Fix uniq filter with string input

.rubocop_todo.yml

@@ -1,11 +1,11 @@
 # This configuration was generated by `rubocop --auto-gen-config`
-# on 2015-06-04 13:07:29 -0400 using RuboCop version 0.31.0.
+# on 2015-06-04 22:53:26 -0400 using RuboCop version 0.31.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 51
+# Offense count: 53
 Metrics/AbcSize:
   Max: 58
 
@@ -18,7 +18,7 @@ Metrics/ClassLength:
 Metrics/CyclomaticComplexity:
   Max: 15
 
-# Offense count: 550
+# Offense count: 552
 # Configuration parameters: AllowURI, URISchemes.
 Metrics/LineLength:
   Max: 294
@@ -31,7 +31,7 @@ Metrics/MethodLength:
 # Offense count: 1
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:
-  Max: 234
+  Max: 235
 
 # Offense count: 6
 Metrics/PerceivedComplexity:

lib/liquid/standardfilters.rb

@@ -138,10 +138,12 @@ module Liquid
     # 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] }
+        ary.uniq
+      elsif ary.first.respond_to?(:[])
+        ary.uniq{ |a| a[property] }
       end
     end
 
@@ -391,6 +393,10 @@ module Liquid
         reverse_each.to_a
       end
 
+      def uniq(&block)
+        to_a.uniq(&block)
+      end
+
       def each
         @input.each do |e|
           yield(e.respond_to?(:to_liquid) ? e.to_liquid : e)

test/integration/standard_filter_test.rb

@@ -170,6 +170,7 @@ class StandardFiltersTest < Minitest::Test
   end
 
   def test_uniq
+    assert_equal ["foo"], @filters.uniq("foo")
     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