Use same approach in scope and environment

Add a CI job to profile memory usage of commit

.travis.yml

@@ -6,18 +6,21 @@ rvm:
   - 2.3
   - 2.4
   - 2.5
+  - &latest_ruby 2.6
   - ruby-head
   - jruby-head
 #  - rbx-2
 
-sudo: false
-
 addons:
   apt:
     packages:
     - libgmp3-dev
 
 matrix:
+  include:
+    - rvm: *latest_ruby
+      script: bundle exec rake memory_profile:run
+      name: Profiling Memory Usage
   allow_failures:
     - rvm: ruby-head
     - rvm: jruby-head

Gemfile

@@ -5,10 +5,10 @@ end
 
 gemspec
 
-
 group :benchmark, :test do
   gem 'benchmark-ips'
   gem 'memory_profiler'
+  gem 'terminal-table'
 
   install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ } do
     gem 'stackprof'
@@ -17,11 +17,8 @@ end
 
 group :test do
   gem 'rubocop', '~> 0.53.0'
-  gem 'awesome_print'
-  gem 'pry'
-  gem 'byebug'
 
   platform :mri do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: '9168659de45d6d576fce30c735f857e597fa26f6'
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'liquid-tag'
   end
 end

Rakefile

@@ -45,17 +45,6 @@ task :test do
   end
 end
 
-desc 'runs the test suite using the superfluid compiler'
-Rake::TestTask.new(:test_superfluid) do |t|
-  t.libs << '.' << 'lib' << 'test'
-  t.test_files = FileList['test/integration/**/*_test.rb']
-  t.verbose = false
-
-  ENV['LIQUID_PARSER_MODE'] = 'strict'
-  ENV['LIQUID-C'] = '1'
-  ENV['SUPERFLUID'] = '1'
-end
-
 task gem: :build
 task :build do
   system "gem build liquid.gemspec"
@@ -82,11 +71,6 @@ namespace :benchmark do
   task :strict do
     ruby "./performance/benchmark.rb strict"
   end
-
-  desc "Run the liquid benchmark with strict parsing"
-  task :superfluid do
-    ruby "./performance/benchmark.rb superfluid"
-  end
 end
 
 namespace :profile do

lib/liquid/block_body.rb

@@ -1,6 +1,7 @@
 module Liquid
   class BlockBody
-    FullToken = /\A#{TagStart}#{WhitespaceControl}?\s*(\w+)\s*(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
+    LiquidTagToken = /\A\s*(\w+)\s*(.*?)\z/o
+    FullToken = /\A#{TagStart}#{WhitespaceControl}?(\s*)(\w+)(\s*)(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
     ContentOfVariable = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
     WhitespaceOrNothing = /\A\s*\z/
     TAGSTART = "{%".freeze
@@ -13,8 +14,42 @@ module Liquid
       @blank = true
     end
 
-    def parse(tokenizer, parse_context)
+    def parse(tokenizer, parse_context, &block)
       parse_context.line_number = tokenizer.line_number
+
+      if tokenizer.for_liquid_tag
+        parse_for_liquid_tag(tokenizer, parse_context, &block)
+      else
+        parse_for_document(tokenizer, parse_context, &block)
+      end
+    end
+
+    private def parse_for_liquid_tag(tokenizer, parse_context)
+      while token = tokenizer.shift
+        unless token.empty? || token =~ WhitespaceOrNothing
+          unless token =~ LiquidTagToken
+            # line isn't empty but didn't match tag syntax, yield and let the
+            # caller raise a syntax error
+            return yield token, token
+          end
+          tag_name = $1
+          markup = $2
+          unless tag = registered_tags[tag_name]
+            # end parsing if we reach an unknown tag and let the caller decide
+            # determine how to proceed
+            return yield tag_name, markup
+          end
+          new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+          @blank &&= new_tag.blank?
+          @nodelist << new_tag
+        end
+        parse_context.line_number = tokenizer.line_number
+      end
+
+      yield nil, nil
+    end
+
+    private def parse_for_document(tokenizer, parse_context, &block)
       while token = tokenizer.shift
         next if token.empty?
         case
@@ -23,9 +58,20 @@ module Liquid
           unless token =~ FullToken
             raise_missing_tag_terminator(token, parse_context)
           end
-          tag_name = $1
+          tag_name = $2
-          markup = $2
+          markup = $4
-          # fetch the tag from registered blocks
+
+          if parse_context.line_number
+            # newlines inside the tag should increase the line number,
+            # particularly important for multiline {% liquid %} tags
+            parse_context.line_number += $1.count("\n".freeze) + $3.count("\n".freeze)
+          end
+
+          if tag_name == 'liquid'.freeze
+            liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)
+            next parse_for_liquid_tag(liquid_tag_tokenizer, parse_context, &block)
+          end
+
           unless tag = registered_tags[tag_name]
             # end parsing if we reach an unknown tag and let the caller decide
             # determine how to proceed
@@ -97,7 +143,7 @@ module Liquid
         end
         idx += 1
 
