Merge branch 'master' into nirvdrum-speed_up_node_mapping

* master: (28 commits) merge changes from ruby trunk Strings that start with non-word characters should double quote without exclamation mark fixing rsync make some header file adjustments for ruby compile updating the version to 2.0 add the license for libyaml Update README.rdoc fix c file name only do have_header checks if we are embedding libyaml mkmf has a global for this test fix build on windows only embed libyaml if the system does not have it * ext/psych/lib/psych/scalar_scanner.rb: avoid raising exceptions when parsing Floats and Integers. Thanks riffraff [ruby-core:44426] * test/psych/test_numeric.rb: associated test * ext/psych/lib/psych/core_ext.rb: move Kernel#y so that it can manually be required as 'psych/y'. for compiling on mswin embedding libyaml * ruby.c (load_file_internal): set default source encoding as UTF-8 instead of US-ASCII. [ruby-core:46021] [Feature #6679] * ext/psych/lib/psych/handlers/recorder.rb: added a class for recording YAML parse and emit events. Use literal style when emitting multiline strings, fixes #64 * ext/psych/lib/psych/visitors/yaml_tree.rb: `tree` should return the same thing on every call. ...
author: Aaron Patterson <aaron.patterson@gmail.com> 2012-12-17 09:59:28 -0800
committer: Aaron Patterson <aaron.patterson@gmail.com> 2012-12-17 09:59:28 -0800
commit: f22f976bce0a82a00759fca1b152276ce97c7236 (patch)
tree: bb885944674dc7d62529fbe79bcde9a9f182fd6a
parent: 2ceb7b685c47a04c4451287ea77aedf2f98f26c4 (diff)
parent: 9ab3a7066b09a5f7b563626676d788125882b581 (diff)
download: psych-f22f976bce0a82a00759fca1b152276ce97c7236.tar.gz
45 files changed, 13077 insertions, 73 deletions
diff --git a/.gitignore b/.gitignore
index 516f23f..574f763 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
-lib/psych/psych.bundle
-tmp
-pkg
+*.swp
+*.bundle
+/pkg
+/tmp
diff --git a/CHANGELOG.rdoc b/CHANGELOG.rdoc
index db8c413..291ce97 100644
--- a/CHANGELOG.rdoc
+++ b/CHANGELOG.rdoc
@@ -1,3 +1,48 @@
+Sat Nov 17 12:03:41 2012  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* ext/psych/lib/psych/scalar_scanner.rb: avoid raising exceptions when
+	  parsing Floats and Integers. Thanks riffraff [ruby-core:44426]
+	* test/psych/test_numeric.rb: associated test
+
+Sat Nov 17 11:26:36 2012  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* ext/psych/lib/psych/core_ext.rb: move Kernel#y so that it can
+	  manually be required as 'psych/y'.
+
+	* ext/psych/lib/psych/y.rb: ditto
+
+Tue Nov  6 09:37:57 2012  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* ruby.c (load_file_internal): set default source encoding as
+	  UTF-8 instead of US-ASCII. [ruby-core:46021] [Feature #6679]
+
+	* parse.y (parser_initialize): set default parser encoding as
+	  UTF-8 instead of US-ASCII.
+
+Mon Oct 29 10:22:00 2012  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* ext/psych/lib/psych/handlers/recorder.rb: added a class for
+	  recording YAML parse and emit events.
+
+	* ext/psych/lib/psych/handler.rb: adding a list of events so that
+	  handler classes can more easily be meta-programmed.
+
+	* test/psych/handlers/test_recorder.rb: tests for the change.
+
+Sun Oct 28 10:12:15 2012  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* ext/psych/lib/psych/visitors/yaml_tree.rb: `tree` should return the
+	  same thing on every call.
+
+	* test/psych/visitors/test_yaml_tree.rb: related test.
+
+Sun Oct 28 10:05:03 2012  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* ext/psych/lib/psych/visitors/yaml_tree.rb: YAML Tree object should
+	  be able to take an emitter object as it's output.
+
+	* test/psych/visitors/test_yaml_tree.rb: related test.
+
 Thu Jul 19 09:33:46 2012  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/emitter.c (initialize): allow a configuration object to be
diff --git a/Manifest.txt b/Manifest.txt
index e7c60c6..deec7df 100644
--- a/Manifest.txt
+++ b/Manifest.txt
@@ -4,23 +4,36 @@ CHANGELOG.rdoc
 Manifest.txt
 README.rdoc
 Rakefile
-ext/psych/emitter.c
-ext/psych/emitter.h
 ext/psych/extconf.rb
-ext/psych/parser.c
-ext/psych/parser.h
 ext/psych/psych.c
 ext/psych/psych.h
-ext/psych/to_ruby.c
-ext/psych/to_ruby.h
-ext/psych/yaml_tree.c
-ext/psych/yaml_tree.h
+ext/psych/psych_emitter.c
+ext/psych/psych_emitter.h
+ext/psych/psych_parser.c
+ext/psych/psych_parser.h
+ext/psych/psych_to_ruby.c
+ext/psych/psych_to_ruby.h
+ext/psych/psych_yaml_tree.c
+ext/psych/psych_yaml_tree.h
+ext/psych/yaml/LICENSE
+ext/psych/yaml/api.c
+ext/psych/yaml/config.h
+ext/psych/yaml/dumper.c
+ext/psych/yaml/emitter.c
+ext/psych/yaml/loader.c
+ext/psych/yaml/parser.c
+ext/psych/yaml/reader.c
+ext/psych/yaml/scanner.c
+ext/psych/yaml/writer.c
+ext/psych/yaml/yaml.h
+ext/psych/yaml/yaml_private.h
 lib/psych.rb
 lib/psych/coder.rb
 lib/psych/core_ext.rb
 lib/psych/deprecated.rb
 lib/psych/handler.rb
 lib/psych/handlers/document_stream.rb
+lib/psych/handlers/recorder.rb
 lib/psych/json/ruby_events.rb
 lib/psych/json/stream.rb
 lib/psych/json/tree_builder.rb
@@ -48,6 +61,8 @@ lib/psych/visitors/json_tree.rb
 lib/psych/visitors/to_ruby.rb
 lib/psych/visitors/visitor.rb
 lib/psych/visitors/yaml_tree.rb
+lib/psych/y.rb
+test/psych/handlers/test_recorder.rb
 test/psych/helper.rb
 test/psych/json/test_stream.rb
 test/psych/nodes/test_enumerable.rb
diff --git a/README.rdoc b/README.rdoc
index 0294e31..91dc542 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -23,8 +23,28 @@ to and from the YAML format.
 
 == Installation
 
-* sudo port install libyaml +universal
-* sudo install_ruby.sh
+Psych has been included with MRI since 1.9.2,
+and is the default YAML parser in 1.9.3.
+
+If you want a newer gem release of Psych, you can use rubygems:
+
+  gem install psych
+
+In order to use the gem release in your app,
+and not the stdlib version, you'll need the following:
+
+  gem 'psych'
+  require 'psych'
+
+Or if you use Bundler add this to your +Gemfile+:
+
+  gem 'psych'
+
+JRuby ships with a pure Java implementation of Psych.
+
+If you're on Rubinius, Psych is available in 1.9 mode, please refer to the
+{Rubinius Documentation}[http://rubini.us/doc/en/build-system/] for more
+information on building and 1.9 mode.
 
 == License
 
diff --git a/Rakefile b/Rakefile
index f9aef47..00f040a 100644
--- a/Rakefile
+++ b/Rakefile
@@ -53,7 +53,7 @@ namespace :merge do
     [basedir, 'test', 'psych/'] => [rubydir, 'test', 'psych/'],
   }
 
-  rsync = 'rsync -av --exclude extconf.rb --exclude lib --exclude ".*" --exclude "*.o" --exclude Makefile --exclude mkmf.log --delete'
+  rsync = 'rsync -av --exclude lib --exclude ".*" --exclude "*.o" --exclude Makefile --exclude mkmf.log --delete'
 
   task :to_ruby do
     mergedirs.each do |from, to|
diff --git a/ext/psych/.gitignore b/ext/psych/.gitignore
new file mode 100644
index 0000000..836058c
--- /dev/null
+++ b/ext/psych/.gitignore
@@ -0,0 +1,11 @@
+/api.c
+/config.h
+/dumper.c
+/emitter.c
+/loader.c
+/parser.c
+/reader.c
+/scanner.c
+/writer.c
+/yaml.h
+/yaml_private.h
diff --git a/ext/psych/extconf.rb b/ext/psych/extconf.rb
index 0edf73c..65e83a3 100644
--- a/ext/psych/extconf.rb
+++ b/ext/psych/extconf.rb
@@ -1,21 +1,37 @@
+# -*- coding: us-ascii -*-
 require 'mkmf'
+require 'fileutils'
 
 # :stopdoc:
 
-RbConfig::MAKEFILE_CONFIG['CC'] = ENV['CC'] if ENV['CC']
+dir_config 'libyaml'
 
-INCLUDEDIR = RbConfig::CONFIG['includedir']
-LIBDIR     = RbConfig::CONFIG['libdir']
-LIB_DIRS   = ['/opt/local/lib', '/usr/local/lib', LIBDIR, '/usr/lib']
-libyaml    = dir_config 'libyaml', '/opt/local/include', '/opt/local/lib'
+if enable_config("bundled-libyaml", false) || !(find_header('yaml.h') && find_library('yaml', 'yaml_get_version'))
+  # Embed libyaml since we could not find it.
 
-def asplode missing
-  abort "#{missing} is missing. Try 'port install libyaml +universal' " +
-        "or 'yum install libyaml-devel'"
-end
+  $VPATH << "$(srcdir)/yaml"
+  $INCFLAGS << " -I$(srcdir)/yaml"
+
+  $srcs = Dir.glob("#{$srcdir}/{,yaml/}*.c").map {|n| File.basename(n)}
+
+  if have_macro("_WIN32")
+    $CPPFLAGS << " -DYAML_DECLARE_STATIC -DHAVE_CONFIG_H"
+  end
 
-asplode('yaml.h')  unless find_header  'yaml.h'
-asplode('libyaml') unless find_library 'yaml', 'yaml_get_version'
+  have_header 'dlfcn.h'
+  have_header 'inttypes.h'
+  have_header 'memory.h'
+  have_header 'stdint.h'
+  have_header 'stdlib.h'
+  have_header 'strings.h'
+  have_header 'string.h'
+  have_header 'sys/stat.h'
+  have_header 'sys/types.h'
+  have_header 'unistd.h'
+
+  find_header 'yaml.h'
+  have_header 'config.h'
+end
 
 create_makefile 'psych'
 
diff --git a/ext/psych/psych.h b/ext/psych/psych.h
index 9f1be44..1830ca4 100644
--- a/ext/psych/psych.h
+++ b/ext/psych/psych.h
@@ -9,10 +9,10 @@
 
 #include <yaml.h>
 
-#include <parser.h>
-#include <emitter.h>
-#include <to_ruby.h>
-#include <yaml_tree.h>
+#include <psych_parser.h>
+#include <psych_emitter.h>
+#include <psych_to_ruby.h>
+#include <psych_yaml_tree.h>
 
 extern VALUE mPsych;
 
diff --git a/ext/psych/emitter.c b/ext/psych/psych_emitter.c
index f0d0326..f0d0326 100644
--- a/ext/psych/emitter.c
+++ b/ext/psych/psych_emitter.c
diff --git a/ext/psych/emitter.h b/ext/psych/psych_emitter.h
index 560451e..560451e 100644
--- a/ext/psych/emitter.h
+++ b/ext/psych/psych_emitter.h
diff --git a/ext/psych/parser.c b/ext/psych/psych_parser.c
index 0908a1b..8c65ce1 100644
--- a/ext/psych/parser.c
+++ b/ext/psych/psych_parser.c
@@ -557,7 +557,7 @@ void Init_psych_parser()
     rb_define_const(cPsychParser, "UTF16BE", INT2NUM(YAML_UTF16BE_ENCODING));
 
     rb_require("psych/syntax_error");
-    ePsychSyntaxError = rb_define_class_under(mPsych, "SyntaxError", rb_eSyntaxError);
+    ePsychSyntaxError = rb_const_get(mPsych, rb_intern("SyntaxError"));
 
