FLOW_ENTRY_TOKEN && token.typ != yaml_FLOW_MAPPING_END_TOKEN {
+			parser.states = append(parser.states, yaml_PARSE_FLOW_MAPPING_KEY_STATE)
+			return yaml_parser_parse_node(parser, event, false, false)
+		}
+	}
+	parser.state = yaml_PARSE_FLOW_MAPPING_KEY_STATE
+	return yaml_parser_process_empty_scalar(parser, event, token.start_mark)
+}
+
+// Generate an empty scalar event.
+func yaml_parser_process_empty_scalar(parser *yaml_parser_t, event *yaml_event_t, mark yaml_mark_t) bool {
+	*event = yaml_event_t{
+		typ:        yaml_SCALAR_EVENT,
+		start_mark: mark,
+		end_mark:   mark,
+		value:      nil, // Empty
+		implicit:   true,
+		style:      yaml_style_t(yaml_PLAIN_SCALAR_STYLE),
+	}
+	return true
+}
+
+var default_tag_directives = []yaml_tag_directive_t{
+	{[]byte("!"), []byte("!")},
+	{[]byte("!!"), []byte("tag:yaml.org,2002:")},
+}
+
+// Parse directives.
+func yaml_parser_process_directives(parser *yaml_parser_t,
+	version_directive_ref **yaml_version_directive_t,
+	tag_directives_ref *[]yaml_tag_directive_t) bool {
+
+	var version_directive *yaml_version_directive_t
+	var tag_directives []yaml_tag_directive_t
+
+	token := peek_token(parser)
+	if token == nil {
+		return false
+	}
+
+	for token.typ == yaml_VERSION_DIRECTIVE_TOKEN || token.typ == yaml_TAG_DIRECTIVE_TOKEN {
+		if token.typ == yaml_VERSION_DIRECTIVE_TOKEN {
+			if version_directive != nil {
+				yaml_parser_set_parser_error(parser,
+					"found duplicate %YAML directive", token.start_mark)
+				return false
+			}
+			if token.major != 1 || token.minor != 1 {
+				yaml_parser_set_parser_error(parser,
+					"found incompatible YAML document", token.start_mark)
+				return false
+			}
+			version_directive = &yaml_version_directive_t{
+				major: token.major,
+				minor: token.minor,
+			}
+		} else if token.typ == yaml_TAG_DIRECTIVE_TOKEN {
+			value := yaml_tag_directive_t{
+				handle: token.value,
+				prefix: token.prefix,
+			}
+			if !yaml_parser_append_tag_directive(parser, value, false, token.start_mark) {
+				return false
+			}
+			tag_directives = append(tag_directives, value)
+		}
+
+		skip_token(parser)
+		token = peek_token(parser)
+		if token == nil {
+			return false
+		}
+	}
+
+	for i := range default_tag_directives {
+		if !yaml_parser_append_tag_directive(parser, default_tag_directives[i], true, token.start_mark) {
+			return false
+		}
+	}
+
+	if version_directive_ref != nil {
+		*version_directive_ref = version_directive
+	}
+	if tag_directives_ref != nil {
+		*tag_directives_ref = tag_directives
+	}
+	return true
+}
+
+// Append a tag directive to the directives stack.
+func yaml_parser_append_tag_directive(parser *yaml_parser_t, value yaml_tag_directive_t, allow_duplicates bool, mark yaml_mark_t) bool {
+	for i := range parser.tag_directives {
+		if bytes.Equal(value.handle, parser.tag_directives[i].handle) {
+			if allow_duplicates {
+				return true
+			}
+			return yaml_parser_set_parser_error(parser, "found duplicate %TAG directive", mark)
+		}
+	}
+
+	// [Go] I suspect the copy is unnecessary. This was likely done
+	// because there was no way to track ownership of the data.
+	value_copy := yaml_tag_directive_t{
+		handle: make([]byte, len(value.handle)),
+		prefix: make([]byte, len(value.prefix)),
+	}
+	copy(value_copy.handle, value.handle)
+	copy(value_copy.prefix, value.prefix)
+	parser.tag_directives = append(parser.tag_directives, value_copy)
+	return true
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/readerc.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/readerc.go
new file mode 100644
index 00000000000..7c1f5fac3db
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/readerc.go
@@ -0,0 +1,412 @@
+package yaml
+
+import (
+	"io"
+)
+
+// Set the reader error and return 0.
+func yaml_parser_set_reader_error(parser *yaml_parser_t, problem string, offset int, value int) bool {
+	parser.error = yaml_READER_ERROR
+	parser.problem = problem
+	parser.problem_offset = offset
+	parser.problem_value = value
+	return false
+}
+
+// Byte order marks.
+const (
+	bom_UTF8    = "\xef\xbb\xbf"
+	bom_UTF16LE = "\xff\xfe"
+	bom_UTF16BE = "\xfe\xff"
+)
+
+// Determine the input stream encoding by checking the BOM symbol. If no BOM is
+// found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
+func yaml_parser_determine_encoding(parser *yaml_parser_t) bool {
+	// Ensure that we had enough bytes in the raw buffer.
+	for !parser.eof && len(parser.raw_buffer)-parser.raw_buffer_pos < 3 {
+		if !yaml_parser_update_raw_buffer(parser) {
+			return false
+		}
+	}
+
+	// Determine the encoding.
+	buf := parser.raw_buffer
+	pos := parser.raw_buffer_pos
+	avail := len(buf) - pos
+	if avail >= 2 && buf[pos] == bom_UTF16LE[0] && buf[pos+1] == bom_UTF16LE[1] {
+		parser.encoding = yaml_UTF16LE_ENCODING
+		parser.raw_buffer_pos += 2
+		parser.offset += 2
+	} else if avail >= 2 && buf[pos] == bom_UTF16BE[0] && buf[pos+1] == bom_UTF16BE[1] {
+		parser.encoding = yaml_UTF16BE_ENCODING
+		parser.raw_buffer_pos += 2
+		parser.offset += 2
+	} else if avail >= 3 && buf[pos] == bom_UTF8[0] && buf[pos+1] == bom_UTF8[1] && buf[pos+2] == bom_UTF8[2] {
+		parser.encoding = yaml_UTF8_ENCODING
+		parser.raw_buffer_pos += 3
+		parser.offset += 3
+	} else {
+		parser.encoding = yaml_UTF8_ENCODING
+	}
+	return true
+}
+
+// Update the raw buffer.
+func yaml_parser_update_raw_buffer(parser *yaml_parser_t) bool {
+	size_read := 0
+
+	// Return if the raw buffer is full.
+	if parser.raw_buffer_pos == 0 && len(parser.raw_buffer) == cap(parser.raw_buffer) {
+		return true
+	}
+
+	// Return on EOF.
+	if parser.eof {
+		return true
+	}
+
+	// Move the remaining bytes in the raw buffer to the beginning.
+	if parser.raw_buffer_pos > 0 && parser.raw_buffer_pos < len(parser.raw_buffer) {
+		copy(parser.raw_buffer, parser.raw_buffer[parser.raw_buffer_pos:])
+	}
+	parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)-parser.raw_buffer_pos]
+	parser.raw_buffer_pos = 0
+
+	// Call the read handler to fill the buffer.
+	size_read, err := parser.read_handler(parser, parser.raw_buffer[len(parser.raw_buffer):cap(parser.raw_buffer)])
+	parser.raw_buffer = parser.raw_buffer[:len(parser.raw_buffer)+size_read]
+	if err == io.EOF {
+		parser.eof = true
+	} else if err != nil {
+		return yaml_parser_set_reader_error(parser, "input error: "+err.Error(), parser.offset, -1)
+	}
+	return true
+}
+
+// Ensure that the buffer contains at least `length` characters.
+// Return true on success, false on failure.
+//
+// The length is supposed to be significantly less that the buffer size.
+func yaml_parser_update_buffer(parser *yaml_parser_t, length int) bool {
+	if parser.read_handler == nil {
+		panic("read handler must be set")
+	}
+
+	// [Go] This function was changed to guarantee the requested length size at EOF.
+	// The fact we need to do this is pretty awful, but the description above implies
+	// for that to be the case, and there are tests 
+
+	// If the EOF flag is set and the raw buffer is empty, do nothing.
+	if parser.eof && parser.raw_buffer_pos == len(parser.raw_buffer) {
+		// [Go] ACTUALLY! Read the documentation of this function above.
+		// This is just broken. To return true, we need to have the
+		// given length in the buffer. Not doing that means every single
+		// check that calls this function to make sure the buffer has a
+		// given length is Go) panicking; or C) accessing invalid memory.
+		//return true
+	}
+
+	// Return if the buffer contains enough characters.
+	if parser.unread >= length {
+		return true
+	}
+
+	// Determine the input encoding if it is not known yet.
+	if parser.encoding == yaml_ANY_ENCODING {
+		if !yaml_parser_determine_encoding(parser) {
+			return false
+		}
+	}
+
+	// Move the unread characters to the beginning of the buffer.
+	buffer_len := len(parser.buffer)
+	if parser.buffer_pos > 0 && parser.buffer_pos < buffer_len {
+		copy(parser.buffer, parser.buffer[parser.buffer_pos:])
+		buffer_len -= parser.buffer_pos
+		parser.buffer_pos = 0
+	} else if parser.buffer_pos == buffer_len {
+		buffer_len = 0
+		parser.buffer_pos = 0
+	}
+
+	// Open the whole buffer for writing, and cut it before returning.
+	parser.buffer = parser.buffer[:cap(parser.buffer)]
+
+	// Fill the buffer until it has enough characters.
+	first := true
+	for parser.unread < length {
+
+		// Fill the raw buffer if necessary.
+		if !first || parser.raw_buffer_pos == len(parser.raw_buffer) {
+			if !yaml_parser_update_raw_buffer(parser) {
+				parser.buffer = parser.buffer[:buffer_len]
+				return false
+			}
+		}
+		first = false
+
+		// Decode the raw buffer.
+	inner:
+		for parser.raw_buffer_pos != len(parser.raw_buffer) {
+			var value rune
+			var width int
+
+			raw_unread := len(parser.raw_buffer) - parser.raw_buffer_pos
+
+			// Decode the next character.
+			switch parser.encoding {
+			case yaml_UTF8_ENCODING:
+				// Decode a UTF-8 character.  Check RFC 3629
+				// (http://www.ietf.org/rfc/rfc3629.txt) for more details.
+				//
+				// The following table (taken from the RFC) is used for
+				// decoding.
+				//
+				//    Char. number range |        UTF-8 octet sequence
+				//      (hexadecimal)    |              (binary)
+				//   --------------------+------------------------------------
+				//   0000 0000-0000 007F | 0xxxxxxx
+				//   0000 0080-0000 07FF | 110xxxxx 10xxxxxx
+				//   0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
+				//   0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+				//
+				// Additionally, the characters in the range 0xD800-0xDFFF
+				// are prohibited as they are reserved for use with UTF-16
+				// surrogate pairs.
+
+				// Determine the length of the UTF-8 sequence.
+				octet := parser.raw_buffer[parser.raw_buffer_pos]
+				switch {
+				case octet&0x80 == 0x00:
+					width = 1
+				case octet&0xE0 == 0xC0:
+					width = 2
+				case octet&0xF0 == 0xE0:
+					width = 3
+				case octet&0xF8 == 0xF0:
+					width = 4
+				default:
+					// The leading octet is invalid.
+					return yaml_parser_set_reader_error(parser,
+						"invalid leading UTF-8 octet",
+						parser.offset, int(octet))
+				}
+
+				// Check if the raw buffer contains an incomplete character.
+				if width > raw_unread {
+					if parser.eof {
+						return yaml_parser_set_reader_error(parser,
+							"incomplete UTF-8 octet sequence",
+							parser.offset, -1)
+					}
+					break inner
+				}
+
+				// Decode the leading octet.
+				switch {
+				case octet&0x80 == 0x00:
+					value = rune(octet & 0x7F)
+				case octet&0xE0 == 0xC0:
+					value = rune(octet & 0x1F)
+				case octet&0xF0 == 0xE0:
+					value = rune(octet & 0x0F)
+				case octet&0xF8 == 0xF0:
+					value = rune(octet & 0x07)
+				default:
+					value = 0
+				}
+
+				// Check and decode the trailing octets.
+				for k := 1; k < width; k++ {
+					octet = parser.raw_buffer[parser.raw_buffer_pos+k]
+
+					// Check if the octet is valid.
+					if (octet & 0xC0) != 0x80 {
+						return yaml_parser_set_reader_error(parser,
+							"invalid trailing UTF-8 octet",
+							parser.offset+k, int(octet))
+					}
+
+					// Decode the octet.
+					value = (value << 6) + rune(octet&0x3F)
+				}
+
+				// Check the length of the sequence against the value.
+				switch {
+				case width == 1:
+				case width == 2 && value >= 0x80:
+				case width == 3 && value >= 0x800:
+				case width == 4 && value >= 0x10000:
+				default:
+					return yaml_parser_set_reader_error(parser,
+						"invalid length of a UTF-8 sequence",
+						parser.offset, -1)
+				}
+
+				// Check the range of the value.
+				if value >= 0xD800 && value <= 0xDFFF || value > 0x10FFFF {
+					return yaml_parser_set_reader_error(parser,
+						"invalid Unicode character",
+						parser.offset, int(value))
+				}
+
+			case yaml_UTF16LE_ENCODING, yaml_UTF16BE_ENCODING:
+				var low, high int
+				if parser.encoding == yaml_UTF16LE_ENCODING {
+					low, high = 0, 1
+				} else {
+					low, high = 1, 0
+				}
+
+				// The UTF-16 encoding is not as simple as one might
+				// naively think.  Check RFC 2781
+				// (http://www.ietf.org/rfc/rfc2781.txt).
+				//
+				// Normally, two subsequent bytes describe a Unicode
+				// character.  However a special technique (called a
+				// surrogate pair) is used for specifying character
+				// values larger than 0xFFFF.
+				//
+				// A surrogate pair consists of two pseudo-characters:
+				//      high surrogate area (0xD800-0xDBFF)
+				//      low surrogate area (0xDC00-0xDFFF)
+				//
+				// The following formulas are used for decoding
+				// and encoding characters using surrogate pairs:
+				//
+				//  U  = U' + 0x10000   (0x01 00 00 <= U <= 0x10 FF FF)
+				//  U' = yyyyyyyyyyxxxxxxxxxx   (0 <= U' <= 0x0F FF FF)
+				//  W1 = 110110yyyyyyyyyy
+				//  W2 = 110111xxxxxxxxxx
+				//
+				// where U is the character value, W1 is the high surrogate
+				// area, W2 is the low surrogate area.
+
+				// Check for incomplete UTF-16 character.
+				if raw_unread < 2 {
+					if parser.eof {
+						return yaml_parser_set_reader_error(parser,
+							"incomplete UTF-16 character",
+							parser.offset, -1)
+					}
+					break inner
+				}
+
+				// Get the character.
+				value = rune(parser.raw_buffer[parser.raw_buffer_pos+low]) +
+					(rune(parser.raw_buffer[parser.raw_buffer_pos+high]) << 8)
+
+				// Check for unexpected low surrogate area.
+				if value&0xFC00 == 0xDC00 {
+					return yaml_parser_set_reader_error(parser,
+						"unexpected low surrogate area",
+						parser.offset, int(value))
+				}
+
+				// Check for a high surrogate area.
+				if value&0xFC00 == 0xD800 {
+					width = 4
+
+					// Check for incomplete surrogate pair.
+					if raw_unread < 4 {
+						if parser.eof {
+							return yaml_parser_set_reader_error(parser,
+								"incomplete UTF-16 surrogate pair",
+								parser.offset, -1)
+						}
+						break inner
+					}
+
+					// Get the next character.
+					value2 := rune(parser.raw_buffer[parser.raw_buffer_pos+low+2]) +
+						(rune(parser.raw_buffer[parser.raw_buffer_pos+high+2]) << 8)
+
+					// Check for a low surrogate area.
+					if value2&0xFC00 != 0xDC00 {
+						return yaml_parser_set_reader_error(parser,
+							"expected low surrogate area",
+							parser.offset+2, int(value2))
+					}
+
+					// Generate the value of the surrogate pair.
+					value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF)
+				} else {
+					width = 2
+				}
+
+			default:
+				panic("impossible")
+			}
+
+			// Check if the character is in the allowed range:
+			//      #x9 | #xA | #xD | [#x20-#x7E]               (8 bit)
+			//      | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD]    (16 bit)
+			//      | [#x10000-#x10FFFF]                        (32 bit)
+			switch {
+			case value == 0x09:
+			case value == 0x0A:
+			case value == 0x0D:
+			case value >= 0x20 && value <= 0x7E:
+			case value == 0x85:
+			case value >= 0xA0 && value <= 0xD7FF:
+			case value >= 0xE000 && value <= 0xFFFD:
+			case value >= 0x10000 && value <= 0x10FFFF:
+			default:
+				return yaml_parser_set_reader_error(parser,
+					"control characters are not allowed",
+					parser.offset, int(value))
+			}
+
+			// Move the raw pointers.
+			parser.raw_buffer_pos += width
+			parser.offset += width
+
+			// Finally put the character into the buffer.
+			if value <= 0x7F {
+				// 0000 0000-0000 007F . 0xxxxxxx
+				parser.buffer[buffer_len+0] = byte(value)
+				buffer_len += 1
+			} else if value <= 0x7FF {
+				// 0000 0080-0000 07FF . 110xxxxx 10xxxxxx
+				parser.buffer[buffer_len+0] = byte(0xC0 + (value >> 6))
+				parser.buffer[buffer_len+1] = byte(0x80 + (value & 0x3F))
+				buffer_len += 2
+			} else if value <= 0xFFFF {
+				// 0000 0800-0000 FFFF . 1110xxxx 10xxxxxx 10xxxxxx
+				parser.buffer[buffer_len+0] = byte(0xE0 + (value >> 12))
+				parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 6) & 0x3F))
+				parser.buffer[buffer_len+2] = byte(0x80 + (value & 0x3F))
+				buffer_len += 3
+			} else {
+				// 0001 0000-0010 FFFF . 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+				parser.buffer[buffer_len+0] = byte(0xF0 + (value >> 18))
+				parser.buffer[buffer_len+1] = byte(0x80 + ((value >> 12) & 0x3F))
+				parser.buffer[buffer_len+2] = byte(0x80 + ((value >> 6) & 0x3F))
+				parser.buffer[buffer_len+3] = byte(0x80 + (value & 0x3F))
+				buffer_len += 4
+			}
+
+			parser.unread++
+		}
+
+		// On EOF, put NUL into the buffer and return.
+		if parser.eof {
+			parser.buffer[buffer_len] = 0
+			buffer_len++
+			parser.unread++
+			break
+		}
+	}
+	// [Go] Read the documentation of this function above. To return true,
+	// we need to have the given length in the buffer. Not doing that means
+	// every single check that calls this function to make sure the buffer
+	// has a given length is Go) panicking; or C) accessing invalid memory.
+	// This happens here due to the EOF above breaking early.
