SERVER-31390 Use a templating language to generate error_codes.{h,cpp,js}

8 files changed, 320 insertions, 311 deletions

diff --git a/.eslintignore b/.eslintignore
index a1ded284b11..97755b3f9df 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -1 +1,2 @@
 src/mongo/gotools/*
+*.tpl.js
diff --git a/buildscripts/requirements.txt b/buildscripts/requirements.txt
index 1aef1166655..83242c053ff 100644
--- a/buildscripts/requirements.txt
+++ b/buildscripts/requirements.txt
@@ -10,3 +10,5 @@ pylint == 1.6.5
 pydocstyle == 1.1.1
 # resmoke.py
 -r resmokelib/requirements.txt
+# generate_error_codes.py
+cheetah3 == 3.0.0; python_version < "3"
diff --git a/src/mongo/base/SConscript b/src/mongo/base/SConscript
index db569f842a5..80dc007a4bb 100644
--- a/src/mongo/base/SConscript
+++ b/src/mongo/base/SConscript
@@ -4,10 +4,29 @@ Import("env")
 
 env = env.Clone()
 
-generateErrorCodes = env.Command(
-    target=['error_codes.h', 'error_codes.cpp'],
-    source=['generate_error_codes.py', 'error_codes.err'],
-    action=['$PYTHON ${SOURCES[0]} cpp ${SOURCES[1]} --cpp-header=${TARGETS[0]} --cpp-source=${TARGETS[1]}'])
+
+# This needs to use its own env to tell scons to suppress scanning the .tpl.h and .tpl.cpp inputs
+# for #includes since they aren't directly preprocessed. Scons will still scan the generated files
+# to produce the correct implicit dependencies when they are compiled.
+env_for_error_codes = env.Clone()
+env_for_error_codes['SCANNERS'] = []
+generateErrorCodes = env_for_error_codes.Command(
+    target=[
+        'error_codes.h',
+        'error_codes.cpp'
+    ],
+    source=[
+        'generate_error_codes.py',
+        'error_codes.err',
+        'error_codes.tpl.h',
+        'error_codes.tpl.cpp',
+    ],
+    action=['$PYTHON ${SOURCES[0]} ${SOURCES[1]} '
+            '${SOURCES[2]}=${TARGETS[0]} '
+            '${SOURCES[3]}=${TARGETS[1]}'
+    ],
+)
+
 env.Alias('generated-sources', generateErrorCodes)
 