     rb_define_method(cPsychParser, "parse", parse, -1);
     rb_define_method(cPsychParser, "mark", mark, 0);
diff --git a/ext/psych/parser.h b/ext/psych/psych_parser.h
index 25e896f..25e896f 100644
--- a/ext/psych/parser.h
+++ b/ext/psych/psych_parser.h
diff --git a/ext/psych/to_ruby.c b/ext/psych/psych_to_ruby.c
index ed5245e..ed5245e 100644
--- a/ext/psych/to_ruby.c
+++ b/ext/psych/psych_to_ruby.c
diff --git a/ext/psych/to_ruby.h b/ext/psych/psych_to_ruby.h
index 7b8e757..7b8e757 100644
--- a/ext/psych/to_ruby.h
+++ b/ext/psych/psych_to_ruby.h
diff --git a/ext/psych/yaml_tree.c b/ext/psych/psych_yaml_tree.c
index bcf24d2..bcf24d2 100644
--- a/ext/psych/yaml_tree.c
+++ b/ext/psych/psych_yaml_tree.c
diff --git a/ext/psych/yaml_tree.h b/ext/psych/psych_yaml_tree.h
index 4628a69..4628a69 100644
--- a/ext/psych/yaml_tree.h
+++ b/ext/psych/psych_yaml_tree.h
diff --git a/ext/psych/yaml/LICENSE b/ext/psych/yaml/LICENSE
new file mode 100644
index 0000000..050ced2
--- /dev/null
+++ b/ext/psych/yaml/LICENSE
@@ -0,0 +1,19 @@
+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/ext/psych/yaml/api.c b/ext/psych/yaml/api.c
new file mode 100644
index 0000000..0c4732e
--- /dev/null
+++ b/ext/psych/yaml/api.c
@@ -0,0 +1,1392 @@
+
+#include "yaml_private.h"
+
+/*
+ * Get the library version.
+ */
+
+YAML_DECLARE(const char *)
+yaml_get_version_string(void)
+{
+    return YAML_VERSION_STRING;
+}
+
+/*
+ * Get the library version numbers.
+ */
+
+YAML_DECLARE(void)
+yaml_get_version(int *major, int *minor, int *patch)
+{
+    *major = YAML_VERSION_MAJOR;
+    *minor = YAML_VERSION_MINOR;
+    *patch = YAML_VERSION_PATCH;
+}
+
+/*
+ * Allocate a dynamic memory block.
+ */
+
+YAML_DECLARE(void *)
+yaml_malloc(size_t size)
+{
+    return malloc(size ? size : 1);
+}
+
+/*
+ * Reallocate a dynamic memory block.
+ */
+
+YAML_DECLARE(void *)
+yaml_realloc(void *ptr, size_t size)
+{
+    return ptr ? realloc(ptr, size ? size : 1) : malloc(size ? size : 1);
+}
+
+/*
+ * Free a dynamic memory block.
+ */
+
+YAML_DECLARE(void)
+yaml_free(void *ptr)
+{
+    if (ptr) free(ptr);
+}
+
+/*
+ * Duplicate a string.
+ */
+
+YAML_DECLARE(yaml_char_t *)
+yaml_strdup(const yaml_char_t *str)
+{
+    if (!str)
+        return NULL;
+
+    return (yaml_char_t *)strdup((char *)str);
+}
+
+/*
+ * Extend a string.
+ */
+
+YAML_DECLARE(int)
+yaml_string_extend(yaml_char_t **start,
+        yaml_char_t **pointer, yaml_char_t **end)
+{
+    yaml_char_t *new_start = yaml_realloc(*start, (*end - *start)*2);
+
+    if (!new_start) return 0;
+
+    memset(new_start + (*end - *start), 0, *end - *start);
+
+    *pointer = new_start + (*pointer - *start);
+    *end = new_start + (*end - *start)*2;
+    *start = new_start;
+
+    return 1;
+}
+
+/*
+ * Append a string B to a string A.
+ */
+
+YAML_DECLARE(int)
+yaml_string_join(
+        yaml_char_t **a_start, yaml_char_t **a_pointer, yaml_char_t **a_end,
+        yaml_char_t **b_start, yaml_char_t **b_pointer, yaml_char_t **b_end)
+{
+    if (*b_start == *b_pointer)
+        return 1;
+
+    while (*a_end - *a_pointer <= *b_pointer - *b_start) {
+        if (!yaml_string_extend(a_start, a_pointer, a_end))
+            return 0;
+    }
+
+    memcpy(*a_pointer, *b_start, *b_pointer - *b_start);
+    *a_pointer += *b_pointer - *b_start;
+
+    return 1;
+}
+
+/*
+ * Extend a stack.
+ */
+
+YAML_DECLARE(int)
+yaml_stack_extend(void **start, void **top, void **end)
+{
+    void *new_start = yaml_realloc(*start, ((char *)*end - (char *)*start)*2);
+
+    if (!new_start) return 0;
+
+    *top = (char *)new_start + ((char *)*top - (char *)*start);
+    *end = (char *)new_start + ((char *)*end - (char *)*start)*2;
+    *start = new_start;
+
+    return 1;
+}
+
+/*
+ * Extend or move a queue.
+ */
+
+YAML_DECLARE(int)
+yaml_queue_extend(void **start, void **head, void **tail, void **end)
+{
+    /* Check if we need to resize the queue. */
+
+    if (*start == *head && *tail == *end) {
+        void *new_start = yaml_realloc(*start,
+                ((char *)*end - (char *)*start)*2);
+
+        if (!new_start) return 0;
+
+        *head = (char *)new_start + ((char *)*head - (char *)*start);
+        *tail = (char *)new_start + ((char *)*tail - (char *)*start);
+        *end = (char *)new_start + ((char *)*end - (char *)*start)*2;
+        *start = new_start;
+    }
+
+    /* Check if we need to move the queue at the beginning of the buffer. */
+
+    if (*tail == *end) {
+        if (*head != *tail) {
+            memmove(*start, *head, (char *)*tail - (char *)*head);
+        }
+        *tail = (char *)*tail - (char *)*head + (char *)*start;
+        *head = *start;
+    }
+
+    return 1;
+}
+
+
+/*
+ * Create a new parser object.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_initialize(yaml_parser_t *parser)
+{
+    assert(parser);     /* Non-NULL parser object expected. */
+
+    memset(parser, 0, sizeof(yaml_parser_t));
+    if (!BUFFER_INIT(parser, parser->raw_buffer, INPUT_RAW_BUFFER_SIZE))
+        goto error;
+    if (!BUFFER_INIT(parser, parser->buffer, INPUT_BUFFER_SIZE))
+        goto error;
+    if (!QUEUE_INIT(parser, parser->tokens, INITIAL_QUEUE_SIZE))
+        goto error;
+    if (!STACK_INIT(parser, parser->indents, INITIAL_STACK_SIZE))
+        goto error;
+    if (!STACK_INIT(parser, parser->simple_keys, INITIAL_STACK_SIZE))
+        goto error;
+    if (!STACK_INIT(parser, parser->states, INITIAL_STACK_SIZE))
+        goto error;
+    if (!STACK_INIT(parser, parser->marks, INITIAL_STACK_SIZE))
+        goto error;
+    if (!STACK_INIT(parser, parser->tag_directives, INITIAL_STACK_SIZE))
+        goto error;
+
+    return 1;
+
+error:
+
+    BUFFER_DEL(parser, parser->raw_buffer);
+    BUFFER_DEL(parser, parser->buffer);
+    QUEUE_DEL(parser, parser->tokens);
+    STACK_DEL(parser, parser->indents);
+    STACK_DEL(parser, parser->simple_keys);
+    STACK_DEL(parser, parser->states);
+    STACK_DEL(parser, parser->marks);
+    STACK_DEL(parser, parser->tag_directives);
+
+    return 0;
+}
+
+/*
+ * Destroy a parser object.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_delete(yaml_parser_t *parser)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+
+    BUFFER_DEL(parser, parser->raw_buffer);
+    BUFFER_DEL(parser, parser->buffer);
+    while (!QUEUE_EMPTY(parser, parser->tokens)) {
+        yaml_token_delete(&DEQUEUE(parser, parser->tokens));
+    }
+    QUEUE_DEL(parser, parser->tokens);
+    STACK_DEL(parser, parser->indents);
+    STACK_DEL(parser, parser->simple_keys);
+    STACK_DEL(parser, parser->states);
+    STACK_DEL(parser, parser->marks);
+    while (!STACK_EMPTY(parser, parser->tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(parser, parser->tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+    STACK_DEL(parser, parser->tag_directives);
+
+    memset(parser, 0, sizeof(yaml_parser_t));
+}
+
+/*
+ * String read handler.
+ */
+
+static int
+yaml_string_read_handler(void *data, unsigned char *buffer, size_t size,
+        size_t *size_read)
+{
+    yaml_parser_t *parser = data;
+
+    if (parser->input.string.current == parser->input.string.end) {
+        *size_read = 0;
+        return 1;
+    }
+
+    if (size > (size_t)(parser->input.string.end
+                - parser->input.string.current)) {
+        size = parser->input.string.end - parser->input.string.current;
+    }
+
+    memcpy(buffer, parser->input.string.current, size);
+    parser->input.string.current += size;
+    *size_read = size;
+    return 1;
+}
+
+/*
+ * File read handler.
+ */
+
+static int
+yaml_file_read_handler(void *data, unsigned char *buffer, size_t size,
+        size_t *size_read)
+{
+    yaml_parser_t *parser = data;
+
+    *size_read = fread(buffer, 1, size, parser->input.file);
+    return !ferror(parser->input.file);
+}
+
+/*
+ * Set a string input.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input_string(yaml_parser_t *parser,
+        const unsigned char *input, size_t size)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->read_handler);  /* You can set the source only once. */
+    assert(input);  /* Non-NULL input string expected. */
+
+    parser->read_handler = yaml_string_read_handler;
+    parser->read_handler_data = parser;
+
+    parser->input.string.start = input;
+    parser->input.string.current = input;
+    parser->input.string.end = input+size;
+}
+
+/*
+ * Set a file input.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input_file(yaml_parser_t *parser, FILE *file)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->read_handler);  /* You can set the source only once. */
+    assert(file);   /* Non-NULL file object expected. */
+
+    parser->read_handler = yaml_file_read_handler;
+    parser->read_handler_data = parser;
+
+    parser->input.file = file;
+}
+
+/*
+ * Set a generic input.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input(yaml_parser_t *parser,
+        yaml_read_handler_t *handler, void *data)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->read_handler);  /* You can set the source only once. */
+    assert(handler);    /* Non-NULL read handler expected. */
+
+    parser->read_handler = handler;
+    parser->read_handler_data = data;
+}
+
+/*
+ * Set the source encoding.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_encoding(yaml_parser_t *parser, yaml_encoding_t encoding)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->encoding); /* Encoding is already set or detected. */
+
+    parser->encoding = encoding;
+}
+
+/*
+ * Create a new emitter object.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_initialize(yaml_emitter_t *emitter)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    memset(emitter, 0, sizeof(yaml_emitter_t));
+    if (!BUFFER_INIT(emitter, emitter->buffer, OUTPUT_BUFFER_SIZE))
+        goto error;
+    if (!BUFFER_INIT(emitter, emitter->raw_buffer, OUTPUT_RAW_BUFFER_SIZE))
+        goto error;
+    if (!STACK_INIT(emitter, emitter->states, INITIAL_STACK_SIZE))
+        goto error;
+    if (!QUEUE_INIT(emitter, emitter->events, INITIAL_QUEUE_SIZE))
+        goto error;
+    if (!STACK_INIT(emitter, emitter->indents, INITIAL_STACK_SIZE))
+        goto error;
+    if (!STACK_INIT(emitter, emitter->tag_directives, INITIAL_STACK_SIZE))
+        goto error;
+
+    return 1;
+
+error:
+
+    BUFFER_DEL(emitter, emitter->buffer);
+    BUFFER_DEL(emitter, emitter->raw_buffer);
+    STACK_DEL(emitter, emitter->states);
+    QUEUE_DEL(emitter, emitter->events);
+    STACK_DEL(emitter, emitter->indents);
+    STACK_DEL(emitter, emitter->tag_directives);
+
+    return 0;
+}
+
+/*
+ * Destroy an emitter object.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_delete(yaml_emitter_t *emitter)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    BUFFER_DEL(emitter, emitter->buffer);
+    BUFFER_DEL(emitter, emitter->raw_buffer);
+    STACK_DEL(emitter, emitter->states);
+    while (!QUEUE_EMPTY(emitter, emitter->events)) {
+        yaml_event_delete(&DEQUEUE(emitter, emitter->events));
+    }
+    QUEUE_DEL(emitter, emitter->events);
+    STACK_DEL(emitter, emitter->indents);
+    while (!STACK_EMPTY(empty, emitter->tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(emitter, emitter->tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+    STACK_DEL(emitter, emitter->tag_directives);
+    yaml_free(emitter->anchors);
+
+    memset(emitter, 0, sizeof(yaml_emitter_t));
+}
+
+/*
+ * String write handler.
+ */
+
+static int
+yaml_string_write_handler(void *data, unsigned char *buffer, size_t size)
+{
+    yaml_emitter_t *emitter = data;
+
+    if (emitter->output.string.size + *emitter->output.string.size_written
+            < size) {
+        memcpy(emitter->output.string.buffer
+                + *emitter->output.string.size_written,
+                buffer,
+                emitter->output.string.size
+                - *emitter->output.string.size_written);
+        *emitter->output.string.size_written = emitter->output.string.size;
+        return 0;
+    }
+
+    memcpy(emitter->output.string.buffer
+            + *emitter->output.string.size_written, buffer, size);
+    *emitter->output.string.size_written += size;
+    return 1;
+}
+
+/*
+ * File write handler.
+ */
+
+static int
+yaml_file_write_handler(void *data, unsigned char *buffer, size_t size)
+{
+    yaml_emitter_t *emitter = data;
+
+    return (fwrite(buffer, 1, size, emitter->output.file) == size);
+}
+/*
+ * Set a string output.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output_string(yaml_emitter_t *emitter,
+        unsigned char *output, size_t size, size_t *size_written)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->write_handler);    /* You can set the output only once. */
+    assert(output);     /* Non-NULL output string expected. */
+
+    emitter->write_handler = yaml_string_write_handler;
+    emitter->write_handler_data = emitter;
+
+    emitter->output.string.buffer = output;
+    emitter->output.string.size = size;
+    emitter->output.string.size_written = size_written;
+    *size_written = 0;
+}
+
+/*
+ * Set a file output.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output_file(yaml_emitter_t *emitter, FILE *file)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->write_handler);    /* You can set the output only once. */
+    assert(file);       /* Non-NULL file object expected. */
+
+    emitter->write_handler = yaml_file_write_handler;
+    emitter->write_handler_data = emitter;
+
+    emitter->output.file = file;
+}
+
+/*
+ * Set a generic output handler.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output(yaml_emitter_t *emitter,
+        yaml_write_handler_t *handler, void *data)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->write_handler);    /* You can set the output only once. */
+    assert(handler);    /* Non-NULL handler object expected. */
+
+    emitter->write_handler = handler;
+    emitter->write_handler_data = data;
+}
+
+/*
+ * Set the output encoding.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_encoding(yaml_emitter_t *emitter, yaml_encoding_t encoding)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->encoding);     /* You can set encoding only once. */
+
+    emitter->encoding = encoding;
+}
+
+/*
+ * Set the canonical output style.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_canonical(yaml_emitter_t *emitter, int canonical)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->canonical = (canonical != 0);
+}
+
+/*
+ * Set the indentation increment.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_indent(yaml_emitter_t *emitter, int indent)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->best_indent = (1 < indent && indent < 10) ? indent : 2;
+}
+
+/*
+ * Set the preferred line width.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_width(yaml_emitter_t *emitter, int width)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->best_width = (width >= 0) ? width : -1;
+}
+
+/*
+ * Set if unescaped non-ASCII characters are allowed.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_unicode(yaml_emitter_t *emitter, int unicode)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->unicode = (unicode != 0);
+}
+
+/*
+ * Set the preferred line break character.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_break(yaml_emitter_t *emitter, yaml_break_t line_break)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    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.
+ */
+
+YAML_DECLARE(int)
+yaml_stream_start_event_initialize(yaml_event_t *event,
+        yaml_encoding_t encoding)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);  /* Non-NULL event object is expected. */
+
+    STREAM_START_EVENT_INIT(*event, encoding, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create STREAM-END.
+ */
+
+YAML_DECLARE(int)
+yaml_stream_end_event_initialize(yaml_event_t *event)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);  /* Non-NULL event object is expected. */
+
+    STREAM_END_EVENT_INIT(*event, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create DOCUMENT-START.
+ */
+
+YAML_DECLARE(int)
+yaml_document_start_event_initialize(yaml_event_t *event,
+        yaml_version_directive_t *version_directive,
+        yaml_tag_directive_t *tag_directives_start,
+        yaml_tag_directive_t *tag_directives_end,
+        int implicit)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_version_directive_t *version_directive_copy = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+        yaml_tag_directive_t *top;
+    } tag_directives_copy = { NULL, NULL, NULL };
+    yaml_tag_directive_t value = { NULL, NULL };
+
+    assert(event);          /* Non-NULL event object is expected. */
+    assert((tag_directives_start && tag_directives_end) ||
+            (tag_directives_start == tag_directives_end));
+                            /* Valid tag directives are expected. */
+
+    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) {
+        yaml_tag_directive_t *tag_directive;
+        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_START_EVENT_INIT(*event, version_directive_copy,
+            tag_directives_copy.start, tag_directives_copy.top,
+            implicit, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(version_directive_copy);
+    while (!STACK_EMPTY(context, tag_directives_copy)) {
+        yaml_tag_directive_t value = 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;
+}
+
+/*
+ * Create DOCUMENT-END.
+ */
+
+YAML_DECLARE(int)
+yaml_document_end_event_initialize(yaml_event_t *event, int implicit)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);      /* Non-NULL emitter object is expected. */
+
+    DOCUMENT_END_EVENT_INIT(*event, implicit, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create ALIAS.
+ */
+
+YAML_DECLARE(int)
+yaml_alias_event_initialize(yaml_event_t *event, yaml_char_t *anchor)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = 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.
+ */
+
+YAML_DECLARE(int)
+yaml_scalar_event_initialize(yaml_event_t *event,
+        yaml_char_t *anchor, yaml_char_t *tag,
+        yaml_char_t *value, int length,
+        int plain_implicit, int quoted_implicit,
+        yaml_scalar_style_t style)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+    yaml_char_t *tag_copy = NULL;
+    yaml_char_t *value_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+    assert(value);      /* Non-NULL anchor is expected. */
+
+    if (anchor) {
+        if (!yaml_check_utf8(anchor, strlen((char *)anchor))) goto error;
+        anchor_copy = yaml_strdup(anchor);
+        if (!anchor_copy) goto error;
+    }
+
+    if (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_EVENT_INIT(*event, anchor_copy, tag_copy, value_copy, length,
+            plain_implicit, quoted_implicit, style, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(anchor_copy);
+    yaml_free(tag_copy);
+    yaml_free(value_copy);
+
+    return 0;
+}
+
+/*
+ * Create SEQUENCE-START.
+ */
+
+YAML_DECLARE(int)
+yaml_sequence_start_event_initialize(yaml_event_t *event,
+        yaml_char_t *anchor, yaml_char_t *tag, int implicit,
+        yaml_sequence_style_t style)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+    yaml_char_t *tag_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    if (anchor) {
+        if (!yaml_check_utf8(anchor, strlen((char *)anchor))) goto error;
+        anchor_copy = yaml_strdup(anchor);
+        if (!anchor_copy) goto error;
+    }
+
+    if (tag) {
+        if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+        tag_copy = yaml_strdup(tag);
+        if (!tag_copy) goto error;
+    }
+
+    SEQUENCE_START_EVENT_INIT(*event, anchor_copy, tag_copy,
+            implicit, style, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(anchor_copy);
+    yaml_free(tag_copy);
+
+    return 0;
+}
+
+/*
+ * Create SEQUENCE-END.
+ */
+
+YAML_DECLARE(int)
+yaml_sequence_end_event_initialize(yaml_event_t *event)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    SEQUENCE_END_EVENT_INIT(*event, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create MAPPING-START.
+ */
+
+YAML_DECLARE(int)
+yaml_mapping_start_event_initialize(yaml_event_t *event,
+        yaml_char_t *anchor, yaml_char_t *tag, int implicit,
+        yaml_mapping_style_t style)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+    yaml_char_t *tag_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    if (anchor) {
+        if (!yaml_check_utf8(anchor, strlen((char *)anchor))) goto error;
+        anchor_copy = yaml_strdup(anchor);
+        if (!anchor_copy) goto error;
+    }
+
+    if (tag) {
+        if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+        tag_copy = yaml_strdup(tag);
+        if (!tag_copy) goto error;
+    }
+
+    MAPPING_START_EVENT_INIT(*event, anchor_copy, tag_copy,
+            implicit, style, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(anchor_copy);
+    yaml_free(tag_copy);
+
+    return 0;
+}
+
+/*
+ * Create MAPPING-END.
+ */
+
+YAML_DECLARE(int)
+yaml_mapping_end_event_initialize(yaml_event_t *event)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    MAPPING_END_EVENT_INIT(*event, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Destroy an event object.
+ */
+
+YAML_DECLARE(void)
+yaml_event_delete(yaml_event_t *event)
+{
+    yaml_tag_directive_t *tag_directive;
+
+    assert(event);  /* Non-NULL event object expected. */
+
+    switch (event->type)
+    {
+        case YAML_DOCUMENT_START_EVENT:
+            yaml_free(event->data.document_start.version_directive);
+            for (tag_directive = event->data.document_start.tag_directives.start;
+                    tag_directive != event->data.document_start.tag_directives.end;
+                    tag_directive++) {
+                yaml_free(tag_directive->handle);
+                yaml_free(tag_directive->prefix);
+            }
+            yaml_free(event->data.document_start.tag_directives.start);
+            break;
+
+        case YAML_ALIAS_EVENT:
+            yaml_free(event->data.alias.anchor);
+            break;
+
+        case YAML_SCALAR_EVENT:
+            yaml_free(event->data.scalar.anchor);
+            yaml_free(event->data.scalar.tag);
+            yaml_free(event->data.scalar.value);
+            break;
+
+        case YAML_SEQUENCE_START_EVENT:
+            yaml_free(event->data.sequence_start.anchor);
+            yaml_free(event->data.sequence_start.tag);
+            break;
+
+        case YAML_MAPPING_START_EVENT:
+            yaml_free(event->data.mapping_start.anchor);
+            yaml_free(event->data.mapping_start.tag);
+            break;
+
+        default:
+            break;
+    }
+
+    memset(event, 0, sizeof(yaml_event_t));
+}
+
+/*
+ * Create a document object.
+ */
+
+YAML_DECLARE(int)
+yaml_document_initialize(yaml_document_t *document,
+        yaml_version_directive_t *version_directive,
+        yaml_tag_directive_t *tag_directives_start,
+        yaml_tag_directive_t *tag_directives_end,
+        int start_implicit, int end_implicit)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    struct {
+        yaml_node_t *start;
+        yaml_node_t *end;
+        yaml_node_t *top;
+    } nodes = { NULL, NULL, NULL };
+    yaml_version_directive_t *version_directive_copy = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+        yaml_tag_directive_t *top;
+    } tag_directives_copy = { NULL, NULL, NULL };
+    yaml_tag_directive_t value = { NULL, NULL };
+    yaml_mark_t mark = { 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) {
+        yaml_tag_directive_t *tag_directive;
+        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)) {
+        yaml_tag_directive_t value = 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(yaml_document_t *document)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_tag_directive_t *tag_directive;
+
+    context.error = YAML_NO_ERROR;  /* Eliminate a compliler warning. */
+
+    assert(document);   /* Non-NULL document object is expected. */
+
+    while (!STACK_EMPTY(&context, document->nodes)) {
+        yaml_node_t node = 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(yaml_document_t *document, int index)
+{
+    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(yaml_document_t *document)
+{
+    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(yaml_document_t *document,
+        yaml_char_t *tag, yaml_char_t *value, int length,
+        yaml_scalar_style_t style)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *tag_copy = NULL;
+    yaml_char_t *value_copy = NULL;
+    yaml_node_t node;
+
+    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(yaml_document_t *document,
+        yaml_char_t *tag, yaml_sequence_style_t style)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *tag_copy = NULL;
+    struct {
+        yaml_node_item_t *start;
+        yaml_node_item_t *end;
+        yaml_node_item_t *top;
+    } items = { NULL, NULL, NULL };
+    yaml_node_t node;
+
+    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(yaml_document_t *document,
+        yaml_char_t *tag, yaml_mapping_style_t style)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *tag_copy = NULL;
+    struct {
+        yaml_node_pair_t *start;
+        yaml_node_pair_t *end;
+        yaml_node_pair_t *top;
+    } pairs = { NULL, NULL, NULL };
+    yaml_node_t node;
+
+    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(yaml_document_t *document,
+        int sequence, int item)
+{
+    struct {
+        yaml_error_type_t error;
+    } 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(yaml_document_t *document,
+        int mapping, int key, int value)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+
+    yaml_node_pair_t pair;
+
+    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/ext/psych/yaml/config.h b/ext/psych/yaml/config.h
new file mode 100644
index 0000000..6d6c25b
--- /dev/null
+++ b/ext/psych/yaml/config.h
@@ -0,0 +1,11 @@
+
+#define PACKAGE_NAME "yaml"
+#define PACKAGE_TARNAME "yaml"
+#define PACKAGE_VERSION "0.1.4"
+#define PACKAGE_STRING "yaml 0.1.4"
+#define PACKAGE_BUGREPORT "http://pyyaml.org/newticket?component libyaml"
+#define PACKAGE_URL ""
+#define YAML_VERSION_MAJOR 0
+#define YAML_VERSION_MINOR 1
+#define YAML_VERSION_PATCH 4
+#define YAML_VERSION_STRING "0.1.4"
diff --git a/ext/psych/yaml/dumper.c b/ext/psych/yaml/dumper.c
new file mode 100644
index 0000000..203c6a7
--- /dev/null
+++ b/ext/psych/yaml/dumper.c
@@ -0,0 +1,394 @@
+
+#include "yaml_private.h"
+
+/*
+ * API functions.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_open(yaml_emitter_t *emitter);
+
+YAML_DECLARE(int)
+yaml_emitter_close(yaml_emitter_t *emitter);
+
+YAML_DECLARE(int)
+yaml_emitter_dump(yaml_emitter_t *emitter, yaml_document_t *document);
+
+/*
+ * Clean up functions.
+ */
+
+static void
+yaml_emitter_delete_document_and_anchors(yaml_emitter_t *emitter);
+
+/*
+ * Anchor functions.
+ */
+
+static void
+yaml_emitter_anchor_node(yaml_emitter_t *emitter, int index);
+
+static yaml_char_t *
+yaml_emitter_generate_anchor(yaml_emitter_t *emitter, int anchor_id);
+
+
+/*
+ * Serialize functions.
+ */
+
+static int
+yaml_emitter_dump_node(yaml_emitter_t *emitter, int index);
+
+static int
+yaml_emitter_dump_alias(yaml_emitter_t *emitter, yaml_char_t *anchor);
+
+static int
+yaml_emitter_dump_scalar(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor);
+
+static int
+yaml_emitter_dump_sequence(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor);
+
+static int
+yaml_emitter_dump_mapping(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor);
+
+/*
+ * Issue a STREAM-START event.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_open(yaml_emitter_t *emitter)
+{
+    yaml_event_t event;
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(emitter);            /* Non-NULL emitter object is required. */
+    assert(!emitter->opened);   /* Emitter should not be opened yet. */
+
+    STREAM_START_EVENT_INIT(event, YAML_ANY_ENCODING, mark, mark);
+
+    if (!yaml_emitter_emit(emitter, &event)) {
+        return 0;
+    }
+
+    emitter->opened = 1;
+
+    return 1;
+}
+
+/*
+ * Issue a STREAM-END event.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_close(yaml_emitter_t *emitter)
+{
+    yaml_event_t event;
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(emitter);            /* Non-NULL emitter object is required. */
+    assert(emitter->opened);    /* Emitter should be opened. */
+
+    if (emitter->closed) return 1;
+
+    STREAM_END_EVENT_INIT(event, mark, mark);
+
+    if (!yaml_emitter_emit(emitter, &event)) {
+        return 0;
+    }
+
+    emitter->closed = 1;
+
+    return 1;
+}
+
+/*
+ * Dump a YAML document.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_dump(yaml_emitter_t *emitter, yaml_document_t *document)
+{
+    yaml_event_t event;
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(emitter);            /* Non-NULL emitter object is required. */
+    assert(document);           /* Non-NULL emitter object is expected. */
+
+    emitter->document = document;
+
+    if (!emitter->opened) {
+        if (!yaml_emitter_open(emitter)) goto error;
+    }
+
+    if (STACK_EMPTY(emitter, document->nodes)) {
+        if (!yaml_emitter_close(emitter)) goto error;
+        yaml_emitter_delete_document_and_anchors(emitter);
+        return 1;
+    }
+
+    assert(emitter->opened);    /* Emitter should be opened. */
+
+    emitter->anchors = yaml_malloc(sizeof(*(emitter->anchors))
+            * (document->nodes.top - document->nodes.start));
+    if (!emitter->anchors) goto error;
+    memset(emitter->anchors, 0, sizeof(*(emitter->anchors))
+            * (document->nodes.top - document->nodes.start));
+
+    DOCUMENT_START_EVENT_INIT(event, document->version_directive,
+            document->tag_directives.start, document->tag_directives.end,
+            document->start_implicit, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) goto error;
+
+    yaml_emitter_anchor_node(emitter, 1);
+    if (!yaml_emitter_dump_node(emitter, 1)) goto error;
+
+    DOCUMENT_END_EVENT_INIT(event, document->end_implicit, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) goto error;
+
+    yaml_emitter_delete_document_and_anchors(emitter);
+
+    return 1;
+
+error:
+
+    yaml_emitter_delete_document_and_anchors(emitter);
+
+    return 0;
+}
+
+/*
+ * Clean up the emitter object after a document is dumped.
+ */
+
+static void
+yaml_emitter_delete_document_and_anchors(yaml_emitter_t *emitter)
+{
+    int index;
+
+    if (!emitter->anchors) {
+        yaml_document_delete(emitter->document);
+        emitter->document = NULL;
+        return;
+    }
+
+    for (index = 0; emitter->document->nodes.start + index
+            < emitter->document->nodes.top; index ++) {
+        yaml_node_t node = emitter->document->nodes.start[index];
+        if (!emitter->anchors[index].serialized) {
+            yaml_free(node.tag);
+            if (node.type == YAML_SCALAR_NODE) {
+                yaml_free(node.data.scalar.value);
+            }
+        }
+        if (node.type == YAML_SEQUENCE_NODE) {
+            STACK_DEL(emitter, node.data.sequence.items);
+        }
+        if (node.type == YAML_MAPPING_NODE) {
+            STACK_DEL(emitter, node.data.mapping.pairs);
+        }
+    }
+
+    STACK_DEL(emitter, emitter->document->nodes);
+    yaml_free(emitter->anchors);
+
+    emitter->anchors = NULL;
+    emitter->last_anchor_id = 0;
+    emitter->document = NULL;
+}
+
+/*
+ * Check the references of a node and assign the anchor id if needed.
+ */
+
+static void
+yaml_emitter_anchor_node(yaml_emitter_t *emitter, int index)
+{
+    yaml_node_t *node = emitter->document->nodes.start + index - 1;
+    yaml_node_item_t *item;
+    yaml_node_pair_t *pair;
+
+    emitter->anchors[index-1].references ++;
+
+    if (emitter->anchors[index-1].references == 1) {
+        switch (node->type) {
+            case YAML_SEQUENCE_NODE:
+                for (item = node->data.sequence.items.start;
+                        item < node->data.sequence.items.top; item ++) {
+                    yaml_emitter_anchor_node(emitter, *item);
+                }
+                break;
+            case YAML_MAPPING_NODE:
+                for (pair = node->data.mapping.pairs.start;
+                        pair < node->data.mapping.pairs.top; pair ++) {
+                    yaml_emitter_anchor_node(emitter, pair->key);
+                    yaml_emitter_anchor_node(emitter, pair->value);
+                }
+                break;
+            default:
+                break;
+        }
+    }
+
+    else if (emitter->anchors[index-1].references == 2) {
+        emitter->anchors[index-1].anchor = (++ emitter->last_anchor_id);
+    }
+}
+
+/*
+ * Generate a textual representation for an anchor.
+ */
+
+#define ANCHOR_TEMPLATE         "id%03d"
+#define ANCHOR_TEMPLATE_LENGTH  16
+
+static yaml_char_t *
+yaml_emitter_generate_anchor(yaml_emitter_t *emitter, int anchor_id)
+{
+    yaml_char_t *anchor = yaml_malloc(ANCHOR_TEMPLATE_LENGTH);
+
+    if (!anchor) return NULL;
+
+    sprintf((char *)anchor, ANCHOR_TEMPLATE, anchor_id);
+
+    return anchor;
+}
+
+/*
+ * Serialize a node.
+ */
+
+static int
+yaml_emitter_dump_node(yaml_emitter_t *emitter, int index)
+{
+    yaml_node_t *node = emitter->document->nodes.start + index - 1;
+    int anchor_id = emitter->anchors[index-1].anchor;
+    yaml_char_t *anchor = NULL;
+
+    if (anchor_id) {
+        anchor = yaml_emitter_generate_anchor(emitter, anchor_id);
+        if (!anchor) return 0;
+    }
+
+    if (emitter->anchors[index-1].serialized) {
+        return yaml_emitter_dump_alias(emitter, anchor);
+    }
+
+    emitter->anchors[index-1].serialized = 1;
+
+    switch (node->type) {
+        case YAML_SCALAR_NODE:
+            return yaml_emitter_dump_scalar(emitter, node, anchor);
+        case YAML_SEQUENCE_NODE:
+            return yaml_emitter_dump_sequence(emitter, node, anchor);
+        case YAML_MAPPING_NODE:
+            return yaml_emitter_dump_mapping(emitter, node, anchor);
+        default:
+            assert(0);      /* Could not happen. */
+            break;
+    }
+
+    return 0;       /* Could not happen. */
+}
+
+/*
+ * Serialize an alias.
+ */
+
+static int
+yaml_emitter_dump_alias(yaml_emitter_t *emitter, yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    ALIAS_EVENT_INIT(event, anchor, mark, mark);
+
+    return yaml_emitter_emit(emitter, &event);
+}
+
+/*
+ * Serialize a scalar.
+ */
+
+static int
+yaml_emitter_dump_scalar(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    int plain_implicit = (strcmp((char *)node->tag,
+                YAML_DEFAULT_SCALAR_TAG) == 0);
+    int quoted_implicit = (strcmp((char *)node->tag,
+                YAML_DEFAULT_SCALAR_TAG) == 0);
+
+    SCALAR_EVENT_INIT(event, anchor, node->tag, node->data.scalar.value,
+            node->data.scalar.length, plain_implicit, quoted_implicit,
+            node->data.scalar.style, mark, mark);
+
+    return yaml_emitter_emit(emitter, &event);
+}
+
+/*
+ * Serialize a sequence.
+ */
+
+static int
+yaml_emitter_dump_sequence(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    int implicit = (strcmp((char *)node->tag, YAML_DEFAULT_SEQUENCE_TAG) == 0);
+
+    yaml_node_item_t *item;
+
+    SEQUENCE_START_EVENT_INIT(event, anchor, node->tag, implicit,
+            node->data.sequence.style, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    for (item = node->data.sequence.items.start;
+            item < node->data.sequence.items.top; item ++) {
+        if (!yaml_emitter_dump_node(emitter, *item)) return 0;
+    }
+
+    SEQUENCE_END_EVENT_INIT(event, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    return 1;
+}
+
+/*
+ * Serialize a mapping.
+ */
+
+static int
+yaml_emitter_dump_mapping(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    int implicit = (strcmp((char *)node->tag, YAML_DEFAULT_MAPPING_TAG) == 0);
+
+    yaml_node_pair_t *pair;
+
+    MAPPING_START_EVENT_INIT(event, anchor, node->tag, implicit,
+            node->data.mapping.style, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    for (pair = node->data.mapping.pairs.start;
+            pair < node->data.mapping.pairs.top; pair ++) {
+        if (!yaml_emitter_dump_node(emitter, pair->key)) return 0;
+        if (!yaml_emitter_dump_node(emitter, pair->value)) return 0;
+    }
+
+    MAPPING_END_EVENT_INIT(event, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    return 1;
+}
+
diff --git a/ext/psych/yaml/emitter.c b/ext/psych/yaml/emitter.c
new file mode 100644
index 0000000..c852f93
--- /dev/null
+++ b/ext/psych/yaml/emitter.c
@@ -0,0 +1,2329 @@
+
+#include "yaml_private.h"
+
+/*
+ * Flush the buffer if needed.
+ */
+
+#define FLUSH(emitter)                                                          \
+    ((emitter->buffer.pointer+5 < emitter->buffer.end)                          \
+     || yaml_emitter_flush(emitter))
+
+/*
+ * Put a character to the output buffer.
+ */
+
+#define PUT(emitter,value)                                                      \
+    (FLUSH(emitter)                                                             \
+     && (*(emitter->buffer.pointer++) = (yaml_char_t)(value),                   \
+         emitter->column ++,                                                    \
+         1))
+
+/*
+ * Put a line break to the output buffer.
+ */
+
+#define PUT_BREAK(emitter)                                                      \
+    (FLUSH(emitter)                                                             \
+     && ((emitter->line_break == YAML_CR_BREAK ?                                \
+             (*(emitter->buffer.pointer++) = (yaml_char_t) '\r') :              \
+          emitter->line_break == YAML_LN_BREAK ?                                \
+             (*(emitter->buffer.pointer++) = (yaml_char_t) '\n') :              \
+          emitter->line_break == YAML_CRLN_BREAK ?                              \
+             (*(emitter->buffer.pointer++) = (yaml_char_t) '\r',                \
+              *(emitter->buffer.pointer++) = (yaml_char_t) '\n') : 0),          \
+         emitter->column = 0,                                                   \
+         emitter->line ++,                                                      \
+         1))
+
+/*
+ * Copy a character from a string into buffer.
+ */
+
+#define WRITE(emitter,string)                                                   \
+    (FLUSH(emitter)                                                             \
+     && (COPY(emitter->buffer,string),                                          \
+         emitter->column ++,                                                    \
+         1))
+
+/*
+ * Copy a line break character from a string into buffer.
+ */
+
+#define WRITE_BREAK(emitter,string)                                             \
+    (FLUSH(emitter)                                                             \
+     && (CHECK(string,'\n') ?                                                   \
+         (PUT_BREAK(emitter),                                                   \
+          string.pointer ++,                                                    \
+          1) :                                                                  \
+         (COPY(emitter->buffer,string),                                         \
+          emitter->column = 0,                                                  \
+          emitter->line ++,                                                     \
+          1)))
+
+/*
+ * API functions.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_emit(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/*
+ * Utility functions.
+ */
+
+static int
+yaml_emitter_set_emitter_error(yaml_emitter_t *emitter, const char *problem);
+
+static int
+yaml_emitter_need_more_events(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_append_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t value, int allow_duplicates);
+
+static int
+yaml_emitter_increase_indent(yaml_emitter_t *emitter,
+        int flow, int indentless);
+
+/*
+ * State functions.
+ */
+
+static int
+yaml_emitter_state_machine(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_stream_start(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+static int
+yaml_emitter_emit_document_start(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_document_content(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+static int
+yaml_emitter_emit_document_end(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+static int
+yaml_emitter_emit_flow_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_flow_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_flow_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple);
+
+static int
+yaml_emitter_emit_block_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_block_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_block_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple);
+
+static int
+yaml_emitter_emit_node(yaml_emitter_t *emitter, yaml_event_t *event,
+        int root, int sequence, int mapping, int simple_key);
+
+static int
+yaml_emitter_emit_alias(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_scalar(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_sequence_start(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_mapping_start(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/*
+ * Checkers.
+ */
+
+static int
+yaml_emitter_check_empty_document(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_check_empty_sequence(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_check_empty_mapping(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_check_simple_key(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_select_scalar_style(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/*
+ * Processors.
+ */
+
+static int
+yaml_emitter_process_anchor(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_process_tag(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_process_scalar(yaml_emitter_t *emitter);
+
+/*
+ * Analyzers.
+ */
+
+static int
+yaml_emitter_analyze_version_directive(yaml_emitter_t *emitter,
+        yaml_version_directive_t version_directive);
+
+static int
+yaml_emitter_analyze_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t tag_directive);
+
+static int
+yaml_emitter_analyze_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *anchor, int alias);
+
+static int
+yaml_emitter_analyze_tag(yaml_emitter_t *emitter,
+        yaml_char_t *tag);
+
+static int
+yaml_emitter_analyze_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_analyze_event(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+/*
+ * Writers.
+ */
+
+static int
+yaml_emitter_write_bom(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_write_indent(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_write_indicator(yaml_emitter_t *emitter,
+        const char *indicator, int need_whitespace,
+        int is_whitespace, int is_indention);
+
+static int
+yaml_emitter_write_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_write_tag_handle(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_write_tag_content(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int need_whitespace);
+
+static int
+yaml_emitter_write_plain_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks);
+
+static int
+yaml_emitter_write_single_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks);
+
+static int
+yaml_emitter_write_double_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks);
+
+static int
+yaml_emitter_write_block_scalar_hints(yaml_emitter_t *emitter,
+        yaml_string_t string);
+
+static int
+yaml_emitter_write_literal_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_write_folded_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+/*
+ * Set an emitter error and return 0.
+ */
+
+static int
+yaml_emitter_set_emitter_error(yaml_emitter_t *emitter, const char *problem)
+{
+    emitter->error = YAML_EMITTER_ERROR;
+    emitter->problem = problem;
+
+    return 0;
+}
+
+/*
+ * Emit an event.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_emit(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!ENQUEUE(emitter, emitter->events, *event)) {
+        yaml_event_delete(event);
+        return 0;
+    }
+
+    while (!yaml_emitter_need_more_events(emitter)) {
+        if (!yaml_emitter_analyze_event(emitter, emitter->events.head))
+            return 0;
+        if (!yaml_emitter_state_machine(emitter, emitter->events.head))
+            return 0;
+        yaml_event_delete(&DEQUEUE(emitter, emitter->events));
+    }
+
+    return 1;
+}
+
+/*
+ * 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
+ */
+
+static int
+yaml_emitter_need_more_events(yaml_emitter_t *emitter)
+{
+    int level = 0;
+    int accumulate = 0;
+    yaml_event_t *event;
+
+    if (QUEUE_EMPTY(emitter, emitter->events))
+        return 1;
+
+    switch (emitter->events.head->type) {
+        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 0;
+    }
+
+    if (emitter->events.tail - emitter->events.head > accumulate)
+        return 0;
+
+    for (event = emitter->events.head; event != emitter->events.tail; event ++) {
+        switch (event->type) {
+            case YAML_STREAM_START_EVENT:
+            case YAML_DOCUMENT_START_EVENT:
+            case YAML_SEQUENCE_START_EVENT:
+            case YAML_MAPPING_START_EVENT:
+                level += 1;
+                break;
+            case YAML_STREAM_END_EVENT:
+            case YAML_DOCUMENT_END_EVENT:
+            case YAML_SEQUENCE_END_EVENT:
+            case YAML_MAPPING_END_EVENT:
+                level -= 1;
+                break;
+            default:
+                break;
+        }
+        if (!level)
+            return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Append a directive to the directives stack.
+ */
+
+static int
+yaml_emitter_append_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t value, int allow_duplicates)
+{
+    yaml_tag_directive_t *tag_directive;
+    yaml_tag_directive_t copy = { NULL, NULL };
+
+    for (tag_directive = emitter->tag_directives.start;
+            tag_directive != emitter->tag_directives.top; tag_directive ++) {
+        if (strcmp((char *)value.handle, (char *)tag_directive->handle) == 0) {
+            if (allow_duplicates)
+                return 1;
+            return yaml_emitter_set_emitter_error(emitter,
+                    "duplicate %TAG directive");
+        }
+    }
+
+    copy.handle = yaml_strdup(value.handle);
+    copy.prefix = yaml_strdup(value.prefix);
+    if (!copy.handle || !copy.prefix) {
+        emitter->error = YAML_MEMORY_ERROR;
+        goto error;
+    }
+
+    if (!PUSH(emitter, emitter->tag_directives, copy))
+        goto error;
+
+    return 1;
+
+error:
+    yaml_free(copy.handle);
+    yaml_free(copy.prefix);
+    return 0;
+}
+
+/*
+ * Increase the indentation level.
+ */
+
+static int
+yaml_emitter_increase_indent(yaml_emitter_t *emitter,
+        int flow, int indentless)
+{
+    if (!PUSH(emitter, emitter->indents, emitter->indent))
+        return 0;
+
+    if (emitter->indent < 0) {
+        emitter->indent = flow ? emitter->best_indent : 0;
+    }
+    else if (!indentless) {
+        emitter->indent += emitter->best_indent;
+    }
+
+    return 1;
+}
+
+/*
+ * State dispatcher.
+ */
+
+static int
+yaml_emitter_state_machine(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    switch (emitter->state)
+    {
+        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, 1);
+
+        case YAML_EMIT_DOCUMENT_START_STATE:
+            return yaml_emitter_emit_document_start(emitter, event, 0);
+
+        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, 1);
+
+        case YAML_EMIT_FLOW_SEQUENCE_ITEM_STATE:
+            return yaml_emitter_emit_flow_sequence_item(emitter, event, 0);
+
+        case YAML_EMIT_FLOW_MAPPING_FIRST_KEY_STATE:
+            return yaml_emitter_emit_flow_mapping_key(emitter, event, 1);
+
+        case YAML_EMIT_FLOW_MAPPING_KEY_STATE:
+            return yaml_emitter_emit_flow_mapping_key(emitter, event, 0);
+
+        case YAML_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE:
+            return yaml_emitter_emit_flow_mapping_value(emitter, event, 1);
+
+        case YAML_EMIT_FLOW_MAPPING_VALUE_STATE:
+            return yaml_emitter_emit_flow_mapping_value(emitter, event, 0);
+
+        case YAML_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE:
+            return yaml_emitter_emit_block_sequence_item(emitter, event, 1);
+
+        case YAML_EMIT_BLOCK_SEQUENCE_ITEM_STATE:
+            return yaml_emitter_emit_block_sequence_item(emitter, event, 0);
+
+        case YAML_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE:
+            return yaml_emitter_emit_block_mapping_key(emitter, event, 1);
+
+        case YAML_EMIT_BLOCK_MAPPING_KEY_STATE:
+            return yaml_emitter_emit_block_mapping_key(emitter, event, 0);
+
+        case YAML_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE:
+            return yaml_emitter_emit_block_mapping_value(emitter, event, 1);
+
+        case YAML_EMIT_BLOCK_MAPPING_VALUE_STATE:
+            return yaml_emitter_emit_block_mapping_value(emitter, event, 0);
+
+        case YAML_EMIT_END_STATE:
+            return yaml_emitter_set_emitter_error(emitter,
+                    "expected nothing after STREAM-END");
+
+        default:
+            assert(1);      /* Invalid state. */
+    }
+
+    return 0;
+}
+
+/*
+ * Expect STREAM-START.
+ */
+
+static int
+yaml_emitter_emit_stream_start(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    if (event->type == YAML_STREAM_START_EVENT)
+    {
+        if (!emitter->encoding) {
+            emitter->encoding = event->data.stream_start.encoding;
+        }
+
+        if (!emitter->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 = INT_MAX;
+        }
+
+        if (!emitter->line_break) {
+            emitter->line_break = YAML_LN_BREAK;
+        }
+
+        emitter->indent = -1;
+
+        emitter->line = 0;
+        emitter->column = 0;
+        emitter->whitespace = 1;
+        emitter->indention = 1;
+
+        if (emitter->encoding != YAML_UTF8_ENCODING) {
+            if (!yaml_emitter_write_bom(emitter))
+                return 0;
+        }
+
+        emitter->state = YAML_EMIT_FIRST_DOCUMENT_START_STATE;
+
+        return 1;
+    }
+
+    return yaml_emitter_set_emitter_error(emitter,
+            "expected STREAM-START");
+}
+
+/*
+ * Expect DOCUMENT-START or STREAM-END.
+ */
+
+static int
+yaml_emitter_emit_document_start(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (event->type == YAML_DOCUMENT_START_EVENT)
+    {
+        yaml_tag_directive_t default_tag_directives[] = {
+            {(yaml_char_t *)"!", (yaml_char_t *)"!"},
+            {(yaml_char_t *)"!!", (yaml_char_t *)"tag:yaml.org,2002:"},
+            {NULL, NULL}
+        };
+        yaml_tag_directive_t *tag_directive;
+        int implicit;
+
+        if (event->data.document_start.version_directive) {
+            if (!yaml_emitter_analyze_version_directive(emitter,
+                        *event->data.document_start.version_directive))
+                return 0;
+        }
+
+        for (tag_directive = event->data.document_start.tag_directives.start;
+                tag_directive != event->data.document_start.tag_directives.end;
+                tag_directive ++) {
+            if (!yaml_emitter_analyze_tag_directive(emitter, *tag_directive))
+                return 0;
+            if (!yaml_emitter_append_tag_directive(emitter, *tag_directive, 0))
+                return 0;
+        }
+
+        for (tag_directive = default_tag_directives;
+                tag_directive->handle; tag_directive ++) {
+            if (!yaml_emitter_append_tag_directive(emitter, *tag_directive, 1))
+                return 0;
+        }
+
+        implicit = event->data.document_start.implicit;
+        if (!first || emitter->canonical) {
+            implicit = 0;
+        }
+
+        if ((event->data.document_start.version_directive ||
+                    (event->data.document_start.tag_directives.start
+                     != event->data.document_start.tag_directives.end)) &&
+                emitter->open_ended)
+        {
+            if (!yaml_emitter_write_indicator(emitter, "...", 1, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+
+        if (event->data.document_start.version_directive) {
+            implicit = 0;
+            if (!yaml_emitter_write_indicator(emitter, "%YAML", 1, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indicator(emitter, "1.1", 1, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+
+        if (event->data.document_start.tag_directives.start
+                != event->data.document_start.tag_directives.end) {
+            implicit = 0;
+            for (tag_directive = event->data.document_start.tag_directives.start;
+                    tag_directive != event->data.document_start.tag_directives.end;
+                    tag_directive ++) {
+                if (!yaml_emitter_write_indicator(emitter, "%TAG", 1, 0, 0))
+                    return 0;
+                if (!yaml_emitter_write_tag_handle(emitter, tag_directive->handle,
+                            strlen((char *)tag_directive->handle)))
+                    return 0;
+                if (!yaml_emitter_write_tag_content(emitter, tag_directive->prefix,
+                            strlen((char *)tag_directive->prefix), 1))
+                    return 0;
+                if (!yaml_emitter_write_indent(emitter))
+                    return 0;
+            }
+        }
+
+        if (yaml_emitter_check_empty_document(emitter)) {
+            implicit = 0;
+        }
+
+        if (!implicit) {
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+            if (!yaml_emitter_write_indicator(emitter, "---", 1, 0, 0))
+                return 0;
+            if (emitter->canonical) {
+                if (!yaml_emitter_write_indent(emitter))
+                    return 0;
+            }
+        }
+
+        emitter->state = YAML_EMIT_DOCUMENT_CONTENT_STATE;
+
+        return 1;
+    }
+
+    else if (event->type == YAML_STREAM_END_EVENT)
+    {
+        if (emitter->open_ended)
+        {
+            if (!yaml_emitter_write_indicator(emitter, "...", 1, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+
+        if (!yaml_emitter_flush(emitter))
+            return 0;
+
+        emitter->state = YAML_EMIT_END_STATE;
+
+        return 1;
+    }
+
+    return yaml_emitter_set_emitter_error(emitter,
+            "expected DOCUMENT-START or STREAM-END");
+}
+
+/*
+ * Expect the root node.
+ */
+
+static int
+yaml_emitter_emit_document_content(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    if (!PUSH(emitter, emitter->states, YAML_EMIT_DOCUMENT_END_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 1, 0, 0, 0);
+}
+
+/*
+ * Expect DOCUMENT-END.
+ */
+
+static int
+yaml_emitter_emit_document_end(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    if (event->type == YAML_DOCUMENT_END_EVENT)
+    {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+        if (!event->data.document_end.implicit) {
+            if (!yaml_emitter_write_indicator(emitter, "...", 1, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_flush(emitter))
+            return 0;
+
+        emitter->state = YAML_EMIT_DOCUMENT_START_STATE;
+
+        while (!STACK_EMPTY(emitter, emitter->tag_directives)) {
+            yaml_tag_directive_t tag_directive = POP(emitter,
+                    emitter->tag_directives);
+            yaml_free(tag_directive.handle);
+            yaml_free(tag_directive.prefix);
+        }
+
+        return 1;
+    }
+
+    return yaml_emitter_set_emitter_error(emitter,
+            "expected DOCUMENT-END");
+}
+
+/*
+ *
+ * Expect a flow item node.
+ */
+
+static int
+yaml_emitter_emit_flow_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_write_indicator(emitter, "[", 1, 1, 0))
+            return 0;
+        if (!yaml_emitter_increase_indent(emitter, 1, 0))
+            return 0;
+        emitter->flow_level ++;
+    }
+
+    if (event->type == YAML_SEQUENCE_END_EVENT)
+    {
+        emitter->flow_level --;
+        emitter->indent = POP(emitter, emitter->indents);
+        if (emitter->canonical && !first) {
+            if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_write_indicator(emitter, "]", 0, 0, 0))
+            return 0;
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!first) {
+        if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+            return 0;
+    }
+
+    if (emitter->canonical || emitter->column > emitter->best_width) {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+    }
+    if (!PUSH(emitter, emitter->states, YAML_EMIT_FLOW_SEQUENCE_ITEM_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 0, 1, 0, 0);
+}
+
+/*
+ * Expect a flow key node.
+ */
+
+static int
+yaml_emitter_emit_flow_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_write_indicator(emitter, "{", 1, 1, 0))
+            return 0;
+        if (!yaml_emitter_increase_indent(emitter, 1, 0))
+            return 0;
+        emitter->flow_level ++;
+    }
+
+    if (event->type == YAML_MAPPING_END_EVENT)
+    {
+        emitter->flow_level --;
+        emitter->indent = POP(emitter, emitter->indents);
+        if (emitter->canonical && !first) {
+            if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_write_indicator(emitter, "}", 0, 0, 0))
+            return 0;
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!first) {
+        if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+            return 0;
+    }
+    if (emitter->canonical || emitter->column > emitter->best_width) {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+    }
+
+    if (!emitter->canonical && yaml_emitter_check_simple_key(emitter))
+    {
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 1);
+    }
+    else
+    {
+        if (!yaml_emitter_write_indicator(emitter, "?", 1, 0, 0))
+            return 0;
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_FLOW_MAPPING_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+    }
+}
+
+/*
+ * Expect a flow value node.
+ */
+
+static int
+yaml_emitter_emit_flow_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple)
+{
+    if (simple) {
+        if (!yaml_emitter_write_indicator(emitter, ":", 0, 0, 0))
+            return 0;
+    }
+    else {
+        if (emitter->canonical || emitter->column > emitter->best_width) {
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_write_indicator(emitter, ":", 1, 0, 0))
+            return 0;
+    }
+    if (!PUSH(emitter, emitter->states, YAML_EMIT_FLOW_MAPPING_KEY_STATE))
+        return 0;
+    return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+}
+
+/*
+ * Expect a block item node.
+ */
+
+static int
+yaml_emitter_emit_block_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_increase_indent(emitter, 0,
+                    (emitter->mapping_context && !emitter->indention)))
+            return 0;
+    }
+
+    if (event->type == YAML_SEQUENCE_END_EVENT)
+    {
+        emitter->indent = POP(emitter, emitter->indents);
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!yaml_emitter_write_indent(emitter))
+        return 0;
+    if (!yaml_emitter_write_indicator(emitter, "-", 1, 0, 1))
+        return 0;
+    if (!PUSH(emitter, emitter->states,
+                YAML_EMIT_BLOCK_SEQUENCE_ITEM_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 0, 1, 0, 0);
+}
+
+/*
+ * Expect a block key node.
+ */
+
+static int
+yaml_emitter_emit_block_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_increase_indent(emitter, 0, 0))
+            return 0;
+    }
+
+    if (event->type == YAML_MAPPING_END_EVENT)
+    {
+        emitter->indent = POP(emitter, emitter->indents);
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!yaml_emitter_write_indent(emitter))
+        return 0;
+
+    if (yaml_emitter_check_simple_key(emitter))
+    {
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 1);
+    }
+    else
+    {
+        if (!yaml_emitter_write_indicator(emitter, "?", 1, 0, 1))
+            return 0;
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_BLOCK_MAPPING_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+    }
+}
+
+/*
+ * Expect a block value node.
+ */
+
+static int
+yaml_emitter_emit_block_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple)
+{
+    if (simple) {
+        if (!yaml_emitter_write_indicator(emitter, ":", 0, 0, 0))
+            return 0;
+    }
+    else {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+        if (!yaml_emitter_write_indicator(emitter, ":", 1, 0, 1))
+            return 0;
+    }
+    if (!PUSH(emitter, emitter->states,
+                YAML_EMIT_BLOCK_MAPPING_KEY_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+}
+
+/*
+ * Expect a node.
+ */
+
+static int
+yaml_emitter_emit_node(yaml_emitter_t *emitter, yaml_event_t *event,
+        int root, int sequence, int mapping, int simple_key)
+{
+    emitter->root_context = root;
+    emitter->sequence_context = sequence;
+    emitter->mapping_context = mapping;
+    emitter->simple_key_context = simple_key;
+
+    switch (event->type)
+    {
+        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,
+                    "expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS");
+    }
+
+    return 0;
+}
+
+/*
+ * Expect ALIAS.
+ */
+
+static int
+yaml_emitter_emit_alias(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    emitter->state = POP(emitter, emitter->states);
+
+    return 1;
+}
+
+/*
+ * Expect SCALAR.
+ */
+
+static int
+yaml_emitter_emit_scalar(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_select_scalar_style(emitter, event))
+        return 0;
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (!yaml_emitter_process_tag(emitter))
+        return 0;
+    if (!yaml_emitter_increase_indent(emitter, 1, 0))
+        return 0;
+    if (!yaml_emitter_process_scalar(emitter))
+        return 0;
+    emitter->indent = POP(emitter, emitter->indents);
+    emitter->state = POP(emitter, emitter->states);
+
+    return 1;
+}
+
+/*
+ * Expect SEQUENCE-START.
+ */
+
+static int
+yaml_emitter_emit_sequence_start(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (!yaml_emitter_process_tag(emitter))
+        return 0;
+
+    if (emitter->flow_level || emitter->canonical
+            || event->data.sequence_start.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 1;
+}
+
+/*
+ * Expect MAPPING-START.
+ */
+
+static int
+yaml_emitter_emit_mapping_start(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (!yaml_emitter_process_tag(emitter))
+        return 0;
+
+    if (emitter->flow_level || emitter->canonical
+            || event->data.mapping_start.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 1;
+}
+
+/*
+ * Check if the document content is an empty scalar.
+ */
+
+static int
+yaml_emitter_check_empty_document(yaml_emitter_t *emitter)
+{
+    return 0;
+}
+
+/*
+ * Check if the next events represent an empty sequence.
+ */
+
+static int
+yaml_emitter_check_empty_sequence(yaml_emitter_t *emitter)
+{
+    if (emitter->events.tail - emitter->events.head < 2)
+        return 0;
+
+    return (emitter->events.head[0].type == YAML_SEQUENCE_START_EVENT
+            && emitter->events.head[1].type == YAML_SEQUENCE_END_EVENT);
+}
+
+/*
+ * Check if the next events represent an empty mapping.
+ */
+
+static int
+yaml_emitter_check_empty_mapping(yaml_emitter_t *emitter)
+{
+    if (emitter->events.tail - emitter->events.head < 2)
+        return 0;
+
+    return (emitter->events.head[0].type == YAML_MAPPING_START_EVENT
+            && emitter->events.head[1].type == YAML_MAPPING_END_EVENT);
+}
+
+/*
+ * Check if the next node can be expressed as a simple key.
+ */
+
+static int
+yaml_emitter_check_simple_key(yaml_emitter_t *emitter)
+{
+    yaml_event_t *event = emitter->events.head;
+    size_t length = 0;
+
+    switch (event->type)
+    {
+        case YAML_ALIAS_EVENT:
+            length += emitter->anchor_data.anchor_length;
+            break;
+
+        case YAML_SCALAR_EVENT:
+            if (emitter->scalar_data.multiline)
+                return 0;
+            length += emitter->anchor_data.anchor_length
+                + emitter->tag_data.handle_length
+                + emitter->tag_data.suffix_length
+                + emitter->scalar_data.length;
+            break;
+
+        case YAML_SEQUENCE_START_EVENT:
+            if (!yaml_emitter_check_empty_sequence(emitter))
+                return 0;
+            length += emitter->anchor_data.anchor_length
+                + emitter->tag_data.handle_length
+                + emitter->tag_data.suffix_length;
+            break;
+
+        case YAML_MAPPING_START_EVENT:
+            if (!yaml_emitter_check_empty_mapping(emitter))
+                return 0;
+            length += emitter->anchor_data.anchor_length
+                + emitter->tag_data.handle_length
+                + emitter->tag_data.suffix_length;
+            break;
+
+        default:
+            return 0;
+    }
+
+    if (length > 128)
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Determine an acceptable scalar style.
+ */
+
+static int
+yaml_emitter_select_scalar_style(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    yaml_scalar_style_t style = event->data.scalar.style;
+    int no_tag = (!emitter->tag_data.handle && !emitter->tag_data.suffix);
+
+    if (no_tag && !event->data.scalar.plain_implicit
+            && !event->data.scalar.quoted_implicit) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "neither tag nor implicit flags are specified");
+    }
+
+    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 && !emitter->scalar_data.flow_plain_allowed)
+                || (!emitter->flow_level && !emitter->scalar_data.block_plain_allowed))
+            style = YAML_SINGLE_QUOTED_SCALAR_STYLE;
+        if (!emitter->scalar_data.length
+                && (emitter->flow_level || emitter->simple_key_context))
+            style = YAML_SINGLE_QUOTED_SCALAR_STYLE;
+        if (no_tag && !event->data.scalar.plain_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 || emitter->simple_key_context)
+            style = YAML_DOUBLE_QUOTED_SCALAR_STYLE;
+    }
+
+    if (no_tag && !event->data.scalar.quoted_implicit
+            && style != YAML_PLAIN_SCALAR_STYLE)
+    {
+        emitter->tag_data.handle = (yaml_char_t *)"!";
+        emitter->tag_data.handle_length = 1;
+    }
+
+    emitter->scalar_data.style = style;
+
+    return 1;
+}
+
+/*
+ * Write an achor.
+ */
+
+static int
+yaml_emitter_process_anchor(yaml_emitter_t *emitter)
+{
+    if (!emitter->anchor_data.anchor)
+        return 1;
+
+    if (!yaml_emitter_write_indicator(emitter,
+                (emitter->anchor_data.alias ? "*" : "&"), 1, 0, 0))
+        return 0;
+
+    return yaml_emitter_write_anchor(emitter,
+            emitter->anchor_data.anchor, emitter->anchor_data.anchor_length);
+}
+
+/*
+ * Write a tag.
+ */
+
+static int
+yaml_emitter_process_tag(yaml_emitter_t *emitter)
+{
+    if (!emitter->tag_data.handle && !emitter->tag_data.suffix)
+        return 1;
+
+    if (emitter->tag_data.handle)
+    {
+        if (!yaml_emitter_write_tag_handle(emitter, emitter->tag_data.handle,
+                    emitter->tag_data.handle_length))
+            return 0;
+        if (emitter->tag_data.suffix) {
+            if (!yaml_emitter_write_tag_content(emitter, emitter->tag_data.suffix,
+                        emitter->tag_data.suffix_length, 0))
+                return 0;
+        }
+    }
+    else
+    {
+        if (!yaml_emitter_write_indicator(emitter, "!<", 1, 0, 0))
+            return 0;
+        if (!yaml_emitter_write_tag_content(emitter, emitter->tag_data.suffix,
+                    emitter->tag_data.suffix_length, 0))
+            return 0;
+        if (!yaml_emitter_write_indicator(emitter, ">", 0, 0, 0))
+            return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Write a scalar.
+ */
+
+static int
+yaml_emitter_process_scalar(yaml_emitter_t *emitter)
+{
+    switch (emitter->scalar_data.style)
+    {
+        case YAML_PLAIN_SCALAR_STYLE:
+            return yaml_emitter_write_plain_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length,
+                    !emitter->simple_key_context);
+
+        case YAML_SINGLE_QUOTED_SCALAR_STYLE:
+            return yaml_emitter_write_single_quoted_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length,
+                    !emitter->simple_key_context);
+
+        case YAML_DOUBLE_QUOTED_SCALAR_STYLE:
+            return yaml_emitter_write_double_quoted_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length,
+                    !emitter->simple_key_context);
+
+        case YAML_LITERAL_SCALAR_STYLE:
+            return yaml_emitter_write_literal_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length);
+
+        case YAML_FOLDED_SCALAR_STYLE:
+            return yaml_emitter_write_folded_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length);
+
+        default:
+            assert(1);      /* Impossible. */
+    }
+
+    return 0;
+}
+
+/*
+ * Check if a %YAML directive is valid.
+ */
+
+static int
+yaml_emitter_analyze_version_directive(yaml_emitter_t *emitter,
+        yaml_version_directive_t version_directive)
+{
+    if (version_directive.major != 1 || version_directive.minor != 1) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "incompatible %YAML directive");
+    }
+
+    return 1;
+}
+
+/*
+ * Check if a %TAG directive is valid.
+ */
+
+static int
+yaml_emitter_analyze_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t tag_directive)
+{
+    yaml_string_t handle;
+    yaml_string_t prefix;
+    size_t handle_length;
+    size_t prefix_length;
+
+    handle_length = strlen((char *)tag_directive.handle);
+    prefix_length = strlen((char *)tag_directive.prefix);
+    STRING_ASSIGN(handle, tag_directive.handle, handle_length);
+    STRING_ASSIGN(prefix, tag_directive.prefix, prefix_length);
+
+    if (handle.start == handle.end) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag handle must not be empty");
+    }
+
+    if (handle.start[0] != '!') {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag handle must start with '!'");
+    }
+
+    if (handle.end[-1] != '!') {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag handle must end with '!'");
+    }
+
+    handle.pointer ++;
+
+    while (handle.pointer < handle.end-1) {
+        if (!IS_ALPHA(handle)) {
+            return yaml_emitter_set_emitter_error(emitter,
+                    "tag handle must contain alphanumerical characters only");
+        }
+        MOVE(handle);
+    }
+
+    if (prefix.start == prefix.end) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag prefix must not be empty");
+    }
+
+    return 1;
+}
+
+/*
+ * Check if an anchor is valid.
+ */
+
+static int
+yaml_emitter_analyze_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *anchor, int alias)
+{
+    size_t anchor_length;
+    yaml_string_t string;
+
+    anchor_length = strlen((char *)anchor);
+    STRING_ASSIGN(string, anchor, anchor_length);
+
+    if (string.start == string.end) {
+        return yaml_emitter_set_emitter_error(emitter, alias ?
+                "alias value must not be empty" :
+                "anchor value must not be empty");
+    }
+
+    while (string.pointer != string.end) {
+        if (!IS_ALPHA(string)) {
+            return yaml_emitter_set_emitter_error(emitter, alias ?
+                    "alias value must contain alphanumerical characters only" :
+                    "anchor value must contain alphanumerical characters only");
+        }
+        MOVE(string);
+    }
+
+    emitter->anchor_data.anchor = string.start;
+    emitter->anchor_data.anchor_length = string.end - string.start;
+    emitter->anchor_data.alias = alias;
+
+    return 1;
+}
+
+/*
+ * Check if a tag is valid.
+ */
+
+static int
+yaml_emitter_analyze_tag(yaml_emitter_t *emitter,
+        yaml_char_t *tag)
+{
+    size_t tag_length;
+    yaml_string_t string;
+    yaml_tag_directive_t *tag_directive;
+
+    tag_length = strlen((char *)tag);
+    STRING_ASSIGN(string, tag, tag_length);
+
+    if (string.start == string.end) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag value must not be empty");
+    }
+
+    for (tag_directive = emitter->tag_directives.start;
+            tag_directive != emitter->tag_directives.top; tag_directive ++) {
+        size_t prefix_length = strlen((char *)tag_directive->prefix);
+        if (prefix_length < (size_t)(string.end - string.start)
+                && strncmp((char *)tag_directive->prefix, (char *)string.start,
+                    prefix_length) == 0)
+        {
+            emitter->tag_data.handle = tag_directive->handle;
+            emitter->tag_data.handle_length =
+                strlen((char *)tag_directive->handle);
+            emitter->tag_data.suffix = string.start + prefix_length;
+            emitter->tag_data.suffix_length =
+                (string.end - string.start) - prefix_length;
+            return 1;
+        }
+    }
+
+    emitter->tag_data.suffix = string.start;
+    emitter->tag_data.suffix_length = string.end - string.start;
+
+    return 1;
+}
+
+/*
+ * Check if a scalar is valid.
+ */
+
+static int
+yaml_emitter_analyze_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+
+    int block_indicators = 0;
+    int flow_indicators = 0;
+    int line_breaks = 0;
+    int special_characters = 0;
+
+    int leading_space = 0;
+    int leading_break = 0;
+    int trailing_space = 0;
+    int trailing_break = 0;
+    int break_space = 0;
+    int space_break = 0;
+
+    int preceeded_by_whitespace = 0;
+    int followed_by_whitespace = 0;
+    int previous_space = 0;
+    int previous_break = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    emitter->scalar_data.value = value;
+    emitter->scalar_data.length = length;
+
+    if (string.start == string.end)
+    {
+        emitter->scalar_data.multiline = 0;
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 1;
+        emitter->scalar_data.single_quoted_allowed = 1;
+        emitter->scalar_data.block_allowed = 0;
+
+        return 1;
+    }
+
+    if ((CHECK_AT(string, '-', 0)
+                && CHECK_AT(string, '-', 1)
+                && CHECK_AT(string, '-', 2))
+            || (CHECK_AT(string, '.', 0)
+                && CHECK_AT(string, '.', 1)
+                && CHECK_AT(string, '.', 2))) {
+        block_indicators = 1;
+        flow_indicators = 1;
+    }
+
+    preceeded_by_whitespace = 1;
+    followed_by_whitespace = IS_BLANKZ_AT(string, WIDTH(string));
+
+    while (string.pointer != string.end)
+    {
+        if (string.start == string.pointer)
+        {
+            if (CHECK(string, '#') || CHECK(string, ',')
+                    || CHECK(string, '[') || CHECK(string, ']')
+                    || CHECK(string, '{') || CHECK(string, '}')
+                    || CHECK(string, '&') || CHECK(string, '*')
+                    || CHECK(string, '!') || CHECK(string, '|')
+                    || CHECK(string, '>') || CHECK(string, '\'')
+                    || CHECK(string, '"') || CHECK(string, '%')
+                    || CHECK(string, '@') || CHECK(string, '`')) {
+                flow_indicators = 1;
+                block_indicators = 1;
+            }
+
+            if (CHECK(string, '?') || CHECK(string, ':')) {
+                flow_indicators = 1;
+                if (followed_by_whitespace) {
+                    block_indicators = 1;
+                }
+            }
+
+            if (CHECK(string, '-') && followed_by_whitespace) {
+                flow_indicators = 1;
+                block_indicators = 1;
+            }
+        }
+        else
+        {
+            if (CHECK(string, ',') || CHECK(string, '?')
+                    || CHECK(string, '[') || CHECK(string, ']')
+                    || CHECK(string, '{') || CHECK(string, '}')) {
+                flow_indicators = 1;
+            }
+
+            if (CHECK(string, ':')) {
+                flow_indicators = 1;
+                if (followed_by_whitespace) {
+                    block_indicators = 1;
+                }
+            }
+
+            if (CHECK(string, '#') && preceeded_by_whitespace) {
+                flow_indicators = 1;
+                block_indicators = 1;
+            }
+        }
+
+        if (!IS_PRINTABLE(string)
+                || (!IS_ASCII(string) && !emitter->unicode)) {
+            special_characters = 1;
+        }
+
+        if (IS_BREAK(string)) {
+            line_breaks = 1;
+        }
+
+        if (IS_SPACE(string))
+        {
+            if (string.start == string.pointer) {
+                leading_space = 1;
+            }
+            if (string.pointer+WIDTH(string) == string.end) {
+                trailing_space = 1;
+            }
+            if (previous_break) {
+                break_space = 1;
+            }
+            previous_space = 1;
+            previous_break = 0;
+        }