+	for buffer_len < length {
+		parser.buffer[buffer_len] = 0
+		buffer_len++
+	}
+	parser.buffer = parser.buffer[:buffer_len]
+	return true
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/resolve.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/resolve.go
new file mode 100644
index 00000000000..4120e0c9160
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/resolve.go
@@ -0,0 +1,258 @@
+package yaml
+
+import (
+	"encoding/base64"
+	"math"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type resolveMapItem struct {
+	value interface{}
+	tag   string
+}
+
+var resolveTable = make([]byte, 256)
+var resolveMap = make(map[string]resolveMapItem)
+
+func init() {
+	t := resolveTable
+	t[int('+')] = 'S' // Sign
+	t[int('-')] = 'S'
+	for _, c := range "0123456789" {
+		t[int(c)] = 'D' // Digit
+	}
+	for _, c := range "yYnNtTfFoO~" {
+		t[int(c)] = 'M' // In map
+	}
+	t[int('.')] = '.' // Float (potentially in map)
+
+	var resolveMapList = []struct {
+		v   interface{}
+		tag string
+		l   []string
+	}{
+		{true, yaml_BOOL_TAG, []string{"y", "Y", "yes", "Yes", "YES"}},
+		{true, yaml_BOOL_TAG, []string{"true", "True", "TRUE"}},
+		{true, yaml_BOOL_TAG, []string{"on", "On", "ON"}},
+		{false, yaml_BOOL_TAG, []string{"n", "N", "no", "No", "NO"}},
+		{false, yaml_BOOL_TAG, []string{"false", "False", "FALSE"}},
+		{false, yaml_BOOL_TAG, []string{"off", "Off", "OFF"}},
+		{nil, yaml_NULL_TAG, []string{"", "~", "null", "Null", "NULL"}},
+		{math.NaN(), yaml_FLOAT_TAG, []string{".nan", ".NaN", ".NAN"}},
+		{math.Inf(+1), yaml_FLOAT_TAG, []string{".inf", ".Inf", ".INF"}},
+		{math.Inf(+1), yaml_FLOAT_TAG, []string{"+.inf", "+.Inf", "+.INF"}},
+		{math.Inf(-1), yaml_FLOAT_TAG, []string{"-.inf", "-.Inf", "-.INF"}},
+		{"<<", yaml_MERGE_TAG, []string{"<<"}},
+	}
+
+	m := resolveMap
+	for _, item := range resolveMapList {
+		for _, s := range item.l {
+			m[s] = resolveMapItem{item.v, item.tag}
+		}
+	}
+}
+
+const longTagPrefix = "tag:yaml.org,2002:"
+
+func shortTag(tag string) string {
+	// TODO This can easily be made faster and produce less garbage.
+	if strings.HasPrefix(tag, longTagPrefix) {
+		return "!!" + tag[len(longTagPrefix):]
+	}
+	return tag
+}
+
+func longTag(tag string) string {
+	if strings.HasPrefix(tag, "!!") {
+		return longTagPrefix + tag[2:]
+	}
+	return tag
+}
+
+func resolvableTag(tag string) bool {
+	switch tag {
+	case "", yaml_STR_TAG, yaml_BOOL_TAG, yaml_INT_TAG, yaml_FLOAT_TAG, yaml_NULL_TAG, yaml_TIMESTAMP_TAG:
+		return true
+	}
+	return false
+}
+
+var yamlStyleFloat = regexp.MustCompile(`^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?$`)
+
+func resolve(tag string, in string) (rtag string, out interface{}) {
+	if !resolvableTag(tag) {
+		return tag, in
+	}
+
+	defer func() {
+		switch tag {
+		case "", rtag, yaml_STR_TAG, yaml_BINARY_TAG:
+			return
+		case yaml_FLOAT_TAG:
+			if rtag == yaml_INT_TAG {
+				switch v := out.(type) {
+				case int64:
+					rtag = yaml_FLOAT_TAG
+					out = float64(v)
+					return
+				case int:
+					rtag = yaml_FLOAT_TAG
+					out = float64(v)
+					return
+				}
+			}
+		}
+		failf("cannot decode %s `%s` as a %s", shortTag(rtag), in, shortTag(tag))
+	}()
+
+	// Any data is accepted as a !!str or !!binary.
+	// Otherwise, the prefix is enough of a hint about what it might be.
+	hint := byte('N')
+	if in != "" {
+		hint = resolveTable[in[0]]
+	}
+	if hint != 0 && tag != yaml_STR_TAG && tag != yaml_BINARY_TAG {
+		// Handle things we can lookup in a map.
+		if item, ok := resolveMap[in]; ok {
+			return item.tag, item.value
+		}
+
+		// Base 60 floats are a bad idea, were dropped in YAML 1.2, and
+		// are purposefully unsupported here. They're still quoted on
+		// the way out for compatibility with other parser, though.
+
+		switch hint {
+		case 'M':
+			// We've already checked the map above.
+
+		case '.':
+			// Not in the map, so maybe a normal float.
+			floatv, err := strconv.ParseFloat(in, 64)
+			if err == nil {
+				return yaml_FLOAT_TAG, floatv
+			}
+
+		case 'D', 'S':
+			// Int, float, or timestamp.
+			// Only try values as a timestamp if the value is unquoted or there's an explicit
+			// !!timestamp tag.
+			if tag == "" || tag == yaml_TIMESTAMP_TAG {
+				t, ok := parseTimestamp(in)
+				if ok {
+					return yaml_TIMESTAMP_TAG, t
+				}
+			}
+
+			plain := strings.Replace(in, "_", "", -1)
+			intv, err := strconv.ParseInt(plain, 0, 64)
+			if err == nil {
+				if intv == int64(int(intv)) {
+					return yaml_INT_TAG, int(intv)
+				} else {
+					return yaml_INT_TAG, intv
+				}
+			}
+			uintv, err := strconv.ParseUint(plain, 0, 64)
+			if err == nil {
+				return yaml_INT_TAG, uintv
+			}
+			if yamlStyleFloat.MatchString(plain) {
+				floatv, err := strconv.ParseFloat(plain, 64)
+				if err == nil {
+					return yaml_FLOAT_TAG, floatv
+				}
+			}
+			if strings.HasPrefix(plain, "0b") {
+				intv, err := strconv.ParseInt(plain[2:], 2, 64)
+				if err == nil {
+					if intv == int64(int(intv)) {
+						return yaml_INT_TAG, int(intv)
+					} else {
+						return yaml_INT_TAG, intv
+					}
+				}
+				uintv, err := strconv.ParseUint(plain[2:], 2, 64)
+				if err == nil {
+					return yaml_INT_TAG, uintv
+				}
+			} else if strings.HasPrefix(plain, "-0b") {
+				intv, err := strconv.ParseInt("-" + plain[3:], 2, 64)
+				if err == nil {
+					if true || intv == int64(int(intv)) {
+						return yaml_INT_TAG, int(intv)
+					} else {
+						return yaml_INT_TAG, intv
+					}
+				}
+			}
+		default:
+			panic("resolveTable item not yet handled: " + string(rune(hint)) + " (with " + in + ")")
+		}
+	}
+	return yaml_STR_TAG, in
+}
+
+// encodeBase64 encodes s as base64 that is broken up into multiple lines
+// as appropriate for the resulting length.
+func encodeBase64(s string) string {
+	const lineLen = 70
+	encLen := base64.StdEncoding.EncodedLen(len(s))
+	lines := encLen/lineLen + 1
+	buf := make([]byte, encLen*2+lines)
+	in := buf[0:encLen]
+	out := buf[encLen:]
+	base64.StdEncoding.Encode(in, []byte(s))
+	k := 0
+	for i := 0; i < len(in); i += lineLen {
+		j := i + lineLen
+		if j > len(in) {
+			j = len(in)
+		}
+		k += copy(out[k:], in[i:j])
+		if lines > 1 {
+			out[k] = '\n'
+			k++
+		}
+	}
+	return string(out[:k])
+}
+
+// This is a subset of the formats allowed by the regular expression
+// defined at http://yaml.org/type/timestamp.html.
+var allowedTimestampFormats = []string{
+	"2006-1-2T15:4:5.999999999Z07:00", // RCF3339Nano with short date fields.
+	"2006-1-2t15:4:5.999999999Z07:00", // RFC3339Nano with short date fields and lower-case "t".
+	"2006-1-2 15:4:5.999999999",       // space separated with no time zone
+	"2006-1-2",                        // date only
+	// Notable exception: time.Parse cannot handle: "2001-12-14 21:59:43.10 -5"
+	// from the set of examples.
+}
+
+// parseTimestamp parses s as a timestamp string and
+// returns the timestamp and reports whether it succeeded.
+// Timestamp formats are defined at http://yaml.org/type/timestamp.html
+func parseTimestamp(s string) (time.Time, bool) {
+	// TODO write code to check all the formats supported by
+	// http://yaml.org/type/timestamp.html instead of using time.Parse.
+
+	// Quick check: all date formats start with YYYY-.
+	i := 0
+	for ; i < len(s); i++ {
+		if c := s[i]; c < '0' || c > '9' {
+			break
+		}
+	}
+	if i != 4 || i == len(s) || s[i] != '-' {
+		return time.Time{}, false
+	}
+	for _, format := range allowedTimestampFormats {
+		if t, err := time.Parse(format, s); err == nil {
+			return t, true
+		}
+	}
+	return time.Time{}, false
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/scannerc.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/scannerc.go
new file mode 100644
index 00000000000..0b9bb6030a0
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/scannerc.go
@@ -0,0 +1,2711 @@
+package yaml
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// Introduction
+// ************
+//
+// The following notes assume that you are familiar with the YAML specification
+// (http://yaml.org/spec/1.2/spec.html).  We mostly follow it, although in
+// some cases we are less restrictive that it requires.
+//
+// The process of transforming a YAML stream into a sequence of events is
+// divided on two steps: Scanning and Parsing.
+//
+// The Scanner transforms the input stream into a sequence of tokens, while the
+// parser transform the sequence of tokens produced by the Scanner into a
+// sequence of parsing events.
+//
+// The Scanner is rather clever and complicated. The Parser, on the contrary,
+// is a straightforward implementation of a recursive-descendant parser (or,
+// LL(1) parser, as it is usually called).
+//
+// Actually there are two issues of Scanning that might be called "clever", the
+// rest is quite straightforward.  The issues are "block collection start" and
+// "simple keys".  Both issues are explained below in details.
+//
+// Here the Scanning step is explained and implemented.  We start with the list
+// of all the tokens produced by the Scanner together with short descriptions.
+//
+// Now, tokens:
+//
+//      STREAM-START(encoding)          # The stream start.
+//      STREAM-END                      # The stream end.
+//      VERSION-DIRECTIVE(major,minor)  # The '%YAML' directive.
+//      TAG-DIRECTIVE(handle,prefix)    # The '%TAG' directive.
+//      DOCUMENT-START                  # '---'
+//      DOCUMENT-END                    # '...'
+//      BLOCK-SEQUENCE-START            # Indentation increase denoting a block
+//      BLOCK-MAPPING-START             # sequence or a block mapping.
+//      BLOCK-END                       # Indentation decrease.
+//      FLOW-SEQUENCE-START             # '['
+//      FLOW-SEQUENCE-END               # ']'
+//      BLOCK-SEQUENCE-START            # '{'
+//      BLOCK-SEQUENCE-END              # '}'
+//      BLOCK-ENTRY                     # '-'
+//      FLOW-ENTRY                      # ','
+//      KEY                             # '?' or nothing (simple keys).
+//      VALUE                           # ':'
+//      ALIAS(anchor)                   # '*anchor'
+//      ANCHOR(anchor)                  # '&anchor'
+//      TAG(handle,suffix)              # '!handle!suffix'
+//      SCALAR(value,style)             # A scalar.
+//
+// The following two tokens are "virtual" tokens denoting the beginning and the
+// end of the stream:
+//
+//      STREAM-START(encoding)
+//      STREAM-END
+//
+// We pass the information about the input stream encoding with the
+// STREAM-START token.
+//
+// The next two tokens are responsible for tags:
+//
+//      VERSION-DIRECTIVE(major,minor)
+//      TAG-DIRECTIVE(handle,prefix)
+//
+// Example:
+//
+//      %YAML   1.1
+//      %TAG    !   !foo
+//      %TAG    !yaml!  tag:yaml.org,2002:
+//      ---
+//
+// The correspoding sequence of tokens:
+//
+//      STREAM-START(utf-8)
+//      VERSION-DIRECTIVE(1,1)
+//      TAG-DIRECTIVE("!","!foo")
+//      TAG-DIRECTIVE("!yaml","tag:yaml.org,2002:")
+//      DOCUMENT-START
+//      STREAM-END
+//
+// Note that the VERSION-DIRECTIVE and TAG-DIRECTIVE tokens occupy a whole
+// line.
+//
+// The document start and end indicators are represented by:
+//
+//      DOCUMENT-START
+//      DOCUMENT-END
+//
+// Note that if a YAML stream contains an implicit document (without '---'
+// and '...' indicators), no DOCUMENT-START and DOCUMENT-END tokens will be
+// produced.
+//
+// In the following examples, we present whole documents together with the
+// produced tokens.
+//
+//      1. An implicit document:
+//
+//          'a scalar'
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          SCALAR("a scalar",single-quoted)
+//          STREAM-END
+//
+//      2. An explicit document:
+//
+//          ---
+//          'a scalar'
+//          ...
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          DOCUMENT-START
+//          SCALAR("a scalar",single-quoted)
+//          DOCUMENT-END
+//          STREAM-END
+//
+//      3. Several documents in a stream:
+//
+//          'a scalar'
+//          ---
+//          'another scalar'
+//          ---
+//          'yet another scalar'
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          SCALAR("a scalar",single-quoted)
+//          DOCUMENT-START
+//          SCALAR("another scalar",single-quoted)
+//          DOCUMENT-START
+//          SCALAR("yet another scalar",single-quoted)
+//          STREAM-END
+//
+// We have already introduced the SCALAR token above.  The following tokens are
+// used to describe aliases, anchors, tag, and scalars:
+//
+//      ALIAS(anchor)
+//      ANCHOR(anchor)
+//      TAG(handle,suffix)
+//      SCALAR(value,style)
+//
+// The following series of examples illustrate the usage of these tokens:
+//
+//      1. A recursive sequence:
+//
+//          &A [ *A ]
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          ANCHOR("A")
+//          FLOW-SEQUENCE-START
+//          ALIAS("A")
+//          FLOW-SEQUENCE-END
+//          STREAM-END
+//
+//      2. A tagged scalar:
+//
+//          !!float "3.14"  # A good approximation.
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          TAG("!!","float")
+//          SCALAR("3.14",double-quoted)
+//          STREAM-END
+//
+//      3. Various scalar styles:
+//
+//          --- # Implicit empty plain scalars do not produce tokens.
+//          --- a plain scalar
+//          --- 'a single-quoted scalar'
+//          --- "a double-quoted scalar"
+//          --- |-
+//            a literal scalar
+//          --- >-
+//            a folded
+//            scalar
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          DOCUMENT-START
+//          DOCUMENT-START
+//          SCALAR("a plain scalar",plain)
+//          DOCUMENT-START
+//          SCALAR("a single-quoted scalar",single-quoted)
+//          DOCUMENT-START
+//          SCALAR("a double-quoted scalar",double-quoted)
+//          DOCUMENT-START
+//          SCALAR("a literal scalar",literal)
+//          DOCUMENT-START
+//          SCALAR("a folded scalar",folded)
+//          STREAM-END
+//
+// Now it's time to review collection-related tokens. We will start with
+// flow collections:
+//
+//      FLOW-SEQUENCE-START
+//      FLOW-SEQUENCE-END
+//      FLOW-MAPPING-START
+//      FLOW-MAPPING-END
+//      FLOW-ENTRY
+//      KEY
+//      VALUE
+//
+// The tokens FLOW-SEQUENCE-START, FLOW-SEQUENCE-END, FLOW-MAPPING-START, and
+// FLOW-MAPPING-END represent the indicators '[', ']', '{', and '}'
+// correspondingly.  FLOW-ENTRY represent the ',' indicator.  Finally the
+// indicators '?' and ':', which are used for denoting mapping keys and values,
+// are represented by the KEY and VALUE tokens.
+//
+// The following examples show flow collections:
+//
+//      1. A flow sequence:
+//
+//          [item 1, item 2, item 3]
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          FLOW-SEQUENCE-START
+//          SCALAR("item 1",plain)
+//          FLOW-ENTRY
+//          SCALAR("item 2",plain)
+//          FLOW-ENTRY
+//          SCALAR("item 3",plain)
+//          FLOW-SEQUENCE-END
+//          STREAM-END
+//
+//      2. A flow mapping:
+//
+//          {
+//              a simple key: a value,  # Note that the KEY token is produced.
+//              ? a complex key: another value,
+//          }
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          FLOW-MAPPING-START
+//          KEY
+//          SCALAR("a simple key",plain)
+//          VALUE
+//          SCALAR("a value",plain)
+//          FLOW-ENTRY
+//          KEY
+//          SCALAR("a complex key",plain)
+//          VALUE
+//          SCALAR("another value",plain)
+//          FLOW-ENTRY
+//          FLOW-MAPPING-END
+//          STREAM-END
+//
+// A simple key is a key which is not denoted by the '?' indicator.  Note that
+// the Scanner still produce the KEY token whenever it encounters a simple key.
+//
+// For scanning block collections, the following tokens are used (note that we
+// repeat KEY and VALUE here):
+//
+//      BLOCK-SEQUENCE-START
+//      BLOCK-MAPPING-START
+//      BLOCK-END
+//      BLOCK-ENTRY
+//      KEY
+//      VALUE
+//
+// The tokens BLOCK-SEQUENCE-START and BLOCK-MAPPING-START denote indentation
+// increase that precedes a block collection (cf. the INDENT token in Python).
+// The token BLOCK-END denote indentation decrease that ends a block collection
+// (cf. the DEDENT token in Python).  However YAML has some syntax pecularities
+// that makes detections of these tokens more complex.
+//
+// The tokens BLOCK-ENTRY, KEY, and VALUE are used to represent the indicators
+// '-', '?', and ':' correspondingly.
+//
+// The following examples show how the tokens BLOCK-SEQUENCE-START,
+// BLOCK-MAPPING-START, and BLOCK-END are emitted by the Scanner:
+//
+//      1. Block sequences:
+//
+//          - item 1
+//          - item 2
+//          -
+//            - item 3.1
+//            - item 3.2
+//          -
+//            key 1: value 1
+//            key 2: value 2
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          BLOCK-SEQUENCE-START
+//          BLOCK-ENTRY
+//          SCALAR("item 1",plain)
+//          BLOCK-ENTRY
+//          SCALAR("item 2",plain)
+//          BLOCK-ENTRY
+//          BLOCK-SEQUENCE-START
+//          BLOCK-ENTRY
+//          SCALAR("item 3.1",plain)
+//          BLOCK-ENTRY
+//          SCALAR("item 3.2",plain)
+//          BLOCK-END
+//          BLOCK-ENTRY
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("key 1",plain)
+//          VALUE
+//          SCALAR("value 1",plain)
+//          KEY
+//          SCALAR("key 2",plain)
+//          VALUE
+//          SCALAR("value 2",plain)
+//          BLOCK-END
+//          BLOCK-END
+//          STREAM-END
+//
+//      2. Block mappings:
+//
+//          a simple key: a value   # The KEY token is produced here.
+//          ? a complex key
+//          : another value
+//          a mapping:
+//            key 1: value 1
+//            key 2: value 2
+//          a sequence:
+//            - item 1
+//            - item 2
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("a simple key",plain)
+//          VALUE
+//          SCALAR("a value",plain)
+//          KEY
+//          SCALAR("a complex key",plain)
+//          VALUE
+//          SCALAR("another value",plain)
+//          KEY
+//          SCALAR("a mapping",plain)
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("key 1",plain)
+//          VALUE
+//          SCALAR("value 1",plain)
+//          KEY
+//          SCALAR("key 2",plain)
+//          VALUE
+//          SCALAR("value 2",plain)
+//          BLOCK-END
+//          KEY
+//          SCALAR("a sequence",plain)
+//          VALUE
+//          BLOCK-SEQUENCE-START
+//          BLOCK-ENTRY
+//          SCALAR("item 1",plain)
+//          BLOCK-ENTRY
+//          SCALAR("item 2",plain)
+//          BLOCK-END
+//          BLOCK-END
+//          STREAM-END
+//
+// YAML does not always require to start a new block collection from a new
+// line.  If the current line contains only '-', '?', and ':' indicators, a new
+// block collection may start at the current line.  The following examples
+// illustrate this case:
+//
+//      1. Collections in a sequence:
+//
+//          - - item 1
+//            - item 2
+//          - key 1: value 1
+//            key 2: value 2
+//          - ? complex key
+//            : complex value
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          BLOCK-SEQUENCE-START
+//          BLOCK-ENTRY
+//          BLOCK-SEQUENCE-START
+//          BLOCK-ENTRY
+//          SCALAR("item 1",plain)
+//          BLOCK-ENTRY
+//          SCALAR("item 2",plain)
+//          BLOCK-END
+//          BLOCK-ENTRY
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("key 1",plain)
+//          VALUE
+//          SCALAR("value 1",plain)
+//          KEY
+//          SCALAR("key 2",plain)
+//          VALUE
+//          SCALAR("value 2",plain)
+//          BLOCK-END
+//          BLOCK-ENTRY
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("complex key")
+//          VALUE
+//          SCALAR("complex value")
+//          BLOCK-END
+//          BLOCK-END
+//          STREAM-END
+//
+//      2. Collections in a mapping:
+//
+//          ? a sequence
+//          : - item 1
+//            - item 2
+//          ? a mapping
+//          : key 1: value 1
+//            key 2: value 2
+//
+//      Tokens:
+//
+//          STREAM-START(utf-8)
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("a sequence",plain)
+//          VALUE
+//          BLOCK-SEQUENCE-START
+//          BLOCK-ENTRY
+//          SCALAR("item 1",plain)
+//          BLOCK-ENTRY
+//          SCALAR("item 2",plain)
+//          BLOCK-END
+//          KEY
+//          SCALAR("a mapping",plain)
+//          VALUE
+//          BLOCK-MAPPING-START
+//          KEY
+//          SCALAR("key 1",plain)
+//          VALUE
+//          SCALAR("value 1",plain)
+//          KEY
+//          SCALAR("key 2",plain)
+//          VALUE
+//          SCALAR("value 2",plain)
+//          BLOCK-END
+//          BLOCK-END
+//          STREAM-END
+//
+// YAML also permits non-indented sequences if they are included into a block
+// mapping.  In this case, the token BLOCK-SEQUENCE-START is not produced:
+//
+//      key:
+//      - item 1    # BLOCK-SEQUENCE-START is NOT produced here.