 env.CppUnitTest('base_test',
diff --git a/src/mongo/base/error_codes.tpl.cpp b/src/mongo/base/error_codes.tpl.cpp
new file mode 100644
index 00000000000..c1188c3bd15
--- /dev/null
+++ b/src/mongo/base/error_codes.tpl.cpp
@@ -0,0 +1,77 @@
+/**
+ *    Copyright 2017 MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects
+ *    for all of the code used other than as permitted herein. If you modify
+ *    file(s) with this exception, you may extend this exception to your
+ *    version of the file(s), but you are not obligated to do so. If you do not
+ *    wish to do so, delete this exception statement from your version. If you
+ *    delete this exception statement from all source files in the program,
+ *    then also delete it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/base/error_codes.h"
+
+#include "mongo/base/static_assert.h"
+#include "mongo/util/assert_util.h"
+#include "mongo/util/mongoutils/str.h"
+
+namespace mongo {
+
+MONGO_STATIC_ASSERT(sizeof(ErrorCodes::Error) == sizeof(int));
+
+std::string ErrorCodes::errorString(Error err) {
+    switch (err) {
+        //#for $ec in $codes
+        case $ec.name:
+            return "$ec.name";
+        //#end for
+        default:
+            return mongoutils::str::stream() << "Location" << int(err);
+    }
+}
+
+ErrorCodes::Error ErrorCodes::fromString(StringData name) {
+    //#for $ec in $codes
+    if (name == "$ec.name"_sd)
+        return $ec.name;
+    //#end for
+    return UnknownError;
+}
+
+std::ostream& operator<<(std::ostream& stream, ErrorCodes::Error code) {
+    return stream << ErrorCodes::errorString(code);
+}
+
+//#for $cat in $categories
+bool ErrorCodes::is${cat.name}(Error err) {
+    switch (err) {
+        //#for $code in $cat.codes
+        case $code:
+            return true;
+        //#end for
+        default:
+            return false;
+    }
+}
+//#end for
+
+}  // namespace mongo
diff --git a/src/mongo/base/error_codes.tpl.h b/src/mongo/base/error_codes.tpl.h
new file mode 100644
index 00000000000..a5ebd55042b
--- /dev/null
+++ b/src/mongo/base/error_codes.tpl.h
@@ -0,0 +1,82 @@
+/**
+ *    Copyright 2017 MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects
+ *    for all of the code used other than as permitted herein. If you modify
+ *    file(s) with this exception, you may extend this exception to your
+ *    version of the file(s), but you are not obligated to do so. If you do not
+ *    wish to do so, delete this exception statement from your version. If you
+ *    delete this exception statement from all source files in the program,
+ *    then also delete it in the license file.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <iosfwd>
+#include <string>
+
+#include "mongo/base/string_data.h"
+
+namespace mongo {
+
+/**
+ * This is a generated class containing a table of error codes and their corresponding error
+ * strings. The class is derived from the definitions in src/mongo/base/error_codes.err file and the
+ * src/mongo/base/error_codes.tpl.h template.
+ *
+ * Do not update this file directly. Update src/mongo/base/error_codes.err instead.
+ */
+class ErrorCodes {
+public:
+    // Explicitly 32-bits wide so that non-symbolic values,
+    // like uassert codes, are valid.
+    enum Error : std::int32_t {
+        //#for $ec in $codes
+        $ec.name = $ec.code,
+        //#end for
+        MaxError
+    };
+
+    static std::string errorString(Error err);
+
+    /**
+     * Parses an Error from its "name".  Returns UnknownError if "name" is unrecognized.
+     *
+     * NOTE: Also returns UnknownError for the string "UnknownError".
+     */
+    static Error fromString(StringData name);
+
+    /**
+     * Casts an integer "code" to an Error.  Unrecognized codes are preserved, meaning
+     * that the result of a call to fromInt() may not be one of the values in the
+     * Error enumeration.
+     */
+    static Error fromInt(int code) {
+        return static_cast<Error>(code);
+    }
+
+    //#for $cat in $categories
+    static bool is${cat.name}(Error err);
+    //#end for
+};
+
+std::ostream& operator<<(std::ostream& stream, ErrorCodes::Error code);
+
+}  // namespace mongo
diff --git a/src/mongo/base/generate_error_codes.py b/src/mongo/base/generate_error_codes.py
index b431cff415c..d3da9970692 100644
--- a/src/mongo/base/generate_error_codes.py
+++ b/src/mongo/base/generate_error_codes.py
@@ -36,29 +36,62 @@ error_code("symbol2", code2)
 error_class("class1", ["symbol1", "symbol2, ..."])
 
 Usage:
-    python generate_error_codes.py <cpp|js> <path to error_codes.err> [options]
+    python generate_error_codes.py <path to error_codes.err> <template>=<output>...
 """
 
-usage_msg = "usage: %prog <cpp|js> /path/to/error_codes.err [options]"
+usage_msg = "usage: %prog /path/to/error_codes.err <template>=<output>..."
 
