Add replace_last and remove_last filters (#1422)

Co-authored-by: ADTC <[email protected]>
Co-authored-by: Dylan Thacker-Smith <[email protected]>

History.md

@@ -1,10 +1,12 @@
 # Liquid Change Log
 
-## 5.1.1 (unreleased)
+## 5.2.0 (unreleased)
+
+### Features
+* Add `remove_last`, and `replace_last` filters (#1422) [Anders Hagbard]
 
 ### Fixes
-
-* Fix some internal errors in filters from invalid input [Dylan Thacker-Smith]
+* Fix some internal errors in filters from invalid input (#1476) [Dylan Thacker-Smith]
 
 ## 5.1.0 / 2021-09-09
 

lib/liquid/standardfilters.rb

@@ -308,14 +308,34 @@ module Liquid
       input.to_s.sub(string.to_s, replacement.to_s)
     end
 
+    # Replace the last occurrences of a string with another
+    def replace_last(input, string, replacement)
+      input = input.to_s
+      string = string.to_s
+      replacement = replacement.to_s
+
+      start_index = input.rindex(string)
+
+      return input unless start_index
+
+      output = input.dup
+      output[start_index, string.length] = replacement
+      output
+    end
+
     # remove a substring
     def remove(input, string)
-      input.to_s.gsub(string.to_s, '')
+      replace(input, string, '')
     end
 
     # remove the first occurrences of a substring
     def remove_first(input, string)
-      input.to_s.sub(string.to_s, '')
+      replace_first(input, string, '')
+    end
+
+    # remove the last occurences of a substring
+    def remove_last(input, string)
+      replace_last(input, string, '')
     end
 
     # add one string to another

test/integration/standard_filter_test.rb

@@ -539,19 +539,31 @@ class StandardFiltersTest < Minitest::Test
   end
 
   def test_replace
-    assert_equal('2 2 2 2', @filters.replace('1 1 1 1', '1', 2))
+    assert_equal('b b b b', @filters.replace('a a a a', 'a', 'b'))
     assert_equal('2 2 2 2', @filters.replace('1 1 1 1', 1, 2))
-    assert_equal('2 1 1 1', @filters.replace_first('1 1 1 1', '1', 2))
+    assert_equal('1 1 1 1', @filters.replace('1 1 1 1', 2, 3))
+    assert_template_result('2 2 2 2', "{{ '1 1 1 1' | replace: '1', 2 }}")
+
+    assert_equal('b a a a', @filters.replace_first('a a a a', 'a', 'b'))
     assert_equal('2 1 1 1', @filters.replace_first('1 1 1 1', 1, 2))
+    assert_equal('1 1 1 1', @filters.replace_first('1 1 1 1', 2, 3))
     assert_template_result('2 1 1 1', "{{ '1 1 1 1' | replace_first: '1', 2 }}")
+
+    assert_equal('a a a b', @filters.replace_last('a a a a', 'a', 'b'))
+    assert_equal('1 1 1 2', @filters.replace_last('1 1 1 1', 1, 2))
+    assert_equal('1 1 1 1', @filters.replace_last('1 1 1 1', 2, 3))
+    assert_template_result('1 1 1 2', "{{ '1 1 1 1' | replace_last: '1', 2 }}")
   end
 
   def test_remove
     assert_equal('   ', @filters.remove("a a a a", 'a'))
-    assert_equal('   ', @filters.remove("1 1 1 1", 1))
-    assert_equal('a a a', @filters.remove_first("a a a a", 'a '))
-    assert_equal(' 1 1 1', @filters.remove_first("1 1 1 1", 1))
-    assert_template_result('a a a', "{{ 'a a a a' | remove_first: 'a ' }}")
+    assert_template_result('   ', "{{ '1 1 1 1' | remove: 1 }}")
+
+    assert_equal('b a a', @filters.remove_first("a b a a", 'a '))
+    assert_template_result(' 1 1 1', "{{ '1 1 1 1' | remove_first: 1 }}")
+
+    assert_equal('a a b', @filters.remove_last("a a b a", ' a'))
+    assert_template_result('1 1 1 ', "{{ '1 1 1 1' | remove_last: 1 }}")
   end
 
   def test_pipes_in_string_arguments