liquid without the garbage

lib/liquid/block.rb

@@ -13,8 +13,8 @@ module Liquid
       end
     end
 
-    def render(context)
-      @body.render(context)
+    def render(context, output = '')
+      @body.render(context, output)
     end
 
     def blank?

lib/liquid/block_body.rb

@@ -66,8 +66,7 @@ module Liquid
       @blank
     end
 
-    def render(context)
-      output = []
+    def render(context, output = '')
       context.resource_limits.render_score += @nodelist.length
 
       idx = 0
@@ -77,9 +76,9 @@ module Liquid
           check_resources(context, node)
           output << node
         when Variable
-          render_node_to_output(node, output, context)
+          render_node(context, output, node)
         when Block
-          render_node_to_output(node, output, context, node.blank?)
+          render_node(context, node.blank? ? '' : output, node)
           break if context.interrupt? # might have happened in a for-block
         when Continue, Break
           # If we get an Interrupt that means the block must stop processing. An
@@ -88,34 +87,31 @@ module Liquid
           context.push_interrupt(node.interrupt)
           break
         else # Other non-Block tags
-          render_node_to_output(node, output, context)
+          render_node(context, output, node)
           break if context.interrupt? # might have happened through an include
         end
         idx += 1
       end
 
-      output.join
+      output
     end
 
     private
 
-    def render_node_to_output(node, output, context, skip_output = false)
-      node_output = node.render(context)
-      node_output = node_output.is_a?(Array) ? node_output.join : node_output.to_s
-      check_resources(context, node_output)
-      output << node_output unless skip_output
+    def render_node(context, output, node)
+      node.render(context, output)
+      check_resources(context, output)
     rescue MemoryError => e
       raise e
     rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
       context.handle_error(e, node.line_number)
-      output << nil
     rescue ::StandardError => e
       line_number = node.is_a?(String) ? nil : node.line_number
       output << context.handle_error(e, line_number)
     end
 
-    def check_resources(context, node_output)
-      context.resource_limits.render_length += node_output.bytesize
+    def check_resources(context, output)
+      context.resource_limits.render_length = output.bytesize
       return unless context.resource_limits.reached?
       raise MemoryError.new("Memory limits exceeded".freeze)
     end

lib/liquid/profiler/hooks.rb

@@ -1,19 +1,19 @@
 module Liquid
   class BlockBody
-    def render_node_with_profiling(node, output, context, skip_output = false)
+    def render_node_with_profiling(context, output, node)
       Profiler.profile_node_render(node) do
-        render_node_without_profiling(node, output, context, skip_output)
+        render_node_without_profiling(context, output, node)
       end
     end
 
-    alias_method :render_node_without_profiling, :render_node_to_output
-    alias_method :render_node_to_output, :render_node_with_profiling
+    alias_method :render_node_without_profiling, :render_node
+    alias_method :render_node, :render_node_with_profiling
   end
 
   class Include < Tag
-    def render_with_profiling(context)
+    def render_with_profiling(context, output)
       Profiler.profile_children(context.evaluate(@template_name_expr).to_s) do
-        render_without_profiling(context)
+        render_without_profiling(context, output)
       end
     end
 

lib/liquid/tag.rb

@@ -32,8 +32,8 @@ module Liquid
       self.class.name.downcase
     end
 
-    def render(_context)
-      ''.freeze
+    def render(_context, output = '')
+      output
     end
 
     def blank?

lib/liquid/tags/assign.rb

@@ -22,11 +22,11 @@ module Liquid
       end
     end
 
-    def render(context)
-      val = @from.render(context)
+    def render(context, output = '')
+      val = @from.render(context, nil)
       context.scopes.last[@to] = val
       context.resource_limits.assign_score += assign_score_of(val)
-      ''.freeze
+      output
     end
 
     def blank?

lib/liquid/tags/capture.rb

@@ -22,11 +22,11 @@ module Liquid
       end
     end
 
-    def render(context)
-      output = super
+    def render(context, output = '')
+      super
       context.scopes.last[@to] = output
-      context.resource_limits.assign_score += output.bytesize
-      ''.freeze
+      context.resource_limits.assign_score = output.bytesize
+      output
     end
 
     def blank?