+//      - item 2
+//
+// Tokens:
+//
+//      STREAM-START(utf-8)
+//      BLOCK-MAPPING-START
+//      KEY
+//      SCALAR("key",plain)
+//      VALUE
+//      BLOCK-ENTRY
+//      SCALAR("item 1",plain)
+//      BLOCK-ENTRY
+//      SCALAR("item 2",plain)
+//      BLOCK-END
+//
+
+// Ensure that the buffer contains the required number of characters.
+// Return true on success, false on failure (reader error or memory error).
+func cache(parser *yaml_parser_t, length int) bool {
+	// [Go] This was inlined: !cache(A, B) -> unread < B && !update(A, B)
+	return parser.unread >= length || yaml_parser_update_buffer(parser, length)
+}
+
+// Advance the buffer pointer.
+func skip(parser *yaml_parser_t) {
+	parser.mark.index++
+	parser.mark.column++
+	parser.unread--
+	parser.buffer_pos += width(parser.buffer[parser.buffer_pos])
+}
+
+func skip_line(parser *yaml_parser_t) {
+	if is_crlf(parser.buffer, parser.buffer_pos) {
+		parser.mark.index += 2
+		parser.mark.column = 0
+		parser.mark.line++
+		parser.unread -= 2
+		parser.buffer_pos += 2
+	} else if is_break(parser.buffer, parser.buffer_pos) {
+		parser.mark.index++
+		parser.mark.column = 0
+		parser.mark.line++
+		parser.unread--
+		parser.buffer_pos += width(parser.buffer[parser.buffer_pos])
+	}
+}
+
+// Copy a character to a string buffer and advance pointers.
+func read(parser *yaml_parser_t, s []byte) []byte {
+	w := width(parser.buffer[parser.buffer_pos])
+	if w == 0 {
+		panic("invalid character sequence")
+	}
+	if len(s) == 0 {
+		s = make([]byte, 0, 32)
+	}
+	if w == 1 && len(s)+w <= cap(s) {
+		s = s[:len(s)+1]
+		s[len(s)-1] = parser.buffer[parser.buffer_pos]
+		parser.buffer_pos++
+	} else {
+		s = append(s, parser.buffer[parser.buffer_pos:parser.buffer_pos+w]...)
+		parser.buffer_pos += w
+	}
+	parser.mark.index++
+	parser.mark.column++
+	parser.unread--
+	return s
+}
+
+// Copy a line break character to a string buffer and advance pointers.
+func read_line(parser *yaml_parser_t, s []byte) []byte {
+	buf := parser.buffer
+	pos := parser.buffer_pos
+	switch {
+	case buf[pos] == '\r' && buf[pos+1] == '\n':
+		// CR LF . LF
+		s = append(s, '\n')
+		parser.buffer_pos += 2
+		parser.mark.index++
+		parser.unread--
+	case buf[pos] == '\r' || buf[pos] == '\n':
+		// CR|LF . LF
+		s = append(s, '\n')
+		parser.buffer_pos += 1
+	case buf[pos] == '\xC2' && buf[pos+1] == '\x85':
+		// NEL . LF
+		s = append(s, '\n')
+		parser.buffer_pos += 2
+	case buf[pos] == '\xE2' && buf[pos+1] == '\x80' && (buf[pos+2] == '\xA8' || buf[pos+2] == '\xA9'):
+		// LS|PS . LS|PS
+		s = append(s, buf[parser.buffer_pos:pos+3]...)
+		parser.buffer_pos += 3
+	default:
+		return s
+	}
+	parser.mark.index++
+	parser.mark.column = 0
+	parser.mark.line++
+	parser.unread--
+	return s
+}
+
+// Get the next token.
+func yaml_parser_scan(parser *yaml_parser_t, token *yaml_token_t) bool {
+	// Erase the token object.
+	*token = yaml_token_t{} // [Go] Is this necessary?
+
+	// No tokens after STREAM-END or error.
+	if parser.stream_end_produced || parser.error != yaml_NO_ERROR {
+		return true
+	}
+
+	// Ensure that the tokens queue contains enough tokens.
+	if !parser.token_available {
+		if !yaml_parser_fetch_more_tokens(parser) {
+			return false
+		}
+	}
+
+	// Fetch the next token from the queue.
+	*token = parser.tokens[parser.tokens_head]
+	parser.tokens_head++
+	parser.tokens_parsed++
+	parser.token_available = false
+
+	if token.typ == yaml_STREAM_END_TOKEN {
+		parser.stream_end_produced = true
+	}
+	return true
+}
+
+// Set the scanner error and return false.
+func yaml_parser_set_scanner_error(parser *yaml_parser_t, context string, context_mark yaml_mark_t, problem string) bool {
+	parser.error = yaml_SCANNER_ERROR
+	parser.context = context
+	parser.context_mark = context_mark
+	parser.problem = problem
+	parser.problem_mark = parser.mark
+	return false
+}
+
+func yaml_parser_set_scanner_tag_error(parser *yaml_parser_t, directive bool, context_mark yaml_mark_t, problem string) bool {
+	context := "while parsing a tag"
+	if directive {
+		context = "while parsing a %TAG directive"
+	}
+	return yaml_parser_set_scanner_error(parser, context, context_mark, problem)
+}
+
+func trace(args ...interface{}) func() {
+	pargs := append([]interface{}{"+++"}, args...)
+	fmt.Println(pargs...)
+	pargs = append([]interface{}{"---"}, args...)
+	return func() { fmt.Println(pargs...) }
+}
+
+// Ensure that the tokens queue contains at least one token which can be
+// returned to the Parser.
+func yaml_parser_fetch_more_tokens(parser *yaml_parser_t) bool {
+	// While we need more tokens to fetch, do it.
+	for {
+		if parser.tokens_head != len(parser.tokens) {
+			// If queue is non-empty, check if any potential simple key may
+			// occupy the head position.
+			head_tok_idx, ok := parser.simple_keys_by_tok[parser.tokens_parsed]
+			if !ok {
+				break
+			} else if valid, ok := yaml_simple_key_is_valid(parser, &parser.simple_keys[head_tok_idx]); !ok {
+				return false
+			} else if !valid {
+				break
+			}
+		}
+		// Fetch the next token.
+		if !yaml_parser_fetch_next_token(parser) {
+			return false
+		}
+	}
+
+	parser.token_available = true
+	return true
+}
+
+// The dispatcher for token fetchers.
+func yaml_parser_fetch_next_token(parser *yaml_parser_t) bool {
+	// Ensure that the buffer is initialized.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	// Check if we just started scanning.  Fetch STREAM-START then.
+	if !parser.stream_start_produced {
+		return yaml_parser_fetch_stream_start(parser)
+	}
+
+	// Eat whitespaces and comments until we reach the next token.
+	if !yaml_parser_scan_to_next_token(parser) {
+		return false
+	}
+
+	// Check the indentation level against the current column.
+	if !yaml_parser_unroll_indent(parser, parser.mark.column) {
+		return false
+	}
+
+	// Ensure that the buffer contains at least 4 characters.  4 is the length
+	// of the longest indicators ('--- ' and '... ').
+	if parser.unread < 4 && !yaml_parser_update_buffer(parser, 4) {
+		return false
+	}
+
+	// Is it the end of the stream?
+	if is_z(parser.buffer, parser.buffer_pos) {
+		return yaml_parser_fetch_stream_end(parser)
+	}
+
+	// Is it a directive?
+	if parser.mark.column == 0 && parser.buffer[parser.buffer_pos] == '%' {
+		return yaml_parser_fetch_directive(parser)
+	}
+
+	buf := parser.buffer
+	pos := parser.buffer_pos
+
+	// Is it the document start indicator?
+	if parser.mark.column == 0 && buf[pos] == '-' && buf[pos+1] == '-' && buf[pos+2] == '-' && is_blankz(buf, pos+3) {
+		return yaml_parser_fetch_document_indicator(parser, yaml_DOCUMENT_START_TOKEN)
+	}
+
+	// Is it the document end indicator?
+	if parser.mark.column == 0 && buf[pos] == '.' && buf[pos+1] == '.' && buf[pos+2] == '.' && is_blankz(buf, pos+3) {
+		return yaml_parser_fetch_document_indicator(parser, yaml_DOCUMENT_END_TOKEN)
+	}
+
+	// Is it the flow sequence start indicator?
+	if buf[pos] == '[' {
+		return yaml_parser_fetch_flow_collection_start(parser, yaml_FLOW_SEQUENCE_START_TOKEN)
+	}
+
+	// Is it the flow mapping start indicator?
+	if parser.buffer[parser.buffer_pos] == '{' {
+		return yaml_parser_fetch_flow_collection_start(parser, yaml_FLOW_MAPPING_START_TOKEN)
+	}
+
+	// Is it the flow sequence end indicator?
+	if parser.buffer[parser.buffer_pos] == ']' {
+		return yaml_parser_fetch_flow_collection_end(parser,
+			yaml_FLOW_SEQUENCE_END_TOKEN)
+	}
+
+	// Is it the flow mapping end indicator?
+	if parser.buffer[parser.buffer_pos] == '}' {
+		return yaml_parser_fetch_flow_collection_end(parser,
+			yaml_FLOW_MAPPING_END_TOKEN)
+	}
+
+	// Is it the flow entry indicator?
+	if parser.buffer[parser.buffer_pos] == ',' {
+		return yaml_parser_fetch_flow_entry(parser)
+	}
+
+	// Is it the block entry indicator?
+	if parser.buffer[parser.buffer_pos] == '-' && is_blankz(parser.buffer, parser.buffer_pos+1) {
+		return yaml_parser_fetch_block_entry(parser)
+	}
+
+	// Is it the key indicator?
+	if parser.buffer[parser.buffer_pos] == '?' && (parser.flow_level > 0 || is_blankz(parser.buffer, parser.buffer_pos+1)) {
+		return yaml_parser_fetch_key(parser)
+	}
+
+	// Is it the value indicator?
+	if parser.buffer[parser.buffer_pos] == ':' && (parser.flow_level > 0 || is_blankz(parser.buffer, parser.buffer_pos+1)) {
+		return yaml_parser_fetch_value(parser)
+	}
+
+	// Is it an alias?
+	if parser.buffer[parser.buffer_pos] == '*' {
+		return yaml_parser_fetch_anchor(parser, yaml_ALIAS_TOKEN)
+	}
+
+	// Is it an anchor?
+	if parser.buffer[parser.buffer_pos] == '&' {
+		return yaml_parser_fetch_anchor(parser, yaml_ANCHOR_TOKEN)
+	}
+
+	// Is it a tag?
+	if parser.buffer[parser.buffer_pos] == '!' {
+		return yaml_parser_fetch_tag(parser)
+	}
+
+	// Is it a literal scalar?
+	if parser.buffer[parser.buffer_pos] == '|' && parser.flow_level == 0 {
+		return yaml_parser_fetch_block_scalar(parser, true)
+	}
+
+	// Is it a folded scalar?
+	if parser.buffer[parser.buffer_pos] == '>' && parser.flow_level == 0 {
+		return yaml_parser_fetch_block_scalar(parser, false)
+	}
+
+	// Is it a single-quoted scalar?
+	if parser.buffer[parser.buffer_pos] == '\'' {
+		return yaml_parser_fetch_flow_scalar(parser, true)
+	}
+
+	// Is it a double-quoted scalar?
+	if parser.buffer[parser.buffer_pos] == '"' {
+		return yaml_parser_fetch_flow_scalar(parser, false)
+	}
+
+	// Is it a plain scalar?
+	//
+	// A plain scalar may start with any non-blank characters except
+	//
+	//      '-', '?', ':', ',', '[', ']', '{', '}',
+	//      '#', '&', '*', '!', '|', '>', '\'', '\"',
+	//      '%', '@', '`'.
+	//
+	// In the block context (and, for the '-' indicator, in the flow context
+	// too), it may also start with the characters
+	//
+	//      '-', '?', ':'
+	//
+	// if it is followed by a non-space character.
+	//
+	// The last rule is more restrictive than the specification requires.
+	// [Go] Make this logic more reasonable.
+	//switch parser.buffer[parser.buffer_pos] {
+	//case '-', '?', ':', ',', '?', '-', ',', ':', ']', '[', '}', '{', '&', '#', '!', '*', '>', '|', '"', '\'', '@', '%', '-', '`':
+	//}
+	if !(is_blankz(parser.buffer, parser.buffer_pos) || parser.buffer[parser.buffer_pos] == '-' ||
+		parser.buffer[parser.buffer_pos] == '?' || parser.buffer[parser.buffer_pos] == ':' ||
+		parser.buffer[parser.buffer_pos] == ',' || parser.buffer[parser.buffer_pos] == '[' ||
+		parser.buffer[parser.buffer_pos] == ']' || parser.buffer[parser.buffer_pos] == '{' ||
+		parser.buffer[parser.buffer_pos] == '}' || parser.buffer[parser.buffer_pos] == '#' ||
+		parser.buffer[parser.buffer_pos] == '&' || parser.buffer[parser.buffer_pos] == '*' ||
+		parser.buffer[parser.buffer_pos] == '!' || parser.buffer[parser.buffer_pos] == '|' ||
+		parser.buffer[parser.buffer_pos] == '>' || parser.buffer[parser.buffer_pos] == '\'' ||
+		parser.buffer[parser.buffer_pos] == '"' || parser.buffer[parser.buffer_pos] == '%' ||
+		parser.buffer[parser.buffer_pos] == '@' || parser.buffer[parser.buffer_pos] == '`') ||
+		(parser.buffer[parser.buffer_pos] == '-' && !is_blank(parser.buffer, parser.buffer_pos+1)) ||
+		(parser.flow_level == 0 &&
+			(parser.buffer[parser.buffer_pos] == '?' || parser.buffer[parser.buffer_pos] == ':') &&
+			!is_blankz(parser.buffer, parser.buffer_pos+1)) {
+		return yaml_parser_fetch_plain_scalar(parser)
+	}
+
+	// If we don't determine the token type so far, it is an error.
+	return yaml_parser_set_scanner_error(parser,
+		"while scanning for the next token", parser.mark,
+		"found character that cannot start any token")
+}
+
+func yaml_simple_key_is_valid(parser *yaml_parser_t, simple_key *yaml_simple_key_t) (valid, ok bool) {
+	if !simple_key.possible {
+		return false, true
+	}
+
+	// The 1.2 specification says:
+	//
+	//     "If the ? indicator is omitted, parsing needs to see past the
+	//     implicit key to recognize it as such. To limit the amount of
+	//     lookahead required, the “:” indicator must appear at most 1024
+	//     Unicode characters beyond the start of the key. In addition, the key
+	//     is restricted to a single line."
+	//
+	if simple_key.mark.line < parser.mark.line || simple_key.mark.index+1024 < parser.mark.index {
+		// Check if the potential simple key to be removed is required.
+		if simple_key.required {
+			return false, yaml_parser_set_scanner_error(parser,
+				"while scanning a simple key", simple_key.mark,
+				"could not find expected ':'")
+		}
+		simple_key.possible = false
+		return false, true
+	}
+	return true, true
+}
+
+// Check if a simple key may start at the current position and add it if
+// needed.
+func yaml_parser_save_simple_key(parser *yaml_parser_t) bool {
+	// A simple key is required at the current position if the scanner is in
+	// the block context and the current column coincides with the indentation
+	// level.
+
+	required := parser.flow_level == 0 && parser.indent == parser.mark.column
+
+	//
+	// If the current position may start a simple key, save it.
+	//
+	if parser.simple_key_allowed {
+		simple_key := yaml_simple_key_t{
+			possible:     true,
+			required:     required,
+			token_number: parser.tokens_parsed + (len(parser.tokens) - parser.tokens_head),
+			mark:         parser.mark,
+		}
+
+		if !yaml_parser_remove_simple_key(parser) {
+			return false
+		}
+		parser.simple_keys[len(parser.simple_keys)-1] = simple_key
+		parser.simple_keys_by_tok[simple_key.token_number] = len(parser.simple_keys) - 1
+	}
+	return true
+}
+
+// Remove a potential simple key at the current flow level.
+func yaml_parser_remove_simple_key(parser *yaml_parser_t) bool {
+	i := len(parser.simple_keys) - 1
+	if parser.simple_keys[i].possible {
+		// If the key is required, it is an error.
+		if parser.simple_keys[i].required {
+			return yaml_parser_set_scanner_error(parser,
+				"while scanning a simple key", parser.simple_keys[i].mark,
+				"could not find expected ':'")
+		}
+		// Remove the key from the stack.
+		parser.simple_keys[i].possible = false
+		delete(parser.simple_keys_by_tok, parser.simple_keys[i].token_number)
+	}
+	return true
+}
+
+// max_flow_level limits the flow_level
+const max_flow_level = 10000
+
+// Increase the flow level and resize the simple key list if needed.
+func yaml_parser_increase_flow_level(parser *yaml_parser_t) bool {
+	// Reset the simple key on the next level.
+	parser.simple_keys = append(parser.simple_keys, yaml_simple_key_t{
+		possible:     false,
+		required:     false,
+		token_number: parser.tokens_parsed + (len(parser.tokens) - parser.tokens_head),
+		mark:         parser.mark,
+	})
+
+	// Increase the flow level.
+	parser.flow_level++
+	if parser.flow_level > max_flow_level {
+		return yaml_parser_set_scanner_error(parser,
+			"while increasing flow level", parser.simple_keys[len(parser.simple_keys)-1].mark,
+			fmt.Sprintf("exceeded max depth of %d", max_flow_level))
+	}
+	return true
+}
+
+// Decrease the flow level.
+func yaml_parser_decrease_flow_level(parser *yaml_parser_t) bool {
+	if parser.flow_level > 0 {
+		parser.flow_level--
+		last := len(parser.simple_keys) - 1
+		delete(parser.simple_keys_by_tok, parser.simple_keys[last].token_number)
+		parser.simple_keys = parser.simple_keys[:last]
+	}
+	return true
+}
+
+// max_indents limits the indents stack size
+const max_indents = 10000
+
+// Push the current indentation level to the stack and set the new level
+// the current column is greater than the indentation level.  In this case,
+// append or insert the specified token into the token queue.
+func yaml_parser_roll_indent(parser *yaml_parser_t, column, number int, typ yaml_token_type_t, mark yaml_mark_t) bool {
+	// In the flow context, do nothing.
+	if parser.flow_level > 0 {
+		return true
+	}
+
+	if parser.indent < column {
+		// Push the current indentation level to the stack and set the new
+		// indentation level.
+		parser.indents = append(parser.indents, parser.indent)
+		parser.indent = column
+		if len(parser.indents) > max_indents {
+			return yaml_parser_set_scanner_error(parser,
+				"while increasing indent level", parser.simple_keys[len(parser.simple_keys)-1].mark,
+				fmt.Sprintf("exceeded max depth of %d", max_indents))
+		}
+
+		// Create a token and insert it into the queue.
+		token := yaml_token_t{
+			typ:        typ,
+			start_mark: mark,
+			end_mark:   mark,
+		}
+		if number > -1 {
+			number -= parser.tokens_parsed
+		}
+		yaml_insert_token(parser, number, &token)
+	}
+	return true
+}
+
+// Pop indentation levels from the indents stack until the current level
+// becomes less or equal to the column.  For each indentation level, append
+// the BLOCK-END token.