-        context.raise_if_resource_limits_reached(output.bytesize - previous_output_size)
+        raise_if_resource_limits_reached(context, output.bytesize - previous_output_size)
       end
 
       output
@@ -114,6 +160,12 @@ module Liquid
       output << context.handle_error(e, line_number)
     end
 
+    def raise_if_resource_limits_reached(context, length)
+      context.resource_limits.render_length += length
+      return unless context.resource_limits.reached?
+      raise MemoryError.new("Memory limits exceeded".freeze)
+    end
+
     def create_variable(token, parse_context)
       token.scan(ContentOfVariable) do |content|
         markup = content.first

lib/liquid/condition.rb

@@ -29,7 +29,7 @@ module Liquid
       @@operators
     end
 
-    attr_reader :attachment, :child_condition, :child_relation
+    attr_reader :attachment, :child_condition
     attr_accessor :left, :operator, :right
 
     def initialize(left = nil, operator = nil, right = nil)
@@ -81,6 +81,10 @@ module Liquid
       "#<Condition #{[@left, @operator, @right].compact.join(' '.freeze)}>"
     end
 
+    protected
+
+    attr_reader :child_relation
+
     private
 
     def equal_variables(left, right)

lib/liquid/context.rb

@@ -20,31 +20,17 @@ module Liquid
       @scopes           = [(outer_scope || {})]
       @registers        = registers
       @errors           = []
+      @interrupts       = []
+      @filters          = []
+      @global_filter    = nil
       @partial          = false
       @strict_variables = false
       @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
-      squash_instance_assigns_with_environments
-
-      @this_stack_used = false
 
       self.exception_renderer = Template.default_exception_renderer
-      if rethrow_errors
+      self.exception_renderer = ->(e) { raise } if rethrow_errors
-        self.exception_renderer = ->(e) { raise }
-      end
 
-      @interrupts = []
+      squash_instance_assigns_with_environments
-      @filters = []
-      @global_filter = nil
-    end
-
-    def raise_argument_error(message)
-      raise Liquid::ArgumentError, message
-    end
-
-    def raise_if_resource_limits_reached(length)
-      resource_limits.render_length += length
-      return unless resource_limits.reached?
-      raise MemoryError.new("Memory limits exceeded".freeze)
     end
 
     def warnings
@@ -97,9 +83,9 @@ module Liquid
     end
 
     # Push new local scope on the stack. use <tt>Context#stack</tt> instead
-    def push(new_scope = {})
+    def push
-      @scopes.unshift(new_scope)
+      @scopes.unshift({})
-      raise StackLevelError, "Nesting too deep".freeze if @scopes.length > Block::MAX_DEPTH
+      raise StackLevelError, "Nesting too deep".freeze if @scopes.length > (Block::MAX_DEPTH + 1)
     end
 
     # Merge a hash of variables in the current local scope
@@ -121,31 +107,15 @@ module Liquid
     #   end
     #
     #   context['var]  #=> nil
-    def stack(new_scope = nil)
+    def stack
-      old_stack_used = @this_stack_used
+      push
-      if new_scope
-        push(new_scope)
-        @this_stack_used = true
-      else
-        @this_stack_used = false
-      end
-
       yield
     ensure
-      pop if @this_stack_used
+      pop
-      @this_stack_used = old_stack_used
-    end
-
-    def clear_instance_assigns
-      @scopes[0] = {}
     end
 
     # Only allow String, Numeric, Hash, Array, Proc, Boolean or <tt>Liquid::Drop</tt>
     def []=(key, value)
-      unless @this_stack_used
-        @this_stack_used = true
-        push({})
-      end
       @scopes[0][key] = value
     end
 
@@ -173,27 +143,12 @@ module Liquid
     def find_variable(key, raise_on_not_found: true)
       # This was changed from find() to find_index() because this is a very hot
       # path and find_index() is optimized in MRI to reduce object allocation
-      index = @scopes.find_index { |s| s.key?(key) }
-      scope = @scopes[index] if index
 
-      variable = nil
+      scope = (index = @scopes.find_index { |s| s.key?(key)  }) && @scopes[index]
+      scope ||= (index = @environments.find_index { |s| s.key?(key) }) && @environments[index]
+      scope ||= {}
 
