Adding custom yaml (de-)serialization for OrderedHash

[#3608 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activesupport/CHANGELOG

@@ -1,5 +1,7 @@
 *Edge*
 
+* YAML serialization for OrderedHash.  #3608 [Gregor Schmidt]
+
 * Update bundled TZInfo to v0.3.16 [Geoff Buesing]
 
 * Georgetown TimeZone is now mapped to "America/Guyana" instead of "America/Argentina/San_Juan" #1821 [Geoff Buesing, Reuben Sivan]

activesupport/lib/active_support/ordered_hash.rb

@@ -2,7 +2,8 @@
 module ActiveSupport
   # Hash is ordered in Ruby 1.9!
   if RUBY_VERSION >= '1.9'
-    OrderedHash = ::Hash
+    class OrderedHash < ::Hash #:nodoc:
+    end
   else
     class OrderedHash < Hash #:nodoc:
       def initialize(*args, &block)
@@ -138,4 +139,24 @@ module ActiveSupport
       end
     end
   end
+
+  class OrderedHash #:nodoc:
+    def to_yaml_type
+      "!tag:yaml.org,2002:omap"
+    end
+
+    def to_yaml(opts = {})
+      YAML.quick_emit(self, opts) do |out|
+        out.seq(taguri, to_yaml_style) do |seq|
+          each do |k, v|
+            seq.add(k => v)
+          end
+        end
+      end
+    end
+  end
+
+  YAML.add_builtin_type("omap") do |type, val|
+    ActiveSupport::OrderedHash[val.map(&:to_a).map(&:first)]
+  end
 end

activesupport/test/ordered_hash_test.rb

@@ -198,4 +198,28 @@ class OrderedHashTest < Test::Unit::TestCase
     assert_same original, @ordered_hash
     assert_equal @other_ordered_hash.keys, @ordered_hash.keys
   end
+
+  def test_each_after_yaml_serialization
+    values = []
+    @deserialized_ordered_hash = YAML::load(YAML::dump(@ordered_hash))
+
+    @deserialized_ordered_hash.each {|key, value| values << value}
+    assert_equal @values, values
+  end
+
+  def test_order_after_yaml_serialization
+    @deserialized_ordered_hash = YAML::load(YAML::dump(@ordered_hash))
+
+    assert_equal @keys,   @deserialized_ordered_hash.keys
+    assert_equal @values, @deserialized_ordered_hash.values
+  end
+
+  def test_order_after_yaml_serialization_with_nested_arrays
+    @ordered_hash[:array] = %w(a b c)
+
+    @deserialized_ordered_hash = YAML::load(YAML::dump(@ordered_hash))
+
+    assert_equal @ordered_hash.keys,   @deserialized_ordered_hash.keys
+    assert_equal @ordered_hash.values, @deserialized_ordered_hash.values
+  end
 end