* lib/yaml: Moved to ext/syck/lib, Syck only uses Syck constant.

* lib/yaml.rb: Added an engine manager for choosing YAML engine.
* ext/syck/lib/syck/rubytypes.rb: squashed warnings when using Psych

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27212 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

26 files changed, 643 insertions, 528 deletions

diff --git a/ChangeLog b/ChangeLog
index 762235eef5..0cfbd40e9c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Apr  4 06:46:16 2010  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* lib/yaml: Moved to ext/syck/lib, Syck only uses Syck constant.
+	* lib/yaml.rb: Added an engine manager for choosing YAML engine.
+	* ext/syck/lib/syck/rubytypes.rb: squashed warnings when using Psych
+
 Sat Apr  3 22:47:51 2010  Tanaka Akira  <akr@fsij.org>
 
 	* time.c: don't define STRUCT_WIDEVAL.
diff --git a/ext/syck/lib/syck.rb b/ext/syck/lib/syck.rb
new file mode 100644
index 0000000000..0f43c139bc
--- /dev/null
+++ b/ext/syck/lib/syck.rb
@@ -0,0 +1,456 @@
+# -*- mode: ruby; ruby-indent-level: 4; tab-width: 4 -*- vim: sw=4 ts=4
+# $Id$
+#
+# = yaml.rb: top-level module with methods for loading and parsing YAML documents
+#
+# Author:: why the lucky stiff
+#
+
+require 'stringio'
+require 'syck.so'
+require 'syck/error'
+require 'syck/syck'
+require 'syck/tag'
+require 'syck/stream'
+require 'syck/constants'
+
+# == YAML
+#
+# YAML(tm) (rhymes with 'camel') is a
+# straightforward machine parsable data serialization format designed for
+# human readability and interaction with scripting languages such as Perl
+# and Python. YAML is optimized for data serialization, formatted
+# dumping, configuration files, log files, Internet messaging and
+# filtering. This specification describes the YAML information model and
+# serialization format. Together with the Unicode standard for characters, it
+# provides all the information necessary to understand YAML Version 1.0
+# and construct computer programs to process it.
+#
+# See http://yaml.org/ for more information.  For a quick tutorial, please
+# visit YAML In Five Minutes (http://yaml.kwiki.org/?YamlInFiveMinutes).
+#
+# == About This Library
+#
+# The YAML 1.0 specification outlines four stages of YAML loading and dumping.
+# This library honors all four of those stages, although data is really only
+# available to you in three stages.
+#
+# The four stages are: native, representation, serialization, and presentation.
+#
+# The native stage refers to data which has been loaded completely into Ruby's
+# own types. (See +YAML::load+.)
+#
+# The representation stage means data which has been composed into
+# +YAML::BaseNode+ objects.  In this stage, the document is available as a
+# tree of node objects.  You can perform YPath queries and transformations
+# at this level.  (See +YAML::parse+.)
+#
+# The serialization stage happens inside the parser.  The YAML parser used in
+# Ruby is called Syck.  Serialized nodes are available in the extension as
+# SyckNode structs.
+#
+# The presentation stage is the YAML document itself.  This is accessible
+# to you as a string.  (See +YAML::dump+.)
+#
+# For more information about the various information models, see Chapter
+# 3 of the YAML 1.0 Specification (http://yaml.org/spec/#id2491269).
+#
+# The YAML module provides quick access to the most common loading (YAML::load)
+# and dumping (YAML::dump) tasks.  This module also provides an API for registering
+# global types (YAML::add_domain_type).
+#
+# == Example
+#
+# A simple round-trip (load and dump) of an object.
+#
+#     require "yaml"
+#
+#     test_obj = ["dogs", "cats", "badgers"]
+#
+#     yaml_obj = YAML::dump( test_obj )
+#                         # -> ---
+#                              - dogs
+#                              - cats
+#                              - badgers
+#     ruby_obj = YAML::load( yaml_obj )
+#                         # => ["dogs", "cats", "badgers"]
+#     ruby_obj == test_obj
+#                         # => true
+#
+# To register your custom types with the global resolver, use +add_domain_type+.
+#
+#     YAML::add_domain_type( "your-site.com,2004", "widget" ) do |type, val|
+#         Widget.new( val )
+#     end
+#
+module Syck
+
+    DefaultResolver.use_types_at( @@tagged_classes )
+
+    # Returns a new default parser
+    def self.parser; Parser.new.set_resolver( self.resolver ); end
+
+    # Returns a new generic parser
+    def self.generic_parser
+        warn "#{caller[0]}: YAML.generic_parser is deprecated, switch to psych" if $VERBOSE
+        Parser.new.set_resolver( GenericResolver )
+    end
+
+    # Returns the default resolver
+    def self.resolver
+        warn "#{caller[0]}: YAML.resolver is deprecated" if $VERBOSE
+        DefaultResolver
+    end
+
+    # Returns a new default emitter
+    def self.emitter
+        warn "#{caller[0]}: YAML.emitter is deprecated" if $VERBOSE
+        Emitter.new.set_resolver( self.resolver )
+    end
+
+	#
+	# Converts _obj_ to YAML and writes the YAML result to _io_.
+    #
+    #   File.open( 'animals.yaml', 'w' ) do |out|
+    #     YAML.dump( ['badger', 'elephant', 'tiger'], out )
+    #   end
+    #
+    # If no _io_ is provided, a string containing the dumped YAML
+    # is returned.
+	#
+    #   YAML.dump( :locked )
+    #      #=> "--- :locked"
+    #
+	def self.dump( obj, io = nil )
+        obj.to_yaml( io || io2 = StringIO.new )
+        io || ( io2.rewind; io2.read )
+	end
+
+	#
+	# Load a document from the current _io_ stream.
+	#
+    #   File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
+    #      #=> ['badger', 'elephant', 'tiger']
+    #
+    # Can also load from a string.
+    #
+    #   YAML.load( "--- :locked" )
+    #      #=> :locked
+    #
+	def self.load( io )
+		yp = parser.load( io )
+	end
+
+    #
+    # Load a document from the file located at _filepath_.
+    #
+    #   YAML.load_file( 'animals.yaml' )
+    #      #=> ['badger', 'elephant', 'tiger']
+    #
+    def self.load_file( filepath )
+        File.open( filepath ) do |f|
+            load( f )
+        end
+    end
+
+	#
+	# Parse the first document from the current _io_ stream
+	#
+    #   File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
+    #      #=> #<YAML::Syck::Node:0x82ccce0
+    #           @kind=:seq,
+    #           @value=
+    #            [#<YAML::Syck::Node:0x82ccd94
+    #              @kind=:scalar,
+    #              @type_id="str",
+    #              @value="badger">,
+    #             #<YAML::Syck::Node:0x82ccd58
+    #              @kind=:scalar,
+    #              @type_id="str",
+    #              @value="elephant">,
+    #             #<YAML::Syck::Node:0x82ccd1c
+    #              @kind=:scalar,
+    #              @type_id="str",
+    #              @value="tiger">]>
+    #
+    # Can also load from a string.
+    #
+    #   YAML.parse( "--- :locked" )
+    #      #=> #<YAML::Syck::Node:0x82edddc
+    #            @type_id="tag:ruby.yaml.org,2002:sym",
+    #            @value=":locked", @kind=:scalar>
+    #
+	def self.parse( io )
+		yp = generic_parser.load( io )
+	end
+
+    #
+    # Parse a document from the file located at _filepath_.
+    #
+    #   YAML.parse_file( 'animals.yaml' )
+    #      #=> #<YAML::Syck::Node:0x82ccce0
+    #           @kind=:seq,
+    #           @value=
+    #            [#<YAML::Syck::Node:0x82ccd94
+    #              @kind=:scalar,
+    #              @type_id="str",
+    #              @value="badger">,
+    #             #<YAML::Syck::Node:0x82ccd58