+        else if (IS_BREAK(string))
+        {
+            if (string.start == string.pointer) {
+                leading_break = 1;
+            }
+            if (string.pointer+WIDTH(string) == string.end) {
+                trailing_break = 1;
+            }
+            if (previous_space) {
+                space_break = 1;
+            }
+            previous_space = 0;
+            previous_break = 1;
+        }
+        else
+        {
+            previous_space = 0;
+            previous_break = 0;
+        }
+
+        preceeded_by_whitespace = IS_BLANKZ(string);
+        MOVE(string);
+        if (string.pointer != string.end) {
+            followed_by_whitespace = IS_BLANKZ_AT(string, WIDTH(string));
+        }
+    }
+
+    emitter->scalar_data.multiline = line_breaks;
+
+    emitter->scalar_data.flow_plain_allowed = 1;
+    emitter->scalar_data.block_plain_allowed = 1;
+    emitter->scalar_data.single_quoted_allowed = 1;
+    emitter->scalar_data.block_allowed = 1;
+
+    if (leading_space || leading_break || trailing_space || trailing_break) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+    }
+
+    if (trailing_space) {
+        emitter->scalar_data.block_allowed = 0;
+    }
+
+    if (break_space) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+        emitter->scalar_data.single_quoted_allowed = 0;
+    }
+
+    if (space_break || special_characters) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+        emitter->scalar_data.single_quoted_allowed = 0;
+        emitter->scalar_data.block_allowed = 0;
+    }
+
+    if (line_breaks) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+    }
+
+    if (flow_indicators) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+    }
+
+    if (block_indicators) {
+        emitter->scalar_data.block_plain_allowed = 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Check if the event data is valid.
+ */
+
+static int
+yaml_emitter_analyze_event(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    emitter->anchor_data.anchor = NULL;
+    emitter->anchor_data.anchor_length = 0;
+    emitter->tag_data.handle = NULL;
+    emitter->tag_data.handle_length = 0;
+    emitter->tag_data.suffix = NULL;
+    emitter->tag_data.suffix_length = 0;
+    emitter->scalar_data.value = NULL;
+    emitter->scalar_data.length = 0;
+
+    switch (event->type)
+    {
+        case YAML_ALIAS_EVENT:
+            if (!yaml_emitter_analyze_anchor(emitter,
+                        event->data.alias.anchor, 1))
+                return 0;
+            return 1;
+
+        case YAML_SCALAR_EVENT:
+            if (event->data.scalar.anchor) {
+                if (!yaml_emitter_analyze_anchor(emitter,
+                            event->data.scalar.anchor, 0))
+                    return 0;
+            }
+            if (event->data.scalar.tag && (emitter->canonical ||
+                        (!event->data.scalar.plain_implicit
+                         && !event->data.scalar.quoted_implicit))) {
+                if (!yaml_emitter_analyze_tag(emitter, event->data.scalar.tag))
+                    return 0;
+            }
+            if (!yaml_emitter_analyze_scalar(emitter,
+                        event->data.scalar.value, event->data.scalar.length))
+                return 0;
+            return 1;
+
+        case YAML_SEQUENCE_START_EVENT:
+            if (event->data.sequence_start.anchor) {
+                if (!yaml_emitter_analyze_anchor(emitter,
+                            event->data.sequence_start.anchor, 0))
+                    return 0;
+            }
+            if (event->data.sequence_start.tag && (emitter->canonical ||
+                        !event->data.sequence_start.implicit)) {
+                if (!yaml_emitter_analyze_tag(emitter,
+                            event->data.sequence_start.tag))
+                    return 0;
+            }
+            return 1;
+
+        case YAML_MAPPING_START_EVENT:
+            if (event->data.mapping_start.anchor) {
+                if (!yaml_emitter_analyze_anchor(emitter,
+                            event->data.mapping_start.anchor, 0))
+                    return 0;
+            }
+            if (event->data.mapping_start.tag && (emitter->canonical ||
+                        !event->data.mapping_start.implicit)) {
+                if (!yaml_emitter_analyze_tag(emitter,
+                            event->data.mapping_start.tag))
+                    return 0;
+            }
+            return 1;
+
+        default:
+            return 1;
+    }
+}
+
+/*
+ * Write the BOM character.
+ */
+
+static int
+yaml_emitter_write_bom(yaml_emitter_t *emitter)
+{
+    if (!FLUSH(emitter)) return 0;
+
+    *(emitter->buffer.pointer++) = (yaml_char_t) '\xEF';
+    *(emitter->buffer.pointer++) = (yaml_char_t) '\xBB';
+    *(emitter->buffer.pointer++) = (yaml_char_t) '\xBF';
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_indent(yaml_emitter_t *emitter)
+{
+    int indent = (emitter->indent >= 0) ? emitter->indent : 0;
+
+    if (!emitter->indention || emitter->column > indent
+            || (emitter->column == indent && !emitter->whitespace)) {
+        if (!PUT_BREAK(emitter)) return 0;
+    }
+
+    while (emitter->column < indent) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    emitter->whitespace = 1;
+    emitter->indention = 1;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_indicator(yaml_emitter_t *emitter,
+        const char *indicator, int need_whitespace,
+        int is_whitespace, int is_indention)
+{
+    size_t indicator_length;
+    yaml_string_t string;
+
+    indicator_length = strlen(indicator);
+    STRING_ASSIGN(string, (yaml_char_t *)indicator, indicator_length);
+
+    if (need_whitespace && !emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end) {
+        if (!WRITE(emitter, string)) return 0;
+    }
+
+    emitter->whitespace = is_whitespace;
+    emitter->indention = (emitter->indention && is_indention);
+    emitter->open_ended = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    STRING_ASSIGN(string, value, length);
+
+    while (string.pointer != string.end) {
+        if (!WRITE(emitter, string)) return 0;
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_tag_handle(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    STRING_ASSIGN(string, value, length);
+
+    if (!emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end) {
+        if (!WRITE(emitter, string)) return 0;
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_tag_content(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length,
+        int need_whitespace)
+{
+    yaml_string_t string;
+    STRING_ASSIGN(string, value, length);
+
+    if (need_whitespace && !emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end) {
+        if (IS_ALPHA(string)
+                || CHECK(string, ';') || CHECK(string, '/')
+                || CHECK(string, '?') || CHECK(string, ':')
+                || CHECK(string, '@') || CHECK(string, '&')
+                || CHECK(string, '=') || CHECK(string, '+')
+                || CHECK(string, '$') || CHECK(string, ',')
+                || CHECK(string, '_') || CHECK(string, '.')
+                || CHECK(string, '~') || CHECK(string, '*')
+                || CHECK(string, '\'') || CHECK(string, '(')
+                || CHECK(string, ')') || CHECK(string, '[')
+                || CHECK(string, ']')) {
+            if (!WRITE(emitter, string)) return 0;
+        }
+        else {
+            int width = WIDTH(string);
+            unsigned int value;
+            while (width --) {
+                value = *(string.pointer++);
+                if (!PUT(emitter, '%')) return 0;
+                if (!PUT(emitter, (value >> 4)
+                            + ((value >> 4) < 10 ? '0' : 'A' - 10)))
+                    return 0;
+                if (!PUT(emitter, (value & 0x0F)
+                            + ((value & 0x0F) < 10 ? '0' : 'A' - 10)))
+                    return 0;
+            }
+        }
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_plain_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks)
+{
+    yaml_string_t string;
+    int spaces = 0;
+    int breaks = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end)
+    {
+        if (IS_SPACE(string))
+        {
+            if (allow_breaks && !spaces
+                    && emitter->column > emitter->best_width
+                    && !IS_SPACE_AT(string, 1)) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            spaces = 1;
+        }
+        else if (IS_BREAK(string))
+        {
+            if (!breaks && CHECK(string, '\n')) {
+                if (!PUT_BREAK(emitter)) return 0;
+            }
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+            }
+            if (!WRITE(emitter, string)) return 0;
+            emitter->indention = 0;
+            spaces = 0;
+            breaks = 0;
+        }
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+    if (emitter->root_context)
+    {
+        emitter->open_ended = 1;
+    }
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_single_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks)
+{
+    yaml_string_t string;
+    int spaces = 0;
+    int breaks = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, "'", 1, 0, 0))
+        return 0;
+
+    while (string.pointer != string.end)
+    {
+        if (IS_SPACE(string))
+        {
+            if (allow_breaks && !spaces
+                    && emitter->column > emitter->best_width
+                    && string.pointer != string.start
+                    && string.pointer != string.end - 1
+                    && !IS_SPACE_AT(string, 1)) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            spaces = 1;
+        }
+        else if (IS_BREAK(string))
+        {
+            if (!breaks && CHECK(string, '\n')) {
+                if (!PUT_BREAK(emitter)) return 0;
+            }
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+            }
+            if (CHECK(string, '\'')) {
+                if (!PUT(emitter, '\'')) return 0;
+            }
+            if (!WRITE(emitter, string)) return 0;
+            emitter->indention = 0;
+            spaces = 0;
+            breaks = 0;
+        }
+    }
+
+    if (!yaml_emitter_write_indicator(emitter, "'", 0, 0, 0))
+        return 0;
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_double_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks)
+{
+    yaml_string_t string;
+    int spaces = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, "\"", 1, 0, 0))
+        return 0;
+
+    while (string.pointer != string.end)
+    {
+        if (!IS_PRINTABLE(string) || (!emitter->unicode && !IS_ASCII(string))
+                || IS_BOM(string) || IS_BREAK(string)
+                || CHECK(string, '"') || CHECK(string, '\\'))
+        {
+            unsigned char octet;
+            unsigned int width;
+            unsigned int value;
+            int k;
+
+            octet = string.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;
+            for (k = 1; k < (int)width; k ++) {
+                octet = string.pointer[k];
+                value = (value << 6) + (octet & 0x3F);
+            }
+            string.pointer += width;
+
+            if (!PUT(emitter, '\\')) return 0;
+
+            switch (value)
+            {
+                case 0x00:
+                    if (!PUT(emitter, '0')) return 0;
+                    break;
+
+                case 0x07:
+                    if (!PUT(emitter, 'a')) return 0;
+                    break;
+
+                case 0x08:
+                    if (!PUT(emitter, 'b')) return 0;
+                    break;
+
+                case 0x09:
+                    if (!PUT(emitter, 't')) return 0;
+                    break;
+
+                case 0x0A:
+                    if (!PUT(emitter, 'n')) return 0;
+                    break;
+
+                case 0x0B:
+                    if (!PUT(emitter, 'v')) return 0;
+                    break;
+
+                case 0x0C:
+                    if (!PUT(emitter, 'f')) return 0;
+                    break;
+
+                case 0x0D:
+                    if (!PUT(emitter, 'r')) return 0;
+                    break;
+
+                case 0x1B:
+                    if (!PUT(emitter, 'e')) return 0;
+                    break;
+
+                case 0x22:
+                    if (!PUT(emitter, '\"')) return 0;
+                    break;
+
+                case 0x5C:
+                    if (!PUT(emitter, '\\')) return 0;
+                    break;
+
+                case 0x85:
+                    if (!PUT(emitter, 'N')) return 0;
+                    break;
+
+                case 0xA0:
+                    if (!PUT(emitter, '_')) return 0;
+                    break;
+
+                case 0x2028:
+                    if (!PUT(emitter, 'L')) return 0;
+                    break;
+
+                case 0x2029:
+                    if (!PUT(emitter, 'P')) return 0;
+                    break;
+
+                default:
+                    if (value <= 0xFF) {
+                        if (!PUT(emitter, 'x')) return 0;
+                        width = 2;
+                    }
+                    else if (value <= 0xFFFF) {
+                        if (!PUT(emitter, 'u')) return 0;
+                        width = 4;
+                    }
+                    else {
+                        if (!PUT(emitter, 'U')) return 0;
+                        width = 8;
+                    }
+                    for (k = (width-1)*4; k >= 0; k -= 4) {
+                        int digit = (value >> k) & 0x0F;
+                        if (!PUT(emitter, digit + (digit < 10 ? '0' : 'A'-10)))
+                            return 0;
+                    }
+            }
+            spaces = 0;
+        }
+        else if (IS_SPACE(string))
+        {
+            if (allow_breaks && !spaces
+                    && emitter->column > emitter->best_width
+                    && string.pointer != string.start
+                    && string.pointer != string.end - 1) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                if (IS_SPACE_AT(string, 1)) {
+                    if (!PUT(emitter, '\\')) return 0;
+                }
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            spaces = 1;
+        }
+        else
+        {
+            if (!WRITE(emitter, string)) return 0;
+            spaces = 0;
+        }
+    }
+
+    if (!yaml_emitter_write_indicator(emitter, "\"", 0, 0, 0))
+        return 0;
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_block_scalar_hints(yaml_emitter_t *emitter,
+        yaml_string_t string)
+{
+    char indent_hint[2];
+    const char *chomp_hint = NULL;
+
+    if (IS_SPACE(string) || IS_BREAK(string))
+    {
+        indent_hint[0] = '0' + (char)emitter->best_indent;
+        indent_hint[1] = '\0';
+        if (!yaml_emitter_write_indicator(emitter, indent_hint, 0, 0, 0))
+            return 0;
+    }
+
+    emitter->open_ended = 0;
+
+    string.pointer = string.end;
+    if (string.start == string.pointer)
+    {
+        chomp_hint = "-";
+    }
+    else
+    {
+        do {
+            string.pointer --;
+        } while ((*string.pointer & 0xC0) == 0x80);
+        if (!IS_BREAK(string))
+        {
+            chomp_hint = "-";
+        }
+        else if (string.start == string.pointer)
+        {
+            chomp_hint = "+";
+            emitter->open_ended = 1;
+        }
+        else
+        {
+            do {
+                string.pointer --;
+            } while ((*string.pointer & 0xC0) == 0x80);
+            if (IS_BREAK(string))
+            {
+                chomp_hint = "+";
+                emitter->open_ended = 1;
+            }
+        }
+    }
+
+    if (chomp_hint)
+    {
+        if (!yaml_emitter_write_indicator(emitter, chomp_hint, 0, 0, 0))
+            return 0;
+    }
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_literal_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    int breaks = 1;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, "|", 1, 0, 0))
+        return 0;
+    if (!yaml_emitter_write_block_scalar_hints(emitter, string))
+        return 0;
+    if (!PUT_BREAK(emitter)) return 0;
+    emitter->indention = 1;
+    emitter->whitespace = 1;
+
+    while (string.pointer != string.end)
+    {
+        if (IS_BREAK(string))
+        {
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+            }
+            if (!WRITE(emitter, string)) return 0;
+            emitter->indention = 0;
+            breaks = 0;
+        }
+    }
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_folded_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    int breaks = 1;
+    int leading_spaces = 1;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, ">", 1, 0, 0))
+        return 0;
+    if (!yaml_emitter_write_block_scalar_hints(emitter, string))
+        return 0;
+    if (!PUT_BREAK(emitter)) return 0;
+    emitter->indention = 1;
+    emitter->whitespace = 1;
+
+    while (string.pointer != string.end)
+    {
+        if (IS_BREAK(string))
+        {
+            if (!breaks && !leading_spaces && CHECK(string, '\n')) {
+                int k = 0;
+                while (IS_BREAK_AT(string, k)) {
+                    k += WIDTH_AT(string, k);
+                }
+                if (!IS_BLANKZ_AT(string, k)) {
+                    if (!PUT_BREAK(emitter)) return 0;
+                }
+            }
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                leading_spaces = IS_BLANK(string);
+            }
+            if (!breaks && IS_SPACE(string) && !IS_SPACE_AT(string, 1)
+                    && emitter->column > emitter->best_width) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            emitter->indention = 0;
+            breaks = 0;
+        }
+    }
+
+    return 1;
+}
+
diff --git a/ext/psych/yaml/loader.c b/ext/psych/yaml/loader.c
new file mode 100644
index 0000000..9d3d912
--- /dev/null
+++ b/ext/psych/yaml/loader.c
@@ -0,0 +1,432 @@
+
+#include "yaml_private.h"
+
+/*
+ * API functions.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_load(yaml_parser_t *parser, yaml_document_t *document);
+
+/*
+ * Error handling.
+ */
+
+static int
+yaml_parser_set_composer_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark);
+
+static int
+yaml_parser_set_composer_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark);
+
+
+/*
+ * Alias handling.
+ */
+
+static int
+yaml_parser_register_anchor(yaml_parser_t *parser,
+        int index, yaml_char_t *anchor);
+
+/*
+ * Clean up functions.
+ */
+
+static void
+yaml_parser_delete_aliases(yaml_parser_t *parser);
+
+/*
+ * Composer functions.
+ */
+
+static int
+yaml_parser_load_document(yaml_parser_t *parser, yaml_event_t *first_event);
+
+static int
+yaml_parser_load_node(yaml_parser_t *parser, yaml_event_t *first_event);
+
+static int
+yaml_parser_load_alias(yaml_parser_t *parser, yaml_event_t *first_event);
+
+static int
+yaml_parser_load_scalar(yaml_parser_t *parser, yaml_event_t *first_event);
+
+static int
+yaml_parser_load_sequence(yaml_parser_t *parser, yaml_event_t *first_event);
+
+static int
+yaml_parser_load_mapping(yaml_parser_t *parser, yaml_event_t *first_event);
+
+/*
+ * Load the next document of the stream.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_load(yaml_parser_t *parser, yaml_document_t *document)
+{
+    yaml_event_t event;
+
+    assert(parser);     /* Non-NULL parser object is expected. */
+    assert(document);   /* Non-NULL document object is expected. */
+
+    memset(document, 0, sizeof(yaml_document_t));
+    if (!STACK_INIT(parser, document->nodes, INITIAL_STACK_SIZE))
+        goto error;
+
+    if (!parser->stream_start_produced) {
+        if (!yaml_parser_parse(parser, &event)) goto error;
+        assert(event.type == YAML_STREAM_START_EVENT);
+                        /* STREAM-START is expected. */
+    }
+
+    if (parser->stream_end_produced) {
+        return 1;
+    }
+
+    if (!yaml_parser_parse(parser, &event)) goto error;
+    if (event.type == YAML_STREAM_END_EVENT) {
+        return 1;
+    }
+
+    if (!STACK_INIT(parser, parser->aliases, INITIAL_STACK_SIZE))
+        goto error;
+
+    parser->document = document;
+
+    if (!yaml_parser_load_document(parser, &event)) goto error;
+
+    yaml_parser_delete_aliases(parser);
+    parser->document = NULL;
+
+    return 1;
+
+error:
+
+    yaml_parser_delete_aliases(parser);
+    yaml_document_delete(document);
+    parser->document = NULL;
+
+    return 0;
+}
+
+/*
+ * Set composer error.
+ */
+
+static int
+yaml_parser_set_composer_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_COMPOSER_ERROR;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+/*
+ * Set composer error with context.
+ */
+
+static int
+yaml_parser_set_composer_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_COMPOSER_ERROR;
+    parser->context = context;
+    parser->context_mark = context_mark;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+/*
+ * Delete the stack of aliases.
+ */
+
+static void
+yaml_parser_delete_aliases(yaml_parser_t *parser)
+{
+    while (!STACK_EMPTY(parser, parser->aliases)) {
+        yaml_free(POP(parser, parser->aliases).anchor);
+    }
+    STACK_DEL(parser, parser->aliases);
+}
+
+/*
+ * Compose a document object.
+ */
+
+static int
+yaml_parser_load_document(yaml_parser_t *parser, yaml_event_t *first_event)
+{
+    yaml_event_t event;
+
+    assert(first_event->type == YAML_DOCUMENT_START_EVENT);
+                        /* DOCUMENT-START is expected. */
+
+    parser->document->version_directive
+        = first_event->data.document_start.version_directive;
+    parser->document->tag_directives.start
+        = first_event->data.document_start.tag_directives.start;
+    parser->document->tag_directives.end
+        = first_event->data.document_start.tag_directives.end;
+    parser->document->start_implicit
+        = first_event->data.document_start.implicit;
+    parser->document->start_mark = first_event->start_mark;
+
+    if (!yaml_parser_parse(parser, &event)) return 0;
+
+    if (!yaml_parser_load_node(parser, &event)) return 0;
+
+    if (!yaml_parser_parse(parser, &event)) return 0;
+    assert(event.type == YAML_DOCUMENT_END_EVENT);
+                        /* DOCUMENT-END is expected. */
+
+    parser->document->end_implicit = event.data.document_end.implicit;
+    parser->document->end_mark = event.end_mark;
+
+    return 1;
+}
+
+/*
+ * Compose a node.
+ */
+
+static int
+yaml_parser_load_node(yaml_parser_t *parser, yaml_event_t *first_event)
+{
+    switch (first_event->type) {
+        case YAML_ALIAS_EVENT:
+            return yaml_parser_load_alias(parser, first_event);
+        case YAML_SCALAR_EVENT:
+            return yaml_parser_load_scalar(parser, first_event);
+        case YAML_SEQUENCE_START_EVENT:
+            return yaml_parser_load_sequence(parser, first_event);
+        case YAML_MAPPING_START_EVENT:
+            return yaml_parser_load_mapping(parser, first_event);
+        default:
+            assert(0);  /* Could not happen. */
+            return 0;
+    }
+
+    return 0;
+}
+
+/*
+ * Add an anchor.
+ */
+
+static int
+yaml_parser_register_anchor(yaml_parser_t *parser,
+        int index, yaml_char_t *anchor)
+{
+    yaml_alias_data_t data;
+    yaml_alias_data_t *alias_data;
+
+    if (!anchor) return 1;
+
+    data.anchor = anchor;
+    data.index = index;
+    data.mark = parser->document->nodes.start[index-1].start_mark;
+
+    for (alias_data = parser->aliases.start;
+            alias_data != parser->aliases.top; alias_data ++) {
+        if (strcmp((char *)alias_data->anchor, (char *)anchor) == 0) {
+            yaml_free(anchor);
+            return yaml_parser_set_composer_error_context(parser,
+                    "found duplicate anchor; first occurence",
+                    alias_data->mark, "second occurence", data.mark);
+        }
+    }
+
+    if (!PUSH(parser, parser->aliases, data)) {
+        yaml_free(anchor);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Compose a node corresponding to an alias.
+ */
+
+static int
+yaml_parser_load_alias(yaml_parser_t *parser, yaml_event_t *first_event)
+{
+    yaml_char_t *anchor = first_event->data.alias.anchor;
+    yaml_alias_data_t *alias_data;
+
+    for (alias_data = parser->aliases.start;
+            alias_data != parser->aliases.top; alias_data ++) {
+        if (strcmp((char *)alias_data->anchor, (char *)anchor) == 0) {
+            yaml_free(anchor);
+            return alias_data->index;
+        }
+    }
+
+    yaml_free(anchor);
+    return yaml_parser_set_composer_error(parser, "found undefined alias",
+            first_event->start_mark);
+}
+
+/*
+ * Compose a scalar node.
+ */
+
+static int
+yaml_parser_load_scalar(yaml_parser_t *parser, yaml_event_t *first_event)
+{
+    yaml_node_t node;
+    int index;
+    yaml_char_t *tag = first_event->data.scalar.tag;
+
+    if (!tag || strcmp((char *)tag, "!") == 0) {
+        yaml_free(tag);
+        tag = yaml_strdup((yaml_char_t *)YAML_DEFAULT_SCALAR_TAG);
+        if (!tag) goto error;
+    }
+
+    SCALAR_NODE_INIT(node, tag, first_event->data.scalar.value,
+            first_event->data.scalar.length, first_event->data.scalar.style,
+            first_event->start_mark, first_event->end_mark);
+
+    if (!PUSH(parser, parser->document->nodes, node)) goto error;
+
+    index = parser->document->nodes.top - parser->document->nodes.start;
+
+    if (!yaml_parser_register_anchor(parser, index,
+                first_event->data.scalar.anchor)) return 0;
+
+    return index;
+
+error:
+    yaml_free(tag);
+    yaml_free(first_event->data.scalar.anchor);
+    yaml_free(first_event->data.scalar.value);
+    return 0;
+}
+
+/*
+ * Compose a sequence node.
+ */
+
+static int
+yaml_parser_load_sequence(yaml_parser_t *parser, yaml_event_t *first_event)
+{
+    yaml_event_t event;
+    yaml_node_t node;
+    struct {
+        yaml_node_item_t *start;
+        yaml_node_item_t *end;
+        yaml_node_item_t *top;
+    } items = { NULL, NULL, NULL };
+    int index, item_index;
+    yaml_char_t *tag = first_event->data.sequence_start.tag;
+
+    if (!tag || strcmp((char *)tag, "!") == 0) {
+        yaml_free(tag);
+        tag = yaml_strdup((yaml_char_t *)YAML_DEFAULT_SEQUENCE_TAG);
+        if (!tag) goto error;
+    }
+
+    if (!STACK_INIT(parser, items, INITIAL_STACK_SIZE)) goto error;
+
+    SEQUENCE_NODE_INIT(node, tag, items.start, items.end,
+            first_event->data.sequence_start.style,
+            first_event->start_mark, first_event->end_mark);
+
+    if (!PUSH(parser, parser->document->nodes, node)) goto error;
+
+    index = parser->document->nodes.top - parser->document->nodes.start;
+
+    if (!yaml_parser_register_anchor(parser, index,
+                first_event->data.sequence_start.anchor)) return 0;
+
+    if (!yaml_parser_parse(parser, &event)) return 0;
+
+    while (event.type != YAML_SEQUENCE_END_EVENT) {
+        item_index = yaml_parser_load_node(parser, &event);
+        if (!item_index) return 0;
+        if (!PUSH(parser,
+                    parser->document->nodes.start[index-1].data.sequence.items,
+                    item_index)) return 0;
+        if (!yaml_parser_parse(parser, &event)) return 0;
+    }
+
+    parser->document->nodes.start[index-1].end_mark = event.end_mark;
+
+    return index;
+
+error:
+    yaml_free(tag);
+    yaml_free(first_event->data.sequence_start.anchor);
+    return 0;
+}
+
+/*
+ * Compose a mapping node.
+ */
+
+static int
+yaml_parser_load_mapping(yaml_parser_t *parser, yaml_event_t *first_event)
+{
+    yaml_event_t event;
+    yaml_node_t node;
+    struct {
+        yaml_node_pair_t *start;
+        yaml_node_pair_t *end;
+        yaml_node_pair_t *top;
+    } pairs = { NULL, NULL, NULL };
+    int index;
+    yaml_node_pair_t pair;
+    yaml_char_t *tag = first_event->data.mapping_start.tag;
+
+    if (!tag || strcmp((char *)tag, "!") == 0) {
+        yaml_free(tag);
+        tag = yaml_strdup((yaml_char_t *)YAML_DEFAULT_MAPPING_TAG);
+        if (!tag) goto error;
+    }
+
+    if (!STACK_INIT(parser, pairs, INITIAL_STACK_SIZE)) goto error;
+
+    MAPPING_NODE_INIT(node, tag, pairs.start, pairs.end,
+            first_event->data.mapping_start.style,
+            first_event->start_mark, first_event->end_mark);
+
+    if (!PUSH(parser, parser->document->nodes, node)) goto error;
+
+    index = parser->document->nodes.top - parser->document->nodes.start;
+
+    if (!yaml_parser_register_anchor(parser, index,
+                first_event->data.mapping_start.anchor)) return 0;
+
+    if (!yaml_parser_parse(parser, &event)) return 0;
+
+    while (event.type != YAML_MAPPING_END_EVENT) {
+        pair.key = yaml_parser_load_node(parser, &event);
+        if (!pair.key) return 0;
+        if (!yaml_parser_parse(parser, &event)) return 0;
+        pair.value = yaml_parser_load_node(parser, &event);
+        if (!pair.value) return 0;
+        if (!PUSH(parser,
+                    parser->document->nodes.start[index-1].data.mapping.pairs,
+                    pair)) return 0;
+        if (!yaml_parser_parse(parser, &event)) return 0;
+    }
+
+    parser->document->nodes.start[index-1].end_mark = event.end_mark;
+
+    return index;
+
+error:
+    yaml_free(tag);
+    yaml_free(first_event->data.mapping_start.anchor);
+    return 0;
+}
+
diff --git a/ext/psych/yaml/parser.c b/ext/psych/yaml/parser.c
new file mode 100644
index 0000000..dc5430b
--- /dev/null
+++ b/ext/psych/yaml/parser.c
@@ -0,0 +1,1374 @@
+
+/*
+ * 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?)?
+ */
+
+#include "yaml_private.h"
+
+/*
+ * Peek the next token in the token queue.
+ */
+
+#define PEEK_TOKEN(parser)                                                      \
+    ((parser->token_available || yaml_parser_fetch_more_tokens(parser)) ?       \
+        parser->tokens.head : NULL)
+
+/*
+ * Remove the next token from the queue (must be called after PEEK_TOKEN).
+ */
+
+#define SKIP_TOKEN(parser)                                                      \
+    (parser->token_available = 0,                                               \
+     parser->tokens_parsed ++,                                                  \
+     parser->stream_end_produced =                                              \
+        (parser->tokens.head->type == YAML_STREAM_END_TOKEN),                   \
+     parser->tokens.head ++)
+
+/*
+ * Public API declarations.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_parse(yaml_parser_t *parser, yaml_event_t *event);
+
+/*
+ * Error handling.
+ */
+
+static int
+yaml_parser_set_parser_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark);
+
+static int
+yaml_parser_set_parser_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark);
+
+/*
+ * State functions.
+ */
+
+static int
+yaml_parser_state_machine(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_stream_start(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_document_start(yaml_parser_t *parser, yaml_event_t *event,
+        int implicit);
+
+static int
+yaml_parser_parse_document_content(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_document_end(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_node(yaml_parser_t *parser, yaml_event_t *event,
+        int block, int indentless_sequence);
+
+static int
+yaml_parser_parse_block_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_indentless_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_block_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_block_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_end(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_flow_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event, int empty);
+
+/*
+ * Utility functions.
+ */
+
+static int
+yaml_parser_process_empty_scalar(yaml_parser_t *parser,
+        yaml_event_t *event, yaml_mark_t mark);
+
+static int
+yaml_parser_process_directives(yaml_parser_t *parser,
+        yaml_version_directive_t **version_directive_ref,
+        yaml_tag_directive_t **tag_directives_start_ref,
+        yaml_tag_directive_t **tag_directives_end_ref);
+
+static int
+yaml_parser_append_tag_directive(yaml_parser_t *parser,
+        yaml_tag_directive_t value, int allow_duplicates, yaml_mark_t mark);
+
+/*
+ * Get the next event.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_parse(yaml_parser_t *parser, yaml_event_t *event)
+{
+    assert(parser);     /* Non-NULL parser object is expected. */
+    assert(event);      /* Non-NULL event object is expected. */
+
+    /* Erase the event object. */
+
+    memset(event, 0, sizeof(yaml_event_t));
+
+    /* No events after the end of the stream or error. */
+
+    if (parser->stream_end_produced || parser->error ||
+            parser->state == YAML_PARSE_END_STATE) {
+        return 1;
+    }
+
+    /* Generate the next event. */
+
+    return yaml_parser_state_machine(parser, event);
+}
+
+/*
+ * Set parser error.
+ */
+
+static int
+yaml_parser_set_parser_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_PARSER_ERROR;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+static int
+yaml_parser_set_parser_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_PARSER_ERROR;
+    parser->context = context;
+    parser->context_mark = context_mark;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+
+/*
+ * State dispatcher.
+ */
+
+static int
+yaml_parser_state_machine(yaml_parser_t *parser, yaml_event_t *event)
+{
+    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, 1);
+
+        case YAML_PARSE_DOCUMENT_START_STATE:
+            return yaml_parser_parse_document_start(parser, event, 0);
+
+        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, 1, 0);
+
+        case YAML_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE:
+            return yaml_parser_parse_node(parser, event, 1, 1);
+
+        case YAML_PARSE_FLOW_NODE_STATE:
+            return yaml_parser_parse_node(parser, event, 0, 0);
+
+        case YAML_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE:
+            return yaml_parser_parse_block_sequence_entry(parser, event, 1);
+
+        case YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE:
+            return yaml_parser_parse_block_sequence_entry(parser, event, 0);
+
+        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, 1);
+
+        case YAML_PARSE_BLOCK_MAPPING_KEY_STATE:
+            return yaml_parser_parse_block_mapping_key(parser, event, 0);
+
+        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, 1);
+
+        case YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE:
+            return yaml_parser_parse_flow_sequence_entry(parser, event, 0);
+
+        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, 1);
+
+        case YAML_PARSE_FLOW_MAPPING_KEY_STATE:
+            return yaml_parser_parse_flow_mapping_key(parser, event, 0);
+
+        case YAML_PARSE_FLOW_MAPPING_VALUE_STATE:
+            return yaml_parser_parse_flow_mapping_value(parser, event, 0);
+
+        case YAML_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE:
+            return yaml_parser_parse_flow_mapping_value(parser, event, 1);
+
+        default:
+            assert(1);      /* Invalid state. */
+    }
+
+    return 0;
+}
+
+/*
+ * Parse the production:
+ * stream   ::= STREAM-START implicit_document? explicit_document* STREAM-END
+ *              ************
+ */
+
+static int
+yaml_parser_parse_stream_start(yaml_parser_t *parser, yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != 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;
+    STREAM_START_EVENT_INIT(*event, token->data.stream_start.encoding,
+            token->start_mark, token->start_mark);
+    SKIP_TOKEN(parser);
+
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * implicit_document    ::= block_node DOCUMENT-END*
+ *                          *
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ *                          *************************
+ */
+
+static int
+yaml_parser_parse_document_start(yaml_parser_t *parser, yaml_event_t *event,
+        int implicit)
+{
+    yaml_token_t *token;
+    yaml_version_directive_t *version_directive = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+    } tag_directives = { NULL, NULL };
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    /* Parse extra document end indicators. */
+
+    if (!implicit)
+    {
+        while (token->type == YAML_DOCUMENT_END_TOKEN) {
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) return 0;
+        }
+    }
+
+    /* Parse an implicit document. */
+
+    if (implicit && token->type != YAML_VERSION_DIRECTIVE_TOKEN &&
+            token->type != YAML_TAG_DIRECTIVE_TOKEN &&
+            token->type != YAML_DOCUMENT_START_TOKEN &&
+            token->type != YAML_STREAM_END_TOKEN)
+    {
+        if (!yaml_parser_process_directives(parser, NULL, NULL, NULL))
+            return 0;
+        if (!PUSH(parser, parser->states, YAML_PARSE_DOCUMENT_END_STATE))
+            return 0;
+        parser->state = YAML_PARSE_BLOCK_NODE_STATE;
+        DOCUMENT_START_EVENT_INIT(*event, NULL, NULL, NULL, 1,
+                token->start_mark, token->start_mark);
+        return 1;
+    }
+
+    /* Parse an explicit document. */
+
+    else if (token->type != YAML_STREAM_END_TOKEN)
+    {
+        yaml_mark_t start_mark, end_mark;
+        start_mark = token->start_mark;
+        if (!yaml_parser_process_directives(parser, &version_directive,
+                    &tag_directives.start, &tag_directives.end))
+            return 0;
+        token = PEEK_TOKEN(parser);
+        if (!token) goto error;
+        if (token->type != YAML_DOCUMENT_START_TOKEN) {
+            yaml_parser_set_parser_error(parser,
+                    "did not find expected <document start>", token->start_mark);
+            goto error;
+        }
+        if (!PUSH(parser, parser->states, YAML_PARSE_DOCUMENT_END_STATE))
+            goto error;
+        parser->state = YAML_PARSE_DOCUMENT_CONTENT_STATE;
+        end_mark = token->end_mark;
+        DOCUMENT_START_EVENT_INIT(*event, version_directive,
+                tag_directives.start, tag_directives.end, 0,
+                start_mark, end_mark);
+        SKIP_TOKEN(parser);
+        version_directive = NULL;
+        tag_directives.start = tag_directives.end = NULL;
+        return 1;
+    }
+
+    /* Parse the stream end. */
+
+    else
+    {
+        parser->state = YAML_PARSE_END_STATE;
+        STREAM_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+error:
+    yaml_free(version_directive);
+    while (tag_directives.start != tag_directives.end) {
+        yaml_free(tag_directives.end[-1].handle);
+        yaml_free(tag_directives.end[-1].prefix);
+        tag_directives.end --;
+    }
+    yaml_free(tag_directives.start);
+    return 0;
+}
+
+/*
+ * Parse the productions:
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ *                                                    ***********
+ */
+
+static int
+yaml_parser_parse_document_content(yaml_parser_t *parser, yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_VERSION_DIRECTIVE_TOKEN ||
+            token->type == YAML_TAG_DIRECTIVE_TOKEN ||
+            token->type == YAML_DOCUMENT_START_TOKEN ||
+            token->type == YAML_DOCUMENT_END_TOKEN ||
+            token->type == YAML_STREAM_END_TOKEN) {
+        parser->state = POP(parser, parser->states);
+        return yaml_parser_process_empty_scalar(parser, event,
+                token->start_mark);
+    }
+    else {
+        return yaml_parser_parse_node(parser, event, 1, 0);
+    }
+}
+
+/*
+ * Parse the productions:
+ * implicit_document    ::= block_node DOCUMENT-END*
+ *                                     *************
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ *                                                                *************
+ */
+
+static int
+yaml_parser_parse_document_end(yaml_parser_t *parser, yaml_event_t *event)
+{
+    yaml_token_t *token;
+    yaml_mark_t start_mark, end_mark;
+    int implicit = 1;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    start_mark = end_mark = token->start_mark;
+
+    if (token->type == YAML_DOCUMENT_END_TOKEN) {
+        end_mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        implicit = 0;
+    }
+
+    while (!STACK_EMPTY(parser, parser->tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(parser, parser->tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+
+    parser->state = YAML_PARSE_DOCUMENT_START_STATE;
+    DOCUMENT_END_EVENT_INIT(*event, implicit, start_mark, end_mark);
+
+    return 1;
+}
+
+/*
+ * 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
+ *                                            ******
+ */
+
+static int
+yaml_parser_parse_node(yaml_parser_t *parser, yaml_event_t *event,
+        int block, int indentless_sequence)
+{
+    yaml_token_t *token;
+    yaml_char_t *anchor = NULL;
+    yaml_char_t *tag_handle = NULL;
+    yaml_char_t *tag_suffix = NULL;
+    yaml_char_t *tag = NULL;
+    yaml_mark_t start_mark, end_mark, tag_mark;
+    int implicit;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_ALIAS_TOKEN)
+    {
+        parser->state = POP(parser, parser->states);
+        ALIAS_EVENT_INIT(*event, token->data.alias.value,
+                token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+    else
+    {
+        start_mark = end_mark = token->start_mark;
+
+        if (token->type == YAML_ANCHOR_TOKEN)
+        {
+            anchor = token->data.anchor.value;
+            start_mark = token->start_mark;
+            end_mark = token->end_mark;
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) goto error;
+            if (token->type == YAML_TAG_TOKEN)
+            {
+                tag_handle = token->data.tag.handle;
+                tag_suffix = token->data.tag.suffix;
+                tag_mark = token->start_mark;
+                end_mark = token->end_mark;
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) goto error;
+            }
+        }
+        else if (token->type == YAML_TAG_TOKEN)
+        {
+            tag_handle = token->data.tag.handle;
+            tag_suffix = token->data.tag.suffix;
+            start_mark = tag_mark = token->start_mark;
+            end_mark = token->end_mark;
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) goto error;
+            if (token->type == YAML_ANCHOR_TOKEN)
+            {
+                anchor = token->data.anchor.value;
+                end_mark = token->end_mark;
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) goto error;
+            }
+        }
+
+        if (tag_handle) {
+            if (!*tag_handle) {
+                tag = tag_suffix;
+                yaml_free(tag_handle);
+                tag_handle = tag_suffix = NULL;
+            }
+            else {
+                yaml_tag_directive_t *tag_directive;
+                for (tag_directive = parser->tag_directives.start;
+                        tag_directive != parser->tag_directives.top;
+                        tag_directive ++) {
+                    if (strcmp((char *)tag_directive->handle, (char *)tag_handle) == 0) {
+                        size_t prefix_len = strlen((char *)tag_directive->prefix);
+                        size_t suffix_len = strlen((char *)tag_suffix);
+                        tag = yaml_malloc(prefix_len+suffix_len+1);
+                        if (!tag) {
+                            parser->error = YAML_MEMORY_ERROR;
+                            goto error;
+                        }
+                        memcpy(tag, tag_directive->prefix, prefix_len);
+                        memcpy(tag+prefix_len, tag_suffix, suffix_len);
+                        tag[prefix_len+suffix_len] = '\0';
+                        yaml_free(tag_handle);
+                        yaml_free(tag_suffix);
+                        tag_handle = tag_suffix = NULL;
+                        break;
+                    }
+                }
+                if (!tag) {
+                    yaml_parser_set_parser_error_context(parser,
+                            "while parsing a node", start_mark,
+                            "found undefined tag handle", tag_mark);
+                    goto error;
+                }
+            }
+        }
+
+        implicit = (!tag || !*tag);
+        if (indentless_sequence && token->type == YAML_BLOCK_ENTRY_TOKEN) {
+            end_mark = token->end_mark;
+            parser->state = YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE;
+            SEQUENCE_START_EVENT_INIT(*event, anchor, tag, implicit,
+                    YAML_BLOCK_SEQUENCE_STYLE, start_mark, end_mark);
+            return 1;
+        }
+        else {
+            if (token->type == YAML_SCALAR_TOKEN) {
+                int plain_implicit = 0;
+                int quoted_implicit = 0;
+                end_mark = token->end_mark;
+                if ((token->data.scalar.style == YAML_PLAIN_SCALAR_STYLE && !tag)
+                        || (tag && strcmp((char *)tag, "!") == 0)) {
+                    plain_implicit = 1;
+                }
+                else if (!tag) {
+                    quoted_implicit = 1;
+                }
+                parser->state = POP(parser, parser->states);
+                SCALAR_EVENT_INIT(*event, anchor, tag,
+                        token->data.scalar.value, token->data.scalar.length,
+                        plain_implicit, quoted_implicit,
+                        token->data.scalar.style, start_mark, end_mark);
+                SKIP_TOKEN(parser);
+                return 1;
+            }
+            else if (token->type == YAML_FLOW_SEQUENCE_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE;
+                SEQUENCE_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_FLOW_SEQUENCE_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (token->type == YAML_FLOW_MAPPING_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_FLOW_MAPPING_FIRST_KEY_STATE;
+                MAPPING_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_FLOW_MAPPING_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (block && token->type == YAML_BLOCK_SEQUENCE_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE;
+                SEQUENCE_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_BLOCK_SEQUENCE_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (block && token->type == YAML_BLOCK_MAPPING_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE;
+                MAPPING_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_BLOCK_MAPPING_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (anchor || tag) {
+                yaml_char_t *value = yaml_malloc(1);
+                if (!value) {
+                    parser->error = YAML_MEMORY_ERROR;
+                    goto error;
+                }
+                value[0] = '\0';
+                parser->state = POP(parser, parser->states);
+                SCALAR_EVENT_INIT(*event, anchor, tag, value, 0,
+                        implicit, 0, YAML_PLAIN_SCALAR_STYLE,
+                        start_mark, end_mark);
+                return 1;
+            }
+            else {
+                yaml_parser_set_parser_error_context(parser,
+                        (block ? "while parsing a block node"
+                         : "while parsing a flow node"), start_mark,
+                        "did not find expected node content", token->start_mark);
+                goto error;
+            }
+        }
+    }
+
+error:
+    yaml_free(anchor);
+    yaml_free(tag_handle);
+    yaml_free(tag_suffix);
+    yaml_free(tag);
+
+    return 0;
+}
+
+/*
+ * Parse the productions:
+ * block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
+ *                    ********************  *********** *             *********
+ */
+
+static int
+yaml_parser_parse_block_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_BLOCK_ENTRY_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_BLOCK_ENTRY_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 0);
+        }
+        else {
+            parser->state = YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else if (token->type == YAML_BLOCK_END_TOKEN)
+    {
+        yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
+        parser->state = POP(parser, parser->states);
+        dummy_mark = POP(parser, parser->marks);
+        SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+    else
+    {
+        return yaml_parser_set_parser_error_context(parser,
+                "while parsing a block collection", POP(parser, parser->marks),
+                "did not find expected '-' indicator", token->start_mark);
+    }
+}
+
+/*
+ * Parse the productions:
+ * indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
+ *                           *********** *
+ */
+
+static int
+yaml_parser_parse_indentless_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_BLOCK_ENTRY_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_BLOCK_ENTRY_TOKEN &&
+                token->type != YAML_KEY_TOKEN &&
+                token->type != YAML_VALUE_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 0);
+        }
+        else {
+            parser->state = YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else
+    {
+        parser->state = POP(parser, parser->states);
+        SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->start_mark);
+        return 1;
+    }
+}
+
+/*
+ * Parse the productions:
+ * block_mapping        ::= BLOCK-MAPPING_START
+ *                          *******************
+ *                          ((KEY block_node_or_indentless_sequence?)?
+ *                            *** *
+ *                          (VALUE block_node_or_indentless_sequence?)?)*
+ *
+ *                          BLOCK-END
+ *                          *********
+ */
+
+static int
+yaml_parser_parse_block_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_KEY_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_KEY_TOKEN &&
+                token->type != YAML_VALUE_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_BLOCK_MAPPING_VALUE_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 1);
+        }
+        else {
+            parser->state = YAML_PARSE_BLOCK_MAPPING_VALUE_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else if (token->type == YAML_BLOCK_END_TOKEN)
+    {
+        yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
+        parser->state = POP(parser, parser->states);
+        dummy_mark = POP(parser, parser->marks);
+        MAPPING_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+    else
+    {
+        return yaml_parser_set_parser_error_context(parser,
+                "while parsing a block mapping", POP(parser, parser->marks),
+                "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
+ *
+ */
+
+static int
+yaml_parser_parse_block_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_VALUE_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_KEY_TOKEN &&
+                token->type != YAML_VALUE_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_BLOCK_MAPPING_KEY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 1);
+        }
+        else {
+            parser->state = YAML_PARSE_BLOCK_MAPPING_KEY_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else
+    {
+        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?)?
+ *                          *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+    yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_FLOW_SEQUENCE_END_TOKEN)
+    {
+        if (!first) {
+            if (token->type == YAML_FLOW_ENTRY_TOKEN) {
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) return 0;
+            }
+            else {
+                return yaml_parser_set_parser_error_context(parser,
+                        "while parsing a flow sequence", POP(parser, parser->marks),
+                        "did not find expected ',' or ']'", token->start_mark);
+            }
+        }
+
+        if (token->type == YAML_KEY_TOKEN) {
+            parser->state = YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE;
+            MAPPING_START_EVENT_INIT(*event, NULL, NULL,
+                    1, YAML_FLOW_MAPPING_STYLE,
+                    token->start_mark, token->end_mark);
+            SKIP_TOKEN(parser);
+            return 1;
+        }
+
+        else if (token->type != YAML_FLOW_SEQUENCE_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+
+    parser->state = POP(parser, parser->states);
+    dummy_mark = POP(parser, parser->marks);
+    SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+    SKIP_TOKEN(parser);
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                                      *** *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_VALUE_TOKEN && token->type != YAML_FLOW_ENTRY_TOKEN
+            && token->type != YAML_FLOW_SEQUENCE_END_TOKEN) {
+        if (!PUSH(parser, parser->states,
+                    YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE))
+            return 0;
+        return yaml_parser_parse_node(parser, event, 0, 0);
+    }
+    else {
+        yaml_mark_t 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?)?
+ *                                                      ***** *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_VALUE_TOKEN) {
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_FLOW_ENTRY_TOKEN
+                && token->type != YAML_FLOW_SEQUENCE_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+    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?)?
+ *                                                                      *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_end(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    parser->state = YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE;
+
+    MAPPING_END_EVENT_INIT(*event, token->start_mark, token->start_mark);
+    return 1;
+}
+
+/*
+ * 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?)?
+ *                          *           *** *
+ */
+
+static int
+yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+    yaml_mark_t dummy_mark;     /* Used to eliminate a compiler warning. */
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_FLOW_MAPPING_END_TOKEN)
+    {
+        if (!first) {
+            if (token->type == YAML_FLOW_ENTRY_TOKEN) {
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) return 0;
+            }
+            else {
+                return yaml_parser_set_parser_error_context(parser,
+                        "while parsing a flow mapping", POP(parser, parser->marks),
+                        "did not find expected ',' or '}'", token->start_mark);
+            }
+        }
+
+        if (token->type == YAML_KEY_TOKEN) {
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) return 0;
+            if (token->type != YAML_VALUE_TOKEN
+                    && token->type != YAML_FLOW_ENTRY_TOKEN
+                    && token->type != YAML_FLOW_MAPPING_END_TOKEN) {
+                if (!PUSH(parser, parser->states,
+                            YAML_PARSE_FLOW_MAPPING_VALUE_STATE))
+                    return 0;
+                return yaml_parser_parse_node(parser, event, 0, 0);
+            }
+            else {
+                parser->state = YAML_PARSE_FLOW_MAPPING_VALUE_STATE;
+                return yaml_parser_process_empty_scalar(parser, event,
+                        token->start_mark);
+            }
+        }
+        else if (token->type != YAML_FLOW_MAPPING_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+
+    parser->state = POP(parser, parser->states);
+    dummy_mark = POP(parser, parser->marks);
+    MAPPING_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+    SKIP_TOKEN(parser);
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                                   *                  ***** *
+ */
+
+static int
+yaml_parser_parse_flow_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event, int empty)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (empty) {
+        parser->state = YAML_PARSE_FLOW_MAPPING_KEY_STATE;
+        return yaml_parser_process_empty_scalar(parser, event,
+                token->start_mark);
+    }
+
+    if (token->type == YAML_VALUE_TOKEN) {
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_FLOW_ENTRY_TOKEN
+                && token->type != YAML_FLOW_MAPPING_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_MAPPING_KEY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+
+    parser->state = YAML_PARSE_FLOW_MAPPING_KEY_STATE;
+    return yaml_parser_process_empty_scalar(parser, event, token->start_mark);
+}
+
+/*
+ * Generate an empty scalar event.
+ */
+
+static int
+yaml_parser_process_empty_scalar(yaml_parser_t *parser, yaml_event_t *event,
+        yaml_mark_t mark)
+{
+    yaml_char_t *value;
+
+    value = yaml_malloc(1);
+    if (!value) {
+        parser->error = YAML_MEMORY_ERROR;
+        return 0;
+    }
+    value[0] = '\0';
+
+    SCALAR_EVENT_INIT(*event, NULL, NULL, value, 0,
+            1, 0, YAML_PLAIN_SCALAR_STYLE, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Parse directives.
+ */
+
+static int
+yaml_parser_process_directives(yaml_parser_t *parser,
+        yaml_version_directive_t **version_directive_ref,
+        yaml_tag_directive_t **tag_directives_start_ref,
+        yaml_tag_directive_t **tag_directives_end_ref)
+{
+    yaml_tag_directive_t default_tag_directives[] = {
+        {(yaml_char_t *)"!", (yaml_char_t *)"!"},
+        {(yaml_char_t *)"!!", (yaml_char_t *)"tag:yaml.org,2002:"},
+        {NULL, NULL}
+    };
+    yaml_tag_directive_t *default_tag_directive;
+    yaml_version_directive_t *version_directive = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+        yaml_tag_directive_t *top;
+    } tag_directives = { NULL, NULL, NULL };
+    yaml_token_t *token;
+
+    if (!STACK_INIT(parser, tag_directives, INITIAL_STACK_SIZE))
+        goto error;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) goto error;
+
+    while (token->type == YAML_VERSION_DIRECTIVE_TOKEN ||
+            token->type == YAML_TAG_DIRECTIVE_TOKEN)
+    {
+        if (token->type == YAML_VERSION_DIRECTIVE_TOKEN) {
+            if (version_directive) {
+                yaml_parser_set_parser_error(parser,
+                        "found duplicate %YAML directive", token->start_mark);
+                goto error;
+            }
+            if (token->data.version_directive.major != 1
+                    || token->data.version_directive.minor != 1) {
+                yaml_parser_set_parser_error(parser,
+                        "found incompatible YAML document", token->start_mark);
+                goto error;
+            }
+            version_directive = yaml_malloc(sizeof(yaml_version_directive_t));
+            if (!version_directive) {
+                parser->error = YAML_MEMORY_ERROR;
+                goto error;
+            }
+            version_directive->major = token->data.version_directive.major;
+            version_directive->minor = token->data.version_directive.minor;
+        }
+
+        else if (token->type == YAML_TAG_DIRECTIVE_TOKEN) {
+            yaml_tag_directive_t value;
+            value.handle = token->data.tag_directive.handle;
+            value.prefix = token->data.tag_directive.prefix;
+
+            if (!yaml_parser_append_tag_directive(parser, value, 0,
+                        token->start_mark))
+                goto error;
+            if (!PUSH(parser, tag_directives, value))
+                goto error;
+        }
+
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) goto error;
+    }
+
+    for (default_tag_directive = default_tag_directives;
+            default_tag_directive->handle; default_tag_directive++) {
+        if (!yaml_parser_append_tag_directive(parser, *default_tag_directive, 1,
+                    token->start_mark))
+            goto error;
+    }
+
+    if (version_directive_ref) {
+        *version_directive_ref = version_directive;
+    }
+    if (tag_directives_start_ref) {
+        if (STACK_EMPTY(parser, tag_directives)) {
+            *tag_directives_start_ref = *tag_directives_end_ref = NULL;
+            STACK_DEL(parser, tag_directives);
+        }
+        else {
+            *tag_directives_start_ref = tag_directives.start;
+            *tag_directives_end_ref = tag_directives.top;
+        }
+    }
+    else {
+        STACK_DEL(parser, tag_directives);
+    }
+
+    return 1;
+
+error:
+    yaml_free(version_directive);
+    while (!STACK_EMPTY(parser, tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(parser, tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+    STACK_DEL(parser, tag_directives);
+    return 0;
+}
+
+/*
+ * Append a tag directive to the directives stack.
+ */
+
+static int
+yaml_parser_append_tag_directive(yaml_parser_t *parser,
+        yaml_tag_directive_t value, int allow_duplicates, yaml_mark_t mark)
+{
+    yaml_tag_directive_t *tag_directive;
+    yaml_tag_directive_t copy = { NULL, NULL };
+
+    for (tag_directive = parser->tag_directives.start;
+            tag_directive != parser->tag_directives.top; tag_directive ++) {
+        if (strcmp((char *)value.handle, (char *)tag_directive->handle) == 0) {
+            if (allow_duplicates)
+                return 1;
+            return yaml_parser_set_parser_error(parser,
+                    "found duplicate %TAG directive", mark);
+        }
+    }
+
+    copy.handle = yaml_strdup(value.handle);
+    copy.prefix = yaml_strdup(value.prefix);
+    if (!copy.handle || !copy.prefix) {
+        parser->error = YAML_MEMORY_ERROR;
+        goto error;
+    }
+
+    if (!PUSH(parser, parser->tag_directives, copy))
+        goto error;
+
+    return 1;
+
+error:
+    yaml_free(copy.handle);
+    yaml_free(copy.prefix);
+    return 0;
+}
+
diff --git a/ext/psych/yaml/reader.c b/ext/psych/yaml/reader.c
new file mode 100644
index 0000000..4e48add
--- /dev/null
+++ b/ext/psych/yaml/reader.c
@@ -0,0 +1,465 @@
+
+#include "yaml_private.h"
+
+/*
+ * Declarations.
+ */
+
+static int
+yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
+        size_t offset, int value);
+
+static int
+yaml_parser_update_raw_buffer(yaml_parser_t *parser);
+
+static int
+yaml_parser_determine_encoding(yaml_parser_t *parser);
+
+YAML_DECLARE(int)
+yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);
+
+/*
+ * Set the reader error and return 0.
+ */
+
+static int
+yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
+        size_t offset, int value)
+{
+    parser->error = YAML_READER_ERROR;
+    parser->problem = problem;
+    parser->problem_offset = offset;
+    parser->problem_value = value;
+
+    return 0;
+}
+
+/*
+ * Byte order marks.
+ */
+
+#define BOM_UTF8    "\xef\xbb\xbf"
+#define BOM_UTF16LE "\xff\xfe"
+#define 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.
+ */
+
+static int
+yaml_parser_determine_encoding(yaml_parser_t *parser)
+{
+    /* Ensure that we had enough bytes in the raw buffer. */
+
+    while (!parser->eof
+            && parser->raw_buffer.last - parser->raw_buffer.pointer < 3) {
+        if (!yaml_parser_update_raw_buffer(parser)) {
+            return 0;
+        }
+    }
+
+    /* Determine the encoding. */
+
+    if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
+            && !memcmp(parser->raw_buffer.pointer, BOM_UTF16LE, 2)) {
+        parser->encoding = YAML_UTF16LE_ENCODING;
+        parser->raw_buffer.pointer += 2;
+        parser->offset += 2;
+    }
+    else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
+            && !memcmp(parser->raw_buffer.pointer, BOM_UTF16BE, 2)) {
+        parser->encoding = YAML_UTF16BE_ENCODING;
+        parser->raw_buffer.pointer += 2;
+        parser->offset += 2;
+    }
+    else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 3
+            && !memcmp(parser->raw_buffer.pointer, BOM_UTF8, 3)) {
+        parser->encoding = YAML_UTF8_ENCODING;
+        parser->raw_buffer.pointer += 3;
+        parser->offset += 3;
+    }
+    else {
+        parser->encoding = YAML_UTF8_ENCODING;
+    }
+
+    return 1;
+}
+
+/*
+ * Update the raw buffer.
+ */
+
+static int
+yaml_parser_update_raw_buffer(yaml_parser_t *parser)
+{
+    size_t size_read = 0;
+
+    /* Return if the raw buffer is full. */
+
+    if (parser->raw_buffer.start == parser->raw_buffer.pointer
+            && parser->raw_buffer.last == parser->raw_buffer.end)
+        return 1;
+
+    /* Return on EOF. */
+
+    if (parser->eof) return 1;
+
+    /* Move the remaining bytes in the raw buffer to the beginning. */
+
+    if (parser->raw_buffer.start < parser->raw_buffer.pointer
+            && parser->raw_buffer.pointer < parser->raw_buffer.last) {
+        memmove(parser->raw_buffer.start, parser->raw_buffer.pointer,
+                parser->raw_buffer.last - parser->raw_buffer.pointer);
+    }
+    parser->raw_buffer.last -=
+        parser->raw_buffer.pointer - parser->raw_buffer.start;
+    parser->raw_buffer.pointer = parser->raw_buffer.start;
+
+    /* Call the read handler to fill the buffer. */
+
+    if (!parser->read_handler(parser->read_handler_data, parser->raw_buffer.last,
+                parser->raw_buffer.end - parser->raw_buffer.last, &size_read)) {
+        return yaml_parser_set_reader_error(parser, "input error",
+                parser->offset, -1);
+    }
+    parser->raw_buffer.last += size_read;
+    if (!size_read) {
+        parser->eof = 1;
+    }
+
+    return 1;
+}
+
+/*
+ * Ensure that the buffer contains at least `length` characters.
+ * Return 1 on success, 0 on failure.
+ *
+ * The length is supposed to be significantly less that the buffer size.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_update_buffer(yaml_parser_t *parser, size_t length)
+{
+    int first = 1;
+
+    assert(parser->read_handler);   /* Read handler must be set. */
+
+    /* If the EOF flag is set and the raw buffer is empty, do nothing. */
+
+    if (parser->eof && parser->raw_buffer.pointer == parser->raw_buffer.last)
+        return 1;
+
+    /* Return if the buffer contains enough characters. */
+
+    if (parser->unread >= length)
+        return 1;
+
+    /* Determine the input encoding if it is not known yet. */
+
+    if (!parser->encoding) {
+        if (!yaml_parser_determine_encoding(parser))
+            return 0;
+    }
+
+    /* Move the unread characters to the beginning of the buffer. */
+
+    if (parser->buffer.start < parser->buffer.pointer
+            && parser->buffer.pointer < parser->buffer.last) {
+        size_t size = parser->buffer.last - parser->buffer.pointer;
+        memmove(parser->buffer.start, parser->buffer.pointer, size);
+        parser->buffer.pointer = parser->buffer.start;
+        parser->buffer.last = parser->buffer.start + size;
+    }
+    else if (parser->buffer.pointer == parser->buffer.last) {
+        parser->buffer.pointer = parser->buffer.start;
+        parser->buffer.last = parser->buffer.start;
+    }
+
+    /* Fill the buffer until it has enough characters. */
+
+    while (parser->unread < length)
+    {
+        /* Fill the raw buffer if necessary. */
+
+        if (!first || parser->raw_buffer.pointer == parser->raw_buffer.last) {
+            if (!yaml_parser_update_raw_buffer(parser)) return 0;
+        }
+        first = 0;
+
+        /* Decode the raw buffer. */
+
+        while (parser->raw_buffer.pointer != parser->raw_buffer.last)
+        {
+            unsigned int value = 0, value2 = 0;
+            int incomplete = 0;
+            unsigned char octet;
+            unsigned int width = 0;
+            int low, high;
+            size_t k;
+            size_t raw_unread = parser->raw_buffer.last - parser->raw_buffer.pointer;
+
+            /* 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.pointer[0];
+                    width = (octet & 0x80) == 0x00 ? 1 :
+                            (octet & 0xE0) == 0xC0 ? 2 :
+                            (octet & 0xF0) == 0xE0 ? 3 :
+                            (octet & 0xF8) == 0xF0 ? 4 : 0;
+
+                    /* Check if the leading octet is valid. */
+
+                    if (!width)
+                        return yaml_parser_set_reader_error(parser,
+                                "invalid leading UTF-8 octet",
+                                parser->offset, 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);
+                        }
+                        incomplete = 1;
+                        break;
+                    }
+
+                    /* Decode the leading octet. */
+
+                    value = (octet & 0x80) == 0x00 ? octet & 0x7F :
+                            (octet & 0xE0) == 0xC0 ? octet & 0x1F :
+                            (octet & 0xF0) == 0xE0 ? octet & 0x0F :
+                            (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
+
+                    /* Check and decode the trailing octets. */
+
+                    for (k = 1; k < width; k ++)
+                    {
+                        octet = parser->raw_buffer.pointer[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, octet);
+
+                        /* Decode the octet. */
+
+                        value = (value << 6) + (octet & 0x3F);
+                    }
+
+                    /* Check the length of the sequence against the value. */
+
+                    if (!((width == 1) ||
+                            (width == 2 && value >= 0x80) ||
+                            (width == 3 && value >= 0x800) ||
+                            (width == 4 && value >= 0x10000)))
+                        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, value);
+
+                    break;
+
+                case YAML_UTF16LE_ENCODING:
+                case YAML_UTF16BE_ENCODING:
+
+                    low = (parser->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
+                    high = (parser->encoding == YAML_UTF16LE_ENCODING ? 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);
+                        }
+                        incomplete = 1;
+                        break;
+                    }
+
+                    /* Get the character. */
+
+                    value = parser->raw_buffer.pointer[low]
+                        + (parser->raw_buffer.pointer[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, 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);
+                            }
+                            incomplete = 1;
+                            break;
+                        }
+
+                        /* Get the next character. */
+
+                        value2 = parser->raw_buffer.pointer[low+2]
+                            + (parser->raw_buffer.pointer[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, value2);
+
+                        /* Generate the value of the surrogate pair. */
+
+                        value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF);
+                    }
+
+                    else {
+                        width = 2;
+                    }
+
+                    break;
+
+                default:
+                    assert(1);      /* Impossible. */
+            }
+
+            /* Check if the raw buffer contains enough bytes to form a character. */
+
+            if (incomplete) break;
+
+            /*
+             * 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)
+             */
+
+            if (! (value == 0x09 || value == 0x0A || value == 0x0D
+                        || (value >= 0x20 && value <= 0x7E)
+                        || (value == 0x85) || (value >= 0xA0 && value <= 0xD7FF)
+                        || (value >= 0xE000 && value <= 0xFFFD)
+                        || (value >= 0x10000 && value <= 0x10FFFF)))
+                return yaml_parser_set_reader_error(parser,
+                        "control characters are not allowed",
+                        parser->offset, value);
+
+            /* Move the raw pointers. */
+
+            parser->raw_buffer.pointer += width;
+            parser->offset += width;
+
+            /* Finally put the character into the buffer. */
+
+            /* 0000 0000-0000 007F -> 0xxxxxxx */
+            if (value <= 0x7F) {
+                *(parser->buffer.last++) = value;
+            }
+            /* 0000 0080-0000 07FF -> 110xxxxx 10xxxxxx */
+            else if (value <= 0x7FF) {
+                *(parser->buffer.last++) = 0xC0 + (value >> 6);
+                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
+            }
+            /* 0000 0800-0000 FFFF -> 1110xxxx 10xxxxxx 10xxxxxx */
+            else if (value <= 0xFFFF) {
+                *(parser->buffer.last++) = 0xE0 + (value >> 12);
+                *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
+                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
+            }
+            /* 0001 0000-0010 FFFF -> 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
+            else {
+                *(parser->buffer.last++) = 0xF0 + (value >> 18);
+                *(parser->buffer.last++) = 0x80 + ((value >> 12) & 0x3F);
+                *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
+                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
+            }
+
+            parser->unread ++;
+        }
+
+        /* On EOF, put NUL into the buffer and return. */
+
+        if (parser->eof) {
+            *(parser->buffer.last++) = '\0';
+            parser->unread ++;
+            return 1;
+        }
+
+    }
+
+    return 1;
+}
+
diff --git a/ext/psych/yaml/scanner.c b/ext/psych/yaml/scanner.c
new file mode 100644
index 0000000..f7a305d
--- /dev/null
+++ b/ext/psych/yaml/scanner.c
@@ -0,0 +1,3570 @@
+
+/*
+ * Introduction
+ * ************
+ *
+ * The following notes assume that you are familiar with the YAML specification
+ * (http://yaml.org/spec/cvs/current.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
+ */
+
+#include "yaml_private.h"
+
+/*
+ * Ensure that the buffer contains the required number of characters.
+ * Return 1 on success, 0 on failure (reader error or memory error).
+ */
+
+#define CACHE(parser,length)                                                    \
+    (parser->unread >= (length)                                                 \
+        ? 1                                                                     \
+        : yaml_parser_update_buffer(parser, (length)))
+
+/*
+ * Advance the buffer pointer.
+ */
+
+#define SKIP(parser)                                                            \
+     (parser->mark.index ++,                                                    \
+      parser->mark.column ++,                                                   \
+      parser->unread --,                                                        \
+      parser->buffer.pointer += WIDTH(parser->buffer))
+
+#define SKIP_LINE(parser)                                                       \
+     (IS_CRLF(parser->buffer) ?                                                 \
+      (parser->mark.index += 2,                                                 \
+       parser->mark.column = 0,                                                 \
+       parser->mark.line ++,                                                    \
+       parser->unread -= 2,                                                     \
+       parser->buffer.pointer += 2) :                                           \
+      IS_BREAK(parser->buffer) ?                                                \
+      (parser->mark.index ++,                                                   \
+       parser->mark.column = 0,                                                 \
+       parser->mark.line ++,                                                    \
+       parser->unread --,                                                       \
+       parser->buffer.pointer += WIDTH(parser->buffer)) : 0)
+
+/*
+ * Copy a character to a string buffer and advance pointers.
+ */
+
+#define READ(parser,string)                                                     \
+     (STRING_EXTEND(parser,string) ?                                            \
+         (COPY(string,parser->buffer),                                          \
+          parser->mark.index ++,                                                \
+          parser->mark.column ++,                                               \
+          parser->unread --,                                                    \
+          1) : 0)
+
+/*
+ * Copy a line break character to a string buffer and advance pointers.
+ */
+
+#define READ_LINE(parser,string)                                                \
+    (STRING_EXTEND(parser,string) ?                                             \
+    (((CHECK_AT(parser->buffer,'\r',0)                                          \
+       && CHECK_AT(parser->buffer,'\n',1)) ?        /* CR LF -> LF */           \
+     (*((string).pointer++) = (yaml_char_t) '\n',                               \
+      parser->buffer.pointer += 2,                                              \