-      if scope.nil?
+      variable = lookup_and_evaluate(scope, key, raise_on_not_found: raise_on_not_found).to_liquid
-        @environments.each do |e|
-          variable = lookup_and_evaluate(e, key, raise_on_not_found: raise_on_not_found)
-          # When lookup returned a value OR there is no value but the lookup also did not raise
-          # then it is the value we are looking for.
-          if !variable.nil? || @strict_variables && raise_on_not_found
-            scope = e
-            break
-          end
-        end
-      end
-
-      scope ||= @environments.last || @scopes.last
-      variable ||= lookup_and_evaluate(scope, key, raise_on_not_found: raise_on_not_found)
-
-      variable = variable.to_liquid
       variable.context = self if variable.respond_to?(:context=)
 
       variable

lib/liquid/range_lookup.rb

@@ -15,8 +15,6 @@ module Liquid
       @end_obj = end_obj
     end
 
-    attr_reader :start_obj, :end_obj
-
     def evaluate(context)
       start_int = to_integer(context.evaluate(@start_obj))
       end_int = to_integer(context.evaluate(@end_obj))

lib/liquid/superfluid.rb

@@ -1,632 +0,0 @@
-require 'ap'
-
-require 'pry'
-
-require 'stackprof'
-
-AwesomePrint.defaults = {
-  raw: true
-}
-
-module Liquid
-  Liquid::BlockBody.class_eval do
-    def render_to_output_buffer(context, output)
-
-      ruby = Compiler.compile(@nodelist)
-      
-      if false
-        puts
-        puts "--------------------------- GENERATED RUBY -"
-        line_number = 1
-        puts(ruby.lines.map do |line|
-          "#{line_number}\t#{line}".tap { line_number += 1}
-        end)
-        puts "--------------------------- /GENERATED RUBY -"
-      end
-
-      instructions = RubyVM::InstructionSequence.compile(ruby)
-
-      output_io = StringIO.new
-      instructions.eval.call(output_io, context, Condition)
-
-      output << output_io.string
-    end
-  end
-
-  class SuperfluidError < Exception
-  end
-
-  class Output
-    attr_reader :string, :indent_level
-
-    def initialize(initial_indent)
-      @string = ''.dup
-      @indent_level = initial_indent
-      @indent_str = " " * initial_indent * 2
-    end
-
-    def line(string)
-      @string << @indent_str << string << "\n"
-    end
-
-    def echo(string)
-      output << "liquid_out.write(to_output(#{string}))"
-    end
-
-    def indent(&block)
-      output.indent(&block)
-    end
-
-    def indent
-      @indent_level += 1
-      @indent_str = " " * @indent_level * 2
-      yield
-      @indent_level -= 1
-      @indent_str = " " * @indent_level * 2
-    end
-  end
-
-  class Compiler
-    class << self
-      def compile(template)
-        compiler = new
-        compiler.compile(template)
-        compiler.ruby
-      end
-    end
-
-    def initialize
-      @variables = Set.new
-      @output = Output.new(2)
-      @blank = false
-    end
-
-    def ruby
-      [
-        header,
-        @output.string,
-        trailer
-      ].join("\n")
-    end
-
-
-    def header
-      <<~RUBY
-      module Warning
-        def warn(*)
-        end
-      end
-
-      class ForloopDrop
-        def initialize(name, length, parentloop)
-          @name = name
-          @length = length
-          @parentloop = parentloop
-          @index = 0
-        end
-
-        attr_accessor :parentloop
-
-        def [](value)
-          case value
-          when "length"
-            @length
-          when "name"
-            @name
-          when "index"
-            @index + 1
-          when "index0"
-            @index
-          when "rindex"
-            @length - @index
-          when "rindex0"
-            @length - @index - 1
-          when "first"
-            @index == 0
-          when "last"
-            @index == @length - 1
-          when "parentloop"
-            @parentloop
-          end
-        end
-
-        def to_liquid
-          self
-        end
-
-        def key?(*)
-          true
-        end
-
-        private
-
-        def increment!
-          @index += 1
-        end
-      end
-
-      def slice_collection(collection, from, limit)
-        to = if limit.nil?
-          nil
-        else
-          limit + from
-        end
-
-        if (from != 0 || !to.nil?) && collection.respond_to?(:load_slice)
-          collection.load_slice(from, to)
-        else
-          slice_collection_using_each(collection, from, to)
-        end
-      end
-
-      def slice_collection_using_each(collection, from, to)
-        segments = []
-        index = 0
-
-        if collection.is_a?(String)
-          return collection.empty? ? [] : [collection]