+    #              @kind=:scalar,
+    #              @type_id="str",
+    #              @value="elephant">,
+    #             #<YAML::Syck::Node:0x82ccd1c
+    #              @kind=:scalar,
+    #              @type_id="str",
+    #              @value="tiger">]>
+    #
+    def self.parse_file( filepath )
+        File.open( filepath ) do |f|
+            parse( f )
+        end
+    end
+
+	#
+	# Calls _block_ with each consecutive document in the YAML
+    # stream contained in _io_.
+    #
+    #   File.open( 'many-docs.yaml' ) do |yf|
+    #     YAML.each_document( yf ) do |ydoc|
+    #       ## ydoc contains the single object
+    #       ## from the YAML document
+    #     end
+    #   end
+	#
+    def self.each_document( io, &block )
+        warn "#{caller[0]}: YAML.each_document is deprecated" if $VERBOSE
+		yp = parser.load_documents( io, &block )
+    end
+
+	#
+	# Calls _block_ with each consecutive document in the YAML
+    # stream contained in _io_.
+    #
+    #   File.open( 'many-docs.yaml' ) do |yf|
+    #     YAML.load_documents( yf ) do |ydoc|
+    #       ## ydoc contains the single object
+    #       ## from the YAML document
+    #     end
+    #   end
+	#
+    def self.load_documents( io, &doc_proc )
+		yp = parser.load_documents( io, &doc_proc )
+    end
+
+	#
+	# Calls _block_ with a tree of +YAML::BaseNodes+, one tree for
+    # each consecutive document in the YAML stream contained in _io_.
+    #
+    #   File.open( 'many-docs.yaml' ) do |yf|
+    #     YAML.each_node( yf ) do |ydoc|
+    #       ## ydoc contains a tree of nodes
+    #       ## from the YAML document
+    #     end
+    #   end
+	#
+    def self.each_node( io, &doc_proc )
+        warn "#{caller[0]}: YAML.each_node is deprecated" if $VERBOSE
+		yp = generic_parser.load_documents( io, &doc_proc )
+    end
+
+	#
+	# Calls _block_ with a tree of +YAML::BaseNodes+, one tree for
+    # each consecutive document in the YAML stream contained in _io_.
+    #
+    #   File.open( 'many-docs.yaml' ) do |yf|
+    #     YAML.parse_documents( yf ) do |ydoc|
+    #       ## ydoc contains a tree of nodes
+    #       ## from the YAML document
+    #     end
+    #   end
+	#
+    def self.parse_documents( io, &doc_proc )
+        warn "#{caller[0]}: YAML.parse_documents is deprecated, use load_stream" if $VERBOSE
+		self.each_node( io, &doc_proc )
+    end
+
+	#
+	# Loads all documents from the current _io_ stream,
+    # returning a +YAML::Stream+ object containing all
+    # loaded documents.
+	#
+	def self.load_stream( io )
+		d = nil
+		parser.load_documents( io ) do |doc|
+			d = Stream.new if not d
+			d.add( doc )
+        end
+		return d
+	end
+
+	#
+    # Returns a YAML stream containing each of the items in +objs+,
+    # each having their own document.
+    #
+    #   YAML.dump_stream( 0, [], {} )
+    #     #=> --- 0
+    #         --- []
+    #         --- {}
+    #
+	def self.dump_stream( *objs )
+		d = Stream.new
+        objs.each do |doc|
+			d.add( doc )
+        end
+        d.emit
+	end
+
+	#
+	# Add a global handler for a YAML domain type.
+	#
+	def self.add_domain_type( domain, type_tag, &transfer_proc )
+        resolver.add_type( "tag:#{ domain }:#{ type_tag }", transfer_proc )
+	end
+
+	#
+	# Add a transfer method for a builtin type
+	#
+	def self.add_builtin_type( type_tag, &transfer_proc )
+	    resolver.add_type( "tag:yaml.org,2002:#{ type_tag }", transfer_proc )
+	end
+
+	#
+	# Add a transfer method for a builtin type
+	#
+	def self.add_ruby_type( type_tag, &transfer_proc )
+        warn "#{caller[0]}: YAML.add_ruby_type is deprecated, use add_domain_type" if $VERBOSE
+	    resolver.add_type( "tag:ruby.yaml.org,2002:#{ type_tag }", transfer_proc )
+	end
+
+	#
+	# Add a private document type
+	#
+	def self.add_private_type( type_re, &transfer_proc )
+        warn "#{caller[0]}: YAML.add_private_type is deprecated, use add_domain_type" if $VERBOSE
+	    resolver.add_type( "x-private:" + type_re, transfer_proc )
+	end
+
+    #
+    # Detect typing of a string
+    #
+    def self.detect_implicit( val )
+        warn "#{caller[0]}: YAML.detect_implicit is deprecated" if $VERBOSE
+        resolver.detect_implicit( val )
+    end
+
+    #
+    # Convert a type_id to a taguri
+    #
+    def self.tagurize( val )
+        warn "#{caller[0]}: YAML.tagurize is deprecated" if $VERBOSE
+        resolver.tagurize( val )
+    end
+
+    #
+    # Apply a transfer method to a Ruby object
+    #
+    def self.transfer( type_id, obj )
+        warn "#{caller[0]}: YAML.transfer is deprecated" if $VERBOSE
+        resolver.transfer( tagurize( type_id ), obj )
+    end
+
+	#
+	# Apply any implicit a node may qualify for
+	#
+	def self.try_implicit( obj )
+        warn "#{caller[0]}: YAML.try_implicit is deprecated" if $VERBOSE
+		transfer( detect_implicit( obj ), obj )
+	end
+
+    #
+    # Method to extract colon-seperated type and class, returning
+    # the type and the constant of the class
+    #
+    def self.read_type_class( type, obj_class )
+        warn "#{caller[0]}: YAML.read_type_class is deprecated" if $VERBOSE
+        scheme, domain, type, tclass = type.split( ':', 4 )
+        tclass.split( "::" ).each { |c| obj_class = obj_class.const_get( c ) } if tclass
+        return [ type, obj_class ]
+    end
+
+    #
+    # Allocate blank object
+    #
+    def self.object_maker( obj_class, val )
+        warn "#{caller[0]}: YAML.object_maker is deprecated" if $VERBOSE
+        if Hash === val
+            o = obj_class.allocate
+            val.each_pair { |k,v|
+                o.instance_variable_set("@#{k}", v)
+            }
+            o
+        else
+            raise Error, "Invalid object explicitly tagged !ruby/Object: " + val.inspect
+        end
+    end
+
+	#
+	# Allocate an Emitter if needed
+	#
+	def self.quick_emit( oid, opts = {}, &e )
+        warn "#{caller[0]}: YAML.quick_emit is deprecated" if $VERBOSE
+        out =
+            if opts.is_a? Emitter
+                opts
+            else
+                emitter.reset( opts )
+            end
+        out.emit( oid, &e )
+	end
+
+end
+
+require 'syck/rubytypes'
+require 'syck/types'
+
+module Kernel
+    #
+    # ryan:: You know how Kernel.p is a really convenient way to dump ruby
+    #        structures?  The only downside is that it's not as legible as
+    #        YAML.
+    #
+    # _why:: (listening)
+    #
+    # ryan:: I know you don't want to urinate all over your users' namespaces.
+    #        But, on the other hand, convenience of dumping for debugging is,
+    #        IMO, a big YAML use case.
+    #
+    # _why:: Go nuts!  Have a pony parade!
+    #
+    # ryan:: Either way, I certainly will have a pony parade.
+    #
+
+    # Prints any supplied _objects_ out in YAML.  Intended as
+    # a variation on +Kernel::p+.
+    #
+    #   S = Struct.new(:name, :state)
+    #   s = S['dave', 'TX']
+    #   y s
+    #
+    # _produces:_
+    #
+    #   --- !ruby/struct:S
+    #   name: dave
+    #   state: TX
+    #
+    def y( object, *objects )
+        objects.unshift object
+        puts( if objects.length == 1
+                  YAML.dump( *objects )
+              else
+                  YAML.dump_stream( *objects )
+              end )
+    end
+    private :y
+end
+
+
diff --git a/lib/yaml/baseemitter.rb b/ext/syck/lib/syck/baseemitter.rb
index 59d9eddc76..5e39e450de 100644
--- a/lib/yaml/baseemitter.rb
+++ b/ext/syck/lib/syck/baseemitter.rb
@@ -2,15 +2,15 @@
 # BaseEmitter
 #
 