+      parser->mark.index += 2,                                                  \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread -= 2) :                                                    \
+     (CHECK_AT(parser->buffer,'\r',0)                                           \
+      || CHECK_AT(parser->buffer,'\n',0)) ?         /* CR|LF -> LF */           \
+     (*((string).pointer++) = (yaml_char_t) '\n',                               \
+      parser->buffer.pointer ++,                                                \
+      parser->mark.index ++,                                                    \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread --) :                                                      \
+     (CHECK_AT(parser->buffer,'\xC2',0)                                         \
+      && CHECK_AT(parser->buffer,'\x85',1)) ?       /* NEL -> LF */             \
+     (*((string).pointer++) = (yaml_char_t) '\n',                               \
+      parser->buffer.pointer += 2,                                              \
+      parser->mark.index ++,                                                    \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread --) :                                                      \
+     (CHECK_AT(parser->buffer,'\xE2',0) &&                                      \
+      CHECK_AT(parser->buffer,'\x80',1) &&                                      \
+      (CHECK_AT(parser->buffer,'\xA8',2) ||                                     \
+       CHECK_AT(parser->buffer,'\xA9',2))) ?        /* LS|PS -> LS|PS */        \
+     (*((string).pointer++) = *(parser->buffer.pointer++),                      \
+      *((string).pointer++) = *(parser->buffer.pointer++),                      \
+      *((string).pointer++) = *(parser->buffer.pointer++),                      \
+      parser->mark.index ++,                                                    \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread --) : 0),                                                  \
+    1) : 0)
+
+/*
+ * Public API declarations.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token);
+
+/*
+ * Error handling.
+ */
+
+static int
+yaml_parser_set_scanner_error(yaml_parser_t *parser, const char *context,
+        yaml_mark_t context_mark, const char *problem);
+
+/*
+ * High-level token API.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_fetch_more_tokens(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_next_token(yaml_parser_t *parser);
+
+/*
+ * Potential simple keys.
+ */
+
+static int
+yaml_parser_stale_simple_keys(yaml_parser_t *parser);
+
+static int
+yaml_parser_save_simple_key(yaml_parser_t *parser);
+
+static int
+yaml_parser_remove_simple_key(yaml_parser_t *parser);
+
+static int
+yaml_parser_increase_flow_level(yaml_parser_t *parser);
+
+static int
+yaml_parser_decrease_flow_level(yaml_parser_t *parser);
+
+/*
+ * Indentation treatment.
+ */
+
+static int
+yaml_parser_roll_indent(yaml_parser_t *parser, int column,
+        int number, yaml_token_type_t type, yaml_mark_t mark);
+
+static int
+yaml_parser_unroll_indent(yaml_parser_t *parser, int column);
+
+/*
+ * Token fetchers.
+ */
+
+static int
+yaml_parser_fetch_stream_start(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_stream_end(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_directive(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_flow_entry(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_block_entry(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_key(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_value(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_tag(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal);
+
+static int
+yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single);
+
+static int
+yaml_parser_fetch_plain_scalar(yaml_parser_t *parser);
+
+/*
+ * Token scanners.
+ */
+
+static int
+yaml_parser_scan_to_next_token(yaml_parser_t *parser);
+
+static int
+yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token);
+
+static int
+yaml_parser_scan_directive_name(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **name);
+
+static int
+yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *major, int *minor);
+
+static int
+yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *number);
+
+static int
+yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
+        yaml_mark_t mark, yaml_char_t **handle, yaml_char_t **prefix);
+
+static int
+yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token);
+
+static int
+yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_char_t **handle);
+
+static int
+yaml_parser_scan_tag_uri(yaml_parser_t *parser, int directive,
+        yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri);
+
+static int
+yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_string_t *string);
+
+static int
+yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int literal);
+
+static int
+yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
+        int *indent, yaml_string_t *breaks,
+        yaml_mark_t start_mark, yaml_mark_t *end_mark);
+
+static int
+yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int single);
+
+static int
+yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token);
+
+/*
+ * Get the next token.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token)
+{
+    assert(parser); /* Non-NULL parser object is expected. */
+    assert(token);  /* Non-NULL token object is expected. */
+
+    /* Erase the token object. */
+
+    memset(token, 0, sizeof(yaml_token_t));
+
+    /* No tokens after STREAM-END or error. */
+
+    if (parser->stream_end_produced || parser->error) {
+        return 1;
+    }
+
+    /* Ensure that the tokens queue contains enough tokens. */
+
+    if (!parser->token_available) {
+        if (!yaml_parser_fetch_more_tokens(parser))
+            return 0;
+    }
+
+    /* Fetch the next token from the queue. */
+
+    *token = DEQUEUE(parser, parser->tokens);
+    parser->token_available = 0;
+    parser->tokens_parsed ++;
+
+    if (token->type == YAML_STREAM_END_TOKEN) {
+        parser->stream_end_produced = 1;
+    }
+
+    return 1;
+}
+
+/*
+ * Set the scanner error and return 0.
+ */
+
+static int
+yaml_parser_set_scanner_error(yaml_parser_t *parser, const char *context,
+        yaml_mark_t context_mark, const char *problem)
+{
+    parser->error = YAML_SCANNER_ERROR;
+    parser->context = context;
+    parser->context_mark = context_mark;
+    parser->problem = problem;
+    parser->problem_mark = parser->mark;
+
+    return 0;
+}
+
+/*
+ * Ensure that the tokens queue contains at least one token which can be
+ * returned to the Parser.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_fetch_more_tokens(yaml_parser_t *parser)
+{
+    int need_more_tokens;
+
+    /* While we need more tokens to fetch, do it. */
+
+    while (1)
+    {
+        /*
+         * Check if we really need to fetch more tokens.
+         */
+
+        need_more_tokens = 0;
+
+        if (parser->tokens.head == parser->tokens.tail)
+        {
+            /* Queue is empty. */
+
+            need_more_tokens = 1;
+        }
+        else
+        {
+            yaml_simple_key_t *simple_key;
+
+            /* Check if any potential simple key may occupy the head position. */
+
+            if (!yaml_parser_stale_simple_keys(parser))
+                return 0;
+
+            for (simple_key = parser->simple_keys.start;
+                    simple_key != parser->simple_keys.top; simple_key++) {
+                if (simple_key->possible
+                        && simple_key->token_number == parser->tokens_parsed) {
+                    need_more_tokens = 1;
+                    break;
+                }
+            }
+        }
+
+        /* We are finished. */
+
+        if (!need_more_tokens)
+            break;
+
+        /* Fetch the next token. */
+
+        if (!yaml_parser_fetch_next_token(parser))
+            return 0;
+    }
+
+    parser->token_available = 1;
+
+    return 1;
+}
+
+/*
+ * The dispatcher for token fetchers.
+ */
+
+static int
+yaml_parser_fetch_next_token(yaml_parser_t *parser)
+{
+    /* Ensure that the buffer is initialized. */
+
+    if (!CACHE(parser, 1))
+        return 0;
+
+    /* 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 0;
+
+    /* Remove obsolete potential simple keys. */
+
+    if (!yaml_parser_stale_simple_keys(parser))
+        return 0;
+
+    /* Check the indentation level against the current column. */
+
+    if (!yaml_parser_unroll_indent(parser, parser->mark.column))
+        return 0;
+
+    /*
+     * Ensure that the buffer contains at least 4 characters.  4 is the length
+     * of the longest indicators ('--- ' and '... ').
+     */
+
+    if (!CACHE(parser, 4))
+        return 0;
+
+    /* Is it the end of the stream? */
+
+    if (IS_Z(parser->buffer))
+        return yaml_parser_fetch_stream_end(parser);
+
+    /* Is it a directive? */
+
+    if (parser->mark.column == 0 && CHECK(parser->buffer, '%'))
+        return yaml_parser_fetch_directive(parser);
+
+    /* Is it the document start indicator? */
+
+    if (parser->mark.column == 0
+            && CHECK_AT(parser->buffer, '-', 0)
+            && CHECK_AT(parser->buffer, '-', 1)
+            && CHECK_AT(parser->buffer, '-', 2)
+            && IS_BLANKZ_AT(parser->buffer, 3))
+        return yaml_parser_fetch_document_indicator(parser,
+                YAML_DOCUMENT_START_TOKEN);
+
+    /* Is it the document end indicator? */
+
+    if (parser->mark.column == 0
+            && CHECK_AT(parser->buffer, '.', 0)
+            && CHECK_AT(parser->buffer, '.', 1)
+            && CHECK_AT(parser->buffer, '.', 2)
+            && IS_BLANKZ_AT(parser->buffer, 3))
+        return yaml_parser_fetch_document_indicator(parser,
+                YAML_DOCUMENT_END_TOKEN);
+
+    /* Is it the flow sequence start indicator? */
+
+    if (CHECK(parser->buffer, '['))
+        return yaml_parser_fetch_flow_collection_start(parser,
+                YAML_FLOW_SEQUENCE_START_TOKEN);
+
+    /* Is it the flow mapping start indicator? */
+
+    if (CHECK(parser->buffer, '{'))
+        return yaml_parser_fetch_flow_collection_start(parser,
+                YAML_FLOW_MAPPING_START_TOKEN);
+
+    /* Is it the flow sequence end indicator? */
+
+    if (CHECK(parser->buffer, ']'))
+        return yaml_parser_fetch_flow_collection_end(parser,
+                YAML_FLOW_SEQUENCE_END_TOKEN);
+
+    /* Is it the flow mapping end indicator? */
+
+    if (CHECK(parser->buffer, '}'))
+        return yaml_parser_fetch_flow_collection_end(parser,
+                YAML_FLOW_MAPPING_END_TOKEN);
+
+    /* Is it the flow entry indicator? */
+
+    if (CHECK(parser->buffer, ','))
+        return yaml_parser_fetch_flow_entry(parser);
+
+    /* Is it the block entry indicator? */
+
+    if (CHECK(parser->buffer, '-') && IS_BLANKZ_AT(parser->buffer, 1))
+        return yaml_parser_fetch_block_entry(parser);
+
+    /* Is it the key indicator? */
+
+    if (CHECK(parser->buffer, '?')
+            && (parser->flow_level || IS_BLANKZ_AT(parser->buffer, 1)))
+        return yaml_parser_fetch_key(parser);
+
+    /* Is it the value indicator? */
+
+    if (CHECK(parser->buffer, ':')
+            && (parser->flow_level || IS_BLANKZ_AT(parser->buffer, 1)))
+        return yaml_parser_fetch_value(parser);
+
+    /* Is it an alias? */
+
+    if (CHECK(parser->buffer, '*'))
+        return yaml_parser_fetch_anchor(parser, YAML_ALIAS_TOKEN);
+
+    /* Is it an anchor? */
+
+    if (CHECK(parser->buffer, '&'))
+        return yaml_parser_fetch_anchor(parser, YAML_ANCHOR_TOKEN);
+
+    /* Is it a tag? */
+
+    if (CHECK(parser->buffer, '!'))
+        return yaml_parser_fetch_tag(parser);
+
+    /* Is it a literal scalar? */
+
+    if (CHECK(parser->buffer, '|') && !parser->flow_level)
+        return yaml_parser_fetch_block_scalar(parser, 1);
+
+    /* Is it a folded scalar? */
+
+    if (CHECK(parser->buffer, '>') && !parser->flow_level)
+        return yaml_parser_fetch_block_scalar(parser, 0);
+
+    /* Is it a single-quoted scalar? */
+
+    if (CHECK(parser->buffer, '\''))
+        return yaml_parser_fetch_flow_scalar(parser, 1);
+
+    /* Is it a double-quoted scalar? */
+
+    if (CHECK(parser->buffer, '"'))
+        return yaml_parser_fetch_flow_scalar(parser, 0);
+
+    /*
+     * 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.
+     */
+
+    if (!(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '-')
+                || CHECK(parser->buffer, '?') || CHECK(parser->buffer, ':')
+                || CHECK(parser->buffer, ',') || CHECK(parser->buffer, '[')
+                || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
+                || CHECK(parser->buffer, '}') || CHECK(parser->buffer, '#')
+                || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '*')
+                || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '|')
+                || CHECK(parser->buffer, '>') || CHECK(parser->buffer, '\'')
+                || CHECK(parser->buffer, '"') || CHECK(parser->buffer, '%')
+                || CHECK(parser->buffer, '@') || CHECK(parser->buffer, '`')) ||
+            (CHECK(parser->buffer, '-') && !IS_BLANK_AT(parser->buffer, 1)) ||
+            (!parser->flow_level &&
+             (CHECK(parser->buffer, '?') || CHECK(parser->buffer, ':'))
+             && !IS_BLANKZ_AT(parser->buffer, 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");
+}
+
+/*
+ * Check the list of potential simple keys and remove the positions that
+ * cannot contain simple keys anymore.
+ */
+
+static int
+yaml_parser_stale_simple_keys(yaml_parser_t *parser)
+{
+    yaml_simple_key_t *simple_key;
+
+    /* Check for a potential simple key for each flow level. */
+
+    for (simple_key = parser->simple_keys.start;
+            simple_key != parser->simple_keys.top; simple_key ++)
+    {
+        /*
+         * The specification requires that a simple key
+         *
+         *  - is limited to a single line,
+         *  - is shorter than 1024 characters.
+         */
+
+        if (simple_key->possible
+                && (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 yaml_parser_set_scanner_error(parser,
+                        "while scanning a simple key", simple_key->mark,
+                        "could not find expected ':'");
+            }
+
+            simple_key->possible = 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Check if a simple key may start at the current position and add it if
+ * needed.
+ */
+
+static int
+yaml_parser_save_simple_key(yaml_parser_t *parser)
+{
+    /*
+     * 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.
+     */
+
+    int required = (!parser->flow_level
+            && parser->indent == (int)parser->mark.column);
+
+    /*
+     * A simple key is required only when it is the first token in the current
+     * line.  Therefore it is always allowed.  But we add a check anyway.
+     */
+
+    assert(parser->simple_key_allowed || !required);    /* Impossible. */
+
+    /*
+     * If the current position may start a simple key, save it.
+     */
+
+    if (parser->simple_key_allowed)
+    {
+        yaml_simple_key_t simple_key;
+        simple_key.possible = 1;
+        simple_key.required = required;
+        simple_key.token_number =
+            parser->tokens_parsed + (parser->tokens.tail - parser->tokens.head);
+        simple_key.mark = parser->mark;
+
+        if (!yaml_parser_remove_simple_key(parser)) return 0;
+
+        *(parser->simple_keys.top-1) = simple_key;
+    }
+
+    return 1;
+}
+
+/*
+ * Remove a potential simple key at the current flow level.
+ */
+
+static int
+yaml_parser_remove_simple_key(yaml_parser_t *parser)
+{
+    yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
+
+    if (simple_key->possible)
+    {
+        /* If the key is required, it is an error. */
+
+        if (simple_key->required) {
+            return yaml_parser_set_scanner_error(parser,
+                    "while scanning a simple key", simple_key->mark,
+                    "could not find expected ':'");
+        }
+    }
+
+    /* Remove the key from the stack. */
+
+    simple_key->possible = 0;
+
+    return 1;
+}
+
+/*
+ * Increase the flow level and resize the simple key list if needed.
+ */
+
+static int
+yaml_parser_increase_flow_level(yaml_parser_t *parser)
+{
+    yaml_simple_key_t empty_simple_key = { 0, 0, 0, { 0, 0, 0 } };
+
+    /* Reset the simple key on the next level. */
+
+    if (!PUSH(parser, parser->simple_keys, empty_simple_key))
+        return 0;
+
+    /* Increase the flow level. */
+
+    parser->flow_level++;
+
+    return 1;
+}
+
+/*
+ * Decrease the flow level.
+ */
+
+static int
+yaml_parser_decrease_flow_level(yaml_parser_t *parser)
+{
+    yaml_simple_key_t dummy_key;    /* Used to eliminate a compiler warning. */
+
+    if (parser->flow_level) {
+        parser->flow_level --;
+        dummy_key = POP(parser, parser->simple_keys);
+    }
+
+    return 1;
+}
+
+/*
+ * 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.
+ *
+ */
+
+static int
+yaml_parser_roll_indent(yaml_parser_t *parser, int column,
+        int number, yaml_token_type_t type, yaml_mark_t mark)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    if (parser->indent < column)
+    {
+        /*
+         * Push the current indentation level to the stack and set the new
+         * indentation level.
+         */
+
+        if (!PUSH(parser, parser->indents, parser->indent))
+            return 0;
+
+        parser->indent = column;
+
+        /* Create a token and insert it into the queue. */
+
+        TOKEN_INIT(token, type, mark, mark);
+
+        if (number == -1) {
+            if (!ENQUEUE(parser, parser->tokens, token))
+                return 0;
+        }
+        else {
+            if (!QUEUE_INSERT(parser,
+                        parser->tokens, number - parser->tokens_parsed, token))
+                return 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Pop indentation levels from the indents stack until the current level
+ * becomes less or equal to the column.  For each intendation level, append
+ * the BLOCK-END token.
+ */
+
+
+static int
+yaml_parser_unroll_indent(yaml_parser_t *parser, int column)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    /* Loop through the intendation levels in the stack. */
+
+    while (parser->indent > column)
+    {
+        /* Create a token and append it to the queue. */
+
+        TOKEN_INIT(token, YAML_BLOCK_END_TOKEN, parser->mark, parser->mark);
+
+        if (!ENQUEUE(parser, parser->tokens, token))
+            return 0;
+
+        /* Pop the indentation level. */
+
+        parser->indent = POP(parser, parser->indents);
+    }
+
+    return 1;
+}
+
+/*
+ * Initialize the scanner and produce the STREAM-START token.
+ */
+
+static int
+yaml_parser_fetch_stream_start(yaml_parser_t *parser)
+{
+    yaml_simple_key_t simple_key = { 0, 0, 0, { 0, 0, 0 } };
+    yaml_token_t token;
+
+    /* Set the initial indentation. */
+
+    parser->indent = -1;
+
+    /* Initialize the simple key stack. */
+
+    if (!PUSH(parser, parser->simple_keys, simple_key))
+        return 0;
+
+    /* A simple key is allowed at the beginning of the stream. */
+
+    parser->simple_key_allowed = 1;
+
+    /* We have started. */
+
+    parser->stream_start_produced = 1;
+
+    /* Create the STREAM-START token and append it to the queue. */
+
+    STREAM_START_TOKEN_INIT(token, parser->encoding,
+            parser->mark, parser->mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the STREAM-END token and shut down the scanner.
+ */
+
+static int
+yaml_parser_fetch_stream_end(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* 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 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the STREAM-END token and append it to the queue. */
+
+    STREAM_END_TOKEN_INIT(token, parser->mark, parser->mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce a VERSION-DIRECTIVE or TAG-DIRECTIVE token.
+ */
+
+static int
+yaml_parser_fetch_directive(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the YAML-DIRECTIVE or TAG-DIRECTIVE token. */
+
+    if (!yaml_parser_scan_directive(parser, &token))
+        return 0;
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the DOCUMENT-START or DOCUMENT-END token.
+ */
+
+static int
+yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* 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_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-SEQUENCE-START or FLOW-MAPPING-START token.
+ */
+
+static int
+yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* The indicators '[' and '{' may start a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* Increase the flow level. */
+
+    if (!yaml_parser_increase_flow_level(parser))
+        return 0;
+
+    /* A simple key may follow the indicators '[' and '{'. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-SEQUENCE-START of FLOW-MAPPING-START token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-SEQUENCE-END or FLOW-MAPPING-END token.
+ */
+
+static int
+yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset any potential simple key on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Decrease the flow level. */
+
+    if (!yaml_parser_decrease_flow_level(parser))
+        return 0;
+
+    /* No simple keys after the indicators ']' and '}'. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-SEQUENCE-END of FLOW-MAPPING-END token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-ENTRY token.
+ */
+
+static int
+yaml_parser_fetch_flow_entry(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after ','. */
+
+    parser->simple_key_allowed = 1;
+
+    /* 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_INIT(token, YAML_FLOW_ENTRY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the BLOCK-ENTRY token.
+ */
+
+static int
+yaml_parser_fetch_block_entry(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Check if the scanner is in the block context. */
+
+    if (!parser->flow_level)
+    {
+        /* Check if we are allowed to start a new entry. */
+
+        if (!parser->simple_key_allowed) {
+            return yaml_parser_set_scanner_error(parser, NULL, 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 0;
+    }
+    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 0;
+
+    /* Simple keys are allowed after '-'. */
+
+    parser->simple_key_allowed = 1;
+
+    /* 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_INIT(token, YAML_BLOCK_ENTRY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the KEY token.
+ */
+
+static int
+yaml_parser_fetch_key(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* In the block context, additional checks are required. */
+
+    if (!parser->flow_level)
+    {
+        /* 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, NULL, 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 0;
+    }
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after '?' in the block context. */
+
+    parser->simple_key_allowed = (!parser->flow_level);
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the KEY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_KEY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the VALUE token.
+ */
+
+static int
+yaml_parser_fetch_value(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+    yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
+
+    /* Have we found a simple key? */
+
+    if (simple_key->possible)
+    {
+
+        /* Create the KEY token and insert it into the queue. */
+
+        TOKEN_INIT(token, YAML_KEY_TOKEN, simple_key->mark, simple_key->mark);
+
+        if (!QUEUE_INSERT(parser, parser->tokens,
+                    simple_key->token_number - parser->tokens_parsed, token))
+            return 0;
+
+        /* 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 0;
+
+        /* Remove the simple key. */
+
+        simple_key->possible = 0;
+
+        /* A simple key cannot follow another simple key. */
+
+        parser->simple_key_allowed = 0;
+    }
+    else
+    {
+        /* The ':' indicator follows a complex key. */
+
+        /* In the block context, extra checks are required. */
+
+        if (!parser->flow_level)
+        {
+            /* Check if we are allowed to start a complex value. */
+
+            if (!parser->simple_key_allowed) {
+                return yaml_parser_set_scanner_error(parser, NULL, 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 0;
+        }
+
+        /* Simple keys after ':' are allowed in the block context. */
+
+        parser->simple_key_allowed = (!parser->flow_level);
+    }
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the VALUE token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_VALUE_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the ALIAS or ANCHOR token.
+ */
+
+static int
+yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type)
+{
+    yaml_token_t token;
+
+    /* An anchor or an alias could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow an anchor or an alias. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the ALIAS or ANCHOR token and append it to the queue. */
+
+    if (!yaml_parser_scan_anchor(parser, &token, type))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+    return 1;
+}
+
+/*
+ * Produce the TAG token.
+ */
+
+static int
+yaml_parser_fetch_tag(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* A tag could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a tag. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the TAG token and append it to the queue. */
+
+    if (!yaml_parser_scan_tag(parser, &token))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,literal) or SCALAR(...,folded) tokens.
+ */
+
+static int
+yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal)
+{
+    yaml_token_t token;
+
+    /* Remove any potential simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* A simple key may follow a block scalar. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_block_scalar(parser, &token, literal))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,single-quoted) or SCALAR(...,double-quoted) tokens.
+ */
+
+static int
+yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single)
+{
+    yaml_token_t token;
+
+    /* A plain scalar could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a flow scalar. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_flow_scalar(parser, &token, single))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,plain) token.
+ */
+
+static int
+yaml_parser_fetch_plain_scalar(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* A plain scalar could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a flow scalar. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_plain_scalar(parser, &token))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Eat whitespaces and comments until the next token is found.
+ */
+
+static int
+yaml_parser_scan_to_next_token(yaml_parser_t *parser)
+{
+    /* Until the next token is not found. */
+
+    while (1)
+    {
+        /* Allow the BOM mark to start a line. */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        if (parser->mark.column == 0 && IS_BOM(parser->buffer))
+            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 (!CACHE(parser, 1)) return 0;
+
+        while (CHECK(parser->buffer,' ') ||
+                ((parser->flow_level || !parser->simple_key_allowed) &&
+                 CHECK(parser->buffer, '\t'))) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) return 0;
+        }
+
+        /* Eat a comment until a line break. */
+
+        if (CHECK(parser->buffer, '#')) {
+            while (!IS_BREAKZ(parser->buffer)) {
+                SKIP(parser);
+                if (!CACHE(parser, 1)) return 0;
+            }
+        }
+
+        /* If it is a line break, eat it. */
+
+        if (IS_BREAK(parser->buffer))
+        {
+            if (!CACHE(parser, 2)) return 0;
+            SKIP_LINE(parser);
+
+            /* In the block context, a new line may start a simple key. */
+
+            if (!parser->flow_level) {
+                parser->simple_key_allowed = 1;
+            }
+        }
+        else
+        {
+            /* We have found a token. */
+
+            break;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Scan a YAML-DIRECTIVE or TAG-DIRECTIVE token.
+ *
+ * Scope:
+ *      %YAML    1.1    # a comment \n
+ *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ */
+
+int
+yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_char_t *name = NULL;
+    int major, minor;
+    yaml_char_t *handle = NULL, *prefix = NULL;
+
+    /* Eat '%'. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Scan the directive name. */
+
+    if (!yaml_parser_scan_directive_name(parser, start_mark, &name))
+        goto error;
+
+    /* Is it a YAML directive? */
+
+    if (strcmp((char *)name, "YAML") == 0)
+    {
+        /* Scan the VERSION directive value. */
+
+        if (!yaml_parser_scan_version_directive_value(parser, start_mark,
+                    &major, &minor))
+            goto error;
+
+        end_mark = parser->mark;
+
+        /* Create a VERSION-DIRECTIVE token. */
+
+        VERSION_DIRECTIVE_TOKEN_INIT(*token, major, minor,
+                start_mark, end_mark);
+    }
+
+    /* Is it a TAG directive? */
+
+    else if (strcmp((char *)name, "TAG") == 0)
+    {
+        /* Scan the TAG directive value. */
+
+        if (!yaml_parser_scan_tag_directive_value(parser, start_mark,
+                    &handle, &prefix))
+            goto error;
+
+        end_mark = parser->mark;
+
+        /* Create a TAG-DIRECTIVE token. */
+
+        TAG_DIRECTIVE_TOKEN_INIT(*token, handle, prefix,
+                start_mark, end_mark);
+    }
+
+    /* Unknown directive. */
+
+    else
+    {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "found uknown directive name");
+        goto error;
+    }
+
+    /* Eat the rest of the line including any comments. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    if (CHECK(parser->buffer, '#')) {
+        while (!IS_BREAKZ(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) goto error;
+        }
+    }
+
+    /* Check if we are at the end of the line. */
+
+    if (!IS_BREAKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "did not find expected comment or line break");
+        goto error;
+    }
+
+    /* Eat a line break. */
+
+    if (IS_BREAK(parser->buffer)) {
+        if (!CACHE(parser, 2)) goto error;
+        SKIP_LINE(parser);
+    }
+
+    yaml_free(name);
+
+    return 1;
+
+error:
+    yaml_free(prefix);
+    yaml_free(handle);
+    yaml_free(name);
+    return 0;
+}
+
+/*
+ * Scan the directive name.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *       ^^^^
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *       ^^^
+ */
+
+static int
+yaml_parser_scan_directive_name(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **name)
+{
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Consume the directive name. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer))
+    {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the name is empty. */
+
+    if (string.start == string.pointer) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "could not find expected directive name");
+        goto error;
+    }
+
+    /* Check for an blank character after the name. */
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "found unexpected non-alphabetical character");
+        goto error;
+    }
+
+    *name = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan the value of VERSION-DIRECTIVE.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *           ^^^^^^
+ */
+
+static int
+yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *major, int *minor)
+{
+    /* Eat whitespaces. */
+
+    if (!CACHE(parser, 1)) return 0;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) return 0;
+    }
+
+    /* Consume the major version number. */
+
+    if (!yaml_parser_scan_version_directive_number(parser, start_mark, major))
+        return 0;
+
+    /* Eat '.'. */
+
+    if (!CHECK(parser->buffer, '.')) {
+        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 0;
+
+    return 1;
+}
+
+#define MAX_NUMBER_LENGTH   9
+
+/*
+ * Scan the version number of VERSION-DIRECTIVE.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *              ^
+ *      %YAML   1.1     # a comment \n
+ *                ^
+ */
+
+static int
+yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *number)
+{
+    int value = 0;
+    size_t length = 0;
+
+    /* Repeat while the next character is digit. */
+
+    if (!CACHE(parser, 1)) return 0;
+
+    while (IS_DIGIT(parser->buffer))
+    {
+        /* Check if the number is too long. */
+
+        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 + AS_DIGIT(parser->buffer);
+
+        SKIP(parser);
+
+        if (!CACHE(parser, 1)) return 0;
+    }
+
+    /* Check if the number was present. */
+
+    if (!length) {
+        return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                start_mark, "did not find expected version number");
+    }
+
+    *number = value;
+
+    return 1;
+}
+
+/*
+ * Scan the value of a TAG-DIRECTIVE token.
+ *
+ * Scope:
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ */
+
+static int
+yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **handle, yaml_char_t **prefix)
+{
+    yaml_char_t *handle_value = NULL;
+    yaml_char_t *prefix_value = NULL;
+
+    /* Eat whitespaces. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Scan a handle. */
+
+    if (!yaml_parser_scan_tag_handle(parser, 1, start_mark, &handle_value))
+        goto error;
+
+    /* Expect a whitespace. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANK(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+                start_mark, "did not find expected whitespace");
+        goto error;
+    }
+
+    /* Eat whitespaces. */
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Scan a prefix. */
+
+    if (!yaml_parser_scan_tag_uri(parser, 1, NULL, start_mark, &prefix_value))
+        goto error;
+
+    /* Expect a whitespace or line break. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+                start_mark, "did not find expected whitespace or line break");
+        goto error;
+    }
+
+    *handle = handle_value;
+    *prefix = prefix_value;
+
+    return 1;
+
+error:
+    yaml_free(handle_value);
+    yaml_free(prefix_value);
+    return 0;
+}
+
+static int
+yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
+        yaml_token_type_t type)
+{
+    int length = 0;
+    yaml_mark_t start_mark, end_mark;
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the indicator character. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Consume the value. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer)) {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+        length ++;
+    }
+
+    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 (!length || !(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '?')
+                || CHECK(parser->buffer, ':') || CHECK(parser->buffer, ',')
+                || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '}')
+                || CHECK(parser->buffer, '%') || CHECK(parser->buffer, '@')
+                || CHECK(parser->buffer, '`'))) {
+        yaml_parser_set_scanner_error(parser, type == YAML_ANCHOR_TOKEN ?
+                "while scanning an anchor" : "while scanning an alias", start_mark,
+                "did not find expected alphabetic or numeric character");
+        goto error;
+    }
+
+    /* Create a token. */
+
+    if (type == YAML_ANCHOR_TOKEN) {
+        ANCHOR_TOKEN_INIT(*token, string.start, start_mark, end_mark);
+    }
+    else {
+        ALIAS_TOKEN_INIT(*token, string.start, start_mark, end_mark);
+    }
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan a TAG token.
+ */
+
+static int
+yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_char_t *handle = NULL;
+    yaml_char_t *suffix = NULL;
+    yaml_mark_t start_mark, end_mark;
+
+    start_mark = parser->mark;
+
+    /* Check if the tag is in the canonical form. */
+
+    if (!CACHE(parser, 2)) goto error;
+
+    if (CHECK_AT(parser->buffer, '<', 1))
+    {
+        /* Set the handle to '' */
+
+        handle = yaml_malloc(1);
+        if (!handle) goto error;
+        handle[0] = '\0';
+
+        /* Eat '!<' */
+
+        SKIP(parser);
+        SKIP(parser);
+
+        /* Consume the tag value. */
+
+        if (!yaml_parser_scan_tag_uri(parser, 0, NULL, start_mark, &suffix))
+            goto error;
+
+        /* Check for '>' and eat it. */
+
+        if (!CHECK(parser->buffer, '>')) {
+            yaml_parser_set_scanner_error(parser, "while scanning a tag",
+                    start_mark, "did not find the expected '>'");
+            goto error;
+        }
+
+        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, 0, start_mark, &handle))
+            goto error;
+
+        /* Check if it is, indeed, handle. */
+
+        if (handle[0] == '!' && handle[1] != '\0' && handle[strlen((char *)handle)-1] == '!')
+        {
+            /* Scan the suffix now. */
+
+            if (!yaml_parser_scan_tag_uri(parser, 0, NULL, start_mark, &suffix))
+                goto error;
+        }
+        else
+        {
+            /* It wasn't a handle after all.  Scan the rest of the tag. */
+
+            if (!yaml_parser_scan_tag_uri(parser, 0, handle, start_mark, &suffix))
+                goto error;
+
+            /* Set the handle to '!'. */
+
+            yaml_free(handle);
+            handle = yaml_malloc(2);
+            if (!handle) goto error;
+            handle[0] = '!';
+            handle[1] = '\0';
+
+            /*
+             * A special case: the '!' tag.  Set the handle to '' and the
+             * suffix to '!'.
+             */
+
+            if (suffix[0] == '\0') {
+                yaml_char_t *tmp = handle;
+                handle = suffix;
+                suffix = tmp;
+            }
+        }
+    }
+
+    /* Check the character which ends the tag. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a tag",
+                start_mark, "did not find expected whitespace or line break");
+        goto error;
+    }
+
+    end_mark = parser->mark;
+
+    /* Create a token. */
+
+    TAG_TOKEN_INIT(*token, handle, suffix, start_mark, end_mark);
+
+    return 1;
+
+error:
+    yaml_free(handle);
+    yaml_free(suffix);
+    return 0;
+}
+
+/*
+ * Scan a tag handle.
+ */
+
+static int
+yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_char_t **handle)
+{
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Check the initial '!' character. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!CHECK(parser->buffer, '!')) {
+        yaml_parser_set_scanner_error(parser, directive ?
+                "while scanning a tag directive" : "while scanning a tag",
+                start_mark, "did not find expected '!'");
+        goto error;
+    }
+
+    /* Copy the '!' character. */
+
+    if (!READ(parser, string)) goto error;
+
+    /* Copy all subsequent alphabetical and numerical characters. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer))
+    {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the trailing character is '!' and copy it. */
+
+    if (CHECK(parser->buffer, '!'))
+    {
+        if (!READ(parser, string)) goto error;
+    }
+    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.start[0] == '!' && string.start[1] == '\0')) {
+            yaml_parser_set_scanner_error(parser, "while parsing a tag directive",
+                    start_mark, "did not find expected '!'");
+            goto error;
+        }
+    }
+
+    *handle = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan a tag.
+ */
+
+static int
+yaml_parser_scan_tag_uri(yaml_parser_t *parser, int directive,
+        yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri)
+{
+    size_t length = head ? strlen((char *)head) : 0;
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Resize the string to include the head. */
+
+    while (string.end - string.start <= (int)length) {
+        if (!yaml_string_extend(&string.start, &string.pointer, &string.end)) {
+            parser->error = YAML_MEMORY_ERROR;
+            goto error;
+        }
+    }
+
+    /*
+     * Copy the head if needed.
+     *
+     * Note that we don't copy the leading '!' character.
+     */
+
+    if (length > 1) {
+        memcpy(string.start, head+1, length-1);
+        string.pointer += length-1;
+    }
+
+    /* Scan the tag. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    /*
+     * The set of characters that may appear in URI is as follows:
+     *
+     *      '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
+     *      '=', '+', '$', ',', '.', '!', '~', '*', '\'', '(', ')', '[', ']',
+     *      '%'.
+     */
+
+    while (IS_ALPHA(parser->buffer) || CHECK(parser->buffer, ';')
+            || CHECK(parser->buffer, '/') || CHECK(parser->buffer, '?')
+            || CHECK(parser->buffer, ':') || CHECK(parser->buffer, '@')
+            || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '=')
+            || CHECK(parser->buffer, '+') || CHECK(parser->buffer, '$')
+            || CHECK(parser->buffer, ',') || CHECK(parser->buffer, '.')
+            || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '~')
+            || CHECK(parser->buffer, '*') || CHECK(parser->buffer, '\'')
+            || CHECK(parser->buffer, '(') || CHECK(parser->buffer, ')')
+            || CHECK(parser->buffer, '[') || CHECK(parser->buffer, ']')
+            || CHECK(parser->buffer, '%'))
+    {
+        /* Check if it is a URI-escape sequence. */
+
+        if (CHECK(parser->buffer, '%')) {
+            if (!yaml_parser_scan_uri_escapes(parser,
+                        directive, start_mark, &string)) goto error;
+        }
+        else {
+            if (!READ(parser, string)) goto error;
+        }
+
+        length ++;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the tag is non-empty. */
+
+    if (!length) {
+        if (!STRING_EXTEND(parser, string))
+            goto error;
+
+        yaml_parser_set_scanner_error(parser, directive ?
+                "while parsing a %TAG directive" : "while parsing a tag",
+                start_mark, "did not find expected tag URI");
+        goto error;
+    }
+
+    *uri = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Decode an URI-escape sequence corresponding to a single UTF-8 character.
+ */
+
+static int
+yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_string_t *string)
+{
+    int width = 0;
+
+    /* Decode the required number of characters. */
+
+    do {
+
+        unsigned char octet = 0;
+
+        /* Check for a URI-escaped octet. */
+
+        if (!CACHE(parser, 3)) return 0;
+
+        if (!(CHECK(parser->buffer, '%')
+                    && IS_HEX_AT(parser->buffer, 1)
+                    && IS_HEX_AT(parser->buffer, 2))) {
+            return yaml_parser_set_scanner_error(parser, directive ?
+                    "while parsing a %TAG directive" : "while parsing a tag",
+                    start_mark, "did not find URI escaped octet");
+        }
+
+        /* Get the octet. */
+
+        octet = (AS_HEX_AT(parser->buffer, 1) << 4) + AS_HEX_AT(parser->buffer, 2);
+
+        /* If it is the leading octet, determine the length of the UTF-8 sequence. */
+
+        if (!width)
+        {
+            width = (octet & 0x80) == 0x00 ? 1 :
+                    (octet & 0xE0) == 0xC0 ? 2 :
+                    (octet & 0xF0) == 0xE0 ? 3 :
+                    (octet & 0xF8) == 0xF0 ? 4 : 0;
+            if (!width) {
+                return yaml_parser_set_scanner_error(parser, directive ?
+                        "while parsing a %TAG directive" : "while parsing a tag",
+                        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_error(parser, directive ?
+                        "while parsing a %TAG directive" : "while parsing a tag",
+                        start_mark, "found an incorrect trailing UTF-8 octet");
+            }
+        }
+
+        /* Copy the octet and move the pointers. */
+
+        *(string->pointer++) = octet;
+        SKIP(parser);
+        SKIP(parser);
+        SKIP(parser);
+
+    } while (--width);
+
+    return 1;
+}
+
+/*
+ * Scan a block scalar.
+ */
+
+static int
+yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int literal)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    int chomping = 0;
+    int increment = 0;
+    int indent = 0;
+    int leading_blank = 0;
+    int trailing_blank = 0;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the indicator '|' or '>'. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Scan the additional block scalar indicators. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    /* Check for a chomping indicator. */
+
+    if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-'))
+    {
+        /* Set the chomping method and eat the indicator. */
+
+        chomping = CHECK(parser->buffer, '+') ? +1 : -1;
+
+        SKIP(parser);
+
+        /* Check for an indentation indicator. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        if (IS_DIGIT(parser->buffer))
+        {
+            /* Check that the intendation is greater than 0. */
+
+            if (CHECK(parser->buffer, '0')) {
+                yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                        start_mark, "found an intendation indicator equal to 0");
+                goto error;
+            }
+
+            /* Get the intendation level and eat the indicator. */
+
+            increment = AS_DIGIT(parser->buffer);
+
+            SKIP(parser);
+        }
+    }
+
+    /* Do the same as above, but in the opposite order. */
+
+    else if (IS_DIGIT(parser->buffer))
+    {
+        if (CHECK(parser->buffer, '0')) {
+            yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                    start_mark, "found an intendation indicator equal to 0");
+            goto error;
+        }
+
+        increment = AS_DIGIT(parser->buffer);
+
+        SKIP(parser);
+
+        if (!CACHE(parser, 1)) goto error;
+
+        if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-')) {
+            chomping = CHECK(parser->buffer, '+') ? +1 : -1;
+
+            SKIP(parser);
+        }
+    }
+
+    /* Eat whitespaces and comments to the end of the line. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    if (CHECK(parser->buffer, '#')) {
+        while (!IS_BREAKZ(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) goto error;
+        }
+    }
+
+    /* Check if we are at the end of the line. */
+
+    if (!IS_BREAKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                start_mark, "did not find expected comment or line break");
+        goto error;
+    }
+
+    /* Eat a line break. */
+
+    if (IS_BREAK(parser->buffer)) {
+        if (!CACHE(parser, 2)) goto error;
+        SKIP_LINE(parser);
+    }
+
+    end_mark = parser->mark;
+
+    /* Set the intendation level if it was specified. */
+
+    if (increment) {
+        indent = parser->indent >= 0 ? parser->indent+increment : increment;
+    }
+
+    /* Scan the leading line breaks and determine the indentation level if needed. */
+
+    if (!yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks,
+                start_mark, &end_mark)) goto error;
+
+    /* Scan the block scalar content. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while ((int)parser->mark.column == indent && !IS_Z(parser->buffer))
+    {
+        /*
+         * We are at the beginning of a non-empty line.
+         */
+
+        /* Is it a trailing whitespace? */
+
+        trailing_blank = IS_BLANK(parser->buffer);
+
+        /* Check if we need to fold the leading line break. */
+
+        if (!literal && (*leading_break.start == '\n')
+                && !leading_blank && !trailing_blank)
+        {
+            /* Do we need to join the lines by space? */
+
+            if (*trailing_breaks.start == '\0') {
+                if (!STRING_EXTEND(parser, string)) goto error;
+                *(string.pointer ++) = ' ';
+            }
+
+            CLEAR(parser, leading_break);
+        }
+        else {
+            if (!JOIN(parser, string, leading_break)) goto error;
+            CLEAR(parser, leading_break);
+        }
+
+        /* Append the remaining line breaks. */
+
+        if (!JOIN(parser, string, trailing_breaks)) goto error;
+        CLEAR(parser, trailing_breaks);
+
+        /* Is it a leading whitespace? */
+
+        leading_blank = IS_BLANK(parser->buffer);
+
+        /* Consume the current line. */
+
+        while (!IS_BREAKZ(parser->buffer)) {
+            if (!READ(parser, string)) goto error;
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Consume the line break. */
+
+        if (!CACHE(parser, 2)) goto error;
+
+        if (!READ_LINE(parser, leading_break)) goto error;
+
+        /* Eat the following intendation spaces and line breaks. */
+
+        if (!yaml_parser_scan_block_scalar_breaks(parser,
+                    &indent, &trailing_breaks, start_mark, &end_mark)) goto error;
+    }
+
+    /* Chomp the tail. */
+
+    if (chomping != -1) {
+        if (!JOIN(parser, string, leading_break)) goto error;
+    }
+    if (chomping == 1) {
+        if (!JOIN(parser, string, trailing_breaks)) goto error;
+    }
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            literal ? YAML_LITERAL_SCALAR_STYLE : YAML_FOLDED_SCALAR_STYLE,
+            start_mark, end_mark);
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+
+    return 0;
+}
+
+/*
+ * Scan intendation spaces and line breaks for a block scalar.  Determine the
+ * intendation level if needed.
+ */
+
+static int
+yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
+        int *indent, yaml_string_t *breaks,
+        yaml_mark_t start_mark, yaml_mark_t *end_mark)
+{
+    int max_indent = 0;
+
+    *end_mark = parser->mark;
+
+    /* Eat the intendation spaces and line breaks. */
+
+    while (1)
+    {
+        /* Eat the intendation spaces. */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        while ((!*indent || (int)parser->mark.column < *indent)
+                && IS_SPACE(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) return 0;
+        }
+
+        if ((int)parser->mark.column > max_indent)
+            max_indent = (int)parser->mark.column;
+
+        /* Check for a tab character messing the intendation. */
+
+        if ((!*indent || (int)parser->mark.column < *indent)
+                && IS_TAB(parser->buffer)) {
+            return yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                    start_mark, "found a tab character where an intendation space is expected");
+        }
+
+        /* Have we found a non-empty line? */
+
+        if (!IS_BREAK(parser->buffer)) break;
+
+        /* Consume the line break. */
+
+        if (!CACHE(parser, 2)) return 0;
+        if (!READ_LINE(parser, *breaks)) return 0;
+        *end_mark = parser->mark;
+    }
+
+    /* Determine the indentation level if needed. */
+
+    if (!*indent) {
+        *indent = max_indent;
+        if (*indent < parser->indent + 1)
+            *indent = parser->indent + 1;
+        if (*indent < 1)
+            *indent = 1;
+    }
+
+   return 1;
+}
+
+/*
+ * Scan a quoted scalar.
+ */
+
+static int
+yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int single)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    yaml_string_t whitespaces = NULL_STRING;
+    int leading_blanks;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the left quote. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Consume the content of the quoted scalar. */
+
+    while (1)
+    {
+        /* Check that there are no document indicators at the beginning of the line. */
+
+        if (!CACHE(parser, 4)) goto error;
+
+        if (parser->mark.column == 0 &&
+            ((CHECK_AT(parser->buffer, '-', 0) &&
+              CHECK_AT(parser->buffer, '-', 1) &&
+              CHECK_AT(parser->buffer, '-', 2)) ||
+             (CHECK_AT(parser->buffer, '.', 0) &&
+              CHECK_AT(parser->buffer, '.', 1) &&
+              CHECK_AT(parser->buffer, '.', 2))) &&
+            IS_BLANKZ_AT(parser->buffer, 3))
+        {
+            yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+                    start_mark, "found unexpected document indicator");
+            goto error;
+        }
+
+        /* Check for EOF. */
+
+        if (IS_Z(parser->buffer)) {
+            yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+                    start_mark, "found unexpected end of stream");
+            goto error;
+        }
+
+        /* Consume non-blank characters. */
+
+        if (!CACHE(parser, 2)) goto error;
+
+        leading_blanks = 0;
+
+        while (!IS_BLANKZ(parser->buffer))
+        {
+            /* Check for an escaped single quote. */
+
+            if (single && CHECK_AT(parser->buffer, '\'', 0)
+                    && CHECK_AT(parser->buffer, '\'', 1))
+            {
+                if (!STRING_EXTEND(parser, string)) goto error;
+                *(string.pointer++) = '\'';
+                SKIP(parser);
+                SKIP(parser);
+            }
+
+            /* Check for the right quote. */
+
+            else if (CHECK(parser->buffer, single ? '\'' : '"'))
+            {
+                break;
+            }
+
+            /* Check for an escaped line break. */
+
+            else if (!single && CHECK(parser->buffer, '\\')
+                    && IS_BREAK_AT(parser->buffer, 1))
+            {
+                if (!CACHE(parser, 3)) goto error;
+                SKIP(parser);
+                SKIP_LINE(parser);
+                leading_blanks = 1;
+                break;
+            }
+
+            /* Check for an escape sequence. */
+
+            else if (!single && CHECK(parser->buffer, '\\'))
+            {
+                size_t code_length = 0;
+
+                if (!STRING_EXTEND(parser, string)) goto error;
+
+                /* Check the escape character. */
+
+                switch (parser->buffer.pointer[1])
+                {
+                    case '0':
+                        *(string.pointer++) = '\0';
+                        break;
+
+                    case 'a':
+                        *(string.pointer++) = '\x07';
+                        break;
+
+                    case 'b':
+                        *(string.pointer++) = '\x08';
+                        break;
+
+                    case 't':
+                    case '\t':
+                        *(string.pointer++) = '\x09';
+                        break;
+
+                    case 'n':
+                        *(string.pointer++) = '\x0A';
+                        break;
+
+                    case 'v':
+                        *(string.pointer++) = '\x0B';
+                        break;
+
+                    case 'f':
+                        *(string.pointer++) = '\x0C';
+                        break;
+
+                    case 'r':
+                        *(string.pointer++) = '\x0D';
+                        break;
+
+                    case 'e':
+                        *(string.pointer++) = '\x1B';
+                        break;
+
+                    case ' ':
+                        *(string.pointer++) = '\x20';
+                        break;
+
+                    case '"':
+                        *(string.pointer++) = '"';
+                        break;
+
+                    case '\'':
+                        *(string.pointer++) = '\'';
+                        break;
+
+                    case '\\':
+                        *(string.pointer++) = '\\';
+                        break;
+
+                    case 'N':   /* NEL (#x85) */
+                        *(string.pointer++) = '\xC2';
+                        *(string.pointer++) = '\x85';
+                        break;
+
+                    case '_':   /* #xA0 */
+                        *(string.pointer++) = '\xC2';
+                        *(string.pointer++) = '\xA0';
+                        break;
+
+                    case 'L':   /* LS (#x2028) */
+                        *(string.pointer++) = '\xE2';
+                        *(string.pointer++) = '\x80';
+                        *(string.pointer++) = '\xA8';
+                        break;
+
+                    case 'P':   /* PS (#x2029) */
+                        *(string.pointer++) = '\xE2';
+                        *(string.pointer++) = '\x80';
+                        *(string.pointer++) = '\xA9';
+                        break;
+
+                    case 'x':
+                        code_length = 2;
+                        break;
+
+                    case 'u':
+                        code_length = 4;
+                        break;
+
+                    case 'U':
+                        code_length = 8;
+                        break;
+
+                    default:
+                        yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+                                start_mark, "found unknown escape character");
+                        goto error;
+                }
+
+                SKIP(parser);
+                SKIP(parser);
+
+                /* Consume an arbitrary escape code. */
+
+                if (code_length)
+                {
+                    unsigned int value = 0;
+                    size_t k;
+
+                    /* Scan the character value. */
+
+                    if (!CACHE(parser, code_length)) goto error;
+
+                    for (k = 0; k < code_length; k ++) {
+                        if (!IS_HEX_AT(parser->buffer, k)) {
+                            yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+                                    start_mark, "did not find expected hexdecimal number");
+                            goto error;
+                        }
+                        value = (value << 4) + AS_HEX_AT(parser->buffer, 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");
+                        goto error;
+                    }
+
+                    if (value <= 0x7F) {
+                        *(string.pointer++) = value;
+                    }
+                    else if (value <= 0x7FF) {
+                        *(string.pointer++) = 0xC0 + (value >> 6);
+                        *(string.pointer++) = 0x80 + (value & 0x3F);
+                    }
+                    else if (value <= 0xFFFF) {
+                        *(string.pointer++) = 0xE0 + (value >> 12);
+                        *(string.pointer++) = 0x80 + ((value >> 6) & 0x3F);
+                        *(string.pointer++) = 0x80 + (value & 0x3F);
+                    }
+                    else {
+                        *(string.pointer++) = 0xF0 + (value >> 18);
+                        *(string.pointer++) = 0x80 + ((value >> 12) & 0x3F);
+                        *(string.pointer++) = 0x80 + ((value >> 6) & 0x3F);
+                        *(string.pointer++) = 0x80 + (value & 0x3F);
+                    }
+
+                    /* Advance the pointer. */
+
+                    for (k = 0; k < code_length; k ++) {
+                        SKIP(parser);
+                    }
+                }
+            }
+
+            else
+            {
+                /* It is a non-escaped non-blank character. */
+
+                if (!READ(parser, string)) goto error;
+            }
+
+            if (!CACHE(parser, 2)) goto error;
+        }
+
+        /* Check if we are at the end of the scalar. */
+
+        if (CHECK(parser->buffer, single ? '\'' : '"'))
+            break;
+
+        /* Consume blank characters. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
+        {
+            if (IS_BLANK(parser->buffer))
+            {
+                /* Consume a space or a tab character. */
+
+                if (!leading_blanks) {
+                    if (!READ(parser, whitespaces)) goto error;
+                }
+                else {
+                    SKIP(parser);
+                }
+            }
+            else
+            {
+                if (!CACHE(parser, 2)) goto error;
+
+                /* Check if it is a first line break. */
+
+                if (!leading_blanks)
+                {
+                    CLEAR(parser, whitespaces);
+                    if (!READ_LINE(parser, leading_break)) goto error;
+                    leading_blanks = 1;
+                }
+                else
+                {
+                    if (!READ_LINE(parser, trailing_breaks)) goto error;
+                }
+            }
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Join the whitespaces or fold line breaks. */
+
+        if (leading_blanks)
+        {
+            /* Do we need to fold line breaks? */
+
+            if (leading_break.start[0] == '\n') {
+                if (trailing_breaks.start[0] == '\0') {
+                    if (!STRING_EXTEND(parser, string)) goto error;
+                    *(string.pointer++) = ' ';
+                }
+                else {
+                    if (!JOIN(parser, string, trailing_breaks)) goto error;
+                    CLEAR(parser, trailing_breaks);
+                }
+                CLEAR(parser, leading_break);
+            }
+            else {
+                if (!JOIN(parser, string, leading_break)) goto error;
+                if (!JOIN(parser, string, trailing_breaks)) goto error;
+                CLEAR(parser, leading_break);
+                CLEAR(parser, trailing_breaks);
+            }
+        }
+        else
+        {
+            if (!JOIN(parser, string, whitespaces)) goto error;
+            CLEAR(parser, whitespaces);
+        }
+    }
+
+    /* Eat the right quote. */
+
+    SKIP(parser);
+
+    end_mark = parser->mark;
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            single ? YAML_SINGLE_QUOTED_SCALAR_STYLE : YAML_DOUBLE_QUOTED_SCALAR_STYLE,
+            start_mark, end_mark);
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 0;
+}
+
+/*
+ * Scan a plain scalar.
+ */
+
+static int
+yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    yaml_string_t whitespaces = NULL_STRING;
+    int leading_blanks = 0;
+    int indent = parser->indent+1;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
+
+    start_mark = end_mark = parser->mark;
+
+    /* Consume the content of the plain scalar. */
+
+    while (1)
+    {
+        /* Check for a document indicator. */
+
+        if (!CACHE(parser, 4)) goto error;
+
+        if (parser->mark.column == 0 &&
+            ((CHECK_AT(parser->buffer, '-', 0) &&
+              CHECK_AT(parser->buffer, '-', 1) &&
+              CHECK_AT(parser->buffer, '-', 2)) ||
+             (CHECK_AT(parser->buffer, '.', 0) &&
+              CHECK_AT(parser->buffer, '.', 1) &&
+              CHECK_AT(parser->buffer, '.', 2))) &&
+            IS_BLANKZ_AT(parser->buffer, 3)) break;
+
+        /* Check for a comment. */
+
+        if (CHECK(parser->buffer, '#'))
+            break;
+
+        /* Consume non-blank characters. */
+
+        while (!IS_BLANKZ(parser->buffer))
+        {
+            /* Check for 'x:x' in the flow context. TODO: Fix the test "spec-08-13". */
+
+            if (parser->flow_level
+                    && CHECK(parser->buffer, ':')
+                    && !IS_BLANKZ_AT(parser->buffer, 1)) {
+                yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+                        start_mark, "found unexpected ':'");
+                goto error;
+            }
+
+            /* Check for indicators that may end a plain scalar. */
+
+            if ((CHECK(parser->buffer, ':') && IS_BLANKZ_AT(parser->buffer, 1))
+                    || (parser->flow_level &&
+                        (CHECK(parser->buffer, ',') || CHECK(parser->buffer, ':')
+                         || CHECK(parser->buffer, '?') || CHECK(parser->buffer, '[')
+                         || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
+                         || CHECK(parser->buffer, '}'))))
+                break;
+
+            /* Check if we need to join whitespaces and breaks. */
+
+            if (leading_blanks || whitespaces.start != whitespaces.pointer)
+            {
+                if (leading_blanks)
+                {
+                    /* Do we need to fold line breaks? */
+
+                    if (leading_break.start[0] == '\n') {
+                        if (trailing_breaks.start[0] == '\0') {
+                            if (!STRING_EXTEND(parser, string)) goto error;
+                            *(string.pointer++) = ' ';
+                        }
+                        else {
+                            if (!JOIN(parser, string, trailing_breaks)) goto error;
+                            CLEAR(parser, trailing_breaks);
+                        }
+                        CLEAR(parser, leading_break);
+                    }
+                    else {
+                        if (!JOIN(parser, string, leading_break)) goto error;
+                        if (!JOIN(parser, string, trailing_breaks)) goto error;
+                        CLEAR(parser, leading_break);
+                        CLEAR(parser, trailing_breaks);
+                    }
+
+                    leading_blanks = 0;
+                }
+                else
+                {
+                    if (!JOIN(parser, string, whitespaces)) goto error;
+                    CLEAR(parser, whitespaces);
+                }
+            }
+
+            /* Copy the character. */
+
+            if (!READ(parser, string)) goto error;
+
+            end_mark = parser->mark;
+
+            if (!CACHE(parser, 2)) goto error;
+        }
+
+        /* Is it the end? */
+
+        if (!(IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer)))
+            break;
+
+        /* Consume blank characters. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
+        {
+            if (IS_BLANK(parser->buffer))
+            {
+                /* Check for tab character that abuse intendation. */
+
+                if (leading_blanks && (int)parser->mark.column < indent
+                        && IS_TAB(parser->buffer)) {
+                    yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+                            start_mark, "found a tab character that violate intendation");
+                    goto error;
+                }
+
+                /* Consume a space or a tab character. */
+
+                if (!leading_blanks) {
+                    if (!READ(parser, whitespaces)) goto error;
+                }
+                else {
+                    SKIP(parser);
+                }
+            }
+            else
+            {
+                if (!CACHE(parser, 2)) goto error;
+
+                /* Check if it is a first line break. */
+
+                if (!leading_blanks)
+                {
+                    CLEAR(parser, whitespaces);
+                    if (!READ_LINE(parser, leading_break)) goto error;
+                    leading_blanks = 1;
+                }
+                else
+                {
+                    if (!READ_LINE(parser, trailing_breaks)) goto error;
+                }
+            }
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Check intendation level. */
+
+        if (!parser->flow_level && (int)parser->mark.column < indent)
+            break;
+    }
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            YAML_PLAIN_SCALAR_STYLE, start_mark, end_mark);
+
+    /* Note that we change the 'simple_key_allowed' flag. */
+
+    if (leading_blanks) {
+        parser->simple_key_allowed = 1;
+    }
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 0;
+}
+
diff --git a/ext/psych/yaml/writer.c b/ext/psych/yaml/writer.c
new file mode 100644
index 0000000..5d57f39
--- /dev/null
+++ b/ext/psych/yaml/writer.c
@@ -0,0 +1,141 @@
+
+#include "yaml_private.h"
+
+/*
+ * Declarations.
+ */
+
+static int
+yaml_emitter_set_writer_error(yaml_emitter_t *emitter, const char *problem);
+
+YAML_DECLARE(int)
+yaml_emitter_flush(yaml_emitter_t *emitter);
+
+/*
+ * Set the writer error and return 0.
+ */
+
+static int
+yaml_emitter_set_writer_error(yaml_emitter_t *emitter, const char *problem)
+{
+    emitter->error = YAML_WRITER_ERROR;
+    emitter->problem = problem;
+
+    return 0;
+}
+
+/*
+ * Flush the output buffer.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_flush(yaml_emitter_t *emitter)
+{
+    int low, high;
+
+    assert(emitter);    /* Non-NULL emitter object is expected. */
+    assert(emitter->write_handler); /* Write handler must be set. */
+    assert(emitter->encoding);  /* Output encoding must be set. */
+
+    emitter->buffer.last = emitter->buffer.pointer;
+    emitter->buffer.pointer = emitter->buffer.start;
+
+    /* Check if the buffer is empty. */
+
+    if (emitter->buffer.start == emitter->buffer.last) {
+        return 1;
+    }
+
+    /* If the output encoding is UTF-8, we don't need to recode the buffer. */
+
+    if (emitter->encoding == YAML_UTF8_ENCODING)
+    {
+        if (emitter->write_handler(emitter->write_handler_data,
+                    emitter->buffer.start,
+                    emitter->buffer.last - emitter->buffer.start)) {
+            emitter->buffer.last = emitter->buffer.start;
+            emitter->buffer.pointer = emitter->buffer.start;
+            return 1;
+        }
+        else {
+            return yaml_emitter_set_writer_error(emitter, "write error");
+        }
+    }
+
+    /* Recode the buffer into the raw buffer. */
+
+    low = (emitter->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
+    high = (emitter->encoding == YAML_UTF16LE_ENCODING ? 1 : 0);
+
+    while (emitter->buffer.pointer != emitter->buffer.last)
+    {
+        unsigned char octet;
+        unsigned int width;
+        unsigned int value;
+        size_t k;
+
+        /*
+         * See the "reader.c" code for more details on UTF-8 encoding.  Note
+         * that we assume that the buffer contains a valid UTF-8 sequence.
+         */
+
+        /* Read the next UTF-8 character. */
+
+        octet = emitter->buffer.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;
+
+        for (k = 1; k < width; k ++) {
+            octet = emitter->buffer.pointer[k];
+            value = (value << 6) + (octet & 0x3F);
+        }
+
+        emitter->buffer.pointer += width;
+
+        /* Write the character. */
+
+        if (value < 0x10000)
+        {
+            emitter->raw_buffer.last[high] = value >> 8;
+            emitter->raw_buffer.last[low] = value & 0xFF;
+
+            emitter->raw_buffer.last += 2;
+        }
+        else
+        {
+            /* Write the character using a surrogate pair (check "reader.c"). */
+
+            value -= 0x10000;
+            emitter->raw_buffer.last[high] = 0xD8 + (value >> 18);
+            emitter->raw_buffer.last[low] = (value >> 10) & 0xFF;
+            emitter->raw_buffer.last[high+2] = 0xDC + ((value >> 8) & 0xFF);
+            emitter->raw_buffer.last[low+2] = value & 0xFF;
+
+            emitter->raw_buffer.last += 4;
+        }
+    }
+
+    /* Write the raw buffer. */
+
+    if (emitter->write_handler(emitter->write_handler_data,
+                emitter->raw_buffer.start,
+                emitter->raw_buffer.last - emitter->raw_buffer.start)) {
+        emitter->buffer.last = emitter->buffer.start;
+        emitter->buffer.pointer = emitter->buffer.start;
+        emitter->raw_buffer.last = emitter->raw_buffer.start;
+        emitter->raw_buffer.pointer = emitter->raw_buffer.start;
+        return 1;
+    }
+    else {
+        return yaml_emitter_set_writer_error(emitter, "write error");
+    }
+}
+
diff --git a/ext/psych/yaml/yaml.h b/ext/psych/yaml/yaml.h
new file mode 100644
index 0000000..acd72ad
--- /dev/null
+++ b/ext/psych/yaml/yaml.h
@@ -0,0 +1,1971 @@
+/**
+ * @file yaml.h
+ * @brief Public interface for libyaml.
+ *
+ * Include the header file with the code:
+ * @code
+ * #include <yaml.h>
+ * @endcode
+ */
+
+#ifndef YAML_H
+#define YAML_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/**
+ * @defgroup export Export Definitions
+ * @{
+ */
+
+/** The public API declaration. */
+
+#ifdef _WIN32
+#   if defined(YAML_DECLARE_STATIC)
+#       define  YAML_DECLARE(type)  type
+#   elif defined(YAML_DECLARE_EXPORT)
+#       define  YAML_DECLARE(type)  __declspec(dllexport) type
+#   else
+#       define  YAML_DECLARE(type)  __declspec(dllimport) type
+#   endif
+#else
+#   define  YAML_DECLARE(type)  type
+#endif
+
+/** @} */
+
+/**
+ * @defgroup version Version Information
+ * @{
+ */
+
+/**
+ * Get the library version as a string.
+ *
+ * @returns The function returns the pointer to a static string of the form
+ * @c "X.Y.Z", where @c X is the major version number, @c Y is a minor version
+ * number, and @c Z is the patch version number.
+ */
+
+YAML_DECLARE(const char *)
+yaml_get_version_string(void);
+
+/**
+ * Get the library version numbers.
+ *
+ * @param[out]      major   Major version number.
+ * @param[out]      minor   Minor version number.
+ * @param[out]      patch   Patch version number.
+ */
+
+YAML_DECLARE(void)
+yaml_get_version(int *major, int *minor, int *patch);
+
+/** @} */
+
+/**
+ * @defgroup basic Basic Types
+ * @{
+ */
+
+/** The character type (UTF-8 octet). */
+typedef unsigned char yaml_char_t;
+
+/** The version directive data. */
+typedef struct yaml_version_directive_s {
+    /** The major version number. */
+    int major;
+    /** The minor version number. */
+    int minor;
+} yaml_version_directive_t;
+
+/** The tag directive data. */
+typedef struct yaml_tag_directive_s {
+    /** The tag handle. */
+    yaml_char_t *handle;
+    /** The tag prefix. */
+    yaml_char_t *prefix;
+} yaml_tag_directive_t;
+
+/** The stream encoding. */
+typedef enum yaml_encoding_e {
+    /** Let the parser choose the encoding. */
+    YAML_ANY_ENCODING,
+    /** The default UTF-8 encoding. */
+    YAML_UTF8_ENCODING,
+    /** The UTF-16-LE encoding with BOM. */
+    YAML_UTF16LE_ENCODING,
+    /** The UTF-16-BE encoding with BOM. */
+    YAML_UTF16BE_ENCODING
+} yaml_encoding_t;
+
+/** Line break types. */
+
+typedef enum yaml_break_e {
+    /** Let the parser choose the break type. */
+    YAML_ANY_BREAK,
+    /** Use CR for line breaks (Mac style). */
+    YAML_CR_BREAK,
+    /** Use LN for line breaks (Unix style). */
+    YAML_LN_BREAK,
+    /** Use CR LN for line breaks (DOS style). */
+    YAML_CRLN_BREAK
+} yaml_break_t;
+
+/** Many bad things could happen with the parser and emitter. */
+typedef enum yaml_error_type_e {
+    /** No error is produced. */
+    YAML_NO_ERROR,
+
+    /** Cannot allocate or reallocate a block of memory. */
+    YAML_MEMORY_ERROR,
+
+    /** Cannot read or decode the input stream. */
+    YAML_READER_ERROR,
+    /** Cannot scan the input stream. */
+    YAML_SCANNER_ERROR,
+    /** Cannot parse the input stream. */
+    YAML_PARSER_ERROR,
+    /** Cannot compose a YAML document. */
+    YAML_COMPOSER_ERROR,
+
+    /** Cannot write to the output stream. */
+    YAML_WRITER_ERROR,
+    /** Cannot emit a YAML stream. */
+    YAML_EMITTER_ERROR
+} yaml_error_type_t;
+
+/** The pointer position. */
+typedef struct yaml_mark_s {
+    /** The position index. */
+    size_t index;
+
+    /** The position line. */
+    size_t line;
+
+    /** The position column. */
+    size_t column;
+} yaml_mark_t;
+
+/** @} */
+
+/**
+ * @defgroup styles Node Styles
+ * @{
+ */
+
+/** Scalar styles. */
+typedef enum yaml_scalar_style_e {
+    /** Let the emitter choose the style. */
+    YAML_ANY_SCALAR_STYLE,
+
+    /** The plain scalar style. */
+    YAML_PLAIN_SCALAR_STYLE,
+
+    /** The single-quoted scalar style. */
+    YAML_SINGLE_QUOTED_SCALAR_STYLE,
+    /** The double-quoted scalar style. */
+    YAML_DOUBLE_QUOTED_SCALAR_STYLE,
+
+    /** The literal scalar style. */
+    YAML_LITERAL_SCALAR_STYLE,
+    /** The folded scalar style. */
+    YAML_FOLDED_SCALAR_STYLE
+} yaml_scalar_style_t;
+
+/** Sequence styles. */
+typedef enum yaml_sequence_style_e {
+    /** Let the emitter choose the style. */
+    YAML_ANY_SEQUENCE_STYLE,
+
+    /** The block sequence style. */
+    YAML_BLOCK_SEQUENCE_STYLE,
+    /** The flow sequence style. */
+    YAML_FLOW_SEQUENCE_STYLE
+} yaml_sequence_style_t;
+
+/** Mapping styles. */
+typedef enum yaml_mapping_style_e {
+    /** Let the emitter choose the style. */
+    YAML_ANY_MAPPING_STYLE,
+
+    /** The block mapping style. */
+    YAML_BLOCK_MAPPING_STYLE,
+    /** The flow mapping style. */
+    YAML_FLOW_MAPPING_STYLE
+/*    YAML_FLOW_SET_MAPPING_STYLE   */
+} yaml_mapping_style_t;
+
+/** @} */
+
+/**
+ * @defgroup tokens Tokens
+ * @{
+ */
+
+/** Token types. */
+typedef enum yaml_token_type_e {
+    /** An empty token. */
+    YAML_NO_TOKEN,
+
+    /** A STREAM-START token. */
+    YAML_STREAM_START_TOKEN,
+    /** A STREAM-END token. */
+    YAML_STREAM_END_TOKEN,
+
+    /** A VERSION-DIRECTIVE token. */
+    YAML_VERSION_DIRECTIVE_TOKEN,