-        end
-        return [] unless collection.respond_to?(:each)
-
-        collection.each do |item|
-          if to && to <= index
-            break
-          end
-
-          if from <= index
-            segments << item
-          end
-
-          index += 1
-        end
-
-        segments
-      end
-
-      def apply_operator(left, operator, right)
-        if left.respond_to?(operator) && right.respond_to?(operator) && !left.is_a?(Hash) && !right.is_a?(Hash)
-          begin
-            left.send(operator, right)
-          rescue ::ArgumentError => e
-            raise @context.raise_argument_error(e.message)
-          end
-        end
-      end
-
-      def contains?(left, right)
-        if left && right && left.respond_to?(:include?)
-          right = right.to_s if left.is_a?(String)
-          left.include?(right)
-        else
-          false
-        end
-      end
-
-      class GlobalVariableLookup
-        def method_missing(method_name, *)
-          nil
-        end
-
-        def to_output(value)
-          output = if value.is_a?(Array)
-            value.join
-          elsif value == nil
-          else
-            value.to_s
-          end
-          @context.apply_global_filter(output)
-        end
-
-        def run(liquid_out, context, condition)
-          @condition = condition
-          @context = context
-          @for_offsets = {}
-          @cycle_values = {}
-          @context.registers[:for_stack] = []
-          @context.registers[:cycle] ||= {}
-          @if_changed_last = nil
-          @prev_output_size = 0
-          #{hoisted_variables}
-      RUBY
-    end
-
-    def trailer
-      <<~RUBY
-          end
-        end
-        GlobalVariableLookup.new.method(:run)
-      RUBY
-    end
-
-    def hoisted_variables
-      @variables.map do |variable|
-        normal_name = unvar(variable)
-        "#{variable} = @context.find_variable(#{normal_name.inspect}, raise_on_not_found: false)"
-      end.join("\n")
-    end
-
-    def compile(node)
-      old_blank = @blank
-      @blank = if node.respond_to?(:blank?)
-        node.blank?
-      elsif !(node.is_a?(String) && node =~ /\A\s*\z/)
-        false
-      else
-        @blank
-      end
-
-      case node
-      when Liquid::Document, Liquid::BlockBody
-        node.nodelist.collect(&method(:compile))
-      when Array
-        node.collect(&method(:compile))
-      when Liquid::Variable
-        compile_variable(node)
-      when Liquid::For
-        compile_for(node)
-      when Liquid::If
-        compile_if(node)
-      when Liquid::Ifchanged
-        compile_if_changed(node)
-      when Liquid::Template
-        compile(node.root)
-      when Liquid::Assign
-        compile_assign(node)
-      when Liquid::Case
-        compile_case(node)
-      when Liquid::Capture
-        compile_capture(node)
-      when String
-        compile_echo_literal(node)
-      when Liquid::Break
-        line "break" if @in_loop
-      when Liquid::Continue
-        line "next" if @in_loop
-      when Liquid::Cycle
-        compile_cycle(node)
-      when Liquid::Raw
-        compile_raw(node)
-      when Liquid::Increment
-        compile_increment(node)
-      when Liquid::Decrement
-        compile_decrement(node)
-      when Liquid::Comment
-      else
-        raise SuperfluidError, "Unknown node type #{node.inspect}"
-      end
-
-      @blank = old_blank
-    end
-
-    def compile_for(node)
-      variable_name = node.variable_name
-
-      collection_name = node.collection_name
-
-      iter_target_expr = case collection_name
-      when Liquid::VariableLookup
-        make_variable_lookup_expr(collection_name)
-      when Range
-        collection_name
-      when Liquid::RangeLookup
-        start_expr = make_variable_expr(collection_name.start_obj)
-        end_expr = make_variable_expr(collection_name.end_obj)
-        line "start = #{start_expr}"
-        line "@context.raise_argument_error('bad value for range') unless start.respond_to?(:to_i)"
-        line "start = #{start_expr}.to_i"
-
-        line "finish = #{end_expr}"
-        line "@context.raise_argument_error('bad value for range') unless finish.respond_to?(:to_i)"
-        line "finish = #{end_expr}.to_i"
-
-        "start..finish"
-      when Liquid::Expression::MethodLiteral
-        '[]'
-      else
-        raise SuperfluidError, "Unknown iteration target: #{collection_name.inspect}"
-      end
-
-      from_expr = if node.from == :continue
-        "@for_offsets['#{node.name}'].to_i"
-      elsif node.from
-        make_variable_expr(node.from)