-require 'yaml/constants'
-require 'yaml/encoding'
-require 'yaml/error'
+require 'syck/constants'
+require 'syck/encoding'
+require 'syck/error'
 
-module YAML
+module Syck
   module BaseEmitter
     def options( opt = nil )
       if opt
-        @options[opt] || YAML::DEFAULTS[opt]
+        @options[opt] || DEFAULTS[opt]
       else
         @options
       end
@@ -38,7 +38,7 @@ module YAML
         block =
           if options(:UseBlock)
             '|'
-          elsif not options(:UseFold) and valx =~ /\n[ \t]/ and not valx =~ /#{YAML::ESCAPE_CHAR}/
+          elsif not options(:UseFold) and valx =~ /\n[ \t]/ and not valx =~ /#{ESCAPE_CHAR}/
             '|'
           else
             '>'
@@ -61,7 +61,7 @@ module YAML
       block += "\n"
       if block[0] == ?"
         esc_skip = ( "\t\n" unless valx =~ /^[ \t]/ ) || ""
-        valx = fold( YAML::escape( valx, esc_skip ) + "\"" ).chomp
+        valx = fold( Syck.escape( valx, esc_skip ) + "\"" ).chomp
         self << '"' + indent_text( valx, indt, false )
       else
         if block[0] == ?>
@@ -84,7 +84,7 @@ module YAML
     # Emit double-quoted string
     #
     def double( value )
-      "\"#{YAML.escape( value )}\""
+      "\"#{Syck.escape( value )}\""
     end
 
     #
diff --git a/lib/yaml/basenode.rb b/ext/syck/lib/syck/basenode.rb
index f92f8c8c3a..fc701a99f3 100644
--- a/lib/yaml/basenode.rb
+++ b/ext/syck/lib/syck/basenode.rb
@@ -2,7 +2,7 @@
 # YAML::BaseNode class
 #
 
-module YAML
+module Syck
 
     #
     # YAML Generic Model container
@@ -25,7 +25,7 @@ module YAML
                 matches.each { |m|
                     result.push m.last
                 }
-                YAML.transfer( 'seq', result )
+                Syck.transfer( 'seq', result )
             end
         end
 
diff --git a/lib/yaml/constants.rb b/ext/syck/lib/syck/constants.rb
index 728d3b7932..19fe42ef85 100644
--- a/lib/yaml/constants.rb
+++ b/ext/syck/lib/syck/constants.rb
@@ -1,7 +1,7 @@
 #
 # Constants used throughout the library
 #
-module YAML
+module Syck
 
 	#
 	# Constants
diff --git a/lib/yaml/dbm.rb b/ext/syck/lib/syck/dbm.rb
index a28fd04f19..95611afb04 100644
--- a/lib/yaml/dbm.rb
+++ b/ext/syck/lib/syck/dbm.rb
@@ -1,10 +1,10 @@
-require 'yaml'
+require 'syck'
 require 'dbm'
 #
 # YAML + DBM = YDBM
 # - Same interface as DBM class
 #
-module YAML
+module Syck
 
 class DBM < ::DBM
     VERSION = "0.1"
@@ -17,7 +17,7 @@ class DBM < ::DBM
     def fetch( keystr, ifnone = nil )
         begin
             val = super( keystr )
-            return YAML::load( val ) if String === val
+            return Syck.load( val ) if String === val
         rescue IndexError
         end
         if block_given?
@@ -35,7 +35,7 @@ class DBM < ::DBM
     def delete( key )
         v = super( key )
         if String === v
-            v = YAML::load( v )
+            v = Syck.load( v )
         end
         v
     end
@@ -54,11 +54,11 @@ class DBM < ::DBM
         self
     end
     def each_value
-        super { |v| yield YAML::load( v ) }
+        super { |v| yield Syck.load( v ) }
         self
     end
     def values
-        super.collect { |v| YAML::load( v ) }
+        super.collect { |v| Syck.load( v ) }
     end
     def has_value?( val )
         each_value { |v| return true if v == val }
@@ -75,7 +75,7 @@ class DBM < ::DBM
     end
     def shift
         a = super
-        a[1] = YAML::load( a[1] ) if a
+        a[1] = Syck.load( a[1] ) if a
         a
     end
     def select( *keys )
diff --git a/lib/yaml/encoding.rb b/ext/syck/lib/syck/encoding.rb
index 0a1b1fce24..dad062994c 100644
--- a/lib/yaml/encoding.rb
+++ b/ext/syck/lib/syck/encoding.rb
@@ -2,12 +2,12 @@
 # Handle Unicode-to-Internal conversion
 #
 
-module YAML
+module Syck
 
 	#
 	# Escape the string, condensing common escapes
 	#
-	def YAML.escape( value, skip = "" )
+	def self.escape( value, skip = "" )
               warn "#{caller[0]}: YAML.escape is deprecated" if $VERBOSE
 		value.gsub( /\\/, "\\\\\\" ).
               gsub( /"/, "\\\"" ).
@@ -19,7 +19,7 @@ module YAML
 	#
 	# Unescape the condenses escapes
 	#
-	def YAML.unescape( value )
+	def self.unescape( value )
               warn "#{caller[0]}: YAML.unescape is deprecated" if $VERBOSE
 		value.gsub( /\\(?:([nevfbart\\])|0?x([0-9a-fA-F]{2})|u([0-9a-fA-F]{4}))/ ) {
 			if $3
diff --git a/lib/yaml/error.rb b/ext/syck/lib/syck/error.rb
index 75de0ec18a..0bac872411 100644
--- a/lib/yaml/error.rb
+++ b/ext/syck/lib/syck/error.rb
@@ -2,7 +2,7 @@
 # Error messages and exception class
 #
 