lib/liquid/tags/case.rb

@@ -38,21 +38,21 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render(context, output = '')
       context.stack do
         execute_else_block = true
 
-        output = ''
         @blocks.each do |block|
           if block.else?
-            return block.attachment.render(context) if execute_else_block
+            block.attachment.render(context, output) if execute_else_block
           elsif block.evaluate(context)
             execute_else_block = false
-            output << block.attachment.render(context)
+            block.attachment.render(context, output)
           end
         end
-        output
       end
+
+      output
     end
 
     private

lib/liquid/tags/comment.rb

@@ -1,7 +1,7 @@
 module Liquid
   class Comment < Block
-    def render(_context)
-      ''.freeze
+    def render(_context, output = '')
+      output
     end
 
     def unknown_tag(_tag, _markup, _tokens)

lib/liquid/tags/cycle.rb

@@ -31,18 +31,29 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render(context, output = '')
       context.registers[:cycle] ||= {}
 
       context.stack do
         key = context.evaluate(@name)
         iteration = context.registers[:cycle][key].to_i
-        result = context.evaluate(@variables[iteration])
+
+        val = context.evaluate(@variables[iteration])
+
+        if val.is_a?(Array)
+          val = val.join
+        elsif !val.is_a?(String)
+          val = val.to_s
+        end
+
+        output << val
+
         iteration += 1
         iteration  = 0 if iteration >= @variables.size
         context.registers[:cycle][key] = iteration
-        result
       end
+
+      output
     end
 
     private

lib/liquid/tags/decrement.rb

@@ -23,11 +23,12 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render(context, output = '')
       value = context.environments.first[@variable] ||= 0
       value -= 1
       context.environments.first[@variable] = value
-      value.to_s
+      output << value.to_s
+      output
     end
   end
 

lib/liquid/tags/for.rb

@@ -70,13 +70,13 @@ module Liquid
       @else_block = BlockBody.new
     end
 
-    def render(context)
+    def render(context, output = '')
       segment = collection_segment(context)
 
       if segment.empty?
-        render_else(context)
+        render_else(context, output)
       else
-        render_segment(context, segment)
+        render_segment(context, output, segment)
       end
     end
 
@@ -141,12 +141,10 @@ module Liquid
       segment
     end
 
-    def render_segment(context, segment)
+    def render_segment(context, output, segment)
       for_stack = context.registers[:for_stack] ||= []
       length = segment.length
 
-      result = ''
-
       context.stack do
         loop_vars = Liquid::ForloopDrop.new(@name, length, for_stack[-1])
 
@@ -157,7 +155,7 @@ module Liquid
 
           segment.each do |item|
             context[@variable_name] = item
-            result << @for_block.render(context)
+            @for_block.render(context, output)
             loop_vars.send(:increment!)
 
             # Handle any interrupts if they exist.
@@ -172,7 +170,7 @@ module Liquid
         end
       end
 
-      result
+      output
     end
 
     def set_attribute(key, expr)
@@ -188,8 +186,12 @@ module Liquid
       end
     end
 
-    def render_else(context)
-      @else_block ? @else_block.render(context) : ''.freeze
+    def render_else(context, output)
+      if @else_block
+        @else_block.render(context, output)
+      else
+        output
+      end
     end
 
     class ParseTreeVisitor < Liquid::ParseTreeVisitor

lib/liquid/tags/if.rb

@@ -39,15 +39,16 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render(context, output)
       context.stack do
         @blocks.each do |block|
           if block.evaluate(context)
-            return block.attachment.render(context)
+            return block.attachment.render(context, output)
           end
         end
-        ''.freeze
       end
+
+      output
     end
 
     private

lib/liquid/tags/ifchanged.rb

@@ -1,16 +1,16 @@
 module Liquid
   class Ifchanged < Block
-    def render(context)
+    def render(context, output)
       context.stack do
-        output = super
+        block_output = super(context, '')
 
-        if output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = output
-          output
-        else
-          ''.freeze
+        if block_output != context.registers[:ifchanged]
+          context.registers[:ifchanged] = block_output
+          output << block_output
         end
       end
+
+      output
     end
   end
 

lib/liquid/tags/include.rb

@@ -42,7 +42,7 @@ module Liquid
     def parse(_tokens)
     end
 
-    def render(context)
+    def render(context, output)
       template_name = context.evaluate(@template_name_expr)
       raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
 