+    /** A TAG-DIRECTIVE token. */
+    YAML_TAG_DIRECTIVE_TOKEN,
+    /** A DOCUMENT-START token. */
+    YAML_DOCUMENT_START_TOKEN,
+    /** A DOCUMENT-END token. */
+    YAML_DOCUMENT_END_TOKEN,
+
+    /** A BLOCK-SEQUENCE-START token. */
+    YAML_BLOCK_SEQUENCE_START_TOKEN,
+    /** A BLOCK-SEQUENCE-END token. */
+    YAML_BLOCK_MAPPING_START_TOKEN,
+    /** A BLOCK-END token. */
+    YAML_BLOCK_END_TOKEN,
+
+    /** A FLOW-SEQUENCE-START token. */
+    YAML_FLOW_SEQUENCE_START_TOKEN,
+    /** A FLOW-SEQUENCE-END token. */
+    YAML_FLOW_SEQUENCE_END_TOKEN,
+    /** A FLOW-MAPPING-START token. */
+    YAML_FLOW_MAPPING_START_TOKEN,
+    /** A FLOW-MAPPING-END token. */
+    YAML_FLOW_MAPPING_END_TOKEN,
+
+    /** A BLOCK-ENTRY token. */
+    YAML_BLOCK_ENTRY_TOKEN,
+    /** A FLOW-ENTRY token. */
+    YAML_FLOW_ENTRY_TOKEN,
+    /** A KEY token. */
+    YAML_KEY_TOKEN,
+    /** A VALUE token. */
+    YAML_VALUE_TOKEN,
+
+    /** An ALIAS token. */
+    YAML_ALIAS_TOKEN,
+    /** An ANCHOR token. */
+    YAML_ANCHOR_TOKEN,
+    /** A TAG token. */
+    YAML_TAG_TOKEN,
+    /** A SCALAR token. */
+    YAML_SCALAR_TOKEN
+} yaml_token_type_t;
+
+/** The token structure. */
+typedef struct yaml_token_s {
+
+    /** The token type. */
+    yaml_token_type_t type;
+
+    /** The token data. */
+    union {
+
+        /** The stream start (for @c YAML_STREAM_START_TOKEN). */
+        struct {
+            /** The stream encoding. */
+            yaml_encoding_t encoding;
+        } stream_start;
+
+        /** The alias (for @c YAML_ALIAS_TOKEN). */
+        struct {
+            /** The alias value. */
+            yaml_char_t *value;
+        } alias;
+
+        /** The anchor (for @c YAML_ANCHOR_TOKEN). */
+        struct {
+            /** The anchor value. */
+            yaml_char_t *value;
+        } anchor;
+
+        /** The tag (for @c YAML_TAG_TOKEN). */
+        struct {
+            /** The tag handle. */
+            yaml_char_t *handle;
+            /** The tag suffix. */
+            yaml_char_t *suffix;
+        } tag;
+
+        /** The scalar value (for @c YAML_SCALAR_TOKEN). */
+        struct {
+            /** The scalar value. */
+            yaml_char_t *value;
+            /** The length of the scalar value. */
+            size_t length;
+            /** The scalar style. */
+            yaml_scalar_style_t style;
+        } scalar;
+
+        /** The version directive (for @c YAML_VERSION_DIRECTIVE_TOKEN). */
+        struct {
+            /** The major version number. */
+            int major;
+            /** The minor version number. */
+            int minor;
+        } version_directive;
+
+        /** The tag directive (for @c YAML_TAG_DIRECTIVE_TOKEN). */
+        struct {
+            /** The tag handle. */
+            yaml_char_t *handle;
+            /** The tag prefix. */
+            yaml_char_t *prefix;
+        } tag_directive;
+
+    } data;
+
+    /** The beginning of the token. */
+    yaml_mark_t start_mark;
+    /** The end of the token. */
+    yaml_mark_t end_mark;
+
+} yaml_token_t;
+
+/**
+ * Free any memory allocated for a token object.
+ *
+ * @param[in,out]   token   A token object.
+ */
+
+YAML_DECLARE(void)
+yaml_token_delete(yaml_token_t *token);
+
+/** @} */
+
+/**
+ * @defgroup events Events
+ * @{
+ */
+
+/** Event types. */
+typedef enum yaml_event_type_e {
+    /** An empty event. */
+    YAML_NO_EVENT,
+
+    /** A STREAM-START event. */
+    YAML_STREAM_START_EVENT,
+    /** A STREAM-END event. */
+    YAML_STREAM_END_EVENT,
+
+    /** A DOCUMENT-START event. */
+    YAML_DOCUMENT_START_EVENT,
+    /** A DOCUMENT-END event. */
+    YAML_DOCUMENT_END_EVENT,
+
+    /** An ALIAS event. */
+    YAML_ALIAS_EVENT,
+    /** A SCALAR event. */
+    YAML_SCALAR_EVENT,
+
+    /** A SEQUENCE-START event. */
+    YAML_SEQUENCE_START_EVENT,
+    /** A SEQUENCE-END event. */
+    YAML_SEQUENCE_END_EVENT,
+
+    /** A MAPPING-START event. */
+    YAML_MAPPING_START_EVENT,
+    /** A MAPPING-END event. */
+    YAML_MAPPING_END_EVENT
+} yaml_event_type_t;
+
+/** The event structure. */
+typedef struct yaml_event_s {
+
+    /** The event type. */
+    yaml_event_type_t type;
+
+    /** The event data. */
+    union {
+
+        /** The stream parameters (for @c YAML_STREAM_START_EVENT). */
+        struct {
+            /** The document encoding. */
+            yaml_encoding_t encoding;
+        } stream_start;
+
+        /** The document parameters (for @c YAML_DOCUMENT_START_EVENT). */
+        struct {
+            /** The version directive. */
+            yaml_version_directive_t *version_directive;
+
+            /** The list of tag directives. */
+            struct {
+                /** The beginning of the tag directives list. */
+                yaml_tag_directive_t *start;
+                /** The end of the tag directives list. */
+                yaml_tag_directive_t *end;
+            } tag_directives;
+
+            /** Is the document indicator implicit? */
+            int implicit;
+        } document_start;
+
+        /** The document end parameters (for @c YAML_DOCUMENT_END_EVENT). */
+        struct {
+            /** Is the document end indicator implicit? */
+            int implicit;
+        } document_end;
+
+        /** The alias parameters (for @c YAML_ALIAS_EVENT). */
+        struct {
+            /** The anchor. */
+            yaml_char_t *anchor;
+        } alias;
+
+        /** The scalar parameters (for @c YAML_SCALAR_EVENT). */
+        struct {
+            /** The anchor. */
+            yaml_char_t *anchor;
+            /** The tag. */
+            yaml_char_t *tag;
+            /** The scalar value. */
+            yaml_char_t *value;
+            /** The length of the scalar value. */
+            size_t length;
+            /** Is the tag optional for the plain style? */
+            int plain_implicit;
+            /** Is the tag optional for any non-plain style? */
+            int quoted_implicit;
+            /** The scalar style. */
+            yaml_scalar_style_t style;
+        } scalar;
+
+        /** The sequence parameters (for @c YAML_SEQUENCE_START_EVENT). */
+        struct {
+            /** The anchor. */
+            yaml_char_t *anchor;
+            /** The tag. */
+            yaml_char_t *tag;
+            /** Is the tag optional? */
+            int implicit;
+            /** The sequence style. */
+            yaml_sequence_style_t style;
+        } sequence_start;
+
+        /** The mapping parameters (for @c YAML_MAPPING_START_EVENT). */
+        struct {
+            /** The anchor. */
+            yaml_char_t *anchor;
+            /** The tag. */
+            yaml_char_t *tag;
+            /** Is the tag optional? */
+            int implicit;
+            /** The mapping style. */
+            yaml_mapping_style_t style;
+        } mapping_start;
+
+    } data;
+
+    /** The beginning of the event. */
+    yaml_mark_t start_mark;
+    /** The end of the event. */
+    yaml_mark_t end_mark;
+
+} yaml_event_t;
+
+/**
+ * Create the STREAM-START event.
+ *
+ * @param[out]      event       An empty event object.
+ * @param[in]       encoding    The stream encoding.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_stream_start_event_initialize(yaml_event_t *event,
+        yaml_encoding_t encoding);
+
+/**
+ * Create the STREAM-END event.
+ *
+ * @param[out]      event       An empty event object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_stream_end_event_initialize(yaml_event_t *event);
+
+/**
+ * Create the DOCUMENT-START event.
+ *
+ * The @a implicit argument is considered as a stylistic parameter and may be
+ * ignored by the emitter.
+ *
+ * @param[out]      event                   An empty event object.
+ * @param[in]       version_directive       The %YAML directive value or
+ *                                          @c NULL.
+ * @param[in]       tag_directives_start    The beginning of the %TAG
+ *                                          directives list.
+ * @param[in]       tag_directives_end      The end of the %TAG directives
+ *                                          list.
+ * @param[in]       implicit                If the document start indicator is
+ *                                          implicit.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_start_event_initialize(yaml_event_t *event,
+        yaml_version_directive_t *version_directive,
+        yaml_tag_directive_t *tag_directives_start,
+        yaml_tag_directive_t *tag_directives_end,
+        int implicit);
+
+/**
+ * Create the DOCUMENT-END event.
+ *
+ * The @a implicit argument is considered as a stylistic parameter and may be
+ * ignored by the emitter.
+ *
+ * @param[out]      event       An empty event object.
+ * @param[in]       implicit    If the document end indicator is implicit.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_end_event_initialize(yaml_event_t *event, int implicit);
+
+/**
+ * Create an ALIAS event.
+ *
+ * @param[out]      event       An empty event object.
+ * @param[in]       anchor      The anchor value.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_alias_event_initialize(yaml_event_t *event, yaml_char_t *anchor);
+
+/**
+ * Create a SCALAR event.
+ *
+ * The @a style argument may be ignored by the emitter.
+ *
+ * Either the @a tag attribute or one of the @a plain_implicit and
+ * @a quoted_implicit flags must be set.
+ *
+ * @param[out]      event           An empty event object.
+ * @param[in]       anchor          The scalar anchor or @c NULL.
+ * @param[in]       tag             The scalar tag or @c NULL.
+ * @param[in]       value           The scalar value.
+ * @param[in]       length          The length of the scalar value.
+ * @param[in]       plain_implicit  If the tag may be omitted for the plain
+ *                                  style.
+ * @param[in]       quoted_implicit If the tag may be omitted for any
+ *                                  non-plain style.
+ * @param[in]       style           The scalar style.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_scalar_event_initialize(yaml_event_t *event,
+        yaml_char_t *anchor, yaml_char_t *tag,
+        yaml_char_t *value, int length,
+        int plain_implicit, int quoted_implicit,
+        yaml_scalar_style_t style);
+
+/**
+ * Create a SEQUENCE-START event.
+ *
+ * The @a style argument may be ignored by the emitter.
+ *
+ * Either the @a tag attribute or the @a implicit flag must be set.
+ *
+ * @param[out]      event       An empty event object.
+ * @param[in]       anchor      The sequence anchor or @c NULL.
+ * @param[in]       tag         The sequence tag or @c NULL.
+ * @param[in]       implicit    If the tag may be omitted.
+ * @param[in]       style       The sequence style.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_sequence_start_event_initialize(yaml_event_t *event,
+        yaml_char_t *anchor, yaml_char_t *tag, int implicit,
+        yaml_sequence_style_t style);
+
+/**
+ * Create a SEQUENCE-END event.
+ *
+ * @param[out]      event       An empty event object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_sequence_end_event_initialize(yaml_event_t *event);
+
+/**
+ * Create a MAPPING-START event.
+ *
+ * The @a style argument may be ignored by the emitter.
+ *
+ * Either the @a tag attribute or the @a implicit flag must be set.
+ *
+ * @param[out]      event       An empty event object.
+ * @param[in]       anchor      The mapping anchor or @c NULL.
+ * @param[in]       tag         The mapping tag or @c NULL.
+ * @param[in]       implicit    If the tag may be omitted.
+ * @param[in]       style       The mapping style.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_mapping_start_event_initialize(yaml_event_t *event,
+        yaml_char_t *anchor, yaml_char_t *tag, int implicit,
+        yaml_mapping_style_t style);
+
+/**
+ * Create a MAPPING-END event.
+ *
+ * @param[out]      event       An empty event object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_mapping_end_event_initialize(yaml_event_t *event);
+
+/**
+ * Free any memory allocated for an event object.
+ *
+ * @param[in,out]   event   An event object.
+ */
+
+YAML_DECLARE(void)
+yaml_event_delete(yaml_event_t *event);
+
+/** @} */
+
+/**
+ * @defgroup nodes Nodes
+ * @{
+ */
+
+/** The tag @c !!null with the only possible value: @c null. */
+#define YAML_NULL_TAG       "tag:yaml.org,2002:null"
+/** The tag @c !!bool with the values: @c true and @c falce. */
+#define YAML_BOOL_TAG       "tag:yaml.org,2002:bool"
+/** The tag @c !!str for string values. */
+#define YAML_STR_TAG        "tag:yaml.org,2002:str"
+/** The tag @c !!int for integer values. */
+#define YAML_INT_TAG        "tag:yaml.org,2002:int"
+/** The tag @c !!float for float values. */
+#define YAML_FLOAT_TAG      "tag:yaml.org,2002:float"
+/** The tag @c !!timestamp for date and time values. */
+#define YAML_TIMESTAMP_TAG  "tag:yaml.org,2002:timestamp"
+
+/** The tag @c !!seq is used to denote sequences. */
+#define YAML_SEQ_TAG        "tag:yaml.org,2002:seq"
+/** The tag @c !!map is used to denote mapping. */
+#define YAML_MAP_TAG        "tag:yaml.org,2002:map"
+
+/** The default scalar tag is @c !!str. */
+#define YAML_DEFAULT_SCALAR_TAG     YAML_STR_TAG
+/** The default sequence tag is @c !!seq. */
+#define YAML_DEFAULT_SEQUENCE_TAG   YAML_SEQ_TAG
+/** The default mapping tag is @c !!map. */
+#define YAML_DEFAULT_MAPPING_TAG    YAML_MAP_TAG
+
+/** Node types. */
+typedef enum yaml_node_type_e {
+    /** An empty node. */
+    YAML_NO_NODE,
+
+    /** A scalar node. */
+    YAML_SCALAR_NODE,
+    /** A sequence node. */
+    YAML_SEQUENCE_NODE,
+    /** A mapping node. */
+    YAML_MAPPING_NODE
+} yaml_node_type_t;
+
+/** The forward definition of a document node structure. */
+typedef struct yaml_node_s yaml_node_t;
+
+/** An element of a sequence node. */
+typedef int yaml_node_item_t;
+
+/** An element of a mapping node. */
+typedef struct yaml_node_pair_s {
+    /** The key of the element. */
+    int key;
+    /** The value of the element. */
+    int value;
+} yaml_node_pair_t;
+
+/** The node structure. */
+struct yaml_node_s {
+
+    /** The node type. */
+    yaml_node_type_t type;
+
+    /** The node tag. */
+    yaml_char_t *tag;
+
+    /** The node data. */
+    union {
+
+        /** The scalar parameters (for @c YAML_SCALAR_NODE). */
+        struct {
+            /** The scalar value. */
+            yaml_char_t *value;
+            /** The length of the scalar value. */
+            size_t length;
+            /** The scalar style. */
+            yaml_scalar_style_t style;
+        } scalar;
+
+        /** The sequence parameters (for @c YAML_SEQUENCE_NODE). */
+        struct {
+            /** The stack of sequence items. */
+            struct {
+                /** The beginning of the stack. */
+                yaml_node_item_t *start;
+                /** The end of the stack. */
+                yaml_node_item_t *end;
+                /** The top of the stack. */
+                yaml_node_item_t *top;
+            } items;
+            /** The sequence style. */
+            yaml_sequence_style_t style;
+        } sequence;
+
+        /** The mapping parameters (for @c YAML_MAPPING_NODE). */
+        struct {
+            /** The stack of mapping pairs (key, value). */
+            struct {
+                /** The beginning of the stack. */
+                yaml_node_pair_t *start;
+                /** The end of the stack. */
+                yaml_node_pair_t *end;
+                /** The top of the stack. */
+                yaml_node_pair_t *top;
+            } pairs;
+            /** The mapping style. */
+            yaml_mapping_style_t style;
+        } mapping;
+
+    } data;
+
+    /** The beginning of the node. */
+    yaml_mark_t start_mark;
+    /** The end of the node. */
+    yaml_mark_t end_mark;
+
+};
+
+/** The document structure. */
+typedef struct yaml_document_s {
+
+    /** The document nodes. */
+    struct {
+        /** The beginning of the stack. */
+        yaml_node_t *start;
+        /** The end of the stack. */
+        yaml_node_t *end;
+        /** The top of the stack. */
+        yaml_node_t *top;
+    } nodes;
+
+    /** The version directive. */
+    yaml_version_directive_t *version_directive;
+
+    /** The list of tag directives. */
+    struct {
+        /** The beginning of the tag directives list. */
+        yaml_tag_directive_t *start;
+        /** The end of the tag directives list. */
+        yaml_tag_directive_t *end;
+    } tag_directives;
+
+    /** Is the document start indicator implicit? */
+    int start_implicit;
+    /** Is the document end indicator implicit? */
+    int end_implicit;
+
+    /** The beginning of the document. */
+    yaml_mark_t start_mark;
+    /** The end of the document. */
+    yaml_mark_t end_mark;
+
+} yaml_document_t;
+
+/**
+ * Create a YAML document.
+ *
+ * @param[out]      document                An empty document object.
+ * @param[in]       version_directive       The %YAML directive value or
+ *                                          @c NULL.
+ * @param[in]       tag_directives_start    The beginning of the %TAG
+ *                                          directives list.
+ * @param[in]       tag_directives_end      The end of the %TAG directives
+ *                                          list.
+ * @param[in]       start_implicit          If the document start indicator is
+ *                                          implicit.
+ * @param[in]       end_implicit            If the document end indicator is
+ *                                          implicit.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_initialize(yaml_document_t *document,
+        yaml_version_directive_t *version_directive,
+        yaml_tag_directive_t *tag_directives_start,
+        yaml_tag_directive_t *tag_directives_end,
+        int start_implicit, int end_implicit);
+
+/**
+ * Delete a YAML document and all its nodes.
+ *
+ * @param[in,out]   document        A document object.
+ */
+
+YAML_DECLARE(void)
+yaml_document_delete(yaml_document_t *document);
+
+/**
+ * Get a node of a YAML document.
+ *
+ * The pointer returned by this function is valid until any of the functions
+ * modifying the documents are called.
+ *
+ * @param[in]       document        A document object.
+ * @param[in]       index           The node id.
+ *
+ * @returns the node objct or @c NULL if @c node_id is out of range.
+ */
+
+YAML_DECLARE(yaml_node_t *)
+yaml_document_get_node(yaml_document_t *document, int index);
+
+/**
+ * Get the root of a YAML document node.
+ *
+ * The root object is the first object added to the document.
+ *
+ * The pointer returned by this function is valid until any of the functions
+ * modifying the documents are called.
+ *
+ * An empty document produced by the parser signifies the end of a YAML
+ * stream.
+ *
+ * @param[in]       document        A document object.
+ *
+ * @returns the node object or @c NULL if the document is empty.
+ */
+
+YAML_DECLARE(yaml_node_t *)
+yaml_document_get_root_node(yaml_document_t *document);
+
+/**
+ * Create a SCALAR node and attach it to the document.
+ *
+ * The @a style argument may be ignored by the emitter.
+ *
+ * @param[in,out]   document        A document object.
+ * @param[in]       tag             The scalar tag.
+ * @param[in]       value           The scalar value.
+ * @param[in]       length          The length of the scalar value.
+ * @param[in]       style           The scalar style.
+ *
+ * @returns the node id or @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_add_scalar(yaml_document_t *document,
+        yaml_char_t *tag, yaml_char_t *value, int length,
+        yaml_scalar_style_t style);
+
+/**
+ * Create a SEQUENCE node and attach it to the document.
+ *
+ * The @a style argument may be ignored by the emitter.
+ *
+ * @param[in,out]   document    A document object.
+ * @param[in]       tag         The sequence tag.
+ * @param[in]       style       The sequence style.
+ *
+ * @returns the node id or @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_add_sequence(yaml_document_t *document,
+        yaml_char_t *tag, yaml_sequence_style_t style);
+
+/**
+ * Create a MAPPING node and attach it to the document.
+ *
+ * The @a style argument may be ignored by the emitter.
+ *
+ * @param[in,out]   document    A document object.
+ * @param[in]       tag         The sequence tag.
+ * @param[in]       style       The sequence style.
+ *
+ * @returns the node id or @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_add_mapping(yaml_document_t *document,
+        yaml_char_t *tag, yaml_mapping_style_t style);
+
+/**
+ * Add an item to a SEQUENCE node.
+ *
+ * @param[in,out]   document    A document object.
+ * @param[in]       sequence    The sequence node id.
+ * @param[in]       item        The item node id.
+*
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_append_sequence_item(yaml_document_t *document,
+        int sequence, int item);
+
+/**
+ * Add a pair of a key and a value to a MAPPING node.
+ *
+ * @param[in,out]   document    A document object.
+ * @param[in]       mapping     The mapping node id.
+ * @param[in]       key         The key node id.
+ * @param[in]       value       The value node id.
+*
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_document_append_mapping_pair(yaml_document_t *document,
+        int mapping, int key, int value);
+
+/** @} */
+
+/**
+ * @defgroup parser Parser Definitions
+ * @{
+ */
+
+/**
+ * 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 @a size bytes to the @a
+ * buffer.  The number of written bytes should be set to the @a length variable.
+ *
+ * @param[in,out]   data        A pointer to an application data specified by
+ *                              yaml_parser_set_input().
+ * @param[out]      buffer      The buffer to write the data from the source.
+ * @param[in]       size        The size of the buffer.
+ * @param[out]      size_read   The actual number of bytes read from the source.
+ *
+ * @returns On success, the handler should return @c 1.  If the handler failed,
+ * the returned value should be @c 0.  On EOF, the handler should set the
+ * @a size_read to @c 0 and return @c 1.
+ */
+
+typedef int yaml_read_handler_t(void *data, unsigned char *buffer, size_t size,
+        size_t *size_read);
+
+/**
+ * This structure holds information about a potential simple key.
+ */
+
+typedef struct yaml_simple_key_s {
+    /** Is a simple key possible? */
+    int possible;
+
+    /** Is a simple key required? */
+    int required;
+
+    /** The number of the token. */
+    size_t token_number;
+
+    /** The position mark. */
+    yaml_mark_t mark;
+} yaml_simple_key_t;
+
+/**
+ * The states of the parser.
+ */
+typedef enum yaml_parser_state_e {
+    /** Expect STREAM-START. */
+    YAML_PARSE_STREAM_START_STATE,
+    /** Expect the beginning of an implicit document. */
+    YAML_PARSE_IMPLICIT_DOCUMENT_START_STATE,
+    /** Expect DOCUMENT-START. */
+    YAML_PARSE_DOCUMENT_START_STATE,
+    /** Expect the content of a document. */
+    YAML_PARSE_DOCUMENT_CONTENT_STATE,
+    /** Expect DOCUMENT-END. */
+    YAML_PARSE_DOCUMENT_END_STATE,
+    /** Expect a block node. */
+    YAML_PARSE_BLOCK_NODE_STATE,
+    /** Expect a block node or indentless sequence. */
+    YAML_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE,
+    /** Expect a flow node. */
+    YAML_PARSE_FLOW_NODE_STATE,
+    /** Expect the first entry of a block sequence. */
+    YAML_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE,
+    /** Expect an entry of a block sequence. */
+    YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE,
+    /** Expect an entry of an indentless sequence. */
+    YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE,
+    /** Expect the first key of a block mapping. */
+    YAML_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE,
+    /** Expect a block mapping key. */
+    YAML_PARSE_BLOCK_MAPPING_KEY_STATE,
+    /** Expect a block mapping value. */
+    YAML_PARSE_BLOCK_MAPPING_VALUE_STATE,
+    /** Expect the first entry of a flow sequence. */
+    YAML_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE,
+    /** Expect an entry of a flow sequence. */
+    YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE,
+    /** Expect a key of an ordered mapping. */
+    YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE,
+    /** Expect a value of an ordered mapping. */
+    YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE,
+    /** Expect the and of an ordered mapping entry. */
+    YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE,
+    /** Expect the first key of a flow mapping. */
+    YAML_PARSE_FLOW_MAPPING_FIRST_KEY_STATE,
+    /** Expect a key of a flow mapping. */
+    YAML_PARSE_FLOW_MAPPING_KEY_STATE,
+    /** Expect a value of a flow mapping. */
+    YAML_PARSE_FLOW_MAPPING_VALUE_STATE,
+    /** Expect an empty value of a flow mapping. */
+    YAML_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE,
+    /** Expect nothing. */
+    YAML_PARSE_END_STATE
+} yaml_parser_state_t;
+
+/**
+ * This structure holds aliases data.
+ */
+
+typedef struct yaml_alias_data_s {
+    /** The anchor. */
+    yaml_char_t *anchor;
+    /** The node id. */
+    int index;
+    /** The anchor mark. */
+    yaml_mark_t mark;
+} yaml_alias_data_t;
+
+/**
+ * The parser structure.
+ *
+ * All members are internal.  Manage the structure using the @c yaml_parser_
+ * family of functions.
+ */
+
+typedef struct yaml_parser_s {
+
+    /**
+     * @name Error handling
+     * @{
+     */
+
+    /** Error type. */
+    yaml_error_type_t error;
+    /** Error description. */
+    const char *problem;
+    /** The byte about which the problem occured. */
+    size_t problem_offset;
+    /** The problematic value (@c -1 is none). */
+    int problem_value;
+    /** The problem position. */
+    yaml_mark_t problem_mark;
+    /** The error context. */
+    const char *context;
+    /** The context position. */
+    yaml_mark_t context_mark;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Reader stuff
+     * @{
+     */
+
+    /** Read handler. */
+    yaml_read_handler_t *read_handler;
+
+    /** A pointer for passing to the read handler. */
+    void *read_handler_data;
+
+    /** Standard (string or file) input data. */
+    union {
+        /** String input data. */
+        struct {
+            /** The string start pointer. */
+            const unsigned char *start;
+            /** The string end pointer. */
+            const unsigned char *end;
+            /** The string current position. */
+            const unsigned char *current;
+        } string;
+
+        /** File input data. */
+        FILE *file;
+    } input;
+
+    /** EOF flag */
+    int eof;
+
+    /** The working buffer. */
+    struct {
+        /** The beginning of the buffer. */
+        yaml_char_t *start;
+        /** The end of the buffer. */
+        yaml_char_t *end;
+        /** The current position of the buffer. */
+        yaml_char_t *pointer;
+        /** The last filled position of the buffer. */
+        yaml_char_t *last;
+    } buffer;
+
+    /* The number of unread characters in the buffer. */
+    size_t unread;
+
+    /** The raw buffer. */
+    struct {
+        /** The beginning of the buffer. */
+        unsigned char *start;
+        /** The end of the buffer. */
+        unsigned char *end;
+        /** The current position of the buffer. */
+        unsigned char *pointer;
+        /** The last filled position of the buffer. */
+        unsigned char *last;
+    } raw_buffer;
+
+    /** The input encoding. */
+    yaml_encoding_t encoding;
+
+    /** The offset of the current position (in bytes). */
+    size_t offset;
+
+    /** The mark of the current position. */
+    yaml_mark_t mark;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Scanner stuff
+     * @{
+     */
+
+    /** Have we started to scan the input stream? */
+    int stream_start_produced;
+
+    /** Have we reached the end of the input stream? */
+    int stream_end_produced;
+
+    /** The number of unclosed '[' and '{' indicators. */
+    int flow_level;
+
+    /** The tokens queue. */
+    struct {
+        /** The beginning of the tokens queue. */
+        yaml_token_t *start;
+        /** The end of the tokens queue. */
+        yaml_token_t *end;
+        /** The head of the tokens queue. */
+        yaml_token_t *head;
+        /** The tail of the tokens queue. */
+        yaml_token_t *tail;
+    } tokens;
+
+    /** The number of tokens fetched from the queue. */
+    size_t tokens_parsed;
+
+    /* Does the tokens queue contain a token ready for dequeueing. */
+    int token_available;
+
+    /** The indentation levels stack. */
+    struct {
+        /** The beginning of the stack. */
+        int *start;
+        /** The end of the stack. */
+        int *end;
+        /** The top of the stack. */
+        int *top;
+    } indents;
+
+    /** The current indentation level. */
+    int indent;
+
+    /** May a simple key occur at the current position? */
+    int simple_key_allowed;
+
+    /** The stack of simple keys. */
+    struct {
+        /** The beginning of the stack. */
+        yaml_simple_key_t *start;
+        /** The end of the stack. */
+        yaml_simple_key_t *end;
+        /** The top of the stack. */
+        yaml_simple_key_t *top;
+    } simple_keys;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Parser stuff
+     * @{
+     */
+
+    /** The parser states stack. */
+    struct {
+        /** The beginning of the stack. */
+        yaml_parser_state_t *start;
+        /** The end of the stack. */
+        yaml_parser_state_t *end;
+        /** The top of the stack. */
+        yaml_parser_state_t *top;
+    } states;
+
+    /** The current parser state. */
+    yaml_parser_state_t state;
+
+    /** The stack of marks. */
+    struct {
+        /** The beginning of the stack. */
+        yaml_mark_t *start;
+        /** The end of the stack. */
+        yaml_mark_t *end;
+        /** The top of the stack. */
+        yaml_mark_t *top;
+    } marks;
+
+    /** The list of TAG directives. */
+    struct {
+        /** The beginning of the list. */
+        yaml_tag_directive_t *start;
+        /** The end of the list. */
+        yaml_tag_directive_t *end;
+        /** The top of the list. */
+        yaml_tag_directive_t *top;
+    } tag_directives;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Dumper stuff
+     * @{
+     */
+
+    /** The alias data. */
+    struct {
+        /** The beginning of the list. */
+        yaml_alias_data_t *start;
+        /** The end of the list. */
+        yaml_alias_data_t *end;
+        /** The top of the list. */
+        yaml_alias_data_t *top;
+    } aliases;
+
+    /** The currently parsed document. */
+    yaml_document_t *document;
+
+    /**
+     * @}
+     */
+
+} yaml_parser_t;
+
+/**
+ * Initialize a parser.
+ *
+ * This function creates a new parser object.  An application is responsible
+ * for destroying the object using the yaml_parser_delete() function.
+ *
+ * @param[out]      parser  An empty parser object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_initialize(yaml_parser_t *parser);
+
+/**
+ * Destroy a parser.
+ *
+ * @param[in,out]   parser  A parser object.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_delete(yaml_parser_t *parser);
+
+/**
+ * Set a string input.
+ *
+ * Note that the @a input pointer must be valid while the @a parser object
+ * exists.  The application is responsible for destroing @a input after
+ * destroying the @a parser.
+ *
+ * @param[in,out]   parser  A parser object.
+ * @param[in]       input   A source data.
+ * @param[in]       size    The length of the source data in bytes.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input_string(yaml_parser_t *parser,
+        const unsigned char *input, size_t size);
+
+/**
+ * Set a file input.
+ *
+ * @a file should be a file object open for reading.  The application is
+ * responsible for closing the @a file.
+ *
+ * @param[in,out]   parser  A parser object.
+ * @param[in]       file    An open file.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input_file(yaml_parser_t *parser, FILE *file);
+
+/**
+ * Set a generic input handler.
+ *
+ * @param[in,out]   parser  A parser object.
+ * @param[in]       handler A read handler.
+ * @param[in]       data    Any application data for passing to the read
+ *                          handler.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input(yaml_parser_t *parser,
+        yaml_read_handler_t *handler, void *data);
+
+/**
+ * Set the source encoding.
+ *
+ * @param[in,out]   parser      A parser object.
+ * @param[in]       encoding    The source encoding.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_encoding(yaml_parser_t *parser, yaml_encoding_t encoding);
+
+/**
+ * Scan the input stream and produce the next token.
+ *
+ * Call the function subsequently to produce a sequence of tokens corresponding
+ * to the input stream.  The initial token has the type
+ * @c YAML_STREAM_START_TOKEN while the ending token has the type
+ * @c YAML_STREAM_END_TOKEN.
+ *
+ * An application is responsible for freeing any buffers associated with the
+ * produced token object using the @c yaml_token_delete function.
+ *
+ * An application must not alternate the calls of yaml_parser_scan() with the
+ * calls of yaml_parser_parse() or yaml_parser_load(). Doing this will break
+ * the parser.
+ *
+ * @param[in,out]   parser      A parser object.
+ * @param[out]      token       An empty token object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token);
+
+/**
+ * Parse the input stream and produce the next parsing event.
+ *
+ * Call the function subsequently to produce a sequence of events corresponding
+ * to the input stream.  The initial event has the type
+ * @c YAML_STREAM_START_EVENT while the ending event has the type
+ * @c YAML_STREAM_END_EVENT.
+ *
+ * An application is responsible for freeing any buffers associated with the
+ * produced event object using the yaml_event_delete() function.
+ *
+ * An application must not alternate the calls of yaml_parser_parse() with the
+ * calls of yaml_parser_scan() or yaml_parser_load(). Doing this will break the
+ * parser.
+ *
+ * @param[in,out]   parser      A parser object.
+ * @param[out]      event       An empty event object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_parse(yaml_parser_t *parser, yaml_event_t *event);
+
+/**
+ * Parse the input stream and produce the next YAML document.
+ *
+ * Call this function subsequently to produce a sequence of documents
+ * constituting the input stream.
+ *
+ * If the produced document has no root node, it means that the document
+ * end has been reached.
+ *
+ * An application is responsible for freeing any data associated with the
+ * produced document object using the yaml_document_delete() function.
+ *
+ * An application must not alternate the calls of yaml_parser_load() with the
+ * calls of yaml_parser_scan() or yaml_parser_parse(). Doing this will break
+ * the parser.
+ *
+ * @param[in,out]   parser      A parser object.
+ * @param[out]      document    An empty document object.
+ *
+ * @return @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_load(yaml_parser_t *parser, yaml_document_t *document);
+
+/** @} */
+
+/**
+ * @defgroup emitter 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.
+ */
+
+typedef int yaml_write_handler_t(void *data, unsigned char *buffer, size_t size);
+
+/** The emitter states. */
+typedef enum yaml_emitter_state_e {
+    /** Expect STREAM-START. */
+    YAML_EMIT_STREAM_START_STATE,
+    /** Expect the first DOCUMENT-START or STREAM-END. */
+    YAML_EMIT_FIRST_DOCUMENT_START_STATE,
+    /** Expect DOCUMENT-START or STREAM-END. */
+    YAML_EMIT_DOCUMENT_START_STATE,
+    /** Expect the content of a document. */
+    YAML_EMIT_DOCUMENT_CONTENT_STATE,
+    /** Expect DOCUMENT-END. */
+    YAML_EMIT_DOCUMENT_END_STATE,
+    /** Expect the first item of a flow sequence. */
+    YAML_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE,
+    /** Expect an item of a flow sequence. */
+    YAML_EMIT_FLOW_SEQUENCE_ITEM_STATE,
+    /** Expect the first key of a flow mapping. */
+    YAML_EMIT_FLOW_MAPPING_FIRST_KEY_STATE,
+    /** Expect a key of a flow mapping. */
+    YAML_EMIT_FLOW_MAPPING_KEY_STATE,
+    /** Expect a value for a simple key of a flow mapping. */
+    YAML_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE,
+    /** Expect a value of a flow mapping. */
+    YAML_EMIT_FLOW_MAPPING_VALUE_STATE,
+    /** Expect the first item of a block sequence. */
+    YAML_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE,
+    /** Expect an item of a block sequence. */
+    YAML_EMIT_BLOCK_SEQUENCE_ITEM_STATE,
+    /** Expect the first key of a block mapping. */
+    YAML_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE,
+    /** Expect the key of a block mapping. */
+    YAML_EMIT_BLOCK_MAPPING_KEY_STATE,
+    /** Expect a value for a simple key of a block mapping. */
+    YAML_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE,
+    /** Expect a value of a block mapping. */
+    YAML_EMIT_BLOCK_MAPPING_VALUE_STATE,
+    /** Expect nothing. */
+    YAML_EMIT_END_STATE
+} yaml_emitter_state_t;
+
+/**
+ * The emitter structure.
+ *
+ * All members are internal.  Manage the structure using the @c yaml_emitter_
+ * family of functions.
+ */
+
+typedef struct yaml_emitter_s {
+
+    /**
+     * @name Error handling
+     * @{
+     */
+
+    /** Error type. */
+    yaml_error_type_t error;
+    /** Error description. */
+    const char *problem;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Writer stuff
+     * @{
+     */
+
+    /** Write handler. */
+    yaml_write_handler_t *write_handler;
+
+    /** A pointer for passing to the white handler. */
+    void *write_handler_data;
+
+    /** Standard (string or file) output data. */
+    union {
+        /** String output data. */
+        struct {
+            /** The buffer pointer. */
+            unsigned char *buffer;
+            /** The buffer size. */
+            size_t size;
+            /** The number of written bytes. */
+            size_t *size_written;
+        } string;
+
+        /** File output data. */
+        FILE *file;
+    } output;
+
+    /** The working buffer. */
+    struct {
+        /** The beginning of the buffer. */
+        yaml_char_t *start;
+        /** The end of the buffer. */
+        yaml_char_t *end;
+        /** The current position of the buffer. */
+        yaml_char_t *pointer;
+        /** The last filled position of the buffer. */
+        yaml_char_t *last;
+    } buffer;
+
+    /** The raw buffer. */
+    struct {
+        /** The beginning of the buffer. */
+        unsigned char *start;
+        /** The end of the buffer. */
+        unsigned char *end;
+        /** The current position of the buffer. */
+        unsigned char *pointer;
+        /** The last filled position of the buffer. */
+        unsigned char *last;
+    } raw_buffer;
+
+    /** The stream encoding. */
+    yaml_encoding_t encoding;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Emitter stuff
+     * @{
+     */
+
+    /** If the output is in the canonical style? */
+    int canonical;
+    /** The number of indentation spaces. */
+    int best_indent;
+    /** The preferred width of the output lines. */
+    int best_width;
+    /** Allow unescaped non-ASCII characters? */
+    int unicode;
+    /** The preferred line break. */
+    yaml_break_t line_break;
+
+    /** The stack of states. */
+    struct {
+        /** The beginning of the stack. */
+        yaml_emitter_state_t *start;
+        /** The end of the stack. */
+        yaml_emitter_state_t *end;
+        /** The top of the stack. */
+        yaml_emitter_state_t *top;
+    } states;
+
+    /** The current emitter state. */
+    yaml_emitter_state_t state;
+
+    /** The event queue. */
+    struct {
+        /** The beginning of the event queue. */
+        yaml_event_t *start;
+        /** The end of the event queue. */
+        yaml_event_t *end;
+        /** The head of the event queue. */
+        yaml_event_t *head;
+        /** The tail of the event queue. */
+        yaml_event_t *tail;
+    } events;
+
+    /** The stack of indentation levels. */
+    struct {
+        /** The beginning of the stack. */
+        int *start;
+        /** The end of the stack. */
+        int *end;
+        /** The top of the stack. */
+        int *top;
+    } indents;
+
+    /** The list of tag directives. */
+    struct {
+        /** The beginning of the list. */
+        yaml_tag_directive_t *start;
+        /** The end of the list. */
+        yaml_tag_directive_t *end;
+        /** The top of the list. */
+        yaml_tag_directive_t *top;
+    } tag_directives;
+
+    /** The current indentation level. */
+    int indent;
+
+    /** The current flow level. */
+    int flow_level;
+
+    /** Is it the document root context? */
+    int root_context;
+    /** Is it a sequence context? */
+    int sequence_context;
+    /** Is it a mapping context? */
+    int mapping_context;
+    /** Is it a simple mapping key context? */
+    int simple_key_context;
+
+    /** The current line. */
+    int line;
+    /** The current column. */
+    int column;
+    /** If the last character was a whitespace? */
+    int whitespace;
+    /** If the last character was an indentation character (' ', '-', '?', ':')? */
+    int indention;
+    /** If an explicit document end is required? */
+    int open_ended;
+
+    /** Anchor analysis. */
+    struct {
+        /** The anchor value. */
+        yaml_char_t *anchor;
+        /** The anchor length. */
+        size_t anchor_length;
+        /** Is it an alias? */
+        int alias;
+    } anchor_data;
+
+    /** Tag analysis. */
+    struct {
+        /** The tag handle. */
+        yaml_char_t *handle;
+        /** The tag handle length. */
+        size_t handle_length;
+        /** The tag suffix. */
+        yaml_char_t *suffix;
+        /** The tag suffix length. */
+        size_t suffix_length;
+    } tag_data;
+
+    /** Scalar analysis. */
+    struct {
+        /** The scalar value. */
+        yaml_char_t *value;
+        /** The scalar length. */
+        size_t length;
+        /** Does the scalar contain line breaks? */
+        int multiline;
+        /** Can the scalar be expessed in the flow plain style? */
+        int flow_plain_allowed;
+        /** Can the scalar be expressed in the block plain style? */
+        int block_plain_allowed;
+        /** Can the scalar be expressed in the single quoted style? */
+        int single_quoted_allowed;
+        /** Can the scalar be expressed in the literal or folded styles? */
+        int block_allowed;
+        /** The output style. */
+        yaml_scalar_style_t style;
+    } scalar_data;
+
+    /**
+     * @}
+     */
+
+    /**
+     * @name Dumper stuff
+     * @{
+     */
+
+    /** If the stream was already opened? */
+    int opened;
+    /** If the stream was already closed? */
+    int closed;
+
+    /** The information associated with the document nodes. */
+    struct {
+        /** The number of references. */
+        int references;
+        /** The anchor id. */
+        int anchor;
+        /** If the node has been emitted? */
+        int serialized;
+    } *anchors;
+
+    /** The last assigned anchor id. */
+    int last_anchor_id;
+
+    /** The currently emitted document. */
+    yaml_document_t *document;
+
+    /**
+     * @}
+     */
+
+} yaml_emitter_t;
+
+/**
+ * Initialize an emitter.
+ *
+ * This function creates a new emitter object.  An application is responsible
+ * for destroying the object using the yaml_emitter_delete() function.
+ *
+ * @param[out]      emitter     An empty parser object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_initialize(yaml_emitter_t *emitter);
+
+/**
+ * Destroy an emitter.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_delete(yaml_emitter_t *emitter);
+
+/**
+ * Set a string output.
+ *
+ * The emitter will write the output characters to the @a output buffer of the
+ * size @a size.  The emitter will set @a size_written to the number of written
+ * bytes.  If the buffer is smaller than required, the emitter produces the
+ * YAML_WRITE_ERROR error.
+ *
+ * @param[in,out]   emitter         An emitter object.
+ * @param[in]       output          An output buffer.
+ * @param[in]       size            The buffer size.
+ * @param[in]       size_written    The pointer to save the number of written
+ *                                  bytes.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output_string(yaml_emitter_t *emitter,
+        unsigned char *output, size_t size, size_t *size_written);
+
+/**
+ * Set a file output.
+ *
+ * @a file should be a file object open for writing.  The application is
+ * responsible for closing the @a file.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       file        An open file.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output_file(yaml_emitter_t *emitter, FILE *file);
+
+/**
+ * Set a generic output handler.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       handler     A write handler.
+ * @param[in]       data        Any application data for passing to the write
+ *                              handler.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output(yaml_emitter_t *emitter,
+        yaml_write_handler_t *handler, void *data);
+
+/**
+ * Set the output encoding.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       encoding    The output encoding.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_encoding(yaml_emitter_t *emitter, yaml_encoding_t encoding);
+
+/**
+ * Set if the output should be in the "canonical" format as in the YAML
+ * specification.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       canonical   If the output is canonical.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_canonical(yaml_emitter_t *emitter, int canonical);
+
+/**
+ * Set the intendation increment.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       indent      The indentation increment (1 < . < 10).
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_indent(yaml_emitter_t *emitter, int indent);
+
+/**
+ * Set the preferred line width. @c -1 means unlimited.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       width       The preferred line width.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_width(yaml_emitter_t *emitter, int width);
+
+/**
+ * Set if unescaped non-ASCII characters are allowed.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       unicode     If unescaped Unicode characters are allowed.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_unicode(yaml_emitter_t *emitter, int unicode);
+
+/**
+ * Set the preferred line break.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in]       line_break  The preferred line break.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_break(yaml_emitter_t *emitter, yaml_break_t line_break);
+
+/**
+ * Emit an event.
+ *
+ * The event object may be generated using the yaml_parser_parse() function.
+ * The emitter takes the responsibility for the event object and destroys its
+ * content after it is emitted. The event object is destroyed even if the
+ * function fails.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in,out]   event       An event object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_emit(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/**
+ * Start a YAML stream.
+ *
+ * This function should be used before yaml_emitter_dump() is called.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_open(yaml_emitter_t *emitter);
+
+/**
+ * Finish a YAML stream.
+ *
+ * This function should be used after yaml_emitter_dump() is called.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_close(yaml_emitter_t *emitter);
+
+/**
+ * Emit a YAML document.
+ *
+ * The documen object may be generated using the yaml_parser_load() function
+ * or the yaml_document_initialize() function.  The emitter takes the
+ * responsibility for the document object and destoys its content after
+ * it is emitted. The document object is destroyedeven if the function fails.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ * @param[in,out]   document    A document object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_dump(yaml_emitter_t *emitter, yaml_document_t *document);
+
+/**
+ * Flush the accumulated characters to the output.
+ *
+ * @param[in,out]   emitter     An emitter object.
+ *
+ * @returns @c 1 if the function succeeded, @c 0 on error.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_flush(yaml_emitter_t *emitter);
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* #ifndef YAML_H */
+
diff --git a/ext/psych/yaml/yaml_private.h b/ext/psych/yaml/yaml_private.h
new file mode 100644
index 0000000..af10c83
--- /dev/null
+++ b/ext/psych/yaml/yaml_private.h
@@ -0,0 +1,643 @@
+#ifdef RUBY_EXTCONF_H
+#include RUBY_EXTCONF_H
+#endif
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <yaml.h>
+
+#include <assert.h>
+#include <limits.h>
+
+/*
+ * Memory management.
+ */
+
+YAML_DECLARE(void *)
+yaml_malloc(size_t size);
+
+YAML_DECLARE(void *)
+yaml_realloc(void *ptr, size_t size);
+
+YAML_DECLARE(void)
+yaml_free(void *ptr);
+
+YAML_DECLARE(yaml_char_t *)
+yaml_strdup(const yaml_char_t *);
+
+/*
+ * Reader: Ensure that the buffer contains at least `length` characters.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);
+
+/*
+ * Scanner: Ensure that the token stack contains at least one token ready.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_fetch_more_tokens(yaml_parser_t *parser);
+
+/*
+ * The size of the input raw buffer.
+ */
+
+#define INPUT_RAW_BUFFER_SIZE   16384
+
+/*
+ * The size of the input buffer.
+ *
+ * It should be possible to decode the whole raw buffer.
+ */
+
+#define INPUT_BUFFER_SIZE       (INPUT_RAW_BUFFER_SIZE*3)
+
+/*
+ * The size of the output buffer.
+ */
+
+#define OUTPUT_BUFFER_SIZE      16384
+
+/*
+ * The size of the output raw buffer.
+ *
+ * It should be possible to encode the whole output buffer.
+ */
+
+#define OUTPUT_RAW_BUFFER_SIZE  (OUTPUT_BUFFER_SIZE*2+2)
+
+/*
+ * The size of other stacks and queues.
+ */
+
+#define INITIAL_STACK_SIZE  16
+#define INITIAL_QUEUE_SIZE  16
+#define INITIAL_STRING_SIZE 16
+
+/*
+ * Buffer management.
+ */
+
+#define BUFFER_INIT(context,buffer,size)                                        \
+    (((buffer).start = yaml_malloc(size)) ?                                     \
+        ((buffer).last = (buffer).pointer = (buffer).start,                     \
+         (buffer).end = (buffer).start+(size),                                  \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define BUFFER_DEL(context,buffer)                                              \
+    (yaml_free((buffer).start),                                                 \
+     (buffer).start = (buffer).pointer = (buffer).end = 0)
+
+/*
+ * String management.
+ */
+
+typedef struct {
+    yaml_char_t *start;
+    yaml_char_t *end;
+    yaml_char_t *pointer;
+} yaml_string_t;
+
+YAML_DECLARE(int)
+yaml_string_extend(yaml_char_t **start,
+        yaml_char_t **pointer, yaml_char_t **end);
+
+YAML_DECLARE(int)
+yaml_string_join(
+        yaml_char_t **a_start, yaml_char_t **a_pointer, yaml_char_t **a_end,
+        yaml_char_t **b_start, yaml_char_t **b_pointer, yaml_char_t **b_end);
+
+#define NULL_STRING { NULL, NULL, NULL }
+
+#define STRING(string,length)   { (string), (string)+(length), (string) }
+
+#define STRING_ASSIGN(value,string,length)                                      \
+    ((value).start = (string),                                                  \
+     (value).end = (string)+(length),                                           \
+     (value).pointer = (string))
+
+#define STRING_INIT(context,string,size)                                        \
+    (((string).start = yaml_malloc(size)) ?                                     \
+        ((string).pointer = (string).start,                                     \
+         (string).end = (string).start+(size),                                  \
+         memset((string).start, 0, (size)),                                     \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define STRING_DEL(context,string)                                              \
+    (yaml_free((string).start),                                                 \
+     (string).start = (string).pointer = (string).end = 0)
+
+#define STRING_EXTEND(context,string)                                           \
+    (((string).pointer+5 < (string).end)                                        \
+        || yaml_string_extend(&(string).start,                                  \
+            &(string).pointer, &(string).end))
+
+#define CLEAR(context,string)                                                   \
+    ((string).pointer = (string).start,                                         \
+     memset((string).start, 0, (string).end-(string).start))
+
+#define JOIN(context,string_a,string_b)                                         \
+    ((yaml_string_join(&(string_a).start, &(string_a).pointer,                  \
+                       &(string_a).end, &(string_b).start,                      \
+                       &(string_b).pointer, &(string_b).end)) ?                 \
+        ((string_b).pointer = (string_b).start,                                 \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+/*
+ * String check operations.
+ */
+
+/*
+ * Check the octet at the specified position.
+ */
+
+#define CHECK_AT(string,octet,offset)                                           \
+    ((string).pointer[offset] == (yaml_char_t)(octet))
+
+/*
+ * Check the current octet in the buffer.
+ */
+
+#define CHECK(string,octet) CHECK_AT((string),(octet),0)
+
+/*
+ * Check if the character at the specified position is an alphabetical
+ * character, a digit, '_', or '-'.
+ */
+
+#define IS_ALPHA_AT(string,offset)                                              \
+     (((string).pointer[offset] >= (yaml_char_t) '0' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) '9') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'A' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'Z') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'a' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'z') ||                        \
+      (string).pointer[offset] == '_' ||                                        \
+      (string).pointer[offset] == '-')
+
+#define IS_ALPHA(string)    IS_ALPHA_AT((string),0)
+
+/*
+ * Check if the character at the specified position is a digit.
+ */
+
+#define IS_DIGIT_AT(string,offset)                                              \
+     (((string).pointer[offset] >= (yaml_char_t) '0' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) '9'))
+
+#define IS_DIGIT(string)    IS_DIGIT_AT((string),0)
+
+/*
+ * Get the value of a digit.
+ */
+
+#define AS_DIGIT_AT(string,offset)                                              \
+     ((string).pointer[offset] - (yaml_char_t) '0')
+
+#define AS_DIGIT(string)    AS_DIGIT_AT((string),0)
+
+/*
+ * Check if the character at the specified position is a hex-digit.
+ */
+
+#define IS_HEX_AT(string,offset)                                                \
+     (((string).pointer[offset] >= (yaml_char_t) '0' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) '9') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'A' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'F') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'a' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'f'))
+
+#define IS_HEX(string)    IS_HEX_AT((string),0)
+
+/*
+ * Get the value of a hex-digit.
+ */
+
+#define AS_HEX_AT(string,offset)                                                \
+      (((string).pointer[offset] >= (yaml_char_t) 'A' &&                        \
+        (string).pointer[offset] <= (yaml_char_t) 'F') ?                        \
+       ((string).pointer[offset] - (yaml_char_t) 'A' + 10) :                    \
+       ((string).pointer[offset] >= (yaml_char_t) 'a' &&                        \
+        (string).pointer[offset] <= (yaml_char_t) 'f') ?                        \
+       ((string).pointer[offset] - (yaml_char_t) 'a' + 10) :                    \
+       ((string).pointer[offset] - (yaml_char_t) '0'))
+
+#define AS_HEX(string)  AS_HEX_AT((string),0)
+
+/*
+ * Check if the character is ASCII.
+ */
+
+#define IS_ASCII_AT(string,offset)                                              \
+    ((string).pointer[offset] <= (yaml_char_t) '\x7F')
+
+#define IS_ASCII(string)    IS_ASCII_AT((string),0)
+
+/*
+ * Check if the character can be printed unescaped.
+ */
+
+#define IS_PRINTABLE_AT(string,offset)                                          \
+    (((string).pointer[offset] == 0x0A)         /* . == #x0A */                 \
+     || ((string).pointer[offset] >= 0x20       /* #x20 <= . <= #x7E */         \
+         && (string).pointer[offset] <= 0x7E)                                   \
+     || ((string).pointer[offset] == 0xC2       /* #0xA0 <= . <= #xD7FF */      \
+         && (string).pointer[offset+1] >= 0xA0)                                 \
+     || ((string).pointer[offset] > 0xC2                                        \
+         && (string).pointer[offset] < 0xED)                                    \
+     || ((string).pointer[offset] == 0xED                                       \
+         && (string).pointer[offset+1] < 0xA0)                                  \
+     || ((string).pointer[offset] == 0xEE)                                      \
+     || ((string).pointer[offset] == 0xEF      /* #xE000 <= . <= #xFFFD */      \
+         && !((string).pointer[offset+1] == 0xBB        /* && . != #xFEFF */    \
+             && (string).pointer[offset+2] == 0xBF)                             \
+         && !((string).pointer[offset+1] == 0xBF                                \
+             && ((string).pointer[offset+2] == 0xBE                             \
+                 || (string).pointer[offset+2] == 0xBF))))
+
+#define IS_PRINTABLE(string)    IS_PRINTABLE_AT((string),0)
+
+/*
+ * Check if the character at the specified position is NUL.
+ */
+
+#define IS_Z_AT(string,offset)    CHECK_AT((string),'\0',(offset))
+
+#define IS_Z(string)    IS_Z_AT((string),0)
+
+/*
+ * Check if the character at the specified position is BOM.
+ */
+
+#define IS_BOM_AT(string,offset)                                                \
+     (CHECK_AT((string),'\xEF',(offset))                                        \
+      && CHECK_AT((string),'\xBB',(offset)+1)                                   \
+      && CHECK_AT((string),'\xBF',(offset)+2))  /* BOM (#xFEFF) */
+
+#define IS_BOM(string)  IS_BOM_AT(string,0)
+
+/*
+ * Check if the character at the specified position is space.
+ */
+
+#define IS_SPACE_AT(string,offset)  CHECK_AT((string),' ',(offset))
+
+#define IS_SPACE(string)    IS_SPACE_AT((string),0)
+
+/*
+ * Check if the character at the specified position is tab.
+ */
+
+#define IS_TAB_AT(string,offset)    CHECK_AT((string),'\t',(offset))
+
+#define IS_TAB(string)  IS_TAB_AT((string),0)
+
+/*
+ * Check if the character at the specified position is blank (space or tab).
+ */
+
+#define IS_BLANK_AT(string,offset)                                              \
+    (IS_SPACE_AT((string),(offset)) || IS_TAB_AT((string),(offset)))
+
+#define IS_BLANK(string)    IS_BLANK_AT((string),0)
+
+/*
+ * Check if the character at the specified position is a line break.
+ */
+
+#define IS_BREAK_AT(string,offset)                                              \
+    (CHECK_AT((string),'\r',(offset))               /* CR (#xD)*/               \
+     || CHECK_AT((string),'\n',(offset))            /* LF (#xA) */              \
+     || (CHECK_AT((string),'\xC2',(offset))                                     \
+         && CHECK_AT((string),'\x85',(offset)+1))   /* NEL (#x85) */            \
+     || (CHECK_AT((string),'\xE2',(offset))                                     \
+         && CHECK_AT((string),'\x80',(offset)+1)                                \
+         && CHECK_AT((string),'\xA8',(offset)+2))   /* LS (#x2028) */           \
+     || (CHECK_AT((string),'\xE2',(offset))                                     \
+         && CHECK_AT((string),'\x80',(offset)+1)                                \
+         && CHECK_AT((string),'\xA9',(offset)+2)))  /* PS (#x2029) */
+
+#define IS_BREAK(string)    IS_BREAK_AT((string),0)
+
+#define IS_CRLF_AT(string,offset)                                               \
+     (CHECK_AT((string),'\r',(offset)) && CHECK_AT((string),'\n',(offset)+1))
+
+#define IS_CRLF(string) IS_CRLF_AT((string),0)
+
+/*
+ * Check if the character is a line break or NUL.
+ */
+
+#define IS_BREAKZ_AT(string,offset)                                             \
+    (IS_BREAK_AT((string),(offset)) || IS_Z_AT((string),(offset)))
+
+#define IS_BREAKZ(string)   IS_BREAKZ_AT((string),0)
+
+/*
+ * Check if the character is a line break, space, or NUL.
+ */
+
+#define IS_SPACEZ_AT(string,offset)                                             \
+    (IS_SPACE_AT((string),(offset)) || IS_BREAKZ_AT((string),(offset)))
+
+#define IS_SPACEZ(string)   IS_SPACEZ_AT((string),0)
+
+/*
+ * Check if the character is a line break, space, tab, or NUL.
+ */
+
+#define IS_BLANKZ_AT(string,offset)                                             \
+    (IS_BLANK_AT((string),(offset)) || IS_BREAKZ_AT((string),(offset)))
+
+#define IS_BLANKZ(string)   IS_BLANKZ_AT((string),0)
+
+/*
+ * Determine the width of the character.
+ */
+
+#define WIDTH_AT(string,offset)                                                 \
+     (((string).pointer[offset] & 0x80) == 0x00 ? 1 :                           \
+      ((string).pointer[offset] & 0xE0) == 0xC0 ? 2 :                           \
+      ((string).pointer[offset] & 0xF0) == 0xE0 ? 3 :                           \
+      ((string).pointer[offset] & 0xF8) == 0xF0 ? 4 : 0)
+
+#define WIDTH(string)   WIDTH_AT((string),0)
+
+/*
+ * Move the string pointer to the next character.
+ */
+
+#define MOVE(string)    ((string).pointer += WIDTH((string)))
+
+/*
+ * Copy a character and move the pointers of both strings.
+ */
+
+#define COPY(string_a,string_b)                                                 \
+    ((*(string_b).pointer & 0x80) == 0x00 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++)) :                      \
+     (*(string_b).pointer & 0xE0) == 0xC0 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++)) :                      \
+     (*(string_b).pointer & 0xF0) == 0xE0 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++)) :                      \
+     (*(string_b).pointer & 0xF8) == 0xF0 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++)) : 0)
+
+/*
+ * Stack and queue management.
+ */
+
+YAML_DECLARE(int)
+yaml_stack_extend(void **start, void **top, void **end);
+
+YAML_DECLARE(int)
+yaml_queue_extend(void **start, void **head, void **tail, void **end);
+
+#define STACK_INIT(context,stack,size)                                          \
+    (((stack).start = yaml_malloc((size)*sizeof(*(stack).start))) ?             \
+        ((stack).top = (stack).start,                                           \
+         (stack).end = (stack).start+(size),                                    \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define STACK_DEL(context,stack)                                                \
+    (yaml_free((stack).start),                                                  \
+     (stack).start = (stack).top = (stack).end = 0)
+
+#define STACK_EMPTY(context,stack)                                              \
+    ((stack).start == (stack).top)
+
+#define PUSH(context,stack,value)                                               \
+    (((stack).top != (stack).end                                                \
+      || yaml_stack_extend((void **)&(stack).start,                             \
+              (void **)&(stack).top, (void **)&(stack).end)) ?                  \
+        (*((stack).top++) = value,                                              \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define POP(context,stack)                                                      \
+    (*(--(stack).top))
+
+#define QUEUE_INIT(context,queue,size)                                          \
+    (((queue).start = yaml_malloc((size)*sizeof(*(queue).start))) ?             \
+        ((queue).head = (queue).tail = (queue).start,                           \
+         (queue).end = (queue).start+(size),                                    \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define QUEUE_DEL(context,queue)                                                \
+    (yaml_free((queue).start),                                                  \
+     (queue).start = (queue).head = (queue).tail = (queue).end = 0)
+
+#define QUEUE_EMPTY(context,queue)                                              \
+    ((queue).head == (queue).tail)
+
+#define ENQUEUE(context,queue,value)                                            \
+    (((queue).tail != (queue).end                                               \
+      || yaml_queue_extend((void **)&(queue).start, (void **)&(queue).head,     \
+            (void **)&(queue).tail, (void **)&(queue).end)) ?                   \
+        (*((queue).tail++) = value,                                             \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define DEQUEUE(context,queue)                                                  \
+    (*((queue).head++))
+
+#define QUEUE_INSERT(context,queue,index,value)                                 \
+    (((queue).tail != (queue).end                                               \
+      || yaml_queue_extend((void **)&(queue).start, (void **)&(queue).head,     \
+            (void **)&(queue).tail, (void **)&(queue).end)) ?                   \
+        (memmove((queue).head+(index)+1,(queue).head+(index),                   \
+            ((queue).tail-(queue).head-(index))*sizeof(*(queue).start)),        \
+         *((queue).head+(index)) = value,                                       \
+         (queue).tail++,                                                        \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+/*
+ * Token initializers.
+ */
+
+#define TOKEN_INIT(token,token_type,token_start_mark,token_end_mark)            \
+    (memset(&(token), 0, sizeof(yaml_token_t)),                                 \
+     (token).type = (token_type),                                               \
+     (token).start_mark = (token_start_mark),                                   \
+     (token).end_mark = (token_end_mark))
+
+#define STREAM_START_TOKEN_INIT(token,token_encoding,start_mark,end_mark)       \
+    (TOKEN_INIT((token),YAML_STREAM_START_TOKEN,(start_mark),(end_mark)),       \
+     (token).data.stream_start.encoding = (token_encoding))
+
+#define STREAM_END_TOKEN_INIT(token,start_mark,end_mark)                        \
+    (TOKEN_INIT((token),YAML_STREAM_END_TOKEN,(start_mark),(end_mark)))
+
+#define ALIAS_TOKEN_INIT(token,token_value,start_mark,end_mark)                 \
+    (TOKEN_INIT((token),YAML_ALIAS_TOKEN,(start_mark),(end_mark)),              \
+     (token).data.alias.value = (token_value))
+
+#define ANCHOR_TOKEN_INIT(token,token_value,start_mark,end_mark)                \
+    (TOKEN_INIT((token),YAML_ANCHOR_TOKEN,(start_mark),(end_mark)),             \
+     (token).data.anchor.value = (token_value))
+
+#define TAG_TOKEN_INIT(token,token_handle,token_suffix,start_mark,end_mark)     \
+    (TOKEN_INIT((token),YAML_TAG_TOKEN,(start_mark),(end_mark)),                \
+     (token).data.tag.handle = (token_handle),                                  \
+     (token).data.tag.suffix = (token_suffix))
+
+#define SCALAR_TOKEN_INIT(token,token_value,token_length,token_style,start_mark,end_mark)   \
+    (TOKEN_INIT((token),YAML_SCALAR_TOKEN,(start_mark),(end_mark)),             \
+     (token).data.scalar.value = (token_value),                                 \
+     (token).data.scalar.length = (token_length),                               \
+     (token).data.scalar.style = (token_style))
+
+#define VERSION_DIRECTIVE_TOKEN_INIT(token,token_major,token_minor,start_mark,end_mark)     \
+    (TOKEN_INIT((token),YAML_VERSION_DIRECTIVE_TOKEN,(start_mark),(end_mark)),  \
+     (token).data.version_directive.major = (token_major),                      \
+     (token).data.version_directive.minor = (token_minor))
+
+#define TAG_DIRECTIVE_TOKEN_INIT(token,token_handle,token_prefix,start_mark,end_mark)       \
+    (TOKEN_INIT((token),YAML_TAG_DIRECTIVE_TOKEN,(start_mark),(end_mark)),      \
+     (token).data.tag_directive.handle = (token_handle),                        \
+     (token).data.tag_directive.prefix = (token_prefix))
+
+/*
+ * Event initializers.
+ */
+
+#define EVENT_INIT(event,event_type,event_start_mark,event_end_mark)            \
+    (memset(&(event), 0, sizeof(yaml_event_t)),                                 \
+     (event).type = (event_type),                                               \
+     (event).start_mark = (event_start_mark),                                   \
+     (event).end_mark = (event_end_mark))
+
+#define STREAM_START_EVENT_INIT(event,event_encoding,start_mark,end_mark)       \
+    (EVENT_INIT((event),YAML_STREAM_START_EVENT,(start_mark),(end_mark)),       \
+     (event).data.stream_start.encoding = (event_encoding))
+
+#define STREAM_END_EVENT_INIT(event,start_mark,end_mark)                        \
+    (EVENT_INIT((event),YAML_STREAM_END_EVENT,(start_mark),(end_mark)))
+
+#define DOCUMENT_START_EVENT_INIT(event,event_version_directive,                \
+        event_tag_directives_start,event_tag_directives_end,event_implicit,start_mark,end_mark) \
+    (EVENT_INIT((event),YAML_DOCUMENT_START_EVENT,(start_mark),(end_mark)),     \
+     (event).data.document_start.version_directive = (event_version_directive), \
+     (event).data.document_start.tag_directives.start = (event_tag_directives_start),   \
+     (event).data.document_start.tag_directives.end = (event_tag_directives_end),   \
+     (event).data.document_start.implicit = (event_implicit))
+
+#define DOCUMENT_END_EVENT_INIT(event,event_implicit,start_mark,end_mark)       \
+    (EVENT_INIT((event),YAML_DOCUMENT_END_EVENT,(start_mark),(end_mark)),       \
+     (event).data.document_end.implicit = (event_implicit))
+
+#define ALIAS_EVENT_INIT(event,event_anchor,start_mark,end_mark)                \
+    (EVENT_INIT((event),YAML_ALIAS_EVENT,(start_mark),(end_mark)),              \
+     (event).data.alias.anchor = (event_anchor))
+
+#define SCALAR_EVENT_INIT(event,event_anchor,event_tag,event_value,event_length,    \
+        event_plain_implicit, event_quoted_implicit,event_style,start_mark,end_mark)    \
+    (EVENT_INIT((event),YAML_SCALAR_EVENT,(start_mark),(end_mark)),             \
+     (event).data.scalar.anchor = (event_anchor),                               \
+     (event).data.scalar.tag = (event_tag),                                     \
+     (event).data.scalar.value = (event_value),                                 \
+     (event).data.scalar.length = (event_length),                               \
+     (event).data.scalar.plain_implicit = (event_plain_implicit),               \
+     (event).data.scalar.quoted_implicit = (event_quoted_implicit),             \
+     (event).data.scalar.style = (event_style))
+
+#define SEQUENCE_START_EVENT_INIT(event,event_anchor,event_tag,                 \
+        event_implicit,event_style,start_mark,end_mark)                         \
+    (EVENT_INIT((event),YAML_SEQUENCE_START_EVENT,(start_mark),(end_mark)),     \
+     (event).data.sequence_start.anchor = (event_anchor),                       \
+     (event).data.sequence_start.tag = (event_tag),                             \
+     (event).data.sequence_start.implicit = (event_implicit),                   \
+     (event).data.sequence_start.style = (event_style))
+
+#define SEQUENCE_END_EVENT_INIT(event,start_mark,end_mark)                      \
+    (EVENT_INIT((event),YAML_SEQUENCE_END_EVENT,(start_mark),(end_mark)))
+
+#define MAPPING_START_EVENT_INIT(event,event_anchor,event_tag,                  \
+        event_implicit,event_style,start_mark,end_mark)                         \
+    (EVENT_INIT((event),YAML_MAPPING_START_EVENT,(start_mark),(end_mark)),      \
+     (event).data.mapping_start.anchor = (event_anchor),                        \
+     (event).data.mapping_start.tag = (event_tag),                              \
+     (event).data.mapping_start.implicit = (event_implicit),                    \
+     (event).data.mapping_start.style = (event_style))
+
+#define MAPPING_END_EVENT_INIT(event,start_mark,end_mark)                       \
+    (EVENT_INIT((event),YAML_MAPPING_END_EVENT,(start_mark),(end_mark)))
+
+/*
+ * Document initializer.
+ */
+
+#define DOCUMENT_INIT(document,document_nodes_start,document_nodes_end,         \
+        document_version_directive,document_tag_directives_start,               \
+        document_tag_directives_end,document_start_implicit,                    \
+        document_end_implicit,document_start_mark,document_end_mark)            \
+    (memset(&(document), 0, sizeof(yaml_document_t)),                           \
+     (document).nodes.start = (document_nodes_start),                           \
+     (document).nodes.end = (document_nodes_end),                               \
+     (document).nodes.top = (document_nodes_start),                             \
+     (document).version_directive = (document_version_directive),               \
+     (document).tag_directives.start = (document_tag_directives_start),         \
+     (document).tag_directives.end = (document_tag_directives_end),             \
+     (document).start_implicit = (document_start_implicit),                     \
+     (document).end_implicit = (document_end_implicit),                         \
+     (document).start_mark = (document_start_mark),                             \
+     (document).end_mark = (document_end_mark))
+
+/*
+ * Node initializers.
+ */
+
+#define NODE_INIT(node,node_type,node_tag,node_start_mark,node_end_mark)        \
+    (memset(&(node), 0, sizeof(yaml_node_t)),                                   \
+     (node).type = (node_type),                                                 \
+     (node).tag = (node_tag),                                                   \
+     (node).start_mark = (node_start_mark),                                     \
+     (node).end_mark = (node_end_mark))
+
+#define SCALAR_NODE_INIT(node,node_tag,node_value,node_length,                  \
+        node_style,start_mark,end_mark)                                         \
+    (NODE_INIT((node),YAML_SCALAR_NODE,(node_tag),(start_mark),(end_mark)),     \
+     (node).data.scalar.value = (node_value),                                   \
+     (node).data.scalar.length = (node_length),                                 \
+     (node).data.scalar.style = (node_style))
+
+#define SEQUENCE_NODE_INIT(node,node_tag,node_items_start,node_items_end,       \
+        node_style,start_mark,end_mark)                                         \
+    (NODE_INIT((node),YAML_SEQUENCE_NODE,(node_tag),(start_mark),(end_mark)),   \
+     (node).data.sequence.items.start = (node_items_start),                     \
+     (node).data.sequence.items.end = (node_items_end),                         \
+     (node).data.sequence.items.top = (node_items_start),                       \
+     (node).data.sequence.style = (node_style))
+
+#define MAPPING_NODE_INIT(node,node_tag,node_pairs_start,node_pairs_end,        \
+        node_style,start_mark,end_mark)                                         \
+    (NODE_INIT((node),YAML_MAPPING_NODE,(node_tag),(start_mark),(end_mark)),    \
+     (node).data.mapping.pairs.start = (node_pairs_start),                      \
+     (node).data.mapping.pairs.end = (node_pairs_end),                          \
+     (node).data.mapping.pairs.top = (node_pairs_start),                        \
+     (node).data.mapping.style = (node_style))
+
diff --git a/lib/psych.rb b/lib/psych.rb
index ccbc7fe..9aab728 100644
--- a/lib/psych.rb
+++ b/lib/psych.rb
@@ -18,8 +18,8 @@ require 'psych/handlers/document_stream'
 ###
 # = Overview
 #
-# Psych is a YAML parser and emitter. 
-# Psych leverages libyaml [Home page: http://pyyaml.org/wiki/LibYAML] 
+# Psych is a YAML parser and emitter.
+# Psych leverages libyaml [Home page: http://pyyaml.org/wiki/LibYAML]
 # or [Git repo: https://github.com/zerotao/libyaml] for its YAML parsing
 # and emitting capabilities. In addition to wrapping libyaml, Psych also
 # knows how to serialize and de-serialize most Ruby objects to and from
@@ -95,7 +95,7 @@ require 'psych/handlers/document_stream'
 