-module YAML
+module Syck
 
 	#
 	# Error messages
diff --git a/lib/yaml/loader.rb b/ext/syck/lib/syck/loader.rb
index eb0709e103..925c9ee4b2 100644
--- a/lib/yaml/loader.rb
+++ b/ext/syck/lib/syck/loader.rb
@@ -2,7 +2,7 @@
 # YAML::Loader class
 # .. type handling ..
 #
-module YAML
+module Syck
     class Loader
         TRANSFER_DOMAINS = {
             'yaml.org,2002' => {},
diff --git a/lib/yaml/rubytypes.rb b/ext/syck/lib/syck/rubytypes.rb
index 71f911a738..6b2937bba0 100644
--- a/lib/yaml/rubytypes.rb
+++ b/ext/syck/lib/syck/rubytypes.rb
@@ -20,6 +20,7 @@ class Object
             end
         end
 	end
+    alias :syck_to_yaml :to_yaml
 end
 
 class Hash
@@ -35,6 +36,7 @@ class Hash
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
             out.map( taguri, to_yaml_style ) do |map|
                 each do |k, v|
@@ -83,6 +85,7 @@ class Struct
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
 			#
 			# Basic struct is passed as a YAML map
@@ -104,6 +107,7 @@ class Array
     yaml_as "tag:yaml.org,2002:seq"
     def yaml_initialize( tag, val ); concat( val.to_a ); end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
             out.seq( taguri, to_yaml_style ) do |seq|
                 each do |x|
@@ -124,6 +128,7 @@ class Exception
         o
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
             out.map( taguri, to_yaml_style ) do |map|
                 map.add( 'message', message )
@@ -161,6 +166,7 @@ class String
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( is_complex_yaml? ? self : nil, opts ) do |out|
             if is_binary_data?
                 out.scalar( "tag:yaml.org,2002:binary", [self].pack("m"), :literal )
@@ -190,6 +196,7 @@ class Symbol
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             out.scalar( "tag:yaml.org,2002:str", self.inspect, :plain )
         end
@@ -227,6 +234,7 @@ class Range
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
             # if self.begin.is_complex_yaml? or self.begin.respond_to? :to_str or
             #   self.end.is_complex_yaml? or self.end.respond_to? :to_str or
@@ -276,6 +284,7 @@ class Regexp
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             if to_yaml_properties.empty?
                 out.scalar( taguri, self.inspect, :plain )
@@ -310,6 +319,7 @@ class Time
         end
     end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
             tz = "Z"
             # from the tidy Tobias Peters <t-peters@gmx.de> Thanks!
@@ -347,6 +357,7 @@ end
 class Date
     yaml_as "tag:yaml.org,2002:timestamp#ymd"
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
             out.scalar( "tag:yaml.org,2002:timestamp", self.to_s, :plain )
         end
@@ -356,6 +367,7 @@ end
 class Integer
     yaml_as "tag:yaml.org,2002:int"
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             out.scalar( "tag:yaml.org,2002:int", self.to_s, :plain )
         end
@@ -365,6 +377,7 @@ end
 class Float
     yaml_as "tag:yaml.org,2002:float"
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             str = self.to_s
             if str == "Infinity"
@@ -389,6 +402,7 @@ class Rational
 		end
 	end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
 			out.map( taguri, nil ) do |map|
 				map.add( 'denominator', denominator )
@@ -408,6 +422,7 @@ class Complex
 		end
 	end
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( self, opts ) do |out|
 			out.map( taguri, nil ) do |map|
 				map.add( 'image', imaginary )
@@ -420,6 +435,7 @@ end
 class TrueClass
     yaml_as "tag:yaml.org,2002:bool#yes"
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             out.scalar( taguri, "true", :plain )
         end
@@ -429,6 +445,7 @@ end
 class FalseClass
     yaml_as "tag:yaml.org,2002:bool#no"
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             out.scalar( taguri, "false", :plain )
         end
@@ -438,6 +455,7 @@ end
 class NilClass
     yaml_as "tag:yaml.org,2002:null"
 	def to_yaml( opts = {} )
+        return super unless YAML::ENGINE.syck?
 		YAML::quick_emit( nil, opts ) do |out|
             out.scalar( taguri, "", :plain )
         end
diff --git a/lib/yaml/store.rb b/ext/syck/lib/syck/store.rb
index e3a8e9fcdd..8f27cf49c0 100644
--- a/lib/yaml/store.rb
+++ b/ext/syck/lib/syck/store.rb
@@ -1,12 +1,12 @@
 #
 # YAML::Store
 #
-require 'yaml'
+require 'syck'
 require 'pstore'
 
-class YAML::Store < PStore
+class Syck::Store < PStore
   def initialize( *o )
-    @opt = YAML::DEFAULTS.dup
+    @opt = Syck::DEFAULTS.dup
     if String === o.first
       super(o.shift)
     end
@@ -20,7 +20,7 @@ class YAML::Store < PStore
   end
 
   def load(content)
-    table = YAML::load(content)
+    table = Syck::load(content)
     if table == false
       {}
     else
diff --git a/lib/yaml/stream.rb b/ext/syck/lib/syck/stream.rb
index 3a5227ec9e..cd77a033c6 100644
--- a/lib/yaml/stream.rb
+++ b/ext/syck/lib/syck/stream.rb
@@ -1,4 +1,4 @@
-module YAML
+module Syck
 