-      else
-        '0'
-      end
-
-      limit_expr = node.limit ? make_variable_expr(node.limit) : 'nil'
-      line "from = #{from_expr}"
-      line "limit = #{limit_expr}"
-      line "@context.raise_argument_error('invalid integer') unless from.is_a?(Integer)"
-      line "@context.raise_argument_error('invalid integer') unless !limit || limit.is_a?(Integer)"
-
-      line "segment = slice_collection(#{iter_target_expr}, from, limit)"
-      line "segment.reverse!" if node.reversed
-
-      forloop = var('forloop')
-      hoist_var('forloop')
-      line "#{forloop} = ForloopDrop.new('#{node.name}', segment.length, #{forloop})"
-
-      line "if segment.any?"
-      indent do
-        line "segment.each do |#{var(variable_name)}|"
-          indent do
-            line "@context['forloop'] = #{forloop}"
-
-
-            old_in_loop = @in_loop
-            compile(node.for_block)
-            @in_loop = old_in_loop
-
-            line "#{forloop}.send(:increment!)"
-          end
-        line "end"
-      end
-      line "else"
-      indent do
-        compile(node.else_block) if node.else_block
-      end
-      line "end"
-
-      line "@for_offsets['#{node.name}'] = from + segment.length"
-      line "#{forloop} = #{forloop}.parentloop"
-    end
-
-    def compile_if(node)
-      if_condition = node.blocks.first
-      line "if #{make_condition_expr(if_condition)}"
-      indent { if_condition.attachment.nodelist.each(&method(:compile)) }
-
-      node.blocks.drop(1).each do |condition|
-        if condition.left != nil
-          line "elsif #{make_condition_expr(condition)}"
-        else
-          line "else"
-        end
-        indent { condition.attachment.nodelist.each(&method(:compile)) }
-      end
-
-      line "end"
-    end
-
-    def compile_if_changed(node)
-      line "if_changed = lambda do |; liquid_out|"
-      indent do
-        line "liquid_out = StringIO.new"
-        node.nodelist.each(&method(:compile))
-        line "liquid_out.string"
-      end
-      line "end.call"
-
-      line "if if_changed != @if_changed_last"
-      indent { echo "if_changed" }
-      line "end"
-
-      line "@if_changed_last = if_changed"
-    end
-
-    def compile_capture(node)
-      line "#{var(node.to)} = lambda do |; liquid_out|"
-      hoist_var(node.to)
-      indent do
-        line "liquid_out = StringIO.new"
-        node.nodelist.each(&method(:compile))
-        line "liquid_out.string"
-      end
-      line "end.call"
-    end
-
-    def make_condition_expr(node)
-      condition = make_sub_condition_expr(node)
-      if node.child_condition
-        "(#{condition} #{node.child_relation} #{make_condition_expr(node.child_condition)})"
-      else
-        condition
-      end
-    end
-
-    def make_sub_condition_expr(node)
-      return make_variable_expr(node.left) unless node.operator
-
-      operator = node.operator
-      operator = "!=" if operator == "<>"
-
-      if operator == "=="
-        if node.left.is_a?(Liquid::Expression::MethodLiteral) &&
-          node.right.is_a?(Liquid::Expression::MethodLiteral)
-          return "false"
-        elsif node.right.is_a?(Liquid::Expression::MethodLiteral)
-          target = make_variable_expr(node.left)
-          message = node.right.method_name.inspect
-          return "#{target}.respond_to?(#{message}) ? #{target}.send(#{message}) : nil"
-        elsif node.left.is_a?(Liquid::Expression::MethodLiteral)
-          target = make_variable_expr(node.right)
-          message = node.left.method_name.inspect
-          return "#{target}.respond_to?(#{message}) ? #{target}.send(#{message}) : nil"
-        end
-      end
-
-      left = make_variable_expr(node.left)
-      right = make_variable_expr(node.right)
-
-      case operator
-      when "contains"
-        "contains?(#{left}, #{right})"
-      else
-        "apply_operator(#{left}, #{operator.inspect}, #{right})"
-      end
-    end
-
-    def compile_case(node)
-      line 'if false' # HACK
-      else_nodes, if_nodes = node.blocks.partition { |n| n.is_a?(Liquid::ElseCondition) }
-      raise SuperfluidError, 'Too many else nodes' if else_nodes.count > 1
-      else_node = else_nodes.first
-
-      if_nodes.each do |condition|
-        left = make_variable_expr(condition.left)
-        right = make_variable_expr(condition.right)
-        line "elsif #{left} #{condition.operator} #{right}"
-        indent { condition.attachment.nodelist.each(&method(:compile)) }
-      end
-
-      if else_node
-        line "else"
-        indent { else_node.attachment.nodelist.each(&method(:compile)) }
-      end