 module Psych
   # The version is Psych you're using
-  VERSION         = '1.3.4'
+  VERSION         = '2.0.0'
 
   # The version of libyaml Psych is using
   LIBYAML_VERSION = Psych.libyaml_version.join '.'
diff --git a/lib/psych/core_ext.rb b/lib/psych/core_ext.rb
index 4a04c2d..9c8134d 100644
--- a/lib/psych/core_ext.rb
+++ b/lib/psych/core_ext.rb
@@ -31,12 +31,5 @@ class Module
 end
 
 if defined?(::IRB)
-module Kernel
-  def psych_y *objects
-    puts Psych.dump_stream(*objects)
-  end
-  remove_method :y rescue nil
-  alias y psych_y
-  private :y
-end
+  require 'psych/y'
 end
diff --git a/lib/psych/deprecated.rb b/lib/psych/deprecated.rb
index 333c3a1..1e42859 100644
--- a/lib/psych/deprecated.rb
+++ b/lib/psych/deprecated.rb
@@ -21,6 +21,7 @@ module Psych
     target.psych_to_yaml unless opts[:nodump]
   end
 
+  # This method is deprecated, use Psych.load_stream instead.
   def self.load_documents yaml, &block
     if $VERBOSE
       warn "#{caller[0]}: load_documents is deprecated, use load_stream"
diff --git a/lib/psych/handler.rb b/lib/psych/handler.rb
index d3b9963..c55afe7 100644
--- a/lib/psych/handler.rb
+++ b/lib/psych/handler.rb
@@ -25,6 +25,19 @@ module Psych
     # Default dumping options
     OPTIONS = DumperOptions.new
 