+func yaml_parser_unroll_indent(parser *yaml_parser_t, column int) bool {
+	// In the flow context, do nothing.
+	if parser.flow_level > 0 {
+		return true
+	}
+
+	// Loop through the indentation levels in the stack.
+	for parser.indent > column {
+		// Create a token and append it to the queue.
+		token := yaml_token_t{
+			typ:        yaml_BLOCK_END_TOKEN,
+			start_mark: parser.mark,
+			end_mark:   parser.mark,
+		}
+		yaml_insert_token(parser, -1, &token)
+
+		// Pop the indentation level.
+		parser.indent = parser.indents[len(parser.indents)-1]
+		parser.indents = parser.indents[:len(parser.indents)-1]
+	}
+	return true
+}
+
+// Initialize the scanner and produce the STREAM-START token.
+func yaml_parser_fetch_stream_start(parser *yaml_parser_t) bool {
+
+	// Set the initial indentation.
+	parser.indent = -1
+
+	// Initialize the simple key stack.
+	parser.simple_keys = append(parser.simple_keys, yaml_simple_key_t{})
+
+	parser.simple_keys_by_tok = make(map[int]int)
+
+	// A simple key is allowed at the beginning of the stream.
+	parser.simple_key_allowed = true
+
+	// We have started.
+	parser.stream_start_produced = true
+
+	// Create the STREAM-START token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_STREAM_START_TOKEN,
+		start_mark: parser.mark,
+		end_mark:   parser.mark,
+		encoding:   parser.encoding,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the STREAM-END token and shut down the scanner.
+func yaml_parser_fetch_stream_end(parser *yaml_parser_t) bool {
+
+	// Force new line.
+	if parser.mark.column != 0 {
+		parser.mark.column = 0
+		parser.mark.line++
+	}
+
+	// Reset the indentation level.
+	if !yaml_parser_unroll_indent(parser, -1) {
+		return false
+	}
+
+	// Reset simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	parser.simple_key_allowed = false
+
+	// Create the STREAM-END token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_STREAM_END_TOKEN,
+		start_mark: parser.mark,
+		end_mark:   parser.mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce a VERSION-DIRECTIVE or TAG-DIRECTIVE token.
+func yaml_parser_fetch_directive(parser *yaml_parser_t) bool {
+	// Reset the indentation level.
+	if !yaml_parser_unroll_indent(parser, -1) {
+		return false
+	}
+
+	// Reset simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	parser.simple_key_allowed = false
+
+	// Create the YAML-DIRECTIVE or TAG-DIRECTIVE token.
+	token := yaml_token_t{}
+	if !yaml_parser_scan_directive(parser, &token) {
+		return false
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the DOCUMENT-START or DOCUMENT-END token.
+func yaml_parser_fetch_document_indicator(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// Reset the indentation level.
+	if !yaml_parser_unroll_indent(parser, -1) {
+		return false
+	}
+
+	// Reset simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	parser.simple_key_allowed = false
+
+	// Consume the token.
+	start_mark := parser.mark
+
+	skip(parser)
+	skip(parser)
+	skip(parser)
+
+	end_mark := parser.mark
+
+	// Create the DOCUMENT-START or DOCUMENT-END token.
+	token := yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the FLOW-SEQUENCE-START or FLOW-MAPPING-START token.
+func yaml_parser_fetch_flow_collection_start(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// The indicators '[' and '{' may start a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+
+	// Increase the flow level.
+	if !yaml_parser_increase_flow_level(parser) {
+		return false
+	}
+
+	// A simple key may follow the indicators '[' and '{'.
+	parser.simple_key_allowed = true
+
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create the FLOW-SEQUENCE-START of FLOW-MAPPING-START token.
+	token := yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the FLOW-SEQUENCE-END or FLOW-MAPPING-END token.
+func yaml_parser_fetch_flow_collection_end(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// Reset any potential simple key on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	// Decrease the flow level.
+	if !yaml_parser_decrease_flow_level(parser) {
+		return false
+	}
+
+	// No simple keys after the indicators ']' and '}'.
+	parser.simple_key_allowed = false
+
+	// Consume the token.
+
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create the FLOW-SEQUENCE-END of FLOW-MAPPING-END token.
+	token := yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	// Append the token to the queue.
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the FLOW-ENTRY token.
+func yaml_parser_fetch_flow_entry(parser *yaml_parser_t) bool {
+	// Reset any potential simple keys on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	// Simple keys are allowed after ','.
+	parser.simple_key_allowed = true
+
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create the FLOW-ENTRY token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_FLOW_ENTRY_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the BLOCK-ENTRY token.
+func yaml_parser_fetch_block_entry(parser *yaml_parser_t) bool {
+	// Check if the scanner is in the block context.
+	if parser.flow_level == 0 {
+		// Check if we are allowed to start a new entry.
+		if !parser.simple_key_allowed {
+			return yaml_parser_set_scanner_error(parser, "", parser.mark,
+				"block sequence entries are not allowed in this context")
+		}
+		// Add the BLOCK-SEQUENCE-START token if needed.
+		if !yaml_parser_roll_indent(parser, parser.mark.column, -1, yaml_BLOCK_SEQUENCE_START_TOKEN, parser.mark) {
+			return false
+		}
+	} else {
+		// It is an error for the '-' indicator to occur in the flow context,
+		// but we let the Parser detect and report about it because the Parser
+		// is able to point to the context.
+	}
+
+	// Reset any potential simple keys on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	// Simple keys are allowed after '-'.
+	parser.simple_key_allowed = true
+
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create the BLOCK-ENTRY token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_BLOCK_ENTRY_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the KEY token.
+func yaml_parser_fetch_key(parser *yaml_parser_t) bool {
+
+	// In the block context, additional checks are required.
+	if parser.flow_level == 0 {
+		// Check if we are allowed to start a new key (not nessesary simple).
+		if !parser.simple_key_allowed {
+			return yaml_parser_set_scanner_error(parser, "", parser.mark,
+				"mapping keys are not allowed in this context")
+		}
+		// Add the BLOCK-MAPPING-START token if needed.
+		if !yaml_parser_roll_indent(parser, parser.mark.column, -1, yaml_BLOCK_MAPPING_START_TOKEN, parser.mark) {
+			return false
+		}
+	}
+
+	// Reset any potential simple keys on the current flow level.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	// Simple keys are allowed after '?' in the block context.
+	parser.simple_key_allowed = parser.flow_level == 0
+
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create the KEY token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_KEY_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the VALUE token.
+func yaml_parser_fetch_value(parser *yaml_parser_t) bool {
+
+	simple_key := &parser.simple_keys[len(parser.simple_keys)-1]
+
+	// Have we found a simple key?
+	if valid, ok := yaml_simple_key_is_valid(parser, simple_key); !ok {
+		return false
+
+	} else if valid {
+
+		// Create the KEY token and insert it into the queue.
+		token := yaml_token_t{
+			typ:        yaml_KEY_TOKEN,
+			start_mark: simple_key.mark,
+			end_mark:   simple_key.mark,
+		}
+		yaml_insert_token(parser, simple_key.token_number-parser.tokens_parsed, &token)
+
+		// In the block context, we may need to add the BLOCK-MAPPING-START token.
+		if !yaml_parser_roll_indent(parser, simple_key.mark.column,
+			simple_key.token_number,
+			yaml_BLOCK_MAPPING_START_TOKEN, simple_key.mark) {
+			return false
+		}
+
+		// Remove the simple key.
+		simple_key.possible = false
+		delete(parser.simple_keys_by_tok, simple_key.token_number)
+
+		// A simple key cannot follow another simple key.
+		parser.simple_key_allowed = false
+
+	} else {
+		// The ':' indicator follows a complex key.
+
+		// In the block context, extra checks are required.
+		if parser.flow_level == 0 {
+
+			// Check if we are allowed to start a complex value.
+			if !parser.simple_key_allowed {
+				return yaml_parser_set_scanner_error(parser, "", parser.mark,
+					"mapping values are not allowed in this context")
+			}
+
+			// Add the BLOCK-MAPPING-START token if needed.
+			if !yaml_parser_roll_indent(parser, parser.mark.column, -1, yaml_BLOCK_MAPPING_START_TOKEN, parser.mark) {
+				return false
+			}
+		}
+
+		// Simple keys after ':' are allowed in the block context.
+		parser.simple_key_allowed = parser.flow_level == 0
+	}
+
+	// Consume the token.
+	start_mark := parser.mark
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create the VALUE token and append it to the queue.
+	token := yaml_token_t{
+		typ:        yaml_VALUE_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the ALIAS or ANCHOR token.
+func yaml_parser_fetch_anchor(parser *yaml_parser_t, typ yaml_token_type_t) bool {
+	// An anchor or an alias could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+
+	// A simple key cannot follow an anchor or an alias.
+	parser.simple_key_allowed = false
+
+	// Create the ALIAS or ANCHOR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_anchor(parser, &token, typ) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the TAG token.
+func yaml_parser_fetch_tag(parser *yaml_parser_t) bool {
+	// A tag could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+
+	// A simple key cannot follow a tag.
+	parser.simple_key_allowed = false
+
+	// Create the TAG token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_tag(parser, &token) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the SCALAR(...,literal) or SCALAR(...,folded) tokens.
+func yaml_parser_fetch_block_scalar(parser *yaml_parser_t, literal bool) bool {
+	// Remove any potential simple keys.
+	if !yaml_parser_remove_simple_key(parser) {
+		return false
+	}
+
+	// A simple key may follow a block scalar.
+	parser.simple_key_allowed = true
+
+	// Create the SCALAR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_block_scalar(parser, &token, literal) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the SCALAR(...,single-quoted) or SCALAR(...,double-quoted) tokens.
+func yaml_parser_fetch_flow_scalar(parser *yaml_parser_t, single bool) bool {
+	// A plain scalar could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+
+	// A simple key cannot follow a flow scalar.
+	parser.simple_key_allowed = false
+
+	// Create the SCALAR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_flow_scalar(parser, &token, single) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Produce the SCALAR(...,plain) token.
+func yaml_parser_fetch_plain_scalar(parser *yaml_parser_t) bool {
+	// A plain scalar could be a simple key.
+	if !yaml_parser_save_simple_key(parser) {
+		return false
+	}
+
+	// A simple key cannot follow a flow scalar.
+	parser.simple_key_allowed = false
+
+	// Create the SCALAR token and append it to the queue.
+	var token yaml_token_t
+	if !yaml_parser_scan_plain_scalar(parser, &token) {
+		return false
+	}
+	yaml_insert_token(parser, -1, &token)
+	return true
+}
+
+// Eat whitespaces and comments until the next token is found.
+func yaml_parser_scan_to_next_token(parser *yaml_parser_t) bool {
+
+	// Until the next token is not found.
+	for {
+		// Allow the BOM mark to start a line.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		if parser.mark.column == 0 && is_bom(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+		}
+
+		// Eat whitespaces.
+		// Tabs are allowed:
+		//  - in the flow context
+		//  - in the block context, but not at the beginning of the line or
+		//  after '-', '?', or ':' (complex value).
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+
+		for parser.buffer[parser.buffer_pos] == ' ' || ((parser.flow_level > 0 || !parser.simple_key_allowed) && parser.buffer[parser.buffer_pos] == '\t') {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+
+		// Eat a comment until a line break.
+		if parser.buffer[parser.buffer_pos] == '#' {
+			for !is_breakz(parser.buffer, parser.buffer_pos) {
+				skip(parser)
+				if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+					return false
+				}
+			}
+		}
+
+		// If it is a line break, eat it.
+		if is_break(parser.buffer, parser.buffer_pos) {
+			if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+				return false
+			}
+			skip_line(parser)
+
+			// In the block context, a new line may start a simple key.
+			if parser.flow_level == 0 {
+				parser.simple_key_allowed = true
+			}
+		} else {
+			break // We have found a token.
+		}
+	}
+
+	return true
+}
+
+// Scan a YAML-DIRECTIVE or TAG-DIRECTIVE token.
+//
+// Scope:
+//      %YAML    1.1    # a comment \n
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//      %TAG    !yaml!  tag:yaml.org,2002:  \n
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+func yaml_parser_scan_directive(parser *yaml_parser_t, token *yaml_token_t) bool {
+	// Eat '%'.
+	start_mark := parser.mark
+	skip(parser)
+
+	// Scan the directive name.
+	var name []byte
+	if !yaml_parser_scan_directive_name(parser, start_mark, &name) {
+		return false
+	}
+
+	// Is it a YAML directive?
+	if bytes.Equal(name, []byte("YAML")) {
+		// Scan the VERSION directive value.
+		var major, minor int8
+		if !yaml_parser_scan_version_directive_value(parser, start_mark, &major, &minor) {
+			return false
+		}
+		end_mark := parser.mark
+
+		// Create a VERSION-DIRECTIVE token.
+		*token = yaml_token_t{
+			typ:        yaml_VERSION_DIRECTIVE_TOKEN,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			major:      major,
+			minor:      minor,
+		}
+
+		// Is it a TAG directive?
+	} else if bytes.Equal(name, []byte("TAG")) {
+		// Scan the TAG directive value.
+		var handle, prefix []byte
+		if !yaml_parser_scan_tag_directive_value(parser, start_mark, &handle, &prefix) {
+			return false
+		}
+		end_mark := parser.mark
+
+		// Create a TAG-DIRECTIVE token.
+		*token = yaml_token_t{
+			typ:        yaml_TAG_DIRECTIVE_TOKEN,
+			start_mark: start_mark,
+			end_mark:   end_mark,
+			value:      handle,
+			prefix:     prefix,
+		}
+
+		// Unknown directive.
+	} else {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "found unknown directive name")
+		return false
+	}
+
+	// Eat the rest of the line including any comments.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	if parser.buffer[parser.buffer_pos] == '#' {
+		for !is_breakz(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+	}
+
+	// Check if we are at the end of the line.
+	if !is_breakz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "did not find expected comment or line break")
+		return false
+	}
+
+	// Eat a line break.
+	if is_break(parser.buffer, parser.buffer_pos) {
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		skip_line(parser)
+	}
+
+	return true
+}
+
+// Scan the directive name.
+//
+// Scope:
+//      %YAML   1.1     # a comment \n
+//       ^^^^
+//      %TAG    !yaml!  tag:yaml.org,2002:  \n
+//       ^^^
+//
+func yaml_parser_scan_directive_name(parser *yaml_parser_t, start_mark yaml_mark_t, name *[]byte) bool {
+	// Consume the directive name.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	var s []byte
+	for is_alpha(parser.buffer, parser.buffer_pos) {
+		s = read(parser, s)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	// Check if the name is empty.
+	if len(s) == 0 {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "could not find expected directive name")
+		return false
+	}
+
+	// Check for an blank character after the name.
+	if !is_blankz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a directive",
+			start_mark, "found unexpected non-alphabetical character")
+		return false
+	}
+	*name = s
+	return true
+}
+
+// Scan the value of VERSION-DIRECTIVE.
+//
+// Scope:
+//      %YAML   1.1     # a comment \n
+//           ^^^^^^
+func yaml_parser_scan_version_directive_value(parser *yaml_parser_t, start_mark yaml_mark_t, major, minor *int8) bool {
+	// Eat whitespaces.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	// Consume the major version number.
+	if !yaml_parser_scan_version_directive_number(parser, start_mark, major) {
+		return false
+	}
+
+	// Eat '.'.
+	if parser.buffer[parser.buffer_pos] != '.' {
+		return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+			start_mark, "did not find expected digit or '.' character")
+	}
+
+	skip(parser)
+
+	// Consume the minor version number.
+	if !yaml_parser_scan_version_directive_number(parser, start_mark, minor) {
+		return false
+	}
+	return true
+}
+
+const max_number_length = 2
+
+// Scan the version number of VERSION-DIRECTIVE.
+//
+// Scope:
+//      %YAML   1.1     # a comment \n
+//              ^
+//      %YAML   1.1     # a comment \n
+//                ^
+func yaml_parser_scan_version_directive_number(parser *yaml_parser_t, start_mark yaml_mark_t, number *int8) bool {
+
+	// Repeat while the next character is digit.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	var value, length int8
+	for is_digit(parser.buffer, parser.buffer_pos) {
+		// Check if the number is too long.
+		length++
+		if length > max_number_length {
+			return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+				start_mark, "found extremely long version number")
+		}
+		value = value*10 + int8(as_digit(parser.buffer, parser.buffer_pos))
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	// Check if the number was present.
+	if length == 0 {
+		return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+			start_mark, "did not find expected version number")
+	}
+	*number = value
+	return true
+}
+
+// Scan the value of a TAG-DIRECTIVE token.
+//
+// Scope:
+//      %TAG    !yaml!  tag:yaml.org,2002:  \n
+//          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+func yaml_parser_scan_tag_directive_value(parser *yaml_parser_t, start_mark yaml_mark_t, handle, prefix *[]byte) bool {
+	var handle_value, prefix_value []byte
+
+	// Eat whitespaces.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	// Scan a handle.
+	if !yaml_parser_scan_tag_handle(parser, true, start_mark, &handle_value) {
+		return false
+	}
+
+	// Expect a whitespace.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if !is_blank(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+			start_mark, "did not find expected whitespace")
+		return false
+	}
+
+	// Eat whitespaces.
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	// Scan a prefix.
+	if !yaml_parser_scan_tag_uri(parser, true, nil, start_mark, &prefix_value) {
+		return false
+	}
+
+	// Expect a whitespace or line break.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if !is_blankz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+			start_mark, "did not find expected whitespace or line break")
+		return false
+	}
+
+	*handle = handle_value
+	*prefix = prefix_value
+	return true
+}
+
+func yaml_parser_scan_anchor(parser *yaml_parser_t, token *yaml_token_t, typ yaml_token_type_t) bool {
+	var s []byte
+
+	// Eat the indicator character.
+	start_mark := parser.mark
+	skip(parser)
+
+	// Consume the value.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	for is_alpha(parser.buffer, parser.buffer_pos) {
+		s = read(parser, s)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	end_mark := parser.mark
+
+	/*
+	 * Check if length of the anchor is greater than 0 and it is followed by
+	 * a whitespace character or one of the indicators:
+	 *
+	 *      '?', ':', ',', ']', '}', '%', '@', '`'.
+	 */
+
+	if len(s) == 0 ||
+		!(is_blankz(parser.buffer, parser.buffer_pos) || parser.buffer[parser.buffer_pos] == '?' ||
+			parser.buffer[parser.buffer_pos] == ':' || parser.buffer[parser.buffer_pos] == ',' ||
+			parser.buffer[parser.buffer_pos] == ']' || parser.buffer[parser.buffer_pos] == '}' ||
+			parser.buffer[parser.buffer_pos] == '%' || parser.buffer[parser.buffer_pos] == '@' ||
+			parser.buffer[parser.buffer_pos] == '`') {
+		context := "while scanning an alias"
+		if typ == yaml_ANCHOR_TOKEN {
+			context = "while scanning an anchor"
+		}
+		yaml_parser_set_scanner_error(parser, context, start_mark,
+			"did not find expected alphabetic or numeric character")
+		return false
+	}
+
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        typ,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+	}
+
+	return true
+}
+
+/*
+ * Scan a TAG token.
+ */
+
+func yaml_parser_scan_tag(parser *yaml_parser_t, token *yaml_token_t) bool {
+	var handle, suffix []byte
+
+	start_mark := parser.mark
+
+	// Check if the tag is in the canonical form.
+	if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+		return false
+	}
+
+	if parser.buffer[parser.buffer_pos+1] == '<' {
+		// Keep the handle as ''
+
+		// Eat '!<'
+		skip(parser)
+		skip(parser)
+
+		// Consume the tag value.
+		if !yaml_parser_scan_tag_uri(parser, false, nil, start_mark, &suffix) {
+			return false
+		}
+
+		// Check for '>' and eat it.
+		if parser.buffer[parser.buffer_pos] != '>' {
+			yaml_parser_set_scanner_error(parser, "while scanning a tag",
+				start_mark, "did not find the expected '>'")
+			return false
+		}
+
+		skip(parser)
+	} else {
+		// The tag has either the '!suffix' or the '!handle!suffix' form.