-
-      line "end"
-    end
-
-    def compile_cycle(node)
-      key = node.name
-      key = key.name if key.is_a?(Liquid::VariableLookup)
-
-      line "key = #{key.inspect}"
-      line "iteration = context.registers[:cycle][key].to_i"
-      line "@cycle_values[key] ||= #{node.variables}"
-
-      line "val = @cycle_values[key][iteration]"
-      echo 'val'
-      line "context.registers[:cycle][key] = (iteration + 1) % #{node.variables.size}"
-    end
-
-    def compile_raw(node)
-      echo "#{node.body.inspect}"
-    end
-
-    def compile_increment(node)
-      line "value = context.environments.first[#{node.variable.inspect}] ||= 0"
-      line "@context.environments.first[#{node.variable.inspect}] = value + 1"
-      echo "value"
-    end
-
-    def compile_decrement(node)
-      line "value = context.environments.first[#{node.variable.inspect}] ||= 0"
-      line "value -= 1"
-      line "@context.environments.first[#{node.variable.inspect}] = value"
-      echo "value"
-    end
-
-    def compile_echo_literal(node)
-      echo node.inspect
-    end
-
-    def compile_variable(variable)
-      echo make_variable_expr(variable)
-    end
-
-    def compile_assign(node)
-      from_expr = case node.from
-      when Liquid::Variable
-        make_variable_expr(node.from)
-      else
-        raise SuperfluidError, "Unknown assignment `from`: #{node.from.inspect}"
-      end
-
-      line "#{var(node.to)} = #{from_expr}"
-      hoist_var(node.to)
-    end
-
-    def make_variable_expr(variable)
-      case variable
-      when Liquid::Variable
-        base_expression = case variable.name
-        when TrueClass, FalseClass, Numeric, String
-          variable.name.inspect
-        when Liquid::VariableLookup
-          make_variable_lookup_expr(variable.name)
-        when NilClass, Liquid::Expression::MethodLiteral
-          'nil'
-        else
-          raise SuperfluidError, "Invalid variable name: #{variable.name.inspect}"
-          derp "Bad var name", variable.name
-        end
-        variable.filters.inject(base_expression) do |inner, (filter_name, positional_args, keyword_args)|
-          filter_args = positional_args.map(&method(:make_variable_expr))
-
-          if keyword_args
-             filter_args << "{ " + keyword_args
-              .transform_values(&method(:make_variable_expr))
-              .collect { |(key, value)| "#{key.inspect} => #{value}" }
-              .join(", ") + " }"
-          end
-
-          "context.strainer.invoke(#{filter_name.inspect}, #{inner}, *[#{filter_args.join(", ")}])"
-        end
-      when Liquid::VariableLookup
-        make_variable_lookup_expr(variable)
-      when TrueClass, FalseClass, Numeric, String
-        variable.inspect
-      when NilClass
-        'nil'
-      else
-        raise SuperfluidError, "Unknown expression type: #{variable.inspect}"
-      end
-    end
-
-    def make_variable_lookup_expr(variable_lookup)
-      base_expr = var(variable_lookup.name)
-      hoist_var(variable_lookup.name)
-      return base_expr if variable_lookup.lookups.empty?
-      
-      expr = Output.new(output.indent_level)
-      expr.line "(begin"
-      expr.indent do
-        expr.line "inner = #{base_expr}"
-        variable_lookup.lookups.each_with_index do |lookup, i|
-          lookup_expr = lookup.inspect
-          expr.line "inner = if inner.respond_to?(:[]) && ((inner.respond_to?(:key?) && inner.key?(#{lookup_expr})) || (inner.respond_to?(:fetch) && #{lookup_expr}.is_a?(Integer)))"
-          expr.indent do
-            expr.line "inner[#{lookup_expr}].to_liquid"
-          end
-          if variable_lookup.command_flags & (1 << i) != 0
-            expr.line "elsif inner.respond_to?(#{lookup.inspect})"
-            expr.indent do
-              expr.line "inner.#{lookup}.to_liquid"
-            end
-          end
-          expr.line "end"
-        end
-      end
-      expr.line "end)"
-      expr.string.strip
-    end
-
-    private
-
-    def line(string)
-      output.line(string)
-    end
-
-    def echo(string)
-      unless @blank
-        line "liquid_out.write(to_output(#{string}))"
-      end
-    end
-
-    def indent(&block)
-      output.indent(&block)
-    end
-
-    def var(name)
-      name = name
-        .gsub('_', '__')
-        .gsub('-', '_')
-      "__liquid_#{name}"
-    end
-
-    def unvar(name)
-      name
-        .delete_prefix('__liquid_')
-        .gsub(/([^_])_([^_])/) { "#$1-#$2" }
-        .gsub('__', '_')
-    end
-
-    def hoist_var(name)
-      @variables << var(name)
-    end
-
-    attr_reader :output
-  end
-end

