Merge pull request #312 from Shopify/uniq_filter

uniq filter

History.md

@@ -3,6 +3,7 @@
 ## 3.0.0 / not yet released / branch "master"
 
 * ...
+* Add uniq to standard filters [Florian Weingarten, fw42]
 * Add exception_handler feature, see #397 and #254 [Bogdan Gusiev, bogdan and Florian Weingarten, fw42]
 * Optimize variable parsing to avoid repeated regex evaluation during template rendering #383 [Jason Hiltz-Laforge, jasonhl]
 * Optimize checking for block interrupts to reduce object allocation #380 [Jason Hiltz-Laforge, jasonhl] 

lib/liquid/standardfilters.rb

@@ -101,13 +101,24 @@ module Liquid
       ary = InputIterator.new(input)
       if property.nil?
         ary.sort
-      elsif ary.first.respond_to?('[]'.freeze) && !ary.first[property].nil?
+      elsif ary.first.respond_to?(:[]) && !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
 
+    # Remove duplicate elements from an array
+    # provide optional property with which to determine uniqueness
+    def uniq(input, property = nil)
+      ary = InputIterator.new(input)
+      if property.nil?
+        input.uniq
+      elsif input.first.respond_to?(:[])
+        input.uniq{ |a| a[property] }
+      end
+    end
+
     # Reverse the elements of an array
     def reverse(input)
       ary = InputIterator.new(input)

test/integration/standard_filter_test.rb

@@ -128,6 +128,13 @@ class StandardFiltersTest < Minitest::Test
     assert_equal [{"a" => "10"}, {"a" => "2"}], @filters.sort([{"a" => "10"}, {"a" => "2"}], "a")
   end
 
+  def test_uniq
+    assert_equal [1,3,2,4], @filters.uniq([1,1,3,2,3,1,4,3,2,1])
+    assert_equal [{"a" => 1}, {"a" => 3}, {"a" => 2}], @filters.uniq([{"a" => 1}, {"a" => 3}, {"a" => 1}, {"a" => 2}], "a")
+    testdrop = TestDrop.new
+    assert_equal [testdrop], @filters.uniq([testdrop, TestDrop.new], 'test')
+  end
+
   def test_reverse
     assert_equal [4,3,2,1], @filters.reverse([1,2,3,4])
   end