 	#
 	# YAML::Stream -- for emitting many documents
@@ -28,7 +28,7 @@ module YAML
 		def emit( io = nil )
             # opts = @options.dup
 			# opts[:UseHeader] = true if @documents.length > 1
-            out = YAML.emitter
+            out = Syck.emitter
             out.reset( io || io2 = StringIO.new )
             @documents.each { |v|
                 v.to_yaml( out )
diff --git a/lib/yaml/stringio.rb b/ext/syck/lib/syck/stringio.rb
index 147caf0bcd..77a2b827e5 100644
--- a/lib/yaml/stringio.rb
+++ b/ext/syck/lib/syck/stringio.rb
@@ -54,19 +54,19 @@ rescue LoadError
 	#
 	# Class method for creating streams
 	#
-	def YAML.make_stream( io )
+	def Syck.make_stream( io )
         if String === io
             io = StringIO.new( io )
         elsif not IO === io
-            raise YAML::Error, "YAML stream must be an IO or String object."
+            raise Syck::Error, "YAML stream must be an IO or String object."
         end
-        if YAML::unicode
+        if Syck::unicode
             def io.readline
-                YAML.utf_to_internal( readline( @ln_sep ), @utf_encoding )
+                Syck.utf_to_internal( readline( @ln_sep ), @utf_encoding )
             end
             def io.check_unicode
-                @utf_encoding = YAML.sniff_encoding( read( 4 ) )
-                @ln_sep = YAML.enc_separator( @utf_encoding )
+                @utf_encoding = Syck.sniff_encoding( read( 4 ) )
+                @ln_sep = Syck.enc_separator( @utf_encoding )
                 seek( -4, IO::SEEK_CUR )
             end
 		    def io.utf_encoding
diff --git a/ext/syck/lib/syck/syck.rb b/ext/syck/lib/syck/syck.rb
new file mode 100644
index 0000000000..2bd44e9f2a
--- /dev/null
+++ b/ext/syck/lib/syck/syck.rb
@@ -0,0 +1,17 @@
+#
+# YAML::Syck module
+# .. glues syck and yaml.rb together ..
+#
+require 'syck'
+require 'syck/basenode'
+
+module Syck
+
+  #
+  # Mixin BaseNode functionality
+  #
+  class Node
+    include Syck::BaseNode
+  end
+
+end
diff --git a/lib/yaml/tag.rb b/ext/syck/lib/syck/tag.rb
index ac587165c2..bfb4dc714d 100644
--- a/lib/yaml/tag.rb
+++ b/ext/syck/lib/syck/tag.rb
@@ -5,7 +5,7 @@
 #
 # Author:: why the lucky stiff
 #
-module YAML
+module Syck
     # A dictionary of taguris which map to
     # Ruby classes.
     @@tagged_classes = {}
@@ -32,7 +32,7 @@ module YAML
     #
     #  tag:why@ruby-lang.org,2004:notes/personal
     #
-    def YAML.tag_class( tag, cls )
+    def self.tag_class( tag, cls )
         if @@tagged_classes.has_key? tag
             warn "class #{ @@tagged_classes[tag] } held ownership of the #{ tag } tag"
         end
@@ -45,7 +45,7 @@ module YAML
     #
     #  YAML.tagged_classes["tag:yaml.org,2002:int"] => Integer
     #
-    def YAML.tagged_classes
+    def self.tagged_classes
         @@tagged_classes
     end
 end
@@ -62,11 +62,11 @@ class Module
             attr_writer :taguri
             def taguri
                 if respond_to? :to_yaml_type
-                    YAML::tagurize( to_yaml_type[1..-1] )
+                    Syck.tagurize( to_yaml_type[1..-1] )
                 else
                     return @taguri if defined?(@taguri) and @taguri
                     tag = #{ tag.dump }
-                    if self.class.yaml_tag_subclasses? and self.class != YAML::tagged_classes[tag]
+                    if self.class.yaml_tag_subclasses? and self.class != Syck.tagged_classes[tag]
                         tag = "\#{ tag }:\#{ self.class.yaml_tag_class_name }"
                     end
                     tag
@@ -74,7 +74,7 @@ class Module
             end
             def self.yaml_tag_subclasses?; #{ sc ? 'true' : 'false' }; end
         END
-        YAML::tag_class tag, self
+        Syck.tag_class tag, self
     ensure
         $VERBOSE = verbose
     end
diff --git a/lib/yaml/types.rb b/ext/syck/lib/syck/types.rb
index 60aebc0481..5c129acba4 100644
--- a/lib/yaml/types.rb
+++ b/ext/syck/lib/syck/types.rb
@@ -3,7 +3,7 @@
 # Classes required by the full core typeset
 #
 
-module YAML
+module Syck
 
     #
     # Default private type
@@ -45,7 +45,7 @@ module YAML
     class Object
         def self.tag_subclasses?; false; end
         def to_yaml( opts = {} )
-            YAML::quick_emit( self, opts ) do |out|
+            Syck.quick_emit( self, opts ) do |out|
                 out.map( "tag:ruby.yaml.org,2002:object:#{ @class }", to_yaml_style ) do |map|
                     @ivars.each do |k,v|
                         map.add( k, v )
@@ -67,7 +67,7 @@ module YAML
             self.default.to_s
         end
         def update( h )
-            if YAML::SpecialHash === h
+            if Syck::SpecialHash === h
                 @default = h.default if h.default
             end
             super( h )
@@ -89,11 +89,11 @@ module YAML
                     if Hash === v
                         concat( v.to_a )		# Convert the map to a sequence
                     else
-                        raise YAML::Error, "Invalid !omap entry: " + val.inspect
+                        raise Syck::Error, "Invalid !omap entry: " + val.inspect
                     end
                 end
             else
-                raise YAML::Error, "Invalid !omap: " + val.inspect
+                raise Syck::Error, "Invalid !omap: " + val.inspect
             end
             self
         end
@@ -123,7 +123,7 @@ module YAML
             true
         end
         def to_yaml( opts = {} )
-            YAML::quick_emit( self, opts ) do |out|
+            Syck.quick_emit( self, opts ) do |out|
                 out.seq( taguri, to_yaml_style ) do |seq|
                     self.each do |v|
                         seq.add( Hash[ *v ] )
@@ -144,11 +144,11 @@ module YAML
                     if Hash === v
                         concat( v.to_a )		# Convert the map to a sequence
                     else
-                        raise YAML::Error, "Invalid !pairs entry: " + val.inspect
+                        raise Syck::Error, "Invalid !pairs entry: " + val.inspect
                     end
                 end
             else
-                raise YAML::Error, "Invalid !pairs: " + val.inspect
+                raise Syck::Error, "Invalid !pairs: " + val.inspect
             end
             self
         end
@@ -173,7 +173,7 @@ module YAML
             true
         end
         def to_yaml( opts = {} )
-            YAML::quick_emit( self, opts ) do |out|
+            Syck.quick_emit( self, opts ) do |out|
                 out.seq( taguri, to_yaml_style ) do |seq|
                     self.each do |v|
                         seq.add( Hash[ *v ] )
diff --git a/lib/yaml/yamlnode.rb b/ext/syck/lib/syck/yamlnode.rb
index 8afa142669..2fa57b1f97 100644
--- a/lib/yaml/yamlnode.rb
+++ b/ext/syck/lib/syck/yamlnode.rb
@@ -1,9 +1,9 @@
 #
 # YAML::YamlNode class
 #
-require 'yaml/basenode'
+require 'syck/basenode'
 
-module YAML
+module Syck
 
     #
     # YAML Generic Model container
@@ -46,7 +46,7 @@ module YAML
             else
                 t = @value
             end
-            YAML.transfer_method( @type_id, t )
+            Syck.transfer_method( @type_id, t )
         end
 
     end
diff --git a/lib/yaml/ypath.rb b/ext/syck/lib/syck/ypath.rb
index 470163557d..024dcb7f4e 100644
--- a/lib/yaml/ypath.rb
+++ b/ext/syck/lib/syck/ypath.rb
@@ -4,7 +4,7 @@
 
 warn "#{caller[0]}: YAML::YPath is deprecated" if $VERBOSE
 
-module YAML
+module Syck
 
     class YPath
         attr_accessor :segments, :predicates, :flags
@@ -24,7 +24,7 @@ module YAML
                 @segments.push "."
             end
         end
-        def YPath.each_path( str )
+        def self.each_path( str )
             #
             # Find choices
             #
diff --git a/ext/syck/rubyext.c b/ext/syck/rubyext.c
index 2f78b6ddaf..da741d687c 100644
--- a/ext/syck/rubyext.c
+++ b/ext/syck/rubyext.c
@@ -2111,9 +2111,7 @@ syck_out_scalar(int argc, VALUE *argv, VALUE self)
 void
 Init_syck()
 {
-    VALUE rb_yaml = rb_define_module( "YAML" );
-    VALUE rb_syck = rb_define_module_under( rb_yaml, "Syck" );
-    rb_define_const( rb_syck, "VERSION", rb_str_new2( SYCK_VERSION ) );
+    VALUE rb_syck = rb_define_module_under( rb_cObject, "Syck" );
     rb_define_module_function( rb_syck, "compile", rb_syck_compile, 1 );
 