+    # Events that a Handler should respond to.
+    EVENTS = [ :alias,
+               :empty,
+               :end_document,
+               :end_mapping,
+               :end_sequence,
+               :end_stream,
+               :scalar,
+               :start_document,
+               :start_mapping,
+               :start_sequence,
+               :start_stream ]
+
     ###
     # Called with +encoding+ when the YAML stream starts.  This method is
     # called once per stream.  A stream may contain multiple documents.
diff --git a/lib/psych/handlers/recorder.rb b/lib/psych/handlers/recorder.rb
new file mode 100644
index 0000000..4eae62e
--- /dev/null
+++ b/lib/psych/handlers/recorder.rb
@@ -0,0 +1,39 @@
+require 'psych/handler'
+
+module Psych
+  module Handlers
+    ###
+    # This handler will capture an event and record the event.  Recorder events
+    # are available vial Psych::Handlers::Recorder#events.
+    #
+    # For example:
+    #
+    #   recorder = Psych::Handlers::Recorder.new
+    #   parser = Psych::Parser.new recorder
+    #   parser.parse '--- foo'
+    #
+    #   recorder.events # => [list of events]
+    #
+    #   # Replay the events
+    #
+    #   emitter = Psych::Emitter.new $stdout
+    #   recorder.events.each do |m, args|
+    #     emitter.send m, *args
+    #   end
+
+    class Recorder < Psych::Handler
+      attr_reader :events
+
+      def initialize
+        @events = []
+        super
+      end
+
+      EVENTS.each do |event|
+        define_method event do |*args|
+          @events << [event, args]
+        end
+      end
+    end
+  end
+end
diff --git a/lib/psych/scalar_scanner.rb b/lib/psych/scalar_scanner.rb
index 9130746..d0beee3 100644
--- a/lib/psych/scalar_scanner.rb
+++ b/lib/psych/scalar_scanner.rb
@@ -8,20 +8,28 @@ module Psych
     TIME = /^\d{4}-\d{1,2}-\d{1,2}([Tt]|\s+)\d{1,2}:\d\d:\d\d(\.\d*)?(\s*Z|[-+]\d{1,2}(:\d\d)?)?/
 
