Override some filters of Liquid core.

These filters change the implemntation of sub and gsub to use the block method.
This prevents the evaluation of backreferences in the replacement text. See
https://gist.github.com/1491437 for examples.

Also, it allows split to be called without arguments to split strings on
whitespace.

lib/chili_project/liquid/filters.rb

@@ -13,6 +13,38 @@
 
 module ChiliProject
   module Liquid
+    module OverriddenFilters
+      # These filters are defined in liquid core but are overwritten here
+      # to improve on their implementation
+
+      # Split input string into an array of substrings separated by given pattern.
+      # Default to whitespace
+      def split(input, pattern=nil)
+        input.split(pattern)
+      end
+
+      def strip_newlines(input)
+        input.to_s.gsub(/\r?\n/, '')
+      end
+
+      # Add <br /> tags in front of all newlines in input string
+      def newline_to_br(input)
+        input.to_s.gsub(/(\r?\n)/, "<br />\1")
+      end
+
+      # Use the block systax for sub and gsub to prevent interpretation of
+      # backreferences
+      # See https://gist.github.com/1491437
+      def replace(input, string, replacement = '')
+        input.to_s.gsub(string){replacement}
+      end
+
+      # Replace the first occurrences of a string with another
+      def replace_first(input, string, replacement = '')
+        input.to_s.sub(string){replacement}
+      end
+    end
+
     module Filters
       def default(input, default)
         input.to_s.strip.present? ? input : default
@@ -23,6 +55,7 @@ module ChiliProject
       end
     end
 
+    Template.register_filter(OverriddenFilters)
     Template.register_filter(Filters)
   end
 end