+
+		// First, try to scan a handle.
+		if !yaml_parser_scan_tag_handle(parser, false, start_mark, &handle) {
+			return false
+		}
+
+		// Check if it is, indeed, handle.
+		if handle[0] == '!' && len(handle) > 1 && handle[len(handle)-1] == '!' {
+			// Scan the suffix now.
+			if !yaml_parser_scan_tag_uri(parser, false, nil, start_mark, &suffix) {
+				return false
+			}
+		} else {
+			// It wasn't a handle after all.  Scan the rest of the tag.
+			if !yaml_parser_scan_tag_uri(parser, false, handle, start_mark, &suffix) {
+				return false
+			}
+
+			// Set the handle to '!'.
+			handle = []byte{'!'}
+
+			// A special case: the '!' tag.  Set the handle to '' and the
+			// suffix to '!'.
+			if len(suffix) == 0 {
+				handle, suffix = suffix, handle
+			}
+		}
+	}
+
+	// Check the character which ends the tag.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if !is_blankz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a tag",
+			start_mark, "did not find expected whitespace or line break")
+		return false
+	}
+
+	end_mark := parser.mark
+
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_TAG_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      handle,
+		suffix:     suffix,
+	}
+	return true
+}
+
+// Scan a tag handle.
+func yaml_parser_scan_tag_handle(parser *yaml_parser_t, directive bool, start_mark yaml_mark_t, handle *[]byte) bool {
+	// Check the initial '!' character.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	if parser.buffer[parser.buffer_pos] != '!' {
+		yaml_parser_set_scanner_tag_error(parser, directive,
+			start_mark, "did not find expected '!'")
+		return false
+	}
+
+	var s []byte
+
+	// Copy the '!' character.
+	s = read(parser, s)
+
+	// Copy all subsequent alphabetical and numerical characters.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_alpha(parser.buffer, parser.buffer_pos) {
+		s = read(parser, s)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+
+	// Check if the trailing character is '!' and copy it.
+	if parser.buffer[parser.buffer_pos] == '!' {
+		s = read(parser, s)
+	} else {
+		// It's either the '!' tag or not really a tag handle.  If it's a %TAG
+		// directive, it's an error.  If it's a tag token, it must be a part of URI.
+		if directive && string(s) != "!" {
+			yaml_parser_set_scanner_tag_error(parser, directive,
+				start_mark, "did not find expected '!'")
+			return false
+		}
+	}
+
+	*handle = s
+	return true
+}
+
+// Scan a tag.
+func yaml_parser_scan_tag_uri(parser *yaml_parser_t, directive bool, head []byte, start_mark yaml_mark_t, uri *[]byte) bool {
+	//size_t length = head ? strlen((char *)head) : 0
+	var s []byte
+	hasTag := len(head) > 0
+
+	// Copy the head if needed.
+	//
+	// Note that we don't copy the leading '!' character.
+	if len(head) > 1 {
+		s = append(s, head[1:]...)
+	}
+
+	// Scan the tag.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	// The set of characters that may appear in URI is as follows:
+	//
+	//      '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
+	//      '=', '+', '$', ',', '.', '!', '~', '*', '\'', '(', ')', '[', ']',
+	//      '%'.
+	// [Go] Convert this into more reasonable logic.
+	for is_alpha(parser.buffer, parser.buffer_pos) || parser.buffer[parser.buffer_pos] == ';' ||
+		parser.buffer[parser.buffer_pos] == '/' || parser.buffer[parser.buffer_pos] == '?' ||
+		parser.buffer[parser.buffer_pos] == ':' || parser.buffer[parser.buffer_pos] == '@' ||
+		parser.buffer[parser.buffer_pos] == '&' || parser.buffer[parser.buffer_pos] == '=' ||
+		parser.buffer[parser.buffer_pos] == '+' || parser.buffer[parser.buffer_pos] == '$' ||
+		parser.buffer[parser.buffer_pos] == ',' || parser.buffer[parser.buffer_pos] == '.' ||
+		parser.buffer[parser.buffer_pos] == '!' || parser.buffer[parser.buffer_pos] == '~' ||
+		parser.buffer[parser.buffer_pos] == '*' || parser.buffer[parser.buffer_pos] == '\'' ||
+		parser.buffer[parser.buffer_pos] == '(' || parser.buffer[parser.buffer_pos] == ')' ||
+		parser.buffer[parser.buffer_pos] == '[' || parser.buffer[parser.buffer_pos] == ']' ||
+		parser.buffer[parser.buffer_pos] == '%' {
+		// Check if it is a URI-escape sequence.
+		if parser.buffer[parser.buffer_pos] == '%' {
+			if !yaml_parser_scan_uri_escapes(parser, directive, start_mark, &s) {
+				return false
+			}
+		} else {
+			s = read(parser, s)
+		}
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		hasTag = true
+	}
+
+	if !hasTag {
+		yaml_parser_set_scanner_tag_error(parser, directive,
+			start_mark, "did not find expected tag URI")
+		return false
+	}
+	*uri = s
+	return true
+}
+
+// Decode an URI-escape sequence corresponding to a single UTF-8 character.
+func yaml_parser_scan_uri_escapes(parser *yaml_parser_t, directive bool, start_mark yaml_mark_t, s *[]byte) bool {
+
+	// Decode the required number of characters.
+	w := 1024
+	for w > 0 {
+		// Check for a URI-escaped octet.
+		if parser.unread < 3 && !yaml_parser_update_buffer(parser, 3) {
+			return false
+		}
+
+		if !(parser.buffer[parser.buffer_pos] == '%' &&
+			is_hex(parser.buffer, parser.buffer_pos+1) &&
+			is_hex(parser.buffer, parser.buffer_pos+2)) {
+			return yaml_parser_set_scanner_tag_error(parser, directive,
+				start_mark, "did not find URI escaped octet")
+		}
+
+		// Get the octet.
+		octet := byte((as_hex(parser.buffer, parser.buffer_pos+1) << 4) + as_hex(parser.buffer, parser.buffer_pos+2))
+
+		// If it is the leading octet, determine the length of the UTF-8 sequence.
+		if w == 1024 {
+			w = width(octet)
+			if w == 0 {
+				return yaml_parser_set_scanner_tag_error(parser, directive,
+					start_mark, "found an incorrect leading UTF-8 octet")
+			}
+		} else {
+			// Check if the trailing octet is correct.
+			if octet&0xC0 != 0x80 {
+				return yaml_parser_set_scanner_tag_error(parser, directive,
+					start_mark, "found an incorrect trailing UTF-8 octet")
+			}
+		}
+
+		// Copy the octet and move the pointers.
+		*s = append(*s, octet)
+		skip(parser)
+		skip(parser)
+		skip(parser)
+		w--
+	}
+	return true
+}
+
+// Scan a block scalar.
+func yaml_parser_scan_block_scalar(parser *yaml_parser_t, token *yaml_token_t, literal bool) bool {
+	// Eat the indicator '|' or '>'.
+	start_mark := parser.mark
+	skip(parser)
+
+	// Scan the additional block scalar indicators.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+
+	// Check for a chomping indicator.
+	var chomping, increment int
+	if parser.buffer[parser.buffer_pos] == '+' || parser.buffer[parser.buffer_pos] == '-' {
+		// Set the chomping method and eat the indicator.
+		if parser.buffer[parser.buffer_pos] == '+' {
+			chomping = +1
+		} else {
+			chomping = -1
+		}
+		skip(parser)
+
+		// Check for an indentation indicator.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		if is_digit(parser.buffer, parser.buffer_pos) {
+			// Check that the indentation is greater than 0.
+			if parser.buffer[parser.buffer_pos] == '0' {
+				yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+					start_mark, "found an indentation indicator equal to 0")
+				return false
+			}
+
+			// Get the indentation level and eat the indicator.
+			increment = as_digit(parser.buffer, parser.buffer_pos)
+			skip(parser)
+		}
+
+	} else if is_digit(parser.buffer, parser.buffer_pos) {
+		// Do the same as above, but in the opposite order.
+
+		if parser.buffer[parser.buffer_pos] == '0' {
+			yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+				start_mark, "found an indentation indicator equal to 0")
+			return false
+		}
+		increment = as_digit(parser.buffer, parser.buffer_pos)
+		skip(parser)
+
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		if parser.buffer[parser.buffer_pos] == '+' || parser.buffer[parser.buffer_pos] == '-' {
+			if parser.buffer[parser.buffer_pos] == '+' {
+				chomping = +1
+			} else {
+				chomping = -1
+			}
+			skip(parser)
+		}
+	}
+
+	// Eat whitespaces and comments to the end of the line.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	for is_blank(parser.buffer, parser.buffer_pos) {
+		skip(parser)
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+	}
+	if parser.buffer[parser.buffer_pos] == '#' {
+		for !is_breakz(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+	}
+
+	// Check if we are at the end of the line.
+	if !is_breakz(parser.buffer, parser.buffer_pos) {
+		yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+			start_mark, "did not find expected comment or line break")
+		return false
+	}
+
+	// Eat a line break.
+	if is_break(parser.buffer, parser.buffer_pos) {
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		skip_line(parser)
+	}
+
+	end_mark := parser.mark
+
+	// Set the indentation level if it was specified.
+	var indent int
+	if increment > 0 {
+		if parser.indent >= 0 {
+			indent = parser.indent + increment
+		} else {
+			indent = increment
+		}
+	}
+
+	// Scan the leading line breaks and determine the indentation level if needed.
+	var s, leading_break, trailing_breaks []byte
+	if !yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks, start_mark, &end_mark) {
+		return false
+	}
+
+	// Scan the block scalar content.
+	if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+		return false
+	}
+	var leading_blank, trailing_blank bool
+	for parser.mark.column == indent && !is_z(parser.buffer, parser.buffer_pos) {
+		// We are at the beginning of a non-empty line.
+
+		// Is it a trailing whitespace?
+		trailing_blank = is_blank(parser.buffer, parser.buffer_pos)
+
+		// Check if we need to fold the leading line break.
+		if !literal && !leading_blank && !trailing_blank && len(leading_break) > 0 && leading_break[0] == '\n' {
+			// Do we need to join the lines by space?
+			if len(trailing_breaks) == 0 {
+				s = append(s, ' ')
+			}
+		} else {
+			s = append(s, leading_break...)
+		}
+		leading_break = leading_break[:0]
+
+		// Append the remaining line breaks.
+		s = append(s, trailing_breaks...)
+		trailing_breaks = trailing_breaks[:0]
+
+		// Is it a leading whitespace?
+		leading_blank = is_blank(parser.buffer, parser.buffer_pos)
+
+		// Consume the current line.
+		for !is_breakz(parser.buffer, parser.buffer_pos) {
+			s = read(parser, s)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+
+		// Consume the line break.
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+
+		leading_break = read_line(parser, leading_break)
+
+		// Eat the following indentation spaces and line breaks.
+		if !yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks, start_mark, &end_mark) {
+			return false
+		}
+	}
+
+	// Chomp the tail.
+	if chomping != -1 {
+		s = append(s, leading_break...)
+	}
+	if chomping == 1 {
+		s = append(s, trailing_breaks...)
+	}
+
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_SCALAR_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+		style:      yaml_LITERAL_SCALAR_STYLE,
+	}
+	if !literal {
+		token.style = yaml_FOLDED_SCALAR_STYLE
+	}
+	return true
+}
+
+// Scan indentation spaces and line breaks for a block scalar.  Determine the
+// indentation level if needed.
+func yaml_parser_scan_block_scalar_breaks(parser *yaml_parser_t, indent *int, breaks *[]byte, start_mark yaml_mark_t, end_mark *yaml_mark_t) bool {
+	*end_mark = parser.mark
+
+	// Eat the indentation spaces and line breaks.
+	max_indent := 0
+	for {
+		// Eat the indentation spaces.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+		for (*indent == 0 || parser.mark.column < *indent) && is_space(parser.buffer, parser.buffer_pos) {
+			skip(parser)
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+		if parser.mark.column > max_indent {
+			max_indent = parser.mark.column
+		}
+
+		// Check for a tab character messing the indentation.
+		if (*indent == 0 || parser.mark.column < *indent) && is_tab(parser.buffer, parser.buffer_pos) {
+			return yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+				start_mark, "found a tab character where an indentation space is expected")
+		}
+
+		// Have we found a non-empty line?
+		if !is_break(parser.buffer, parser.buffer_pos) {
+			break
+		}
+
+		// Consume the line break.
+		if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+			return false
+		}
+		// [Go] Should really be returning breaks instead.
+		*breaks = read_line(parser, *breaks)
+		*end_mark = parser.mark
+	}
+
+	// Determine the indentation level if needed.
+	if *indent == 0 {
+		*indent = max_indent
+		if *indent < parser.indent+1 {
+			*indent = parser.indent + 1
+		}
+		if *indent < 1 {
+			*indent = 1
+		}
+	}
+	return true
+}
+
+// Scan a quoted scalar.
+func yaml_parser_scan_flow_scalar(parser *yaml_parser_t, token *yaml_token_t, single bool) bool {
+	// Eat the left quote.
+	start_mark := parser.mark
+	skip(parser)
+
+	// Consume the content of the quoted scalar.
+	var s, leading_break, trailing_breaks, whitespaces []byte
+	for {
+		// Check that there are no document indicators at the beginning of the line.
+		if parser.unread < 4 && !yaml_parser_update_buffer(parser, 4) {
+			return false
+		}
+
+		if parser.mark.column == 0 &&
+			((parser.buffer[parser.buffer_pos+0] == '-' &&
+				parser.buffer[parser.buffer_pos+1] == '-' &&
+				parser.buffer[parser.buffer_pos+2] == '-') ||
+				(parser.buffer[parser.buffer_pos+0] == '.' &&
+					parser.buffer[parser.buffer_pos+1] == '.' &&
+					parser.buffer[parser.buffer_pos+2] == '.')) &&
+			is_blankz(parser.buffer, parser.buffer_pos+3) {
+			yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+				start_mark, "found unexpected document indicator")
+			return false
+		}
+
+		// Check for EOF.
+		if is_z(parser.buffer, parser.buffer_pos) {
+			yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+				start_mark, "found unexpected end of stream")
+			return false
+		}
+
+		// Consume non-blank characters.
+		leading_blanks := false
+		for !is_blankz(parser.buffer, parser.buffer_pos) {
+			if single && parser.buffer[parser.buffer_pos] == '\'' && parser.buffer[parser.buffer_pos+1] == '\'' {
+				// Is is an escaped single quote.
+				s = append(s, '\'')
+				skip(parser)
+				skip(parser)
+
+			} else if single && parser.buffer[parser.buffer_pos] == '\'' {
+				// It is a right single quote.
+				break
+			} else if !single && parser.buffer[parser.buffer_pos] == '"' {
+				// It is a right double quote.
+				break
+
+			} else if !single && parser.buffer[parser.buffer_pos] == '\\' && is_break(parser.buffer, parser.buffer_pos+1) {
+				// It is an escaped line break.
+				if parser.unread < 3 && !yaml_parser_update_buffer(parser, 3) {
+					return false
+				}
+				skip(parser)
+				skip_line(parser)
+				leading_blanks = true
+				break
+
+			} else if !single && parser.buffer[parser.buffer_pos] == '\\' {
+				// It is an escape sequence.
+				code_length := 0
+
+				// Check the escape character.
+				switch parser.buffer[parser.buffer_pos+1] {
+				case '0':
+					s = append(s, 0)
+				case 'a':
+					s = append(s, '\x07')
+				case 'b':
+					s = append(s, '\x08')
+				case 't', '\t':
+					s = append(s, '\x09')
+				case 'n':
+					s = append(s, '\x0A')
+				case 'v':
+					s = append(s, '\x0B')
+				case 'f':
+					s = append(s, '\x0C')
+				case 'r':
+					s = append(s, '\x0D')
+				case 'e':
+					s = append(s, '\x1B')
+				case ' ':
+					s = append(s, '\x20')
+				case '"':
+					s = append(s, '"')
+				case '\'':
+					s = append(s, '\'')
+				case '\\':
+					s = append(s, '\\')
+				case 'N': // NEL (#x85)
+					s = append(s, '\xC2')
+					s = append(s, '\x85')
+				case '_': // #xA0
+					s = append(s, '\xC2')
+					s = append(s, '\xA0')
+				case 'L': // LS (#x2028)
+					s = append(s, '\xE2')
+					s = append(s, '\x80')
+					s = append(s, '\xA8')
+				case 'P': // PS (#x2029)
+					s = append(s, '\xE2')
+					s = append(s, '\x80')
+					s = append(s, '\xA9')
+				case 'x':
+					code_length = 2
+				case 'u':
+					code_length = 4
+				case 'U':
+					code_length = 8
+				default:
+					yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+						start_mark, "found unknown escape character")
+					return false
+				}
+
+				skip(parser)
+				skip(parser)
+
+				// Consume an arbitrary escape code.
+				if code_length > 0 {
+					var value int
+
+					// Scan the character value.
+					if parser.unread < code_length && !yaml_parser_update_buffer(parser, code_length) {
+						return false
+					}
+					for k := 0; k < code_length; k++ {
+						if !is_hex(parser.buffer, parser.buffer_pos+k) {
+							yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+								start_mark, "did not find expected hexdecimal number")
+							return false
+						}
+						value = (value << 4) + as_hex(parser.buffer, parser.buffer_pos+k)
+					}
+
+					// Check the value and write the character.
+					if (value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF {
+						yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+							start_mark, "found invalid Unicode character escape code")
+						return false
+					}
+					if value <= 0x7F {
+						s = append(s, byte(value))
+					} else if value <= 0x7FF {
+						s = append(s, byte(0xC0+(value>>6)))
+						s = append(s, byte(0x80+(value&0x3F)))
+					} else if value <= 0xFFFF {
+						s = append(s, byte(0xE0+(value>>12)))
+						s = append(s, byte(0x80+((value>>6)&0x3F)))
+						s = append(s, byte(0x80+(value&0x3F)))
+					} else {
+						s = append(s, byte(0xF0+(value>>18)))
+						s = append(s, byte(0x80+((value>>12)&0x3F)))
+						s = append(s, byte(0x80+((value>>6)&0x3F)))
+						s = append(s, byte(0x80+(value&0x3F)))
+					}
+
+					// Advance the pointer.
+					for k := 0; k < code_length; k++ {
+						skip(parser)
+					}
+				}
+			} else {
+				// It is a non-escaped non-blank character.
+				s = read(parser, s)
+			}
+			if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+				return false
+			}
+		}
+
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+
+		// Check if we are at the end of the scalar.
+		if single {
+			if parser.buffer[parser.buffer_pos] == '\'' {
+				break
+			}
+		} else {
+			if parser.buffer[parser.buffer_pos] == '"' {
+				break
+			}
+		}
+
+		// Consume blank characters.
+		for is_blank(parser.buffer, parser.buffer_pos) || is_break(parser.buffer, parser.buffer_pos) {
+			if is_blank(parser.buffer, parser.buffer_pos) {
+				// Consume a space or a tab character.
+				if !leading_blanks {
+					whitespaces = read(parser, whitespaces)
+				} else {
+					skip(parser)
+				}
+			} else {
+				if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+					return false
+				}
+
+				// Check if it is a first line break.
+				if !leading_blanks {
+					whitespaces = whitespaces[:0]
+					leading_break = read_line(parser, leading_break)
+					leading_blanks = true
+				} else {
+					trailing_breaks = read_line(parser, trailing_breaks)
+				}
+			}
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+
+		// Join the whitespaces or fold line breaks.
+		if leading_blanks {
+			// Do we need to fold line breaks?
+			if len(leading_break) > 0 && leading_break[0] == '\n' {
+				if len(trailing_breaks) == 0 {
+					s = append(s, ' ')
+				} else {
+					s = append(s, trailing_breaks...)
+				}
+			} else {
+				s = append(s, leading_break...)
+				s = append(s, trailing_breaks...)
+			}
+			trailing_breaks = trailing_breaks[:0]
+			leading_break = leading_break[:0]
+		} else {
+			s = append(s, whitespaces...)
+			whitespaces = whitespaces[:0]
+		}
+	}
+
+	// Eat the right quote.
+	skip(parser)
+	end_mark := parser.mark
+
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_SCALAR_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+		style:      yaml_SINGLE_QUOTED_SCALAR_STYLE,
+	}
+	if !single {
+		token.style = yaml_DOUBLE_QUOTED_SCALAR_STYLE
+	}
+	return true
+}
+
+// Scan a plain scalar.