     # Taken from http://yaml.org/type/float.html
-    FLOAT = /^(?:[-+]?([0-9][0-9_,]*)?\.[0-9.]*([eE][-+][0-9]+)?(?# base 10)
+    FLOAT = /^(?:[-+]?([0-9][0-9_,]*)?\.[0-9]*([eE][-+][0-9]+)?(?# base 10)
               |[-+]?[0-9][0-9_,]*(:[0-5]?[0-9])+\.[0-9_]*(?# base 60)
               |[-+]?\.(inf|Inf|INF)(?# infinity)
               |\.(nan|NaN|NAN)(?# not a number))$/x
 
+    # Taken from http://yaml.org/type/int.html
+    INTEGER = /^(?:[-+]?0b[0-1_]+          (?# base 2)
+                  |[-+]?0[0-7_]+           (?# base 8)
+                  |[-+]?(?:0|[1-9][0-9_]*) (?# base 10)
+                  |[-+]?0x[0-9a-fA-F_]+    (?# base 16))$/x
+
     # Create a new scanner
     def initialize
       @string_cache = {}
+      @symbol_cache = {}
     end
 
     # Tokenize +string+ returning the ruby object
     def tokenize string
       return nil if string.empty?
       return string if @string_cache.key?(string)
+      return @symbol_cache[string] if @symbol_cache.key?(string)
 
       case string
       # Check for a String type, being careful not to get caught by hash keys, hex values, and
@@ -67,9 +75,9 @@ module Psych
         0.0 / 0.0
       when /^:./
         if string =~ /^:(["'])(.*)\1/
-          $2.sub(/^:/, '').to_sym
+          @symbol_cache[string] = $2.sub(/^:/, '').to_sym
         else
-          string.sub(/^:/, '').to_sym
+          @symbol_cache[string] = string.sub(/^:/, '').to_sym
         end
       when /^[-+]?[0-9][0-9_]*(:[0-5]?[0-9])+$/
         i = 0
@@ -84,20 +92,15 @@ module Psych
         end
         i
       when FLOAT
-        begin
-          return Float(string.gsub(/[,_]/, ''))
-        rescue ArgumentError
+        if string == '.'
+          @string_cache[string] = true
+          string
+        else
+          Float(string.gsub(/[,_]/, ''))
         end
-
-        @string_cache[string] = true
-        string
       else
-        if string.count('.') < 2
-          begin
-            return Integer(string.gsub(/[,_]/, ''))
-          rescue ArgumentError
-          end
-        end
+        int = parse_int string.gsub(/[,_]/, '')
+        return int if int
 
         @string_cache[string] = true
         string
@@ -105,6 +108,13 @@ module Psych
     end
 
     ###
+    # Parse and return an int from +string+
+    def parse_int string
+      return unless INTEGER === string
+      Integer(string)
+    end
+
+    ###
     # Parse and return a Time from +string+
     def parse_time string
       date, time = *(string.split(/[ tT]/, 2))
diff --git a/lib/psych/syntax_error.rb b/lib/psych/syntax_error.rb
index f79743d..f972256 100644
--- a/lib/psych/syntax_error.rb
+++ b/lib/psych/syntax_error.rb
@@ -1,5 +1,8 @@
 module Psych
-  class SyntaxError < ::SyntaxError
+  class Error < RuntimeError
+  end
+
+  class SyntaxError < Error
     attr_reader :file, :line, :column, :offset, :problem, :context
 
     def initialize file, line, col, offset, problem, context
diff --git a/lib/psych/visitors/yaml_tree.rb b/lib/psych/visitors/yaml_tree.rb
index 948a976..5efb654 100644
--- a/lib/psych/visitors/yaml_tree.rb
+++ b/lib/psych/visitors/yaml_tree.rb
@@ -47,6 +47,7 @@ module Psych
 
       def tree
         finish unless finished?
+        @emitter.root
       end
 
       def push object
@@ -65,7 +66,7 @@ module Psych
 
         @emitter.start_document version, [], false
         accept object
-        @emitter.end_document
+        @emitter.end_document !@emitter.streaming?
       end
       alias :<< :push
 
@@ -230,15 +231,21 @@ module Psych
         plain = false
         quote = false
         style = Nodes::Scalar::ANY
+        tag   = nil
+        str   = o
 
         if binary?(o)
           str   = [o].pack('m').chomp
           tag   = '!binary' # FIXME: change to below when syck is removed
           #tag   = 'tag:yaml.org,2002:binary'
           style = Nodes::Scalar::LITERAL
+        elsif o =~ /\n/
+          quote = true
+          style = Nodes::Scalar::LITERAL
+        elsif o =~ /^\W/
+          quote = true
+          style = Nodes::Scalar::DOUBLE_QUOTED
         else
-          str   = o
-          tag   = nil
           quote = !(String === @ss.tokenize(o))
           plain = !quote
         end
diff --git a/lib/psych/y.rb b/lib/psych/y.rb
new file mode 100644
index 0000000..f20d2e2
--- /dev/null
+++ b/lib/psych/y.rb
@@ -0,0 +1,7 @@
+module Kernel
+  def y *objects
+    puts Psych.dump_stream(*objects)
+  end
+  private :y
+end
+
diff --git a/test/psych/handlers/test_recorder.rb b/test/psych/handlers/test_recorder.rb
new file mode 100644
index 0000000..96b8eac
--- /dev/null
+++ b/test/psych/handlers/test_recorder.rb
@@ -0,0 +1,25 @@
+require 'psych/helper'
+require 'psych/handlers/recorder'
+
+module Psych
+  module Handlers
+    class TestRecorder < TestCase
+      def test_replay
+        yaml   = "--- foo\n...\n"
+        output = StringIO.new
+
+        recorder = Psych::Handlers::Recorder.new
+        parser   = Psych::Parser.new recorder
+        parser.parse yaml
+
+        assert_equal 5, recorder.events.length
+
+        emitter = Psych::Emitter.new output
+        recorder.events.each do |m, args|
+          emitter.send m, *args
+        end
+        assert_equal yaml, output.string
+      end
+    end
+  end
+end
diff --git a/test/psych/test_engine_manager.rb b/test/psych/test_engine_manager.rb
index b52fd09..e7bfb2e 100644
--- a/test/psych/test_engine_manager.rb
+++ b/test/psych/test_engine_manager.rb
@@ -3,10 +3,6 @@ require 'yaml'
 
 module Psych
  class TestEngineManager < TestCase
-   def teardown
-     YAML::ENGINE.yamler = 'syck'
-   end
-
    def test_bad_engine
      assert_raises(ArgumentError) do
        YAML::ENGINE.yamler = 'foooo'
@@ -19,12 +15,6 @@ module Psych
      assert_equal 'psych', YAML::ENGINE.yamler
    end
 
-   def test_set_syck
-     YAML::ENGINE.yamler = 'syck'
-     assert_equal ::Syck, YAML
-     assert_equal 'syck', YAML::ENGINE.yamler
-   end
-
    A = Struct.new(:name)
 
    def test_dump_types
diff --git a/test/psych/test_exception.rb b/test/psych/test_exception.rb
index c6d98d7..5615fc2 100644
--- a/test/psych/test_exception.rb
+++ b/test/psych/test_exception.rb
@@ -126,5 +126,26 @@ module Psych
       assert_equal 1, w.foo
       assert_nil w.bar
     end
+
+    def test_psych_syntax_error
+      Tempfile.open(['parsefile', 'yml']) do |t|
+        t.binmode
+        t.write '--- `'
+        t.close
+
+        begin
+          Psych.parse_file t.path
+        rescue StandardError
+          assert true # count assertion
+        ensure
+          return unless $!
+
+          ancestors = $!.class.ancestors.inspect
+
+          flunk "Psych::SyntaxError not rescued by StandardError: #{ancestors}"
+        end
+      end
+    end
+
   end
 end
diff --git a/test/psych/test_numeric.rb b/test/psych/test_numeric.rb
index bae723a..200a9f0 100644
--- a/test/psych/test_numeric.rb
+++ b/test/psych/test_numeric.rb
@@ -7,6 +7,15 @@ module Psych
   # http://yaml.org/type/float.html
   # http://yaml.org/type/int.html
   class TestNumeric < TestCase
+    def setup
+      @old_debug = $DEBUG
+      $DEBUG = true
+    end
+
+    def teardown
+      $DEBUG = @old_debug
+    end
+
     def test_non_float_with_0
       str = Psych.load('--- 090')
       assert_equal '090', str
@@ -21,5 +30,12 @@ module Psych
       decimal = BigDecimal("12.34")
       assert_cycle decimal
     end
+
+    def test_does_not_attempt_numeric
+      str = Psych.load('--- 4 roses')
+      assert_equal '4 roses', str
+      str = Psych.load('--- 1.1.1')
+      assert_equal '1.1.1', str
+    end
   end
 end
diff --git a/test/psych/test_object_references.rb b/test/psych/test_object_references.rb
index 2a659a3..51d8085 100644
--- a/test/psych/test_object_references.rb
+++ b/test/psych/test_object_references.rb
@@ -35,7 +35,7 @@ module Psych
 
     def test_float_references
       data = Psych.load <<-eoyml
---- 
+---\s
 - &name 1.2
 - *name
       eoyml
@@ -56,7 +56,7 @@ module Psych
 
     def test_regexp_references
       data = Psych.load <<-eoyml
---- 
+---\s
 - &name !ruby/regexp /pattern/i
 - *name
       eoyml
diff --git a/test/psych/test_yaml.rb b/test/psych/test_yaml.rb
index 807c058..5e1ebb4 100644
--- a/test/psych/test_yaml.rb
+++ b/test/psych/test_yaml.rb
@@ -1,4 +1,4 @@
-# -*- mode: ruby; ruby-indent-level: 4; tab-width: 4 -*-
+# -*- coding: us-ascii; mode: ruby; ruby-indent-level: 4; tab-width: 4 -*-
 #												vim:sw=4:ts=4
 # $Id$
 #
@@ -1266,4 +1266,15 @@ EOY
       Psych.load("2000-01-01 00:00:00.#{"0"*1000} +00:00\n")
       # '[ruby-core:13735]'
     end
+
+    def test_multiline_string_uses_literal_style
+      yaml = Psych.dump("multi\nline\nstring")
+      assert_match("|", yaml)
+    end
+
+    def test_string_starting_with_non_word_character_uses_double_quotes_without_exclamation_mark
+      yaml = Psych.dump("@123'abc")
+      assert_match("\"", yaml)
+      refute_match("!", yaml)
+    end
 end
diff --git a/test/psych/visitors/test_to_ruby.rb b/test/psych/visitors/test_to_ruby.rb
index 5b0702c..ee473c9 100644
--- a/test/psych/visitors/test_to_ruby.rb
+++ b/test/psych/visitors/test_to_ruby.rb
@@ -1,3 +1,4 @@
+# coding: US-ASCII
 require 'psych/helper'
 
 module Psych
diff --git a/test/psych/visitors/test_yaml_tree.rb b/test/psych/visitors/test_yaml_tree.rb
index df77563..496cdd0 100644
--- a/test/psych/visitors/test_yaml_tree.rb
+++ b/test/psych/visitors/test_yaml_tree.rb
@@ -8,6 +8,24 @@ module Psych
         @v = Visitors::YAMLTree.new
       end
 
+      def test_tree_can_be_called_twice
+        @v.start
+        @v << Object.new
+        t = @v.tree
+        assert_equal t, @v.tree
+      end
+
+      def test_yaml_tree_can_take_an_emitter
+        io = StringIO.new
+        e  = Psych::Emitter.new io
+        v = Visitors::YAMLTree.new({}, e)
+        v.start
+        v << "hello world"
+        v.finish
+
+        assert_match "hello world", io.string
+      end
+
       def test_binary_formatting
         gif = "GIF89a\f\x00\f\x00\x84\x00\x00\xFF\xFF\xF7\xF5\xF5\xEE\xE9\xE9\xE5fff\x00\x00\x00\xE7\xE7\xE7^^^\xF3\xF3\xED\x8E\x8E\x8E\xE0\xE0\xE0\x9F\x9F\x9F\x93\x93\x93\xA7\xA7\xA7\x9E\x9E\x9Eiiiccc\xA3\xA3\xA3\x84\x84\x84\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9\xFF\xFE\xF9!\xFE\x0EMade with GIMP\x00,\x00\x00\x00\x00\f\x00\f\x00\x00\x05,  \x8E\x810\x9E\xE3@\x14\xE8i\x10\xC4\xD1\x8A\b\x1C\xCF\x80M$z\xEF\xFF0\x85p\xB8\xB01f\r\e\xCE\x01\xC3\x01\x1E\x10' \x82\n\x01\x00;"
         @v << gif
author	Aaron Patterson <aaron.patterson@gmail.com>	2012-12-17 09:59:28 -0800
committer	Aaron Patterson <aaron.patterson@gmail.com>	2012-12-17 09:59:28 -0800
commit	f22f976bce0a82a00759fca1b152276ce97c7236 (patch)
tree	bb885944674dc7d62529fbe79bcde9a9f182fd6a
parent	2ceb7b685c47a04c4451287ea77aedf2f98f26c4 (diff)
parent	9ab3a7066b09a5f7b563626676d788125882b581 (diff)
download	psych-f22f976bce0a82a00759fca1b152276ce97c7236.tar.gz