-from optparse import OptionParser
+from collections import namedtuple
+from Cheetah.Template import Template
 import sys
+
+def render_template(template_path, **kw):
+    '''Renders the template file located at template_path, using the variables defined by kw, and
+       returns the result as a string'''
+
+    template = Template.compile(
+            file=template_path,
+            compilerSettings=dict(directiveStartToken="//#",directiveEndToken="//#"),
+            baseclass=dict,
+            useCache=False)
+    return str(template(**kw))
+
+ErrorCode = namedtuple('ErrorCode', ['name', 'code'])
+def makeErrorCode(name, code):
+    return ErrorCode(name, code)
+
+ErrorClass = namedtuple('ErrorClass', ['name', 'codes'])
+def makeErrorClass(name, codes):
+    return ErrorClass(name, codes)
+
 def main(argv):
-    generator = argv[1]
-    error_codes, error_classes = parse_error_definitions_from_file(argv[2])
+    # Parse and validate argv.
+    if len(sys.argv) < 2:
+        usage("Must specify error_codes.err")
+    if len(sys.argv) < 3:
+        usage("Must specify at least one template=output pair")
+
+    template_outputs = []
+    for arg in sys.argv[2:]:
+        try:
+            template, output = arg.split('=', 1)
+            template_outputs.append((template, output))
+        except Exception:
+            usage("Error parsing template=output pair: " + arg)
+
+    # Parse and validate error_codes.err.
+    error_codes, error_classes = parse_error_definitions_from_file(argv[1])
     check_for_conflicts(error_codes, error_classes)
-    if (generator == 'cpp'):
-        if (len(argv) != 5):
-            usage('Wrong number of arguments')
-        cpp_gen = cpp_generator(error_codes, error_classes)
-        cpp_gen.generate()
-    elif (generator == 'js'):
-        if (len(argv) != 4):
-            usage('Wrong number of arguments')
-        js_gen = js_generator(error_codes, error_classes)
-        js_gen.generate()
-    else:
-        usage('Must specify which generator(s) to use.')
+
+    # Render the templates to the output files.
+    for template, output in template_outputs:
+        text = render_template(template,
+                codes=error_codes,
+                categories=error_classes,
+                )
+
+        with open(output, 'wb') as outfile:
+            outfile.write(text)
 
 def die(message=None):
     sys.stderr.write(message or "Fatal error\n")
@@ -73,9 +106,10 @@ def parse_error_definitions_from_file(errors_filename):
     errors_code = compile(errors_file.read(), errors_filename, 'exec')
     error_codes = []
     error_classes = []
-    eval(errors_code, dict(error_code=lambda *args: error_codes.append(args),
-                           error_class=lambda *args: error_classes.append(args)))
-    error_codes.sort(key=lambda x: x[1])
+    eval(errors_code,
+            dict(error_code=lambda *args, **kw: error_codes.append(makeErrorCode(*args, **kw)),
+                 error_class=lambda *args: error_classes.append(makeErrorClass(*args))))
+    error_codes.sort(key=lambda x: x.code)
     return error_codes, error_classes
 
 def check_for_conflicts(error_codes, error_classes):
@@ -88,28 +122,30 @@ def check_for_conflicts(error_codes, error_classes):
         die()
 
 def has_duplicate_error_codes(error_codes):
-    sorted_by_name = sorted(error_codes, key=lambda x: x[0])
-    sorted_by_code = sorted(error_codes, key=lambda x: x[1])
+    sorted_by_name = sorted(error_codes, key=lambda x: x.name)
+    sorted_by_code = sorted(error_codes, key=lambda x: x.code)
 
     failed = False
-    prev_name, prev_code = sorted_by_name[0]
-    for name, code in sorted_by_name[1:]:
-        if name == prev_name:
-            sys.stdout.write('Duplicate name %s with codes %s and %s\n' % (name, code, prev_code))
+    prev = sorted_by_name[0]
+    for curr in sorted_by_name[1:]:
+        if curr.name == prev.name:
+            sys.stdout.write('Duplicate name %s with codes %s and %s\n'
+                    % (curr.name, curr.code, prev.code))
             failed = True
-        prev_name, prev_code = name, code
+        prev = curr
 
-    prev_name, prev_code = sorted_by_code[0]
-    for name, code in sorted_by_code[1:]:
-        if code == prev_code:
-            sys.stdout.write('Duplicate code %s with names %s and %s\n' % (code, name, prev_name))
+    prev = sorted_by_code[0]
+    for curr in sorted_by_code[1:]:
+        if curr.code == prev.code:
+            sys.stdout.write('Duplicate code %s with names %s and %s\n'
+                    % (curr.code, curr.name, prev.name))
             failed = True
-        prev_name, prev_code = name, code
+        prev = curr
 
     return failed
 
 def has_duplicate_error_classes(error_classes):
-    names = sorted(ec[0] for ec in error_classes)
+    names = sorted(ec.name for ec in error_classes)
 
     failed = False
     prev_name = names[0]
@@ -130,277 +166,5 @@ def has_missing_error_codes(error_codes, error_classes):
                 failed = True
     return failed
 
