added array sorting and mapping on properties

lib/liquid/standardfilters.rb

@@ -63,9 +63,27 @@ module Liquid
     end
 
     # Sort elements of the array
-    def sort(input)
-      [input].flatten.sort
+    # provide optional property with which to sort an array of hashes or drops
+    def sort(input, property = nil)
+      ary = [input].flatten
+      if property.nil?
+        ary.sort
+      elsif ary.first.respond_to?('[]') and !ary.first[property].nil?
+        ary.sort {|a,b| a[property] <=> b[property] }
+      elsif ary.first.respond_to?(property)
+        ary.sort {|a,b| a.send(property) <=> b.send(property) }
+      end
     end               
+    
+    # map/collect on a given property
+    def map(input, property)
+      ary = [input].flatten
+      if ary.first.respond_to?('[]') and !ary.first[property].nil?
+        ary.map {|e| e[property] }
+      elsif ary.first.respond_to?(property)
+        ary.map {|e| e.send(property) }
+      end
+    end
             
     # Replace occurrences of a string with another
     def replace(input, string, replacement = '')

test/standard_filter_test.rb

@@ -67,6 +67,13 @@ class StandardFiltersTest < Test::Unit::TestCase
   
   def test_sort
     assert_equal [1,2,3,4], @filters.sort([4,3,2,1])    
+    assert_equal [{"a" => 1}, {"a" => 2}, {"a" => 3}, {"a" => 4}], @filters.sort([{"a" => 4}, {"a" => 3}, {"a" => 1}, {"a" => 2}], "a")
+  end
+  
+  def test_map
+    assert_equal [1,2,3,4], @filters.map([{"a" => 1}, {"a" => 2}, {"a" => 3}, {"a" => 4}], 'a')
+    assert_template_result 'abc', "{{ ary | map:'foo' | map:'bar' }}",
+      'ary' => [{'foo' => {'bar' => 'a'}}, {'foo' => {'bar' => 'b'}}, {'foo' => {'bar' => 'c'}}]
   end
   
   def test_date