+func yaml_parser_scan_plain_scalar(parser *yaml_parser_t, token *yaml_token_t) bool {
+
+	var s, leading_break, trailing_breaks, whitespaces []byte
+	var leading_blanks bool
+	var indent = parser.indent + 1
+
+	start_mark := parser.mark
+	end_mark := parser.mark
+
+	// Consume the content of the plain scalar.
+	for {
+		// Check for a document indicator.
+		if parser.unread < 4 && !yaml_parser_update_buffer(parser, 4) {
+			return false
+		}
+		if parser.mark.column == 0 &&
+			((parser.buffer[parser.buffer_pos+0] == '-' &&
+				parser.buffer[parser.buffer_pos+1] == '-' &&
+				parser.buffer[parser.buffer_pos+2] == '-') ||
+				(parser.buffer[parser.buffer_pos+0] == '.' &&
+					parser.buffer[parser.buffer_pos+1] == '.' &&
+					parser.buffer[parser.buffer_pos+2] == '.')) &&
+			is_blankz(parser.buffer, parser.buffer_pos+3) {
+			break
+		}
+
+		// Check for a comment.
+		if parser.buffer[parser.buffer_pos] == '#' {
+			break
+		}
+
+		// Consume non-blank characters.
+		for !is_blankz(parser.buffer, parser.buffer_pos) {
+
+			// Check for indicators that may end a plain scalar.
+			if (parser.buffer[parser.buffer_pos] == ':' && is_blankz(parser.buffer, parser.buffer_pos+1)) ||
+				(parser.flow_level > 0 &&
+					(parser.buffer[parser.buffer_pos] == ',' ||
+						parser.buffer[parser.buffer_pos] == '?' || parser.buffer[parser.buffer_pos] == '[' ||
+						parser.buffer[parser.buffer_pos] == ']' || parser.buffer[parser.buffer_pos] == '{' ||
+						parser.buffer[parser.buffer_pos] == '}')) {
+				break
+			}
+
+			// Check if we need to join whitespaces and breaks.
+			if leading_blanks || len(whitespaces) > 0 {
+				if leading_blanks {
+					// Do we need to fold line breaks?
+					if leading_break[0] == '\n' {
+						if len(trailing_breaks) == 0 {
+							s = append(s, ' ')
+						} else {
+							s = append(s, trailing_breaks...)
+						}
+					} else {
+						s = append(s, leading_break...)
+						s = append(s, trailing_breaks...)
+					}
+					trailing_breaks = trailing_breaks[:0]
+					leading_break = leading_break[:0]
+					leading_blanks = false
+				} else {
+					s = append(s, whitespaces...)
+					whitespaces = whitespaces[:0]
+				}
+			}
+
+			// Copy the character.
+			s = read(parser, s)
+
+			end_mark = parser.mark
+			if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+				return false
+			}
+		}
+
+		// Is it the end?
+		if !(is_blank(parser.buffer, parser.buffer_pos) || is_break(parser.buffer, parser.buffer_pos)) {
+			break
+		}
+
+		// Consume blank characters.
+		if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+			return false
+		}
+
+		for is_blank(parser.buffer, parser.buffer_pos) || is_break(parser.buffer, parser.buffer_pos) {
+			if is_blank(parser.buffer, parser.buffer_pos) {
+
+				// Check for tab characters that abuse indentation.
+				if leading_blanks && parser.mark.column < indent && is_tab(parser.buffer, parser.buffer_pos) {
+					yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+						start_mark, "found a tab character that violates indentation")
+					return false
+				}
+
+				// Consume a space or a tab character.
+				if !leading_blanks {
+					whitespaces = read(parser, whitespaces)
+				} else {
+					skip(parser)
+				}
+			} else {
+				if parser.unread < 2 && !yaml_parser_update_buffer(parser, 2) {
+					return false
+				}
+
+				// Check if it is a first line break.
+				if !leading_blanks {
+					whitespaces = whitespaces[:0]
+					leading_break = read_line(parser, leading_break)
+					leading_blanks = true
+				} else {
+					trailing_breaks = read_line(parser, trailing_breaks)
+				}
+			}
+			if parser.unread < 1 && !yaml_parser_update_buffer(parser, 1) {
+				return false
+			}
+		}
+
+		// Check indentation level.
+		if parser.flow_level == 0 && parser.mark.column < indent {
+			break
+		}
+	}
+
+	// Create a token.
+	*token = yaml_token_t{
+		typ:        yaml_SCALAR_TOKEN,
+		start_mark: start_mark,
+		end_mark:   end_mark,
+		value:      s,
+		style:      yaml_PLAIN_SCALAR_STYLE,
+	}
+
+	// Note that we change the 'simple_key_allowed' flag.
+	if leading_blanks {
+		parser.simple_key_allowed = true
+	}
+	return true
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/sorter.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/sorter.go
new file mode 100644
index 00000000000..4c45e660a8f
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/sorter.go
@@ -0,0 +1,113 @@
+package yaml
+
+import (
+	"reflect"
+	"unicode"
+)
+
+type keyList []reflect.Value
+
+func (l keyList) Len() int      { return len(l) }
+func (l keyList) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
+func (l keyList) Less(i, j int) bool {
+	a := l[i]
+	b := l[j]
+	ak := a.Kind()
+	bk := b.Kind()
+	for (ak == reflect.Interface || ak == reflect.Ptr) && !a.IsNil() {
+		a = a.Elem()
+		ak = a.Kind()
+	}
+	for (bk == reflect.Interface || bk == reflect.Ptr) && !b.IsNil() {
+		b = b.Elem()
+		bk = b.Kind()
+	}
+	af, aok := keyFloat(a)
+	bf, bok := keyFloat(b)
+	if aok && bok {
+		if af != bf {
+			return af < bf
+		}
+		if ak != bk {
+			return ak < bk
+		}
+		return numLess(a, b)
+	}
+	if ak != reflect.String || bk != reflect.String {
+		return ak < bk
+	}
+	ar, br := []rune(a.String()), []rune(b.String())
+	for i := 0; i < len(ar) && i < len(br); i++ {
+		if ar[i] == br[i] {
+			continue
+		}
+		al := unicode.IsLetter(ar[i])
+		bl := unicode.IsLetter(br[i])
+		if al && bl {
+			return ar[i] < br[i]
+		}
+		if al || bl {
+			return bl
+		}
+		var ai, bi int
+		var an, bn int64
+		if ar[i] == '0' || br[i] == '0' {
+			for j := i-1; j >= 0 && unicode.IsDigit(ar[j]); j-- {
+				if ar[j] != '0' {
+					an = 1
+					bn = 1
+					break
+				}
+			}
+		}
+		for ai = i; ai < len(ar) && unicode.IsDigit(ar[ai]); ai++ {
+			an = an*10 + int64(ar[ai]-'0')
+		}
+		for bi = i; bi < len(br) && unicode.IsDigit(br[bi]); bi++ {
+			bn = bn*10 + int64(br[bi]-'0')
+		}
+		if an != bn {
+			return an < bn
+		}
+		if ai != bi {
+			return ai < bi
+		}
+		return ar[i] < br[i]
+	}
+	return len(ar) < len(br)
+}
+
+// keyFloat returns a float value for v if it is a number/bool
+// and whether it is a number/bool or not.
+func keyFloat(v reflect.Value) (f float64, ok bool) {
+	switch v.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return float64(v.Int()), true
+	case reflect.Float32, reflect.Float64:
+		return v.Float(), true
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return float64(v.Uint()), true
+	case reflect.Bool:
+		if v.Bool() {
+			return 1, true
+		}
+		return 0, true
+	}
+	return 0, false
+}
+
+// numLess returns whether a < b.
+// a and b must necessarily have the same kind.
+func numLess(a, b reflect.Value) bool {
+	switch a.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return a.Int() < b.Int()
+	case reflect.Float32, reflect.Float64:
+		return a.Float() < b.Float()
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return a.Uint() < b.Uint()
+	case reflect.Bool:
+		return !a.Bool() && b.Bool()
+	}
+	panic("not a number")
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/suite_test.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/suite_test.go
new file mode 100644
index 00000000000..c5cf1ed4f6e
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/suite_test.go
@@ -0,0 +1,12 @@
+package yaml_test
+
+import (
+	. "gopkg.in/check.v1"
+	"testing"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type S struct{}
+
+var _ = Suite(&S{})
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/writerc.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/writerc.go
new file mode 100644
index 00000000000..a2dde608cb7
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/writerc.go
@@ -0,0 +1,26 @@
+package yaml
+
+// Set the writer error and return false.
+func yaml_emitter_set_writer_error(emitter *yaml_emitter_t, problem string) bool {
+	emitter.error = yaml_WRITER_ERROR
+	emitter.problem = problem
+	return false
+}
+
+// Flush the output buffer.
+func yaml_emitter_flush(emitter *yaml_emitter_t) bool {
+	if emitter.write_handler == nil {
+		panic("write handler not set")
+	}
+
+	// Check if the buffer is empty.
+	if emitter.buffer_pos == 0 {
+		return true
+	}
+
+	if err := emitter.write_handler(emitter, emitter.buffer[:emitter.buffer_pos]); err != nil {
+		return yaml_emitter_set_writer_error(emitter, "write error: "+err.Error())
+	}
+	emitter.buffer_pos = 0
+	return true
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yaml.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yaml.go
new file mode 100644
index 00000000000..89650e293ac
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yaml.go
@@ -0,0 +1,466 @@
+// Package yaml implements YAML support for the Go language.
+//
+// Source code and other details for the project are available at GitHub:
+//
+//   https://github.com/go-yaml/yaml
+//
+package yaml
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"reflect"
+	"strings"
+	"sync"
+)
+
+// MapSlice encodes and decodes as a YAML map.
+// The order of keys is preserved when encoding and decoding.
+type MapSlice []MapItem
+
+// MapItem is an item in a MapSlice.
+type MapItem struct {
+	Key, Value interface{}
+}
+
+// The Unmarshaler interface may be implemented by types to customize their
+// behavior when being unmarshaled from a YAML document. The UnmarshalYAML
+// method receives a function that may be called to unmarshal the original
+// YAML value into a field or variable. It is safe to call the unmarshal
+// function parameter more than once if necessary.
+type Unmarshaler interface {
+	UnmarshalYAML(unmarshal func(interface{}) error) error
+}
+
+// The Marshaler interface may be implemented by types to customize their
+// behavior when being marshaled into a YAML document. The returned value
+// is marshaled in place of the original value implementing Marshaler.
+//
+// If an error is returned by MarshalYAML, the marshaling procedure stops
+// and returns with the provided error.
+type Marshaler interface {
+	MarshalYAML() (interface{}, error)
+}
+
+// Unmarshal decodes the first document found within the in byte slice
+// and assigns decoded values into the out value.
+//
+// Maps and pointers (to a struct, string, int, etc) are accepted as out
+// values. If an internal pointer within a struct is not initialized,
+// the yaml package will initialize it if necessary for unmarshalling
+// the provided data. The out parameter must not be nil.
+//
+// The type of the decoded values should be compatible with the respective
+// values in out. If one or more values cannot be decoded due to a type
+// mismatches, decoding continues partially until the end of the YAML
+// content, and a *yaml.TypeError is returned with details for all
+// missed values.
+//
+// Struct fields are only unmarshalled if they are exported (have an
+// upper case first letter), and are unmarshalled using the field name
+// lowercased as the default key. Custom keys may be defined via the
+// "yaml" name in the field tag: the content preceding the first comma
+// is used as the key, and the following comma-separated options are
+// used to tweak the marshalling process (see Marshal).
+// Conflicting names result in a runtime error.
+//
+// For example:
+//
+//     type T struct {
+//         F int `yaml:"a,omitempty"`
+//         B int
+//     }
+//     var t T
+//     yaml.Unmarshal([]byte("a: 1\nb: 2"), &t)
+//
+// See the documentation of Marshal for the format of tags and a list of
+// supported tag options.
+//
+func Unmarshal(in []byte, out interface{}) (err error) {
+	return unmarshal(in, out, false)
+}
+
+// UnmarshalStrict is like Unmarshal except that any fields that are found
+// in the data that do not have corresponding struct members, or mapping
+// keys that are duplicates, will result in
+// an error.
+func UnmarshalStrict(in []byte, out interface{}) (err error) {
+	return unmarshal(in, out, true)
+}
+
+// A Decoder reads and decodes YAML values from an input stream.
+type Decoder struct {
+	strict bool
+	parser *parser
+}
+
+// NewDecoder returns a new decoder that reads from r.
+//
+// The decoder introduces its own buffering and may read
+// data from r beyond the YAML values requested.
+func NewDecoder(r io.Reader) *Decoder {
+	return &Decoder{
+		parser: newParserFromReader(r),
+	}
+}
+
+// SetStrict sets whether strict decoding behaviour is enabled when
+// decoding items in the data (see UnmarshalStrict). By default, decoding is not strict.
+func (dec *Decoder) SetStrict(strict bool) {
+	dec.strict = strict
+}
+
+// Decode reads the next YAML-encoded value from its input
+// and stores it in the value pointed to by v.
+//
+// See the documentation for Unmarshal for details about the
+// conversion of YAML into a Go value.
+func (dec *Decoder) Decode(v interface{}) (err error) {
+	d := newDecoder(dec.strict)
+	defer handleErr(&err)
+	node := dec.parser.parse()
+	if node == nil {
+		return io.EOF
+	}
+	out := reflect.ValueOf(v)
+	if out.Kind() == reflect.Ptr && !out.IsNil() {
+		out = out.Elem()
+	}
+	d.unmarshal(node, out)
+	if len(d.terrors) > 0 {
+		return &TypeError{d.terrors}
+	}
+	return nil
+}
+
+func unmarshal(in []byte, out interface{}, strict bool) (err error) {
+	defer handleErr(&err)
+	d := newDecoder(strict)
+	p := newParser(in)
+	defer p.destroy()
+	node := p.parse()
+	if node != nil {
+		v := reflect.ValueOf(out)
+		if v.Kind() == reflect.Ptr && !v.IsNil() {
+			v = v.Elem()
+		}
+		d.unmarshal(node, v)
+	}
+	if len(d.terrors) > 0 {
+		return &TypeError{d.terrors}
+	}
+	return nil
+}
+
+// Marshal serializes the value provided into a YAML document. The structure
+// of the generated document will reflect the structure of the value itself.
+// Maps and pointers (to struct, string, int, etc) are accepted as the in value.
+//
+// Struct fields are only marshalled if they are exported (have an upper case
+// first letter), and are marshalled using the field name lowercased as the
+// default key. Custom keys may be defined via the "yaml" name in the field
+// tag: the content preceding the first comma is used as the key, and the
+// following comma-separated options are used to tweak the marshalling process.
+// Conflicting names result in a runtime error.
+//
+// The field tag format accepted is:
+//
+//     `(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)`
+//
+// The following flags are currently supported:
+//
+//     omitempty    Only include the field if it's not set to the zero
+//                  value for the type or to empty slices or maps.
+//                  Zero valued structs will be omitted if all their public
+//                  fields are zero, unless they implement an IsZero
+//                  method (see the IsZeroer interface type), in which
+//                  case the field will be included if that method returns true.
+//
+//     flow         Marshal using a flow style (useful for structs,
+//                  sequences and maps).
+//
+//     inline       Inline the field, which must be a struct or a map,
+//                  causing all of its fields or keys to be processed as if
+//                  they were part of the outer struct. For maps, keys must
+//                  not conflict with the yaml keys of other struct fields.
+//
+// In addition, if the key is "-", the field is ignored.
+//
+// For example:
+//
+//     type T struct {
+//         F int `yaml:"a,omitempty"`
+//         B int
+//     }
+//     yaml.Marshal(&T{B: 2}) // Returns "b: 2\n"
+//     yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n"
+//
+func Marshal(in interface{}) (out []byte, err error) {
+	defer handleErr(&err)
+	e := newEncoder()
+	defer e.destroy()
+	e.marshalDoc("", reflect.ValueOf(in))
+	e.finish()
+	out = e.out
+	return
+}
+
+// An Encoder writes YAML values to an output stream.
+type Encoder struct {
+	encoder *encoder
+}
+
+// NewEncoder returns a new encoder that writes to w.
+// The Encoder should be closed after use to flush all data
+// to w.
+func NewEncoder(w io.Writer) *Encoder {
+	return &Encoder{
+		encoder: newEncoderWithWriter(w),
+	}
+}
+
+// Encode writes the YAML encoding of v to the stream.
+// If multiple items are encoded to the stream, the
+// second and subsequent document will be preceded
+// with a "---" document separator, but the first will not.
+//
+// See the documentation for Marshal for details about the conversion of Go
+// values to YAML.
+func (e *Encoder) Encode(v interface{}) (err error) {
+	defer handleErr(&err)
+	e.encoder.marshalDoc("", reflect.ValueOf(v))
+	return nil
+}
+
+// Close closes the encoder by writing any remaining data.
+// It does not write a stream terminating string "...".
+func (e *Encoder) Close() (err error) {
+	defer handleErr(&err)
+	e.encoder.finish()
+	return nil
+}
+
+func handleErr(err *error) {
+	if v := recover(); v != nil {
+		if e, ok := v.(yamlError); ok {
+			*err = e.err
+		} else {
+			panic(v)
+		}
+	}
+}
+
+type yamlError struct {
+	err error
+}
+
+func fail(err error) {
+	panic(yamlError{err})
+}
+
+func failf(format string, args ...interface{}) {
+	panic(yamlError{fmt.Errorf("yaml: "+format, args...)})
+}
+
+// A TypeError is returned by Unmarshal when one or more fields in
+// the YAML document cannot be properly decoded into the requested
+// types. When this error is returned, the value is still
+// unmarshaled partially.
+type TypeError struct {
+	Errors []string
+}
+
+func (e *TypeError) Error() string {
+	return fmt.Sprintf("yaml: unmarshal errors:\n  %s", strings.Join(e.Errors, "\n  "))
+}
+
+// --------------------------------------------------------------------------
+// Maintain a mapping of keys to structure field indexes
+
+// The code in this section was copied from mgo/bson.
+
+// structInfo holds details for the serialization of fields of
+// a given struct.
+type structInfo struct {
+	FieldsMap  map[string]fieldInfo
+	FieldsList []fieldInfo
+
+	// InlineMap is the number of the field in the struct that
+	// contains an ,inline map, or -1 if there's none.
+	InlineMap int
+}
+
+type fieldInfo struct {
+	Key       string
+	Num       int
+	OmitEmpty bool
+	Flow      bool
+	// Id holds the unique field identifier, so we can cheaply
+	// check for field duplicates without maintaining an extra map.
+	Id int
+
+	// Inline holds the field index if the field is part of an inlined struct.
+	Inline []int
+}
+
+var structMap = make(map[reflect.Type]*structInfo)
+var fieldMapMutex sync.RWMutex
+
+func getStructInfo(st reflect.Type) (*structInfo, error) {
+	fieldMapMutex.RLock()
+	sinfo, found := structMap[st]
+	fieldMapMutex.RUnlock()
+	if found {
+		return sinfo, nil
+	}
+
+	n := st.NumField()
+	fieldsMap := make(map[string]fieldInfo)
+	fieldsList := make([]fieldInfo, 0, n)
+	inlineMap := -1
+	for i := 0; i != n; i++ {
+		field := st.Field(i)
+		if field.PkgPath != "" && !field.Anonymous {
+			continue // Private field
+		}
+
+		info := fieldInfo{Num: i}
+
+		tag := field.Tag.Get("yaml")
+		if tag == "" && strings.Index(string(field.Tag), ":") < 0 {
+			tag = string(field.Tag)
+		}
+		if tag == "-" {
+			continue
+		}
+
+		inline := false
+		fields := strings.Split(tag, ",")
+		if len(fields) > 1 {
+			for _, flag := range fields[1:] {
+				switch flag {
+				case "omitempty":
+					info.OmitEmpty = true
+				case "flow":
+					info.Flow = true
+				case "inline":
+					inline = true
+				default:
+					return nil, errors.New(fmt.Sprintf("Unsupported flag %q in tag %q of type %s", flag, tag, st))
+				}
+			}
+			tag = fields[0]
+		}
+
+		if inline {
+			switch field.Type.Kind() {
+			case reflect.Map:
+				if inlineMap >= 0 {
+					return nil, errors.New("Multiple ,inline maps in struct " + st.String())
+				}
+				if field.Type.Key() != reflect.TypeOf("") {
+					return nil, errors.New("Option ,inline needs a map with string keys in struct " + st.String())
+				}
+				inlineMap = info.Num
+			case reflect.Struct:
+				sinfo, err := getStructInfo(field.Type)
+				if err != nil {
+					return nil, err
+				}
+				for _, finfo := range sinfo.FieldsList {
+					if _, found := fieldsMap[finfo.Key]; found {
+						msg := "Duplicated key '" + finfo.Key + "' in struct " + st.String()
+						return nil, errors.New(msg)
+					}
+					if finfo.Inline == nil {
+						finfo.Inline = []int{i, finfo.Num}
+					} else {
+						finfo.Inline = append([]int{i}, finfo.Inline...)