lib/liquid/tag.rb

@@ -5,8 +5,8 @@ module Liquid
     include ParserSwitching
 
     class << self
-      def parse(tag_name, markup, tokenizer, options)
+      def parse(tag_name, markup, tokenizer, parse_context)
-        tag = new(tag_name, markup, options)
+        tag = new(tag_name, markup, parse_context)
         tag.parse(tokenizer)
         tag
       end

lib/liquid/tags/assign.rb

@@ -10,6 +10,10 @@ module Liquid
   class Assign < Tag
     Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
 
+    def self.syntax_error_translation_key
+      "errors.syntax.assign".freeze
+    end
+
     attr_reader :to, :from
 
     def initialize(tag_name, markup, options)
@@ -18,7 +22,7 @@ module Liquid
         @to = $1
         @from = Variable.new($2, options)
       else
-        raise SyntaxError.new options[:locale].t("errors.syntax.assign".freeze)
+        raise SyntaxError.new(options[:locale].t(self.class.syntax_error_translation_key))
       end
     end
 

lib/liquid/tags/capture.rb

@@ -13,8 +13,6 @@ module Liquid
   class Capture < Block
     Syntax = /(#{VariableSignature}+)/o
 
-    attr_reader :to
-
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
@@ -35,7 +33,6 @@ module Liquid
     def blank?
       true
     end
-
   end
 
   Template.register_tag('capture'.freeze, Capture)

lib/liquid/tags/cycle.rb

@@ -15,7 +15,7 @@ module Liquid
     SimpleSyntax = /\A#{QuotedFragment}+/o
     NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
 
-    attr_reader :variables, :name
+    attr_reader :variables
 
     def initialize(tag_name, markup, options)
       super

lib/liquid/tags/decrement.rb

@@ -23,8 +23,6 @@ module Liquid
       @variable = markup.strip
     end
 
-    attr_reader :variable
-
     def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       value -= 1

lib/liquid/tags/echo.rb

@@ -0,0 +1,24 @@
+module Liquid
+  # Echo outputs an expression
+  #
+  #   {% echo monkey %}
+  #   {% echo user.name %}
+  #
+  # This is identical to variable output syntax, like {{ foo }}, but works
+  # inside {% liquid %} tags. The full syntax is supported, including filters:
+  #
+  #   {% echo user | link %}
+  #
+  class Echo < Tag
+    def initialize(tag_name, markup, parse_context)
+      super
+      @variable = Variable.new(markup, parse_context)
+    end
+
+    def render(context)
+      @variable.render(context)
+    end
+  end
+
+  Template.register_tag('echo'.freeze, Echo)
+end

lib/liquid/tags/for.rb

@@ -46,7 +46,7 @@ module Liquid
   class For < Block
     Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
 
-    attr_reader :collection_name, :variable_name, :limit, :from, :for_block, :else_block, :name, :reversed
+    attr_reader :collection_name, :variable_name, :limit, :from
 
     def initialize(tag_name, markup, options)
       super

lib/liquid/tags/increment.rb

@@ -20,8 +20,6 @@ module Liquid
       @variable = markup.strip
     end
 
-    attr_reader :variable
-
     def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       context.environments.first[@variable] = value + 1

lib/liquid/tags/raw.rb

@@ -3,8 +3,6 @@ module Liquid
     Syntax = /\A\s*\z/
     FullTokenPossiblyInvalid = /\A(.*)#{TagStart}\s*(\w+)\s*(.*)?#{TagEnd}\z/om
 
-    attr_reader :body
-
     def initialize(tag_name, markup, parse_context)
       super
 

lib/liquid/template.rb

@@ -206,7 +206,7 @@ module Liquid
 
       begin
         # render the nodelist.
-
+        # for performance reasons we get an array back here. join will make a string out of it.
         with_profiling(context) do
           @root.render_to_output_buffer(context, output || '')
         end

lib/liquid/tokenizer.rb

@@ -1,25 +1,31 @@
 module Liquid
   class Tokenizer
-    attr_reader :line_number
+    attr_reader :line_number, :for_liquid_tag
 
-    def initialize(source, line_numbers = false)
+    def initialize(source, line_numbers = false, line_number: nil, for_liquid_tag: false)
       @source = source
-      @line_number = line_numbers ? 1 : nil
+      @line_number = line_number || (line_numbers ? 1 : nil)
+      @for_liquid_tag = for_liquid_tag
       @tokens = tokenize
     end
 
     def shift
-      token = @tokens.shift
+      token = @tokens.shift or return
-      @line_number += token.count("\n") if @line_number && token
+
+      if @line_number
+        @line_number += @for_liquid_tag ? 1 : token.count("\n")
+      end
+
       token
     end
 
     private
 
     def tokenize
-      @source = @source.source if @source.respond_to?(:source)
       return [] if @source.to_s.empty?
 