     /*
@@ -2258,7 +2256,7 @@ Init_syck()
     /*
      * Define YAML::PrivateType class
      */
-    cPrivateType = rb_define_class_under( rb_yaml, "PrivateType", rb_cObject );
+    cPrivateType = rb_define_class_under( rb_syck, "PrivateType", rb_cObject );
     rb_define_attr( cPrivateType, "type_id", 1, 1 );
     rb_define_attr( cPrivateType, "value", 1, 1 );
     rb_define_method( cPrivateType, "initialize", syck_privatetype_initialize, 2);
@@ -2266,7 +2264,7 @@ Init_syck()
     /*
      * Define YAML::DomainType class
      */
-    cDomainType = rb_define_class_under( rb_yaml, "DomainType", rb_cObject );
+    cDomainType = rb_define_class_under( rb_syck, "DomainType", rb_cObject );
     rb_define_attr( cDomainType, "domain", 1, 1 );
     rb_define_attr( cDomainType, "type_id", 1, 1 );
     rb_define_attr( cDomainType, "value", 1, 1 );
@@ -2275,7 +2273,7 @@ Init_syck()
     /*
      * Define YAML::Object class
      */
-    cYObject = rb_define_class_under( rb_yaml, "Object", rb_cObject );
+    cYObject = rb_define_class_under( rb_syck, "Object", rb_cObject );
     rb_define_attr( cYObject, "class", 1, 1 );
     rb_define_attr( cYObject, "ivars", 1, 1 );
     rb_define_method( cYObject, "initialize", syck_yobject_initialize, 2);
diff --git a/ext/syck/syck.h b/ext/syck/syck.h
index 81b3d67952..488d27e54a 100644
--- a/ext/syck/syck.h
+++ b/ext/syck/syck.h
@@ -12,7 +12,6 @@
 #define SYCK_YAML_MAJOR 1
 #define SYCK_YAML_MINOR 0
 
-#define SYCK_VERSION    "0.60"
 #define YAML_DOMAIN     "yaml.org,2002"
 
 #include <stdio.h>
diff --git a/lib/yaml.rb b/lib/yaml.rb
index d9802abd76..28e13fe05f 100644
--- a/lib/yaml.rb
+++ b/lib/yaml.rb
@@ -1,460 +1,40 @@
-# -*- mode: ruby; ruby-indent-level: 4; tab-width: 4 -*- vim: sw=4 ts=4
-# $Id$
-#
-# = yaml.rb: top-level module with methods for loading and parsing YAML documents
-#
-# Author:: why the lucky stiff
-#
-
-require 'stringio'
-require 'yaml/error'
-require 'yaml/syck'
-require 'yaml/tag'
-require 'yaml/stream'
-require 'yaml/constants'
-
-# == YAML
-#
-# YAML(tm) (rhymes with 'camel') is a
-# straightforward machine parsable data serialization format designed for
-# human readability and interaction with scripting languages such as Perl
-# and Python. YAML is optimized for data serialization, formatted
-# dumping, configuration files, log files, Internet messaging and
-# filtering. This specification describes the YAML information model and
-# serialization format. Together with the Unicode standard for characters, it
-# provides all the information necessary to understand YAML Version 1.0
-# and construct computer programs to process it.
-#
-# See http://yaml.org/ for more information.  For a quick tutorial, please
-# visit YAML In Five Minutes (http://yaml.kwiki.org/?YamlInFiveMinutes).
-#
-# == About This Library
-#
-# The YAML 1.0 specification outlines four stages of YAML loading and dumping.
-# This library honors all four of those stages, although data is really only
-# available to you in three stages.
-#
-# The four stages are: native, representation, serialization, and presentation.
-#
-# The native stage refers to data which has been loaded completely into Ruby's
-# own types. (See +YAML::load+.)
-#
-# The representation stage means data which has been composed into
-# +YAML::BaseNode+ objects.  In this stage, the document is available as a
-# tree of node objects.  You can perform YPath queries and transformations
-# at this level.  (See +YAML::parse+.)
-#
-# The serialization stage happens inside the parser.  The YAML parser used in
-# Ruby is called Syck.  Serialized nodes are available in the extension as
-# SyckNode structs.
-#
-# The presentation stage is the YAML document itself.  This is accessible
-# to you as a string.  (See +YAML::dump+.)
-#
-# For more information about the various information models, see Chapter
-# 3 of the YAML 1.0 Specification (http://yaml.org/spec/#id2491269).
-#
-# The YAML module provides quick access to the most common loading (YAML::load)
-# and dumping (YAML::dump) tasks.  This module also provides an API for registering
-# global types (YAML::add_domain_type).
-#
-# == Example
-#
-# A simple round-trip (load and dump) of an object.
-#
-#     require "yaml"
-#
-#     test_obj = ["dogs", "cats", "badgers"]
-#
-#     yaml_obj = YAML::dump( test_obj )
-#                         # -> ---
-#                              - dogs
-#                              - cats
-#                              - badgers
-#     ruby_obj = YAML::load( yaml_obj )
-#                         # => ["dogs", "cats", "badgers"]
-#     ruby_obj == test_obj
-#                         # => true
-#
-# To register your custom types with the global resolver, use +add_domain_type+.
-#
-#     YAML::add_domain_type( "your-site.com,2004", "widget" ) do |type, val|
-#         Widget.new( val )
-#     end
-#
 module YAML
+  class EngineManager # :nodoc:
+    attr_reader :yamler
 