+					}
+					finfo.Id = len(fieldsList)
+					fieldsMap[finfo.Key] = finfo
+					fieldsList = append(fieldsList, finfo)
+				}
+			default:
+				//return nil, errors.New("Option ,inline needs a struct value or map field")
+				return nil, errors.New("Option ,inline needs a struct value field")
+			}
+			continue
+		}
+
+		if tag != "" {
+			info.Key = tag
+		} else {
+			info.Key = strings.ToLower(field.Name)
+		}
+
+		if _, found = fieldsMap[info.Key]; found {
+			msg := "Duplicated key '" + info.Key + "' in struct " + st.String()
+			return nil, errors.New(msg)
+		}
+
+		info.Id = len(fieldsList)
+		fieldsList = append(fieldsList, info)
+		fieldsMap[info.Key] = info
+	}
+
+	sinfo = &structInfo{
+		FieldsMap:  fieldsMap,
+		FieldsList: fieldsList,
+		InlineMap:  inlineMap,
+	}
+
+	fieldMapMutex.Lock()
+	structMap[st] = sinfo
+	fieldMapMutex.Unlock()
+	return sinfo, nil
+}
+
+// IsZeroer is used to check whether an object is zero to
+// determine whether it should be omitted when marshaling
+// with the omitempty flag. One notable implementation
+// is time.Time.
+type IsZeroer interface {
+	IsZero() bool
+}
+
+func isZero(v reflect.Value) bool {
+	kind := v.Kind()
+	if z, ok := v.Interface().(IsZeroer); ok {
+		if (kind == reflect.Ptr || kind == reflect.Interface) && v.IsNil() {
+			return true
+		}
+		return z.IsZero()
+	}
+	switch kind {
+	case reflect.String:
+		return len(v.String()) == 0
+	case reflect.Interface, reflect.Ptr:
+		return v.IsNil()
+	case reflect.Slice:
+		return v.Len() == 0
+	case reflect.Map:
+		return v.Len() == 0
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return v.Int() == 0
+	case reflect.Float32, reflect.Float64:
+		return v.Float() == 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return v.Uint() == 0
+	case reflect.Bool:
+		return !v.Bool()
+	case reflect.Struct:
+		vt := v.Type()
+		for i := v.NumField() - 1; i >= 0; i-- {
+			if vt.Field(i).PkgPath != "" {
+				continue // Private field
+			}
+			if !isZero(v.Field(i)) {
+				return false
+			}
+		}
+		return true
+	}
+	return false
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yamlh.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yamlh.go
new file mode 100644
index 00000000000..f6a9c8e34b1
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yamlh.go
@@ -0,0 +1,739 @@
+package yaml
+
+import (
+	"fmt"
+	"io"
+)
+
+// The version directive data.
+type yaml_version_directive_t struct {
+	major int8 // The major version number.
+	minor int8 // The minor version number.
+}
+
+// The tag directive data.
+type yaml_tag_directive_t struct {
+	handle []byte // The tag handle.
+	prefix []byte // The tag prefix.
+}
+
+type yaml_encoding_t int
+
+// The stream encoding.
+const (
+	// Let the parser choose the encoding.
+	yaml_ANY_ENCODING yaml_encoding_t = iota
+
+	yaml_UTF8_ENCODING    // The default UTF-8 encoding.
+	yaml_UTF16LE_ENCODING // The UTF-16-LE encoding with BOM.
+	yaml_UTF16BE_ENCODING // The UTF-16-BE encoding with BOM.
+)
+
+type yaml_break_t int
+
+// Line break types.
+const (
+	// Let the parser choose the break type.
+	yaml_ANY_BREAK yaml_break_t = iota
+
+	yaml_CR_BREAK   // Use CR for line breaks (Mac style).
+	yaml_LN_BREAK   // Use LN for line breaks (Unix style).
+	yaml_CRLN_BREAK // Use CR LN for line breaks (DOS style).
+)
+
+type yaml_error_type_t int
+
+// Many bad things could happen with the parser and emitter.
+const (
+	// No error is produced.
+	yaml_NO_ERROR yaml_error_type_t = iota
+
+	yaml_MEMORY_ERROR   // Cannot allocate or reallocate a block of memory.
+	yaml_READER_ERROR   // Cannot read or decode the input stream.
+	yaml_SCANNER_ERROR  // Cannot scan the input stream.
+	yaml_PARSER_ERROR   // Cannot parse the input stream.
+	yaml_COMPOSER_ERROR // Cannot compose a YAML document.
+	yaml_WRITER_ERROR   // Cannot write to the output stream.
+	yaml_EMITTER_ERROR  // Cannot emit a YAML stream.
+)
+
+// The pointer position.
+type yaml_mark_t struct {
+	index  int // The position index.
+	line   int // The position line.
+	column int // The position column.
+}
+
+// Node Styles
+
+type yaml_style_t int8
+
+type yaml_scalar_style_t yaml_style_t
+
+// Scalar styles.
+const (
+	// Let the emitter choose the style.
+	yaml_ANY_SCALAR_STYLE yaml_scalar_style_t = iota
+
+	yaml_PLAIN_SCALAR_STYLE         // The plain scalar style.
+	yaml_SINGLE_QUOTED_SCALAR_STYLE // The single-quoted scalar style.
+	yaml_DOUBLE_QUOTED_SCALAR_STYLE // The double-quoted scalar style.
+	yaml_LITERAL_SCALAR_STYLE       // The literal scalar style.
+	yaml_FOLDED_SCALAR_STYLE        // The folded scalar style.
+)
+
+type yaml_sequence_style_t yaml_style_t
+
+// Sequence styles.
+const (
+	// Let the emitter choose the style.
+	yaml_ANY_SEQUENCE_STYLE yaml_sequence_style_t = iota
+
+	yaml_BLOCK_SEQUENCE_STYLE // The block sequence style.
+	yaml_FLOW_SEQUENCE_STYLE  // The flow sequence style.
+)
+
+type yaml_mapping_style_t yaml_style_t
+
+// Mapping styles.
+const (
+	// Let the emitter choose the style.
+	yaml_ANY_MAPPING_STYLE yaml_mapping_style_t = iota
+
+	yaml_BLOCK_MAPPING_STYLE // The block mapping style.
+	yaml_FLOW_MAPPING_STYLE  // The flow mapping style.
+)
+
+// Tokens
+
+type yaml_token_type_t int
+
+// Token types.
+const (
+	// An empty token.
+	yaml_NO_TOKEN yaml_token_type_t = iota
+
+	yaml_STREAM_START_TOKEN // A STREAM-START token.
+	yaml_STREAM_END_TOKEN   // A STREAM-END token.
+
+	yaml_VERSION_DIRECTIVE_TOKEN // A VERSION-DIRECTIVE token.
+	yaml_TAG_DIRECTIVE_TOKEN     // A TAG-DIRECTIVE token.
+	yaml_DOCUMENT_START_TOKEN    // A DOCUMENT-START token.
+	yaml_DOCUMENT_END_TOKEN      // A DOCUMENT-END token.
+
+	yaml_BLOCK_SEQUENCE_START_TOKEN // A BLOCK-SEQUENCE-START token.
+	yaml_BLOCK_MAPPING_START_TOKEN  // A BLOCK-SEQUENCE-END token.
+	yaml_BLOCK_END_TOKEN            // A BLOCK-END token.
+
+	yaml_FLOW_SEQUENCE_START_TOKEN // A FLOW-SEQUENCE-START token.
+	yaml_FLOW_SEQUENCE_END_TOKEN   // A FLOW-SEQUENCE-END token.
+	yaml_FLOW_MAPPING_START_TOKEN  // A FLOW-MAPPING-START token.
+	yaml_FLOW_MAPPING_END_TOKEN    // A FLOW-MAPPING-END token.
+
+	yaml_BLOCK_ENTRY_TOKEN // A BLOCK-ENTRY token.
+	yaml_FLOW_ENTRY_TOKEN  // A FLOW-ENTRY token.
+	yaml_KEY_TOKEN         // A KEY token.
+	yaml_VALUE_TOKEN       // A VALUE token.
+
+	yaml_ALIAS_TOKEN  // An ALIAS token.
+	yaml_ANCHOR_TOKEN // An ANCHOR token.
+	yaml_TAG_TOKEN    // A TAG token.
+	yaml_SCALAR_TOKEN // A SCALAR token.
+)
+
+func (tt yaml_token_type_t) String() string {
+	switch tt {
+	case yaml_NO_TOKEN:
+		return "yaml_NO_TOKEN"
+	case yaml_STREAM_START_TOKEN:
+		return "yaml_STREAM_START_TOKEN"
+	case yaml_STREAM_END_TOKEN:
+		return "yaml_STREAM_END_TOKEN"
+	case yaml_VERSION_DIRECTIVE_TOKEN:
+		return "yaml_VERSION_DIRECTIVE_TOKEN"
+	case yaml_TAG_DIRECTIVE_TOKEN:
+		return "yaml_TAG_DIRECTIVE_TOKEN"
+	case yaml_DOCUMENT_START_TOKEN:
+		return "yaml_DOCUMENT_START_TOKEN"
+	case yaml_DOCUMENT_END_TOKEN:
+		return "yaml_DOCUMENT_END_TOKEN"
+	case yaml_BLOCK_SEQUENCE_START_TOKEN:
+		return "yaml_BLOCK_SEQUENCE_START_TOKEN"
+	case yaml_BLOCK_MAPPING_START_TOKEN:
+		return "yaml_BLOCK_MAPPING_START_TOKEN"
+	case yaml_BLOCK_END_TOKEN:
+		return "yaml_BLOCK_END_TOKEN"
+	case yaml_FLOW_SEQUENCE_START_TOKEN:
+		return "yaml_FLOW_SEQUENCE_START_TOKEN"
+	case yaml_FLOW_SEQUENCE_END_TOKEN:
+		return "yaml_FLOW_SEQUENCE_END_TOKEN"
+	case yaml_FLOW_MAPPING_START_TOKEN:
+		return "yaml_FLOW_MAPPING_START_TOKEN"
+	case yaml_FLOW_MAPPING_END_TOKEN:
+		return "yaml_FLOW_MAPPING_END_TOKEN"
+	case yaml_BLOCK_ENTRY_TOKEN:
+		return "yaml_BLOCK_ENTRY_TOKEN"
+	case yaml_FLOW_ENTRY_TOKEN:
+		return "yaml_FLOW_ENTRY_TOKEN"
+	case yaml_KEY_TOKEN:
+		return "yaml_KEY_TOKEN"
+	case yaml_VALUE_TOKEN:
+		return "yaml_VALUE_TOKEN"
+	case yaml_ALIAS_TOKEN:
+		return "yaml_ALIAS_TOKEN"
+	case yaml_ANCHOR_TOKEN:
+		return "yaml_ANCHOR_TOKEN"
+	case yaml_TAG_TOKEN:
+		return "yaml_TAG_TOKEN"
+	case yaml_SCALAR_TOKEN:
+		return "yaml_SCALAR_TOKEN"
+	}
+	return "<unknown token>"
+}
+
+// The token structure.
+type yaml_token_t struct {
+	// The token type.
+	typ yaml_token_type_t
+
+	// The start/end of the token.
+	start_mark, end_mark yaml_mark_t
+
+	// The stream encoding (for yaml_STREAM_START_TOKEN).
+	encoding yaml_encoding_t
+
+	// The alias/anchor/scalar value or tag/tag directive handle
+	// (for yaml_ALIAS_TOKEN, yaml_ANCHOR_TOKEN, yaml_SCALAR_TOKEN, yaml_TAG_TOKEN, yaml_TAG_DIRECTIVE_TOKEN).
+	value []byte
+
+	// The tag suffix (for yaml_TAG_TOKEN).
+	suffix []byte
+
+	// The tag directive prefix (for yaml_TAG_DIRECTIVE_TOKEN).
+	prefix []byte
+
+	// The scalar style (for yaml_SCALAR_TOKEN).
+	style yaml_scalar_style_t
+
+	// The version directive major/minor (for yaml_VERSION_DIRECTIVE_TOKEN).
+	major, minor int8
+}
+
+// Events
+
+type yaml_event_type_t int8
+
+// Event types.
+const (
+	// An empty event.
+	yaml_NO_EVENT yaml_event_type_t = iota
+
+	yaml_STREAM_START_EVENT   // A STREAM-START event.
+	yaml_STREAM_END_EVENT     // A STREAM-END event.
+	yaml_DOCUMENT_START_EVENT // A DOCUMENT-START event.
+	yaml_DOCUMENT_END_EVENT   // A DOCUMENT-END event.
+	yaml_ALIAS_EVENT          // An ALIAS event.
+	yaml_SCALAR_EVENT         // A SCALAR event.
+	yaml_SEQUENCE_START_EVENT // A SEQUENCE-START event.
+	yaml_SEQUENCE_END_EVENT   // A SEQUENCE-END event.
+	yaml_MAPPING_START_EVENT  // A MAPPING-START event.
+	yaml_MAPPING_END_EVENT    // A MAPPING-END event.
+)
+
+var eventStrings = []string{
+	yaml_NO_EVENT:             "none",
+	yaml_STREAM_START_EVENT:   "stream start",
+	yaml_STREAM_END_EVENT:     "stream end",
+	yaml_DOCUMENT_START_EVENT: "document start",
+	yaml_DOCUMENT_END_EVENT:   "document end",
+	yaml_ALIAS_EVENT:          "alias",
+	yaml_SCALAR_EVENT:         "scalar",
+	yaml_SEQUENCE_START_EVENT: "sequence start",
+	yaml_SEQUENCE_END_EVENT:   "sequence end",
+	yaml_MAPPING_START_EVENT:  "mapping start",
+	yaml_MAPPING_END_EVENT:    "mapping end",
+}
+
+func (e yaml_event_type_t) String() string {
+	if e < 0 || int(e) >= len(eventStrings) {
+		return fmt.Sprintf("unknown event %d", e)
+	}
+	return eventStrings[e]
+}
+
+// The event structure.
+type yaml_event_t struct {
+
+	// The event type.
+	typ yaml_event_type_t
+
+	// The start and end of the event.
+	start_mark, end_mark yaml_mark_t
+
+	// The document encoding (for yaml_STREAM_START_EVENT).
+	encoding yaml_encoding_t
+
+	// The version directive (for yaml_DOCUMENT_START_EVENT).
+	version_directive *yaml_version_directive_t
+
+	// The list of tag directives (for yaml_DOCUMENT_START_EVENT).
+	tag_directives []yaml_tag_directive_t
+
+	// The anchor (for yaml_SCALAR_EVENT, yaml_SEQUENCE_START_EVENT, yaml_MAPPING_START_EVENT, yaml_ALIAS_EVENT).
+	anchor []byte
+
+	// The tag (for yaml_SCALAR_EVENT, yaml_SEQUENCE_START_EVENT, yaml_MAPPING_START_EVENT).
+	tag []byte
+
+	// The scalar value (for yaml_SCALAR_EVENT).
+	value []byte
+
+	// Is the document start/end indicator implicit, or the tag optional?
+	// (for yaml_DOCUMENT_START_EVENT, yaml_DOCUMENT_END_EVENT, yaml_SEQUENCE_START_EVENT, yaml_MAPPING_START_EVENT, yaml_SCALAR_EVENT).
+	implicit bool
+
+	// Is the tag optional for any non-plain style? (for yaml_SCALAR_EVENT).
+	quoted_implicit bool
+
+	// The style (for yaml_SCALAR_EVENT, yaml_SEQUENCE_START_EVENT, yaml_MAPPING_START_EVENT).
+	style yaml_style_t
+}
+
+func (e *yaml_event_t) scalar_style() yaml_scalar_style_t     { return yaml_scalar_style_t(e.style) }
+func (e *yaml_event_t) sequence_style() yaml_sequence_style_t { return yaml_sequence_style_t(e.style) }
+func (e *yaml_event_t) mapping_style() yaml_mapping_style_t   { return yaml_mapping_style_t(e.style) }
+
+// Nodes
+
+const (
+	yaml_NULL_TAG      = "tag:yaml.org,2002:null"      // The tag !!null with the only possible value: null.
+	yaml_BOOL_TAG      = "tag:yaml.org,2002:bool"      // The tag !!bool with the values: true and false.
+	yaml_STR_TAG       = "tag:yaml.org,2002:str"       // The tag !!str for string values.
+	yaml_INT_TAG       = "tag:yaml.org,2002:int"       // The tag !!int for integer values.
+	yaml_FLOAT_TAG     = "tag:yaml.org,2002:float"     // The tag !!float for float values.
+	yaml_TIMESTAMP_TAG = "tag:yaml.org,2002:timestamp" // The tag !!timestamp for date and time values.
+
+	yaml_SEQ_TAG = "tag:yaml.org,2002:seq" // The tag !!seq is used to denote sequences.
+	yaml_MAP_TAG = "tag:yaml.org,2002:map" // The tag !!map is used to denote mapping.
+
+	// Not in original libyaml.
+	yaml_BINARY_TAG = "tag:yaml.org,2002:binary"
+	yaml_MERGE_TAG  = "tag:yaml.org,2002:merge"
+
+	yaml_DEFAULT_SCALAR_TAG   = yaml_STR_TAG // The default scalar tag is !!str.
+	yaml_DEFAULT_SEQUENCE_TAG = yaml_SEQ_TAG // The default sequence tag is !!seq.
+	yaml_DEFAULT_MAPPING_TAG  = yaml_MAP_TAG // The default mapping tag is !!map.
+)
+
+type yaml_node_type_t int
+
+// Node types.
+const (
+	// An empty node.
+	yaml_NO_NODE yaml_node_type_t = iota
+
+	yaml_SCALAR_NODE   // A scalar node.
+	yaml_SEQUENCE_NODE // A sequence node.
+	yaml_MAPPING_NODE  // A mapping node.
+)
+
+// An element of a sequence node.
+type yaml_node_item_t int
+
+// An element of a mapping node.
+type yaml_node_pair_t struct {
+	key   int // The key of the element.
+	value int // The value of the element.
+}
+
+// The node structure.
+type yaml_node_t struct {
+	typ yaml_node_type_t // The node type.
+	tag []byte           // The node tag.
+
+	// The node data.
+
+	// The scalar parameters (for yaml_SCALAR_NODE).
+	scalar struct {
+		value  []byte              // The scalar value.
+		length int                 // The length of the scalar value.
+		style  yaml_scalar_style_t // The scalar style.
+	}
+
+	// The sequence parameters (for YAML_SEQUENCE_NODE).
+	sequence struct {
+		items_data []yaml_node_item_t    // The stack of sequence items.
+		style      yaml_sequence_style_t // The sequence style.
+	}
+
+	// The mapping parameters (for yaml_MAPPING_NODE).
+	mapping struct {
+		pairs_data  []yaml_node_pair_t   // The stack of mapping pairs (key, value).
+		pairs_start *yaml_node_pair_t    // The beginning of the stack.
+		pairs_end   *yaml_node_pair_t    // The end of the stack.
+		pairs_top   *yaml_node_pair_t    // The top of the stack.
+		style       yaml_mapping_style_t // The mapping style.
+	}
+
+	start_mark yaml_mark_t // The beginning of the node.
+	end_mark   yaml_mark_t // The end of the node.
+
+}
+
+// The document structure.
+type yaml_document_t struct {
+
+	// The document nodes.
+	nodes []yaml_node_t
+
+	// The version directive.
+	version_directive *yaml_version_directive_t
+
+	// The list of tag directives.