-class base_generator(object):
-    def __init__(self, error_codes, error_classes):
-        self.error_codes = error_codes
-        self.error_classes = error_classes
-
-    def parseOptions(self, options, usage_msg):
-        parser = OptionParser(usage=usage_msg)
-        for (f,d,n,m,h) in options:
-            parser.add_option(f,dest=d,nargs=n,metavar=m,help=h)
-        (options, args) = parser.parse_args()
-        return options
-
-
-class js_generator(base_generator):
-    def __init__(self, error_codes, error_classes):
-        super(js_generator, self).__init__(error_codes, error_classes)
-        options = [('--js-source','js_source',1,'DEST_JS_SOURCE','specify dest JS source file to save to')]
-        options = self.parseOptions(options, usage_msg)
-        if (options.js_source):
-            self.js_source = options.js_source
-        else:
-            usage('Must specify JS source files')
-
-    def generate(self):
-        self.generate_source()
-
-    def generate_source(self):
-        string_to_int_cases = ',\n    '.join(
-            '%s: %s' % (ec[0], ec[1]) for ec in self.error_codes)
-        int_to_string_cases = ',\n    '.join(
-            '%s: \'%s\'' % (ec[1], ec[0]) for ec in self.error_codes)
-        predicate_definitions = '\n\n'.join(
-            self.generate_error_class_predicate_definition(*ec) for ec in self.error_classes)
-        open(self.js_source, 'wb').write(self.source_template % dict(
-                string_to_int_cases=string_to_int_cases,
-                int_to_string_cases=int_to_string_cases
-                ))
-
-    def generate_error_class_predicate_definition(self, class_name, code_names):
-        cases = '\n        '.join('case \'%s\':' % c for c in code_names)
-        return self.error_class_predicate_template % dict(class_name=class_name, cases=cases)
-
-    source_template = '''// AUTO-GENERATED FILE DO NOT EDIT
-// See src/mongo/base/generate_error_codes.py
-/*    Copyright 2015 MongoDB, Inc.
-*
-*    This program is free software: you can redistribute it and/or  modify
-*    it under the terms of the GNU Affero General Public License, version 3,
-*    as published by the Free Software Foundation.
-*
-*    This program is distributed in the hope that it will be useful,
-*    but WITHOUT ANY WARRANTY; without even the implied warranty of
-*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-*    GNU Affero General Public License for more details.
-*
-*    You should have received a copy of the GNU Affero General Public License
-*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*
-*    As a special exception, the copyright holders give permission to link the
-*    code of portions of this program with the OpenSSL library under certain
-*    conditions as described in each individual source file and distribute
-*    linked combinations including the program with the OpenSSL library. You
-*    must comply with the GNU Affero General Public License in all respects
-*    for all of the code used other than as permitted herein. If you modify
-*    file(s) with this exception, you may extend this exception to your
-*    version of the file(s), but you are not obligated to do so. If you do not
-*    wish to do so, delete this exception statement from your version. If you
-*    delete this exception statement from all source files in the program,
-*    then also delete it in the license file.
-*/
-
-var ErrorCodes = {
-    %(string_to_int_cases)s
-};
-
-var ErrorCodeStrings = {
-    %(int_to_string_cases)s
-};
-'''
-
-    error_class_predicate_template = '''function is%(class_name)s(err) {
-    if (typeof err === 'string') {
-        error = err;
-    } else if (typeof err === 'number') {
-        error = ErrorCodeStrings[err];
-    }
-    switch (error) {
-        %(cases)s
-            return true;
-        default:
-            return false;
-    }
-}
-'''
-
-class cpp_generator(base_generator):
-    def __init__(self, error_codes, error_classes):
-        super(cpp_generator, self).__init__(error_codes, error_classes)
-        options = [('--cpp-header','cpp_header',1,'DEST_CPP_HEADER','specify dest CPP header file to save to'), ('--cpp-source','cpp_source',1,'DEST_CPP_SOURCE','specify dest CPP source file to save to')]
-        options = self.parseOptions(options, usage_msg)
-        if (options.cpp_header and options.cpp_source):
-            self.cpp_header = options.cpp_header
-            self.cpp_source = options.cpp_source
-        else:
-            usage('Must specify CPP header and source files')
-
-    def generate(self):
-        self.generate_header()
-        self.generate_source()
-
-    def generate_header(self):
-
-        enum_declarations = ',\n            '.join('%s = %s' % ec for ec in self.error_codes)
-        predicate_declarations = ';\n        '.join(
-            'static bool is%s(Error err)' % ec[0] for ec in self.error_classes)
-
-        open(self.cpp_header, 'wb').write(self.header_template % dict(
-                error_code_enum_declarations=enum_declarations,
-                error_code_class_predicate_declarations=predicate_declarations))
-
-    def generate_source(self):
-        symbol_to_string_cases = ';\n        '.join(
