fixing Hash subclass dump and load support. fixes #14

3 files changed, 48 insertions, 23 deletions

diff --git a/lib/psych/visitors/to_ruby.rb b/lib/psych/visitors/to_ruby.rb
index 3f5be4d..2562816 100644
--- a/lib/psych/visitors/to_ruby.rb
+++ b/lib/psych/visitors/to_ruby.rb
@@ -120,6 +120,7 @@ module Psych
 
       def visit_Psych_Nodes_Mapping o
         return revive(Psych.load_tags[o.tag], o) if Psych.load_tags[o.tag]
+        return revive_hash({}, o) unless o.tag
 
         case o.tag
         when '!str', 'tag:yaml.org,2002:str'
@@ -183,30 +184,12 @@ module Psych
           obj = revive((resolve_class(name) || Object), o)
           @st[o.anchor] = obj if o.anchor
           obj
-        else
-          hash = {}
-          @st[o.anchor] = hash if o.anchor
 
-          o.children.each_slice(2) { |k,v|
-            key = accept(k)
-
-            if key == '<<'
-              case v
-              when Nodes::Alias
-                hash.merge! accept(v)
-              when Nodes::Sequence
-                accept(v).reverse_each do |value|
-                  hash.merge! value
-                end
-              else
-                hash[key] = accept(v)
-              end
-            else
-              hash[key] = accept(v)
-            end
+        when /^!map:(.*)$/, /^!ruby\/hash:(.*)$/
+          revive_hash resolve_class($1).new, o
 
-          }
-          hash
+        else
+          revive_hash({}, o)
         end
       end
 
@@ -223,6 +206,31 @@ module Psych
       end
 
       private
+      def revive_hash hash, o
+        @st[o.anchor] = hash if o.anchor
+
+          o.children.each_slice(2) { |k,v|
+          key = accept(k)
+
+          if key == '<<'
+            case v
+            when Nodes::Alias
+              hash.merge! accept(v)
+            when Nodes::Sequence
+              accept(v).reverse_each do |value|
+                hash.merge! value
+              end
+            else
+              hash[key] = accept(v)
+            end
+          else
+            hash[key] = accept(v)
+          end
+
+        }
+        hash
+      end
+
       def revive klass, node
         s = klass.allocate
         h = Hash[*node.children.map { |c| accept c }]
diff --git a/lib/psych/visitors/yaml_tree.rb b/lib/psych/visitors/yaml_tree.rb
index 4019859..eef6125 100644
--- a/lib/psych/visitors/yaml_tree.rb
+++ b/lib/psych/visitors/yaml_tree.rb
@@ -265,7 +265,10 @@ module Psych
       end
 
       def visit_Hash o
-        register(o, @emitter.start_mapping(nil, nil, true, Psych::Nodes::Mapping::BLOCK))
+        tag      = o.class == ::Hash ? nil : "!ruby/hash:#{o.class}"
+        implicit = !tag
+
+        register(o, @emitter.start_mapping(nil, tag, implicit, Psych::Nodes::Mapping::BLOCK))
 
         o.each do |k,v|
           accept k
diff --git a/test/psych/test_hash.rb b/test/psych/test_hash.rb
index 3147076..4bd4edf 100644
--- a/test/psych/test_hash.rb
+++ b/test/psych/test_hash.rb
@@ -2,11 +2,25 @@ require 'psych/helper'
 
 module Psych
   class TestHash < TestCase
+    class X < Hash
+    end
+
     def setup
       super
       @hash = { :a => 'b' }
     end
 
+    def test_empty_subclass
+      assert_match "!ruby/hash:#{X}", Psych.dump(X.new)
+      x = Psych.load Psych.dump X.new
+      assert_equal X, x.class
+    end
+
+    def test_map
+      x = Psych.load "--- !map:#{X} { }\n"
+      assert_equal X, x.class
+    end
+
     def test_self_referential
       @hash['self'] = @hash
       assert_cycle(@hash)