+	tag_directives_data  []yaml_tag_directive_t
+	tag_directives_start int // The beginning of the tag directives list.
+	tag_directives_end   int // The end of the tag directives list.
+
+	start_implicit int // Is the document start indicator implicit?
+	end_implicit   int // Is the document end indicator implicit?
+
+	// The start/end of the document.
+	start_mark, end_mark yaml_mark_t
+}
+
+// The prototype of a read handler.
+//
+// The read handler is called when the parser needs to read more bytes from the
+// source. The handler should write not more than size bytes to the buffer.
+// The number of written bytes should be set to the size_read variable.
+//
+// [in,out]   data        A pointer to an application data specified by
+//                        yaml_parser_set_input().
+// [out]      buffer      The buffer to write the data from the source.
+// [in]       size        The size of the buffer.
+// [out]      size_read   The actual number of bytes read from the source.
+//
+// On success, the handler should return 1.  If the handler failed,
+// the returned value should be 0. On EOF, the handler should set the
+// size_read to 0 and return 1.
+type yaml_read_handler_t func(parser *yaml_parser_t, buffer []byte) (n int, err error)
+
+// This structure holds information about a potential simple key.
+type yaml_simple_key_t struct {
+	possible     bool        // Is a simple key possible?
+	required     bool        // Is a simple key required?
+	token_number int         // The number of the token.
+	mark         yaml_mark_t // The position mark.
+}
+
+// The states of the parser.
+type yaml_parser_state_t int
+
+const (
+	yaml_PARSE_STREAM_START_STATE yaml_parser_state_t = iota
+
+	yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE           // Expect the beginning of an implicit document.
+	yaml_PARSE_DOCUMENT_START_STATE                    // Expect DOCUMENT-START.
+	yaml_PARSE_DOCUMENT_CONTENT_STATE                  // Expect the content of a document.
+	yaml_PARSE_DOCUMENT_END_STATE                      // Expect DOCUMENT-END.
+	yaml_PARSE_BLOCK_NODE_STATE                        // Expect a block node.
+	yaml_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE // Expect a block node or indentless sequence.
+	yaml_PARSE_FLOW_NODE_STATE                         // Expect a flow node.
+	yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE        // Expect the first entry of a block sequence.
+	yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE              // Expect an entry of a block sequence.
+	yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE         // Expect an entry of an indentless sequence.
+	yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE           // Expect the first key of a block mapping.
+	yaml_PARSE_BLOCK_MAPPING_KEY_STATE                 // Expect a block mapping key.
+	yaml_PARSE_BLOCK_MAPPING_VALUE_STATE               // Expect a block mapping value.
+	yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE         // Expect the first entry of a flow sequence.
+	yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE               // Expect an entry of a flow sequence.
+	yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE   // Expect a key of an ordered mapping.
+	yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE // Expect a value of an ordered mapping.
+	yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE   // Expect the and of an ordered mapping entry.
+	yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE            // Expect the first key of a flow mapping.
+	yaml_PARSE_FLOW_MAPPING_KEY_STATE                  // Expect a key of a flow mapping.
+	yaml_PARSE_FLOW_MAPPING_VALUE_STATE                // Expect a value of a flow mapping.
+	yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE          // Expect an empty value of a flow mapping.
+	yaml_PARSE_END_STATE                               // Expect nothing.
+)
+
+func (ps yaml_parser_state_t) String() string {
+	switch ps {
+	case yaml_PARSE_STREAM_START_STATE:
+		return "yaml_PARSE_STREAM_START_STATE"
+	case yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE:
+		return "yaml_PARSE_IMPLICIT_DOCUMENT_START_STATE"
+	case yaml_PARSE_DOCUMENT_START_STATE:
+		return "yaml_PARSE_DOCUMENT_START_STATE"
+	case yaml_PARSE_DOCUMENT_CONTENT_STATE:
+		return "yaml_PARSE_DOCUMENT_CONTENT_STATE"
+	case yaml_PARSE_DOCUMENT_END_STATE:
+		return "yaml_PARSE_DOCUMENT_END_STATE"
+	case yaml_PARSE_BLOCK_NODE_STATE:
+		return "yaml_PARSE_BLOCK_NODE_STATE"
+	case yaml_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE:
+		return "yaml_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE"
+	case yaml_PARSE_FLOW_NODE_STATE:
+		return "yaml_PARSE_FLOW_NODE_STATE"
+	case yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE:
+		return "yaml_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE"
+	case yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE:
+		return "yaml_PARSE_BLOCK_SEQUENCE_ENTRY_STATE"
+	case yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE:
+		return "yaml_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE"
+	case yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE:
+		return "yaml_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE"
+	case yaml_PARSE_BLOCK_MAPPING_KEY_STATE:
+		return "yaml_PARSE_BLOCK_MAPPING_KEY_STATE"
+	case yaml_PARSE_BLOCK_MAPPING_VALUE_STATE:
+		return "yaml_PARSE_BLOCK_MAPPING_VALUE_STATE"
+	case yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE:
+		return "yaml_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE"
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE:
+		return "yaml_PARSE_FLOW_SEQUENCE_ENTRY_STATE"
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE:
+		return "yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE"
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE:
+		return "yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE"
+	case yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE:
+		return "yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE"
+	case yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE:
+		return "yaml_PARSE_FLOW_MAPPING_FIRST_KEY_STATE"
+	case yaml_PARSE_FLOW_MAPPING_KEY_STATE:
+		return "yaml_PARSE_FLOW_MAPPING_KEY_STATE"
+	case yaml_PARSE_FLOW_MAPPING_VALUE_STATE:
+		return "yaml_PARSE_FLOW_MAPPING_VALUE_STATE"
+	case yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE:
+		return "yaml_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE"
+	case yaml_PARSE_END_STATE:
+		return "yaml_PARSE_END_STATE"
+	}
+	return "<unknown parser state>"
+}
+
+// This structure holds aliases data.
+type yaml_alias_data_t struct {
+	anchor []byte      // The anchor.
+	index  int         // The node id.
+	mark   yaml_mark_t // The anchor mark.
+}
+
+// The parser structure.
+//
+// All members are internal. Manage the structure using the
+// yaml_parser_ family of functions.
+type yaml_parser_t struct {
+
+	// Error handling
+
+	error yaml_error_type_t // Error type.
+
+	problem string // Error description.
+
+	// The byte about which the problem occurred.
+	problem_offset int
+	problem_value  int
+	problem_mark   yaml_mark_t
+
+	// The error context.
+	context      string
+	context_mark yaml_mark_t
+
+	// Reader stuff
+
+	read_handler yaml_read_handler_t // Read handler.
+
+	input_reader io.Reader // File input data.
+	input        []byte    // String input data.
+	input_pos    int
+
+	eof bool // EOF flag
+
+	buffer     []byte // The working buffer.
+	buffer_pos int    // The current position of the buffer.
+
+	unread int // The number of unread characters in the buffer.
+
+	raw_buffer     []byte // The raw buffer.
+	raw_buffer_pos int    // The current position of the buffer.
+
+	encoding yaml_encoding_t // The input encoding.
+
+	offset int         // The offset of the current position (in bytes).
+	mark   yaml_mark_t // The mark of the current position.
+
+	// Scanner stuff
+
+	stream_start_produced bool // Have we started to scan the input stream?
+	stream_end_produced   bool // Have we reached the end of the input stream?
+
+	flow_level int // The number of unclosed '[' and '{' indicators.
+
+	tokens          []yaml_token_t // The tokens queue.
+	tokens_head     int            // The head of the tokens queue.
+	tokens_parsed   int            // The number of tokens fetched from the queue.
+	token_available bool           // Does the tokens queue contain a token ready for dequeueing.
+
+	indent  int   // The current indentation level.
+	indents []int // The indentation levels stack.
+
+	simple_key_allowed bool                // May a simple key occur at the current position?
+	simple_keys        []yaml_simple_key_t // The stack of simple keys.
+	simple_keys_by_tok map[int]int         // possible simple_key indexes indexed by token_number
+
+	// Parser stuff
+
+	state          yaml_parser_state_t    // The current parser state.
+	states         []yaml_parser_state_t  // The parser states stack.
+	marks          []yaml_mark_t          // The stack of marks.
+	tag_directives []yaml_tag_directive_t // The list of TAG directives.
+
+	// Dumper stuff
+
+	aliases []yaml_alias_data_t // The alias data.
+
+	document *yaml_document_t // The currently parsed document.
+}
+
+// Emitter Definitions
+
+// The prototype of a write handler.
+//
+// The write handler is called when the emitter needs to flush the accumulated
+// characters to the output.  The handler should write @a size bytes of the
+// @a buffer to the output.
+//
+// @param[in,out]   data        A pointer to an application data specified by
+//                              yaml_emitter_set_output().
+// @param[in]       buffer      The buffer with bytes to be written.
+// @param[in]       size        The size of the buffer.
+//
+// @returns On success, the handler should return @c 1.  If the handler failed,
+// the returned value should be @c 0.
+//
+type yaml_write_handler_t func(emitter *yaml_emitter_t, buffer []byte) error
+
+type yaml_emitter_state_t int
+
+// The emitter states.
+const (
+	// Expect STREAM-START.
+	yaml_EMIT_STREAM_START_STATE yaml_emitter_state_t = iota
+
+	yaml_EMIT_FIRST_DOCUMENT_START_STATE       // Expect the first DOCUMENT-START or STREAM-END.
+	yaml_EMIT_DOCUMENT_START_STATE             // Expect DOCUMENT-START or STREAM-END.
+	yaml_EMIT_DOCUMENT_CONTENT_STATE           // Expect the content of a document.
+	yaml_EMIT_DOCUMENT_END_STATE               // Expect DOCUMENT-END.
+	yaml_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE   // Expect the first item of a flow sequence.
+	yaml_EMIT_FLOW_SEQUENCE_ITEM_STATE         // Expect an item of a flow sequence.
+	yaml_EMIT_FLOW_MAPPING_FIRST_KEY_STATE     // Expect the first key of a flow mapping.
+	yaml_EMIT_FLOW_MAPPING_KEY_STATE           // Expect a key of a flow mapping.
+	yaml_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE  // Expect a value for a simple key of a flow mapping.
+	yaml_EMIT_FLOW_MAPPING_VALUE_STATE         // Expect a value of a flow mapping.
+	yaml_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE  // Expect the first item of a block sequence.
+	yaml_EMIT_BLOCK_SEQUENCE_ITEM_STATE        // Expect an item of a block sequence.
+	yaml_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE    // Expect the first key of a block mapping.
+	yaml_EMIT_BLOCK_MAPPING_KEY_STATE          // Expect the key of a block mapping.
+	yaml_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE // Expect a value for a simple key of a block mapping.
+	yaml_EMIT_BLOCK_MAPPING_VALUE_STATE        // Expect a value of a block mapping.
+	yaml_EMIT_END_STATE                        // Expect nothing.
+)
+
+// The emitter structure.
+//
+// All members are internal.  Manage the structure using the @c yaml_emitter_
+// family of functions.
+type yaml_emitter_t struct {
+
+	// Error handling
+
+	error   yaml_error_type_t // Error type.
+	problem string            // Error description.
+
+	// Writer stuff
+
+	write_handler yaml_write_handler_t // Write handler.
+
+	output_buffer *[]byte   // String output data.
+	output_writer io.Writer // File output data.
+
+	buffer     []byte // The working buffer.
+	buffer_pos int    // The current position of the buffer.
+
+	raw_buffer     []byte // The raw buffer.
+	raw_buffer_pos int    // The current position of the buffer.
+
+	encoding yaml_encoding_t // The stream encoding.
+
+	// Emitter stuff
+
+	canonical   bool         // If the output is in the canonical style?
+	best_indent int          // The number of indentation spaces.
+	best_width  int          // The preferred width of the output lines.
+	unicode     bool         // Allow unescaped non-ASCII characters?
+	line_break  yaml_break_t // The preferred line break.
+
+	state  yaml_emitter_state_t   // The current emitter state.
+	states []yaml_emitter_state_t // The stack of states.
+
+	events      []yaml_event_t // The event queue.
+	events_head int            // The head of the event queue.
+
+	indents []int // The stack of indentation levels.
+
+	tag_directives []yaml_tag_directive_t // The list of tag directives.
+
+	indent int // The current indentation level.
+
+	flow_level int // The current flow level.
+
+	root_context       bool // Is it the document root context?
+	sequence_context   bool // Is it a sequence context?
+	mapping_context    bool // Is it a mapping context?
+	simple_key_context bool // Is it a simple mapping key context?
+
+	line       int  // The current line.
+	column     int  // The current column.
+	whitespace bool // If the last character was a whitespace?
+	indention  bool // If the last character was an indentation character (' ', '-', '?', ':')?
+	open_ended bool // If an explicit document end is required?
+
+	// Anchor analysis.
+	anchor_data struct {
+		anchor []byte // The anchor value.
+		alias  bool   // Is it an alias?
+	}
+
+	// Tag analysis.
+	tag_data struct {
+		handle []byte // The tag handle.
+		suffix []byte // The tag suffix.
+	}
+
+	// Scalar analysis.
+	scalar_data struct {
+		value                 []byte              // The scalar value.
+		multiline             bool                // Does the scalar contain line breaks?
+		flow_plain_allowed    bool                // Can the scalar be expessed in the flow plain style?
+		block_plain_allowed   bool                // Can the scalar be expressed in the block plain style?
+		single_quoted_allowed bool                // Can the scalar be expressed in the single quoted style?
+		block_allowed         bool                // Can the scalar be expressed in the literal or folded styles?
+		style                 yaml_scalar_style_t // The output style.
+	}
+
+	// Dumper stuff
+
+	opened bool // If the stream was already opened?
+	closed bool // If the stream was already closed?
+
+	// The information associated with the document nodes.
+	anchors *struct {
+		references int  // The number of references.
+		anchor     int  // The anchor id.
+		serialized bool // If the node has been emitted?
+	}
+
+	last_anchor_id int // The last assigned anchor id.
+
+	document *yaml_document_t // The currently emitted document.
+}
diff --git a/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yamlprivateh.go b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yamlprivateh.go
new file mode 100644
index 00000000000..8110ce3c37a
--- /dev/null
+++ b/src/mongo/gotools/src/github.com/mongodb/mongo-tools/vendor/gopkg.in/yaml.v2/yamlprivateh.go
@@ -0,0 +1,173 @@
+package yaml
+
+const (
+	// The size of the input raw buffer.
+	input_raw_buffer_size = 512
+
+	// The size of the input buffer.
+	// It should be possible to decode the whole raw buffer.
+	input_buffer_size = input_raw_buffer_size * 3
+
+	// The size of the output buffer.
+	output_buffer_size = 128
+
+	// The size of the output raw buffer.
+	// It should be possible to encode the whole output buffer.
+	output_raw_buffer_size = (output_buffer_size*2 + 2)
+
+	// The size of other stacks and queues.
+	initial_stack_size  = 16
+	initial_queue_size  = 16
+	initial_string_size = 16
+)
+
+// Check if the character at the specified position is an alphabetical
+// character, a digit, '_', or '-'.
+func is_alpha(b []byte, i int) bool {
+	return b[i] >= '0' && b[i] <= '9' || b[i] >= 'A' && b[i] <= 'Z' || b[i] >= 'a' && b[i] <= 'z' || b[i] == '_' || b[i] == '-'
+}
+
+// Check if the character at the specified position is a digit.
+func is_digit(b []byte, i int) bool {
+	return b[i] >= '0' && b[i] <= '9'
+}
+
+// Get the value of a digit.
+func as_digit(b []byte, i int) int {
+	return int(b[i]) - '0'
+}
+
+// Check if the character at the specified position is a hex-digit.
+func is_hex(b []byte, i int) bool {
+	return b[i] >= '0' && b[i] <= '9' || b[i] >= 'A' && b[i] <= 'F' || b[i] >= 'a' && b[i] <= 'f'
+}
+
+// Get the value of a hex-digit.
+func as_hex(b []byte, i int) int {
+	bi := b[i]
+	if bi >= 'A' && bi <= 'F' {
+		return int(bi) - 'A' + 10
+	}
+	if bi >= 'a' && bi <= 'f' {
+		return int(bi) - 'a' + 10
+	}
+	return int(bi) - '0'
+}
+
+// Check if the character is ASCII.
+func is_ascii(b []byte, i int) bool {
+	return b[i] <= 0x7F
+}
+
+// Check if the character at the start of the buffer can be printed unescaped.
+func is_printable(b []byte, i int) bool {
+	return ((b[i] == 0x0A) || // . == #x0A
+		(b[i] >= 0x20 && b[i] <= 0x7E) || // #x20 <= . <= #x7E
+		(b[i] == 0xC2 && b[i+1] >= 0xA0) || // #0xA0 <= . <= #xD7FF
+		(b[i] > 0xC2 && b[i] < 0xED) ||
+		(b[i] == 0xED && b[i+1] < 0xA0) ||
+		(b[i] == 0xEE) ||
+		(b[i] == 0xEF && // #xE000 <= . <= #xFFFD
+			!(b[i+1] == 0xBB && b[i+2] == 0xBF) && // && . != #xFEFF
+			!(b[i+1] == 0xBF && (b[i+2] == 0xBE || b[i+2] == 0xBF))))
+}
+
+// Check if the character at the specified position is NUL.
+func is_z(b []byte, i int) bool {
+	return b[i] == 0x00
+}
+
+// Check if the beginning of the buffer is a BOM.
+func is_bom(b []byte, i int) bool {
+	return b[0] == 0xEF && b[1] == 0xBB && b[2] == 0xBF
+}
+
+// Check if the character at the specified position is space.
+func is_space(b []byte, i int) bool {
+	return b[i] == ' '
+}
+
+// Check if the character at the specified position is tab.
+func is_tab(b []byte, i int) bool {
+	return b[i] == '\t'
+}
+
+// Check if the character at the specified position is blank (space or tab).
+func is_blank(b []byte, i int) bool {
+	//return is_space(b, i) || is_tab(b, i)
+	return b[i] == ' ' || b[i] == '\t'
+}
+
+// Check if the character at the specified position is a line break.
+func is_break(b []byte, i int) bool {
+	return (b[i] == '\r' || // CR (#xD)
+		b[i] == '\n' || // LF (#xA)
+		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9) // PS (#x2029)
+}
+
+func is_crlf(b []byte, i int) bool {
+	return b[i] == '\r' && b[i+1] == '\n'
+}
+
+// Check if the character is a line break or NUL.
+func is_breakz(b []byte, i int) bool {
+	//return is_break(b, i) || is_z(b, i)
+	return (        // is_break:
+	b[i] == '\r' || // CR (#xD)
+		b[i] == '\n' || // LF (#xA)
+		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9 || // PS (#x2029)
+		// is_z:
+		b[i] == 0)
+}
+
+// Check if the character is a line break, space, or NUL.
+func is_spacez(b []byte, i int) bool {
+	//return is_space(b, i) || is_breakz(b, i)
+	return ( // is_space:
+	b[i] == ' ' ||
+		// is_breakz:
+		b[i] == '\r' || // CR (#xD)
+		b[i] == '\n' || // LF (#xA)
+		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9 || // PS (#x2029)
+		b[i] == 0)
+}
+
+// Check if the character is a line break, space, tab, or NUL.
+func is_blankz(b []byte, i int) bool {
+	//return is_blank(b, i) || is_breakz(b, i)
+	return ( // is_blank:
+	b[i] == ' ' || b[i] == '\t' ||
+		// is_breakz:
+		b[i] == '\r' || // CR (#xD)
+		b[i] == '\n' || // LF (#xA)
+		b[i] == 0xC2 && b[i+1] == 0x85 || // NEL (#x85)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA8 || // LS (#x2028)
+		b[i] == 0xE2 && b[i+1] == 0x80 && b[i+2] == 0xA9 || // PS (#x2029)
+		b[i] == 0)
+}
+
+// Determine the width of the character.
+func width(b byte) int {
+	// Don't replace these by a switch without first
+	// confirming that it is being inlined.
+	if b&0x80 == 0x00 {
+		return 1
+	}
+	if b&0xE0 == 0xC0 {
+		return 2
+	}
+	if b&0xF0 == 0xE0 {
+		return 3
+	}
+	if b&0xF8 == 0xF0 {
+		return 4
+	}
+	return 0
+
+}