-            'case %s: return "%s"' % (ec[0], ec[0]) for ec in self.error_codes)
-        string_to_symbol_cases = ';\n        '.join(
-            'if (name == "%s") return %s' % (ec[0], ec[0])
-            for ec in self.error_codes)
-        int_to_symbol_cases = ';\n        '.join(
-            'case %s: return %s' % (ec[0], ec[0]) for ec in self.error_codes)
-        predicate_definitions = '\n    '.join(
-            self.generate_error_class_predicate_definition(*ec) for ec in self.error_classes)
-        open(self.cpp_source, 'wb').write(self.source_template % dict(
-                symbol_to_string_cases=symbol_to_string_cases,
-                string_to_symbol_cases=string_to_symbol_cases,
-                int_to_symbol_cases=int_to_symbol_cases,
-                error_code_class_predicate_definitions=predicate_definitions))
-
-    def generate_error_class_predicate_definition(self, class_name, code_names):
-        cases = '\n        '.join('case %s:' % c for c in code_names)
-        return self.error_class_predicate_template % dict(class_name=class_name, cases=cases)
-
-    header_template = '''// AUTO-GENERATED FILE DO NOT EDIT
-// See src/mongo/base/generate_error_codes.py
-/*    Copyright 2014 MongoDB, Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the GNU Affero General Public License in all respects
- *    for all of the code used other than as permitted herein. If you modify
- *    file(s) with this exception, you may extend this exception to your
- *    version of the file(s), but you are not obligated to do so. If you do not
- *    wish to do so, delete this exception statement from your version. If you
- *    delete this exception statement from all source files in the program,
- *    then also delete it in the license file.
- */
-#pragma once
-#include <string>
-#include <cstdint>
-#include <iosfwd>
-#include "mongo/base/string_data.h"
-namespace mongo {
-    /**
-     * This is a generated class containing a table of error codes and their corresponding error
-     * strings. The class is derived from the definitions in src/mongo/base/error_codes.err file.
-     *
-     * Do not update this file directly. Update src/mongo/base/error_codes.err instead.
-     */
-    class ErrorCodes {
-    public:
-        // Explicitly 32-bits wide so that non-symbolic values,
-        // like uassert codes, are valid.
-        enum Error : std::int32_t {
-            %(error_code_enum_declarations)s,
-            MaxError
-        };
-        static std::string errorString(Error err);
-        /**
-         * Parses an Error from its "name".  Returns UnknownError if "name" is unrecognized.
-         *
-         * NOTE: Also returns UnknownError for the string "UnknownError".
-         */
-        static Error fromString(StringData name);
-        /**
-         * Casts an integer "code" to an Error.  Unrecognized codes are preserved, meaning
-         * that the result of a call to fromInt() may not be one of the values in the
-         * Error enumeration.
-         */
-        static Error fromInt(int code) {
-            return static_cast<Error>(code);
-        }
-        %(error_code_class_predicate_declarations)s;
-    };
-
-    std::ostream& operator<<(std::ostream& stream, ErrorCodes::Error code);
-}  // namespace mongo
-'''
-
-    source_template = '''// AUTO-GENERATED FILE DO NOT EDIT
-// See src/mongo/base/generate_error_codes.py
-/*    Copyright 2014 MongoDB, Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the GNU Affero General Public License in all respects
- *    for all of the code used other than as permitted herein. If you modify
- *    file(s) with this exception, you may extend this exception to your
- *    version of the file(s), but you are not obligated to do so. If you do not
- *    wish to do so, delete this exception statement from your version. If you
- *    delete this exception statement from all source files in the program,
- *    then also delete it in the license file.
- */
-#include "mongo/base/error_codes.h"
-#include "mongo/util/mongoutils/str.h"
-namespace mongo {
-    std::string ErrorCodes::errorString(Error err) {
-        switch (err) {
-        %(symbol_to_string_cases)s;
-        default: return mongoutils::str::stream() << "Location" << int(err);
-        }
-    }
-    ErrorCodes::Error ErrorCodes::fromString(StringData name) {
-        %(string_to_symbol_cases)s;
-        return UnknownError;
-    }
-    std::ostream& operator<<(std::ostream& stream, ErrorCodes::Error code) {
-        return stream << ErrorCodes::errorString(code);
-    }
-    %(error_code_class_predicate_definitions)s
-namespace {
-    static_assert(sizeof(ErrorCodes::Error) == sizeof(int), "sizeof(ErrorCodes::Error) == sizeof(int)");
-}  // namespace
-}  // namespace mongo
-'''
-
-    error_class_predicate_template = '''bool ErrorCodes::is%(class_name)s(Error err) {
-        switch (err) {
-        %(cases)s
-            return true;
-        default:
-            return false;
-        }
-    }
-'''
-
-
 if __name__ == '__main__':
     main(sys.argv)
diff --git a/src/mongo/shell/SConscript b/src/mongo/shell/SConscript
index d342f1edc68..090ec5b7cc6 100644
--- a/src/mongo/shell/SConscript
+++ b/src/mongo/shell/SConscript
@@ -6,8 +6,12 @@ env = env.Clone()
 
