Make 'map' filter work on Enumerable drops

lib/liquid/standardfilters.rb

@@ -99,7 +99,14 @@ module Liquid
 
     # map/collect on a given property
     def map(input, property)
-      ary = [input].flatten
+      ary = if input.is_a?(Array)
+        input.flatten
+      elsif !input.class.include?(Enumerable)
+        [input].flatten
+      else
+        input
+      end
+
       ary.map do |e|
         e = e.call if e.is_a?(Proc)
         e = e.to_liquid if e.respond_to?(:to_liquid)

test/liquid/standard_filter_test.rb

@@ -27,6 +27,14 @@ class TestDrop < Liquid::Drop
   end
 end
 
+class TestEnumerable < Liquid::Drop
+  include Enumerable
+
+  def each(&block)
+    [ { "foo" => 1 }, { "foo" => 2 }, { "foo" => 3 } ].each(&block)
+  end
+end
+
 class StandardFiltersTest < Test::Unit::TestCase
   include Liquid
 
@@ -135,6 +143,10 @@ class StandardFiltersTest < Test::Unit::TestCase
     assert_equal "testfoo", Liquid::Template.parse(templ).render("procs" => [p])
   end
 
+  def test_map_works_on_enumerables
+    assert_equal "123", Liquid::Template.parse('{{ foo | map: "foo" }}').render!("foo" => TestEnumerable.new)
+  end
+
   def test_date
     assert_equal 'May', @filters.date(Time.parse("2006-05-05 10:00:00"), "%B")
     assert_equal 'June', @filters.date(Time.parse("2006-06-05 10:00:00"), "%B")