-    Resolver = YAML::Syck::Resolver
-    DefaultResolver = YAML::Syck::DefaultResolver
-    DefaultResolver.use_types_at( @@tagged_classes )
-    GenericResolver = YAML::Syck::GenericResolver
-    Parser = YAML::Syck::Parser
-    Emitter = YAML::Syck::Emitter
-
-    # Returns a new default parser
-    def YAML.parser; Parser.new.set_resolver( YAML.resolver ); end
-
-    # Returns a new generic parser
-    def YAML.generic_parser
-        warn "#{caller[0]}: YAML.generic_parser is deprecated, switch to psych" if $VERBOSE
-        Parser.new.set_resolver( GenericResolver )
-    end
-
-    # Returns the default resolver
-    def YAML.resolver
-        warn "#{caller[0]}: YAML.resolver is deprecated" if $VERBOSE
-        DefaultResolver
-    end
-
-    # Returns a new default emitter
-    def YAML.emitter
-        warn "#{caller[0]}: YAML.emitter is deprecated" if $VERBOSE
-        Emitter.new.set_resolver( YAML.resolver )
-    end
-
-	#
-	# Converts _obj_ to YAML and writes the YAML result to _io_.
-    #
-    #   File.open( 'animals.yaml', 'w' ) do |out|
-    #     YAML.dump( ['badger', 'elephant', 'tiger'], out )
-    #   end
-    #
-    # If no _io_ is provided, a string containing the dumped YAML
-    # is returned.
-	#
-    #   YAML.dump( :locked )
-    #      #=> "--- :locked"
-    #
-	def YAML.dump( obj, io = nil )
-        obj.to_yaml( io || io2 = StringIO.new )
-        io || ( io2.rewind; io2.read )
-	end
-
-	#
-	# Load a document from the current _io_ stream.
-	#
-    #   File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
-    #      #=> ['badger', 'elephant', 'tiger']
-    #
-    # Can also load from a string.
-    #
-    #   YAML.load( "--- :locked" )
-    #      #=> :locked
-    #
-	def YAML.load( io )
-		yp = parser.load( io )
-	end
-
-    #
-    # Load a document from the file located at _filepath_.
-    #
-    #   YAML.load_file( 'animals.yaml' )
-    #      #=> ['badger', 'elephant', 'tiger']
-    #
-    def YAML.load_file( filepath )
-        File.open( filepath ) do |f|
-            load( f )
-        end
-    end
-
-	#
-	# Parse the first document from the current _io_ stream
-	#
-    #   File.open( 'animals.yaml' ) { |yf| YAML::load( yf ) }
-    #      #=> #<YAML::Syck::Node:0x82ccce0
-    #           @kind=:seq,
-    #           @value=
-    #            [#<YAML::Syck::Node:0x82ccd94
-    #              @kind=:scalar,
-    #              @type_id="str",
-    #              @value="badger">,
-    #             #<YAML::Syck::Node:0x82ccd58
-    #              @kind=:scalar,
-    #              @type_id="str",
-    #              @value="elephant">,
-    #             #<YAML::Syck::Node:0x82ccd1c
-    #              @kind=:scalar,
-    #              @type_id="str",
-    #              @value="tiger">]>
-    #
-    # Can also load from a string.
-    #
-    #   YAML.parse( "--- :locked" )
-    #      #=> #<YAML::Syck::Node:0x82edddc
-    #            @type_id="tag:ruby.yaml.org,2002:sym",
-    #            @value=":locked", @kind=:scalar>
-    #
-	def YAML.parse( io )
-		yp = generic_parser.load( io )
-	end
-
-    #
-    # Parse a document from the file located at _filepath_.
-    #
-    #   YAML.parse_file( 'animals.yaml' )
-    #      #=> #<YAML::Syck::Node:0x82ccce0
-    #           @kind=:seq,
-    #           @value=
-    #            [#<YAML::Syck::Node:0x82ccd94
-    #              @kind=:scalar,
-    #              @type_id="str",
-    #              @value="badger">,
-    #             #<YAML::Syck::Node:0x82ccd58
-    #              @kind=:scalar,
-    #              @type_id="str",
-    #              @value="elephant">,
-    #             #<YAML::Syck::Node:0x82ccd1c
-    #              @kind=:scalar,
-    #              @type_id="str",
-    #              @value="tiger">]>
-    #
-    def YAML.parse_file( filepath )
-        File.open( filepath ) do |f|
-            parse( f )
-        end
+    def initialize
+      @yamler = nil
     end
 
-	#
-	# Calls _block_ with each consecutive document in the YAML
-    # stream contained in _io_.
-    #
-    #   File.open( 'many-docs.yaml' ) do |yf|
-    #     YAML.each_document( yf ) do |ydoc|
-    #       ## ydoc contains the single object
-    #       ## from the YAML document
-    #     end
-    #   end
-	#
-    def YAML.each_document( io, &block )
-        warn "#{caller[0]}: YAML.each_document is deprecated" if $VERBOSE
-		yp = parser.load_documents( io, &block )
+    def syck?
+      'syck' == @yamler
     end
 
-	#
-	# Calls _block_ with each consecutive document in the YAML
-    # stream contained in _io_.
-    #
-    #   File.open( 'many-docs.yaml' ) do |yf|
-    #     YAML.load_documents( yf ) do |ydoc|
-    #       ## ydoc contains the single object
-    #       ## from the YAML document
-    #     end
-    #   end
-	#
-    def YAML.load_documents( io, &doc_proc )
-		yp = parser.load_documents( io, &doc_proc )
-    end
+    def yamler= engine
+      raise(ArgumentError, "bad engine") unless %w{syck psych}.include?(engine)
 
-	#
-	# Calls _block_ with a tree of +YAML::BaseNodes+, one tree for
-    # each consecutive document in the YAML stream contained in _io_.
-    #
-    #   File.open( 'many-docs.yaml' ) do |yf|
-    #     YAML.each_node( yf ) do |ydoc|
-    #       ## ydoc contains a tree of nodes
-    #       ## from the YAML document
-    #     end
-    #   end
-	#
-    def YAML.each_node( io, &doc_proc )
-        warn "#{caller[0]}: YAML.each_node is deprecated" if $VERBOSE
-		yp = generic_parser.load_documents( io, &doc_proc )
-    end
+      @yamler = engine
+      require engine
 
-	#
-	# Calls _block_ with a tree of +YAML::BaseNodes+, one tree for
-    # each consecutive document in the YAML stream contained in _io_.
-    #
-    #   File.open( 'many-docs.yaml' ) do |yf|
-    #     YAML.parse_documents( yf ) do |ydoc|
-    #       ## ydoc contains a tree of nodes
-    #       ## from the YAML document
-    #     end
-    #   end
-	#
-    def YAML.parse_documents( io, &doc_proc )
-        warn "#{caller[0]}: YAML.parse_documents is deprecated, use load_stream" if $VERBOSE
-		YAML.each_node( io, &doc_proc )
+      Object.class_eval <<-eorb, __FILE__, __LINE__ + 1
+        remove_const 'YAML'
+        YAML = #{engine.capitalize}
+        remove_method :to_yaml
+        alias :to_yaml :#{engine}_to_yaml
+      eorb
+      engine
     end
+  end
 
