Revert "* lib/yaml.rb: Remove Psych::EngineManager [Bug #8344]"

zzak is not the maintainer of yaml.
This reverts commit r46097.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46102 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -16,11 +16,6 @@ Sun May 25 11:56:33 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 	  start cannot exceed the size, the comparison was always false.
 	  [ruby-core:62737] [Bug #9861]
 
-Sun May 25 11:32:42 2014  Zachary Scott  <e@zzak.io>
-
-	* lib/yaml.rb: Remove Psych::EngineManager [Bug #8344]
-	* test/psych/*: ditto.
-
 Sun May 25 10:34:15 2014  Zachary Scott  <e@zzak.io>
 
 	* doc/regexp.rdoc: [DOC] Clarify whitespace matching by @allolex

NEWS

@@ -120,9 +120,6 @@ with all sufficient information, see the ChangeLog file.
     * Prime.prime? now returns false for negative numbers. This method
       should not be used to know the number is composite or not. [Bug #7395]
 
-* Psych
-  * Removed Psych::EngineManager [Bug #8344]
-
 === Built-in global variables compatibility issues
 
 === C API updates

lib/yaml.rb

@@ -12,6 +12,40 @@ end
 
 YAML = Psych # :nodoc:
 
+module Psych # :nodoc:
+  # For compatibility, deprecated
+  class EngineManager # :nodoc:
+    attr_reader :yamler # :nodoc:
+
+    def initialize # :nodoc:
+      @yamler = 'psych'
+    end
+
+    def syck? # :nodoc:
+      false
+    end
+
+    # Psych is always used and this method has no effect.
+    #
+    # This method is still present for compatibility.
+    #
+    # You may still use the Syck engine by installing
+    # the 'syck' gem and using the Syck constant.
+    def yamler= engine # :nodoc:
+      case engine
+      when 'syck' then warn "syck has been removed, psych is used instead"
+      when 'psych' then @yamler = 'psych'
+      else
+        raise(ArgumentError, "bad engine")
+      end
+
+      engine
+    end
+  end
+
+  ENGINE = EngineManager.new # :nodoc:
+end
+
 # YAML Ain't Markup Language
 #
 # This module provides a Ruby interface for data serialization in YAML format.

test/psych/test_engine_manager.rb

@@ -0,0 +1,47 @@
+require_relative 'helper'
+require 'yaml'
+
+module Psych
+ class TestEngineManager < TestCase
+   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
+
+   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

test/psych/test_yamldbm.rb

@@ -13,6 +13,7 @@ module Psych
 
   class YAMLDBMTest < TestCase
     def setup
+      @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'psych'
       @dir = Dir.mktmpdir("rubytest-file")
       File.chown(-1, Process.gid, @dir)
       @yamldbm_file = make_tmp_filename("yamldbm")
@@ -20,6 +21,7 @@ module Psych
     end
 
     def teardown
+      YAML::ENGINE.yamler = @engine
       @yamldbm.clear
       @yamldbm.close
       FileUtils.remove_entry_secure @dir

test/psych/test_yamlstore.rb

@@ -7,6 +7,7 @@ module Psych
 
   class YAMLStoreTest < TestCase
     def setup
+      @engine, YAML::ENGINE.yamler = YAML::ENGINE.yamler, 'psych'
       @dir = Dir.mktmpdir("rubytest-file")
       File.chown(-1, Process.gid, @dir)
       @yamlstore_file = make_tmp_filename("yamlstore")
@@ -14,6 +15,7 @@ module Psych
     end
 
     def teardown
+      YAML::ENGINE.yamler = @engine
       FileUtils.remove_entry_secure @dir
     end