@@ -66,19 +66,21 @@ module Liquid
           end
 
           if variable.is_a?(Array)
-            variable.collect do |var|
+            variable.each do |var|
               context[context_variable_name] = var
-              partial.render(context)
+              partial.render(context, output: output)
             end
           else
             context[context_variable_name] = variable
-            partial.render(context)
+            partial.render(context, output: output)
           end
         end
       ensure
         context.template_name = old_template_name
         context.partial = old_partial
       end
+
+      output
     end
 
     private

lib/liquid/tags/increment.rb

@@ -20,10 +20,11 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render(context, output = '')
       value = context.environments.first[@variable] ||= 0
       context.environments.first[@variable] = value + 1
-      value.to_s
+      output << value.to_s
+      output
     end
   end
 

lib/liquid/tags/raw.rb

@@ -22,8 +22,9 @@ module Liquid
       raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
     end
 
-    def render(_context)
-      @body
+    def render(_context, output = '')
+      output << @body
+      output
     end
 
     def nodelist

lib/liquid/tags/table_row.rb

@@ -18,7 +18,7 @@ module Liquid
       end
     end
 
-    def render(context)
+    def render(context, output = '')
       collection = context.evaluate(@collection_name) or return ''.freeze
 
       from = @attributes.key?('offset'.freeze) ? context.evaluate(@attributes['offset'.freeze]).to_i : 0
@@ -30,7 +30,7 @@ module Liquid
 
       cols = context.evaluate(@attributes['cols'.freeze]).to_i
 
-      result = "<tr class=\"row1\">\n"
+      output << "<tr class=\"row1\">\n"
       context.stack do
         tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
         context['tablerowloop'.freeze] = tablerowloop
@@ -38,17 +38,20 @@ module Liquid
         collection.each do |item|
           context[@variable_name] = item
 
-          result << "<td class=\"col#{tablerowloop.col}\">" << super << '</td>'
+          output << "<td class=\"col#{tablerowloop.col}\">"
+          super
+          output << '</td>'
 
           if tablerowloop.col_last && !tablerowloop.last
-            result << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
+            output << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
           end
 
           tablerowloop.send(:increment!)
         end
       end
-      result << "</tr>\n"
-      result
+
+      output << "</tr>\n"
+      output
     end
 
     class ParseTreeVisitor < Liquid::ParseTreeVisitor

lib/liquid/tags/unless.rb

@@ -6,23 +6,23 @@ module Liquid
   #   {% unless x < 0 %} x is greater than zero {% endunless %}
   #
   class Unless < If
-    def render(context)
+    def render(context, output = '')
       context.stack do
         # First condition is interpreted backwards ( if not )
         first_block = @blocks.first
         unless first_block.evaluate(context)
-          return first_block.attachment.render(context)
+          return first_block.attachment.render(context, output)
         end
 
         # After the first condition unless works just like if
         @blocks[1..-1].each do |block|
           if block.evaluate(context)
-            return block.attachment.render(context)
+            return block.attachment.render(context, output)
           end
         end
-
-        ''.freeze
       end
+
+      output
     end
   end
 

lib/liquid/template.rb

@@ -187,9 +187,12 @@ module Liquid
         raise ArgumentError, "Expected Hash or Liquid::Context as parameter"
       end
 
+      output = nil
+
       case args.last
       when Hash
         options = args.pop
+        output = options[:output] if options[:output]
 
         registers.merge!(options[:registers]) if options[:registers].is_a?(Hash)
 
@@ -205,7 +208,8 @@ module Liquid
         # render the nodelist.
         # for performance reasons we get an array back here. join will make a string out of it.
         result = with_profiling(context) do
-          @root.render(context)
+          output ||= self.class.output_buffer.clear
+          @root.render(context, output)
         end
         result.respond_to?(:join) ? result.join : result
       rescue Liquid::MemoryError => e
@@ -215,6 +219,10 @@ module Liquid
       end
     end
 