-	#
-	# Loads all documents from the current _io_ stream,
-    # returning a +YAML::Stream+ object containing all
-    # loaded documents.
-	#
-	def YAML.load_stream( io )
-		d = nil
-		parser.load_documents( io ) do |doc|
-			d = YAML::Stream.new if not d
-			d.add( doc )
-        end
-		return d
-	end
-
-	#
-    # Returns a YAML stream containing each of the items in +objs+,
-    # each having their own document.
-    #
-    #   YAML.dump_stream( 0, [], {} )
-    #     #=> --- 0
-    #         --- []
-    #         --- {}
-    #
-	def YAML.dump_stream( *objs )
-		d = YAML::Stream.new
-        objs.each do |doc|
-			d.add( doc )
-        end
-        d.emit
-	end
-
-	#
-	# Add a global handler for a YAML domain type.
-	#
-	def YAML.add_domain_type( domain, type_tag, &transfer_proc )
-        resolver.add_type( "tag:#{ domain }:#{ type_tag }", transfer_proc )
-	end
-
-	#
-	# Add a transfer method for a builtin type
-	#
-	def YAML.add_builtin_type( type_tag, &transfer_proc )
-	    resolver.add_type( "tag:yaml.org,2002:#{ type_tag }", transfer_proc )
-	end
-
-	#
-	# Add a transfer method for a builtin type
-	#
-	def YAML.add_ruby_type( type_tag, &transfer_proc )
-        warn "#{caller[0]}: YAML.add_ruby_type is deprecated, use add_domain_type" if $VERBOSE
-	    resolver.add_type( "tag:ruby.yaml.org,2002:#{ type_tag }", transfer_proc )
-	end
-
-	#
-	# Add a private document type
-	#
-	def YAML.add_private_type( type_re, &transfer_proc )
-        warn "#{caller[0]}: YAML.add_private_type is deprecated, use add_domain_type" if $VERBOSE
-	    resolver.add_type( "x-private:" + type_re, transfer_proc )
-	end
-
-    #
-    # Detect typing of a string
-    #
-    def YAML.detect_implicit( val )
-        warn "#{caller[0]}: YAML.detect_implicit is deprecated" if $VERBOSE
-        resolver.detect_implicit( val )
-    end
-
-    #
-    # Convert a type_id to a taguri
-    #
-    def YAML.tagurize( val )
-        warn "#{caller[0]}: YAML.tagurize is deprecated" if $VERBOSE
-        resolver.tagurize( val )
-    end
-
-    #
-    # Apply a transfer method to a Ruby object
-    #
-    def YAML.transfer( type_id, obj )
-        warn "#{caller[0]}: YAML.transfer is deprecated" if $VERBOSE
-        resolver.transfer( YAML.tagurize( type_id ), obj )
-    end
-
-	#
-	# Apply any implicit a node may qualify for
-	#
-	def YAML.try_implicit( obj )
-        warn "#{caller[0]}: YAML.try_implicit is deprecated" if $VERBOSE
-		YAML.transfer( YAML.detect_implicit( obj ), obj )
-	end
-
-    #
-    # Method to extract colon-seperated type and class, returning
-    # the type and the constant of the class
-    #
-    def YAML.read_type_class( type, obj_class )
-        warn "#{caller[0]}: YAML.read_type_class is deprecated" if $VERBOSE
-        scheme, domain, type, tclass = type.split( ':', 4 )
-        tclass.split( "::" ).each { |c| obj_class = obj_class.const_get( c ) } if tclass
-        return [ type, obj_class ]
-    end
-
-    #
-    # Allocate blank object
-    #
-    def YAML.object_maker( obj_class, val )
-        warn "#{caller[0]}: YAML.object_maker is deprecated" if $VERBOSE
-        if Hash === val
-            o = obj_class.allocate
-            val.each_pair { |k,v|
-                o.instance_variable_set("@#{k}", v)
-            }
-            o
-        else
-            raise YAML::Error, "Invalid object explicitly tagged !ruby/Object: " + val.inspect
-        end
-    end
-
-	#
-	# Allocate an Emitter if needed
-	#
-	def YAML.quick_emit( oid, opts = {}, &e )
-        warn "#{caller[0]}: YAML.quick_emit is deprecated" if $VERBOSE
-        out =
-            if opts.is_a? YAML::Emitter
-                opts
-            else
-                emitter.reset( opts )
-            end
-        out.emit( oid, &e )
-	end
-
+  ENGINE = YAML::EngineManager.new
 end
 
-require 'yaml/rubytypes'
-require 'yaml/types'
-
-module Kernel
-    #
-    # ryan:: You know how Kernel.p is a really convenient way to dump ruby
-    #        structures?  The only downside is that it's not as legible as
-    #        YAML.
-    #
-    # _why:: (listening)
-    #
-    # ryan:: I know you don't want to urinate all over your users' namespaces.
-    #        But, on the other hand, convenience of dumping for debugging is,
-    #        IMO, a big YAML use case.
-    #
-    # _why:: Go nuts!  Have a pony parade!
-    #
-    # ryan:: Either way, I certainly will have a pony parade.
-    #
-
-    # Prints any supplied _objects_ out in YAML.  Intended as
-    # a variation on +Kernel::p+.
-    #
-    #   S = Struct.new(:name, :state)
-    #   s = S['dave', 'TX']
-    #   y s
-    #
-    # _produces:_
-    #
-    #   --- !ruby/struct:S
-    #   name: dave
-    #   state: TX
-    #
-    def y( object, *objects )
-        objects.unshift object
-        puts( if objects.length == 1
-                  YAML::dump( *objects )
-              else
-                  YAML::dump_stream( *objects )
-              end )
-    end
-    private :y
+module Syck
+  ENGINE = YAML::ENGINE
 end
 
+module Psych
+  ENGINE = YAML::ENGINE
+end
 
+YAML::ENGINE.yamler = 'syck'
diff --git a/lib/yaml/syck.rb b/lib/yaml/syck.rb
deleted file mode 100644
index faf57e8036..0000000000
--- a/lib/yaml/syck.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-#
-# YAML::Syck module
-# .. glues syck and yaml.rb together ..
-#
-require 'syck'
-require 'yaml/basenode'
-
-module YAML
-    module Syck
-
-        #
-        # Mixin BaseNode functionality
-        #
-        class Node
-            include YAML::BaseNode
-        end
-
-    end
-end
diff --git a/test/psych/test_engine_manager.rb b/test/psych/test_engine_manager.rb
new file mode 100644
index 0000000000..8bd7d6c1da
--- /dev/null
+++ b/test/psych/test_engine_manager.rb
@@ -0,0 +1,57 @@
+require_relative 'helper'
+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'
+     end
+   end
+
+   def test_set_psych
+     YAML::ENGINE.yamler = 'psych'
+     assert_equal Psych, YAML
+     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
+     YAML::ENGINE.yamler = 'psych'
+
+     assert_to_yaml ::Object.new
+     assert_to_yaml Time.now
+     assert_to_yaml Date.today
+     assert_to_yaml('a' => 'b')
+     assert_to_yaml A.new('foo')
+     assert_to_yaml %w{a b}
+     assert_to_yaml Exception.new('foo')
+     assert_to_yaml "hello!"
+     assert_to_yaml :fooo
+     assert_to_yaml(1..10)
+     assert_to_yaml(/hello!~/)
+     assert_to_yaml 1
+     assert_to_yaml 1.2
+     assert_to_yaml Rational(1, 2)
+     assert_to_yaml Complex(1, 2)
+     assert_to_yaml true
+     assert_to_yaml false
+     assert_to_yaml nil
+   end
+
+   def assert_to_yaml obj
+     assert obj.to_yaml, "#{obj.class} to_yaml works"
+   end
+ end
+end
diff --git a/test/yaml/test_engine_manager.rb b/test/yaml/test_engine_manager.rb
new file mode 100644
index 0000000000..529fc49d38
--- /dev/null
+++ b/test/yaml/test_engine_manager.rb
@@ -0,0 +1,3 @@
+require 'test/unit'
+require 'yaml'
+
diff --git a/test/yaml/test_yaml.rb b/test/yaml/test_yaml.rb
index bda68cccf3..606c2676f1 100644
--- a/test/yaml/test_yaml.rb
+++ b/test/yaml/test_yaml.rb
@@ -4,7 +4,7 @@
 #
 require 'test/unit'
 require 'yaml'
-require 'yaml/ypath'
+require 'syck/ypath'
 
 # [ruby-core:01946]
 module YAML_Tests
diff --git a/test/yaml/test_yamlstore.rb b/test/yaml/test_yamlstore.rb
index 69302095e5..1374d32d24 100644
--- a/test/yaml/test_yamlstore.rb
+++ b/test/yaml/test_yamlstore.rb
@@ -1,5 +1,5 @@
 require 'test/unit'
-require 'yaml/store'
+require 'syck/store'
 
 class YAMLStoreTest < Test::Unit::TestCase
   def setup