2-0-stable: Enumerable#group_by uses ActiveSupport::OrderedHash

git-svn-id: http://svn-commit.rubyonrails.org/rails/branches/2-0-stable@8946 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

Author: NZKoz

activesupport/lib/active_support/core_ext/enumerable.rb

@@ -15,23 +15,10 @@ module Enumerable
   #   "2006-02-24 -> Transcript, Transcript"
   #   "2006-02-23 -> Transcript"
   def group_by
-    groups = []
-
-    inject({}) do |grouped, element|
-      index = yield(element)
-
-      if group = grouped[index]
-        group << element
-      else
-        group = [element]
-        groups << [index, group]
-        grouped[index] = group
-      end
-
+    inject ActiveSupport::OrderedHash.new do |grouped, element|
+      (grouped[yield(element)] ||= []) << element
       grouped
     end
-
-    groups
   end if RUBY_VERSION < '1.9'
 
   # Calculates a sum from the elements. Examples:

activesupport/test/core_ext/enumerable_test.rb

@@ -21,7 +21,7 @@ def test_group_by
       assert group.all? { |person| person.name == name }
     end
 
-    assert_equal objects.uniq.map(&:name), grouped.map { |name, group| name }
+    assert_equal objects.uniq.map(&:name), grouped.keys
   end
 
   def test_sums