Add sort_numeric filter

lib/liquid/standardfilters.rb

@@ -193,6 +193,23 @@ def where(input, property, target_value = nil)
       end
     end
 
+    # Sort elements of an array in numeric order
+    # provide optional property with which to sort an array of hashes or drops
+    def sort_numeric(input, property = nil)
+      ary = InputIterator.new(input)
+      if property.nil?
+        ary.sort do |a, b|
+          Utils.to_number(a) <=> Utils.to_number(b)
+        end
+      elsif ary.empty? # The next two cases assume a non-empty array.
+        []
+      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
+        ary.sort do |a, b|
+          Utils.to_number(a[property]) <=> Utils.to_number(b[property])
+        end
+      end
+    end
+
     # Remove duplicate elements from an array
     # provide optional property with which to determine uniqueness
     def uniq(input, property = nil)

test/integration/standard_filter_test.rb

@@ -198,6 +198,12 @@ def test_sort
     assert_equal [{ "a" => 1 }, { "a" => 2 }, { "a" => 3 }, { "a" => 4 }], @filters.sort([{ "a" => 4 }, { "a" => 3 }, { "a" => 1 }, { "a" => 2 }], "a")
   end
 
+  def test_sort_numeric
+    assert_equal ['1', '2', '3', '10'], @filters.sort_numeric(['10', '3', '2', '1'])
+    assert_equal [{ "a" => '1' }, { "a" => '2' }, { "a" => '3' }, { "a" => '10' }],
+      @filters.sort_numeric([{ "a" => '10' }, { "a" => '3' }, { "a" => '1' }, { "a" => '2' }], "a")
+  end
+
   def test_sort_with_nils
     assert_equal [1, 2, 3, 4, nil], @filters.sort([nil, 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")
@@ -292,6 +298,10 @@ def test_sort_natural_empty_array
     assert_equal [], @filters.sort_natural([], "a")
   end
 
+  def test_sort_numeric_empty_array
+    assert_equal [], @filters.sort_numeric([], "a")
+  end
+
   def test_sort_natural_invalid_property
     foo = [
       [1],