 generateJSErrorCodes = env.Command(
     target=['error_codes.js'],
-    source=['$BUILD_DIR/mongo/base/generate_error_codes.py', '$BUILD_DIR/mongo/base/error_codes.err'],
-    action=['$PYTHON ${SOURCES[0]} js ${SOURCES[1]} --js-source=${TARGETS[0]}'])
+    source=[
+        '$BUILD_DIR/mongo/base/generate_error_codes.py',
+        '$BUILD_DIR/mongo/base/error_codes.err',
+        'error_codes.tpl.js',
+    ],
+    action=['$PYTHON ${SOURCES[0]} ${SOURCES[1]} ${SOURCES[2]}=${TARGETS[0]}'])
 env.Alias('generated-sources', generateJSErrorCodes)
 
 # Files added here need to be added in scripting/engine.cpp and buildscripts/vcxproj.header as well.
diff --git a/src/mongo/shell/error_codes.tpl.js b/src/mongo/shell/error_codes.tpl.js
new file mode 100644
index 00000000000..120c0626eb2
--- /dev/null
+++ b/src/mongo/shell/error_codes.tpl.js
@@ -0,0 +1,60 @@
+/**
+ *    Copyright 2017 MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects
+ *    for all of the code used other than as permitted herein. If you modify
+ *    file(s) with this exception, you may extend this exception to your
+ *    version of the file(s), but you are not obligated to do so. If you do not
+ *    wish to do so, delete this exception statement from your version. If you
+ *    delete this exception statement from all source files in the program,
+ *    then also delete it in the license file.
+ */
+
+var ErrorCodes = {
+    //#for $ec in $codes
+    '$ec.name': $ec.code,
+    //#end for
+};
+
+var ErrorCodeStrings = {
+    //#for $ec in $codes
+    $ec.code: '$ec.name',
+    //#end for
+};
+
+//#for $cat in $categories
+ErrorCodes.is${cat.name} = function(err) {
+    'use strict';
+
+    var error;
+    if (typeof err === 'string') {
+        error = err;
+    } else if (typeof err === 'number') {
+        error = ErrorCodeStrings[err];
+    }
+    switch (error) {
+        //#for $code in $cat.codes
+        case '$code':
+            return true;
+        //#end for
+        default:
+            return false;
+    }
+};
+//#end for