1 files changed, 43 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/ordered_hash.rb b/activesupport/lib/active_support/ordered_hash.rb
new file mode 100644
index 0000000000..6993621ef9
--- /dev/null
+++ b/activesupport/lib/active_support/ordered_hash.rb
@@ -0,0 +1,43 @@
+# OrderedHash is namespaced to prevent conflicts with other implementations
+module ActiveSupport
+  # Hash is ordered in Ruby 1.9!
+  if RUBY_VERSION >= '1.9'
+    OrderedHash = ::Hash
+  else
+    class OrderedHash < Array #:nodoc:
+      def []=(key, value)
+        if pair = assoc(key)
+          pair.pop
+          pair << value
+        else
+          self << [key, value]
+        end
+      end
+
+      def [](key)
+        pair = assoc(key)
+        pair ? pair.last : nil
+      end
+
+      def delete(key)
+        pair = assoc(key)
+        pair ? array_index = index(pair) : nil
+        array_index ? delete_at(array_index).last : nil
+      end
+
+      def keys
+        collect { |key, value| key }
+      end
+
+      def values
+        collect { |key, value| value }
+      end
+
+      def to_hash
+        returning({}) do |hash|
+          each { |array| hash[array[0]] = array[1] }
+        end
+      end
+    end
+  end
+end