+    def self.output_buffer
+      @output_buffer ||= String.new(capacity: 1024)
+    end
+
     def render!(*args)
       @rethrow_errors = true
       render(*args)

lib/liquid/variable.rb

@@ -78,7 +78,7 @@ module Liquid
       filterargs
     end
 
-    def render(context)
+    def render(context, output = '')
       obj = @filters.inject(context.evaluate(@name)) do |output, (filter_name, filter_args, filter_kwargs)|
         filter_args = evaluate_filter_expressions(context, filter_args, filter_kwargs)
         context.invoke(filter_name, output, *filter_args)
@@ -88,7 +88,20 @@ module Liquid
 
       taint_check(context, obj)
 
-      obj
+      if output
+        if obj.is_a?(Array)
+          output << obj.join
+        elsif obj.nil?
+        elsif !obj.is_a?(String)
+          output << obj.to_s
+        else
+          output << obj
+        end
+
+        output
+      else
+        obj
+      end
     end
 
     private

performance/shopify/comment_form.rb

@@ -12,7 +12,7 @@ class CommentForm < Liquid::Block
     end
   end
 
-  def render(context)
+  def render(context, output = '')
     article = context[@variable_name]
 
     context.stack do
@@ -23,7 +23,9 @@ class CommentForm < Liquid::Block
         'email'  => context['comment.email'],
         'body'   => context['comment.body']
       }
-      wrap_in_form(article, render_all(@nodelist, context))
+
+      output << wrap_in_form(article, render_all(@nodelist, context, output))
+      output
     end
   end
 

performance/shopify/paginate.rb

@@ -21,7 +21,7 @@ class Paginate < Liquid::Block
     end
   end
 
-  def render(context)
+  def render(context, output = '')
     @context = context
 
     context.stack do

test/integration/blank_test.rb

@@ -1,8 +1,9 @@
 require 'test_helper'
 
 class FoobarTag < Liquid::Tag
-  def render(*args)
-    " "
+  def render(context, output = '')
+    output << ' '
+    output
   end
 
   Liquid::Template.register_tag('foobar', FoobarTag)

test/integration/tags/include_tag_test.rb

@@ -66,8 +66,9 @@ class CustomInclude < Liquid::Tag
   def parse(tokens)
   end
 
-  def render(context)
-    @template_name[1..-2]
+  def render(context, output = '')
+    output << @template_name[1..-2]
+    output
   end
 end
 

test/integration/template_test.rb

@@ -177,31 +177,31 @@ class TemplateTest < Minitest::Test
 
   def test_render_length_persists_between_blocks
     t = Template.parse("{% if true %}aaaa{% endif %}")
-    t.resource_limits.render_length_limit = 7
+    t.resource_limits.render_length_limit = 3
     assert_equal "Liquid error: Memory limits exceeded", t.render
-    t.resource_limits.render_length_limit = 8
+    t.resource_limits.render_length_limit = 4
     assert_equal "aaaa", t.render
 
     t = Template.parse("{% if true %}aaaa{% endif %}{% if true %}bbb{% endif %}")
-    t.resource_limits.render_length_limit = 13
+    t.resource_limits.render_length_limit = 6
     assert_equal "Liquid error: Memory limits exceeded", t.render
-    t.resource_limits.render_length_limit = 14
+    t.resource_limits.render_length_limit = 7
     assert_equal "aaaabbb", t.render
 
     t = Template.parse("{% if true %}a{% endif %}{% if true %}b{% endif %}{% if true %}a{% endif %}{% if true %}b{% endif %}{% if true %}a{% endif %}{% if true %}b{% endif %}")
+    t.resource_limits.render_length_limit = 4
+    assert_equal "Liquid error: Memory limits exceeded", t.render
     t.resource_limits.render_length_limit = 5
     assert_equal "Liquid error: Memory limits exceeded", t.render
-    t.resource_limits.render_length_limit = 11
-    assert_equal "Liquid error: Memory limits exceeded", t.render
-    t.resource_limits.render_length_limit = 12
+    t.resource_limits.render_length_limit = 6
     assert_equal "ababab", t.render
   end
 
   def test_render_length_uses_number_of_bytes_not_characters
     t = Template.parse("{% if true %}すごい{% endif %}")
-    t.resource_limits.render_length_limit = 10
+    t.resource_limits.render_length_limit = 8
     assert_equal "Liquid error: Memory limits exceeded", t.render
-    t.resource_limits.render_length_limit = 18
+    t.resource_limits.render_length_limit = 9
     assert_equal "すごい", t.render
   end