+      return @source.split("\n") if @for_liquid_tag
+
       tokens = @source.split(TemplateParser)
 
       # removes the rogue empty element at the beginning of the array

lib/liquid/variable_lookup.rb

@@ -3,7 +3,7 @@ module Liquid
     SQUARE_BRACKETED = /\A\[(.*)\]\z/m
     COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze].freeze
 
-    attr_reader :name, :lookups, :command_flags
+    attr_reader :name, :lookups
 
     def self.parse(markup)
       new(markup)

performance/benchmark.rb

@@ -1,16 +1,7 @@
 require 'benchmark/ips'
 require_relative 'theme_runner'
 
-case ARGV.first.to_sym
+Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
-when :lax
-  Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
-when :strict
-  Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
-when :superfluid
-  require 'liquid/superfluid'
-  Liquid::Template.error_mode = :strict
-end
-
 profiler = ThemeRunner.new
 
 Benchmark.ips do |x|

performance/memory_profile.rb

@@ -1,26 +1,62 @@
 # frozen_string_literal: true
 
-requirf 'benchmark/ips'
+require 'benchmark/ips'
 require 'memory_profiler'
+require 'terminal-table'
 require_relative 'theme_runner'
 
-def profile(phase, &block)
+class Profiler
-  puts
+  LOG_LABEL   = "Profiling: ".rjust(14).freeze
-  puts "#{phase}:"
+  REPORTS_DIR = File.expand_path('.memprof', __dir__).freeze
-  puts
 
-  report = MemoryProfiler.report(&block)
+  def self.run
+    puts
+    yield new
+  end
 
-  report.pretty_print(
+  def initialize
-    color_output: true,
+    @allocated = []
-    scale_bytes: true,
+    @retained  = []
-    detailed_report: true
+    @headings  = []
-  )
+  end
+
+  def profile(phase, &block)
+    print LOG_LABEL
+    print "#{phase}.. ".ljust(10)
+    report = MemoryProfiler.report(&block)
+    puts 'Done.'
+    @headings  << phase.capitalize
+    @allocated << "#{report.scale_bytes(report.total_allocated_memsize)} (#{report.total_allocated} objects)"
+    @retained  << "#{report.scale_bytes(report.total_retained_memsize)} (#{report.total_retained} objects)"
+
+    return if ENV['CI']
+    require 'fileutils'
+    report_file = File.join(REPORTS_DIR, "#{sanitize(phase)}.txt")
+    FileUtils.mkdir_p(REPORTS_DIR)
+    report.pretty_print(to_file: report_file, scale_bytes: true)
+  end
+
+  def tabulate
+    table = Terminal::Table.new(headings: @headings.unshift('Phase')) do |t|
+      t << @allocated.unshift('Total allocated')
+      t << @retained.unshift('Total retained')
+    end
+
+    puts
+    puts table
+    puts "\nDetailed report(s) saved to #{REPORTS_DIR}/" unless ENV['CI']
+  end
+
+  def sanitize(string)
+    string.downcase.gsub(/[\W]/, '-').squeeze('-')
+  end
 end
 
 Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 
-profiler = ThemeRunner.new
+runner = ThemeRunner.new
-
+Profiler.run do |x|
-profile("Parsing") { profiler.compile }
+  x.profile('parse') { runner.compile }
-profile("Rendering") { profiler.render }
+  x.profile('render') { runner.render }
+  x.tabulate
+end

test/integration/tags/echo_test.rb

@@ -0,0 +1,11 @@
+require 'test_helper'
+
+class EchoTest < Minitest::Test
+  include Liquid
+
+  def test_echo_outputs_its_input
+    assert_template_result('BAR', <<~LIQUID, { 'variable-name' => 'bar' })
+      {%- echo variable-name | upcase -%}
+    LIQUID
+  end
+end

test/integration/tags/liquid_tag_test.rb

@@ -0,0 +1,104 @@
+require 'test_helper'
+
+class LiquidTagTest < Minitest::Test
+  include Liquid
+
+  def test_liquid_tag
+    assert_template_result('1 2 3', <<~LIQUID, 'array' => [1, 2, 3])
+    {%- liquid
+      echo array | join: " "
+    -%}
+    LIQUID
+
+    assert_template_result('1 2 3', <<~LIQUID, 'array' => [1, 2, 3])
+    {%- liquid
+      for value in array
+        echo value
+        unless forloop.last
+          echo " "
+        endunless
+      endfor
+    -%}
+    LIQUID
+
+    assert_template_result('4 8 12 6', <<~LIQUID, 'array' => [1, 2, 3])
+    {%- liquid
+      for value in array
+        assign double_value = value | times: 2
+        echo double_value | times: 2
+        unless forloop.last
+          echo " "
+        endunless
+      endfor
+
+      echo " "
+      echo double_value
+    -%}
+    LIQUID
+
+    assert_template_result('abc', <<~LIQUID)
+    {%- liquid echo "a" -%}
+    b
+    {%- liquid echo "c" -%}
+    LIQUID
+  end
+
+  def test_liquid_tag_errors
+    assert_match_syntax_error("syntax error (line 1): Unknown tag 'error'", <<~LIQUID)
+    {%- liquid error no such tag -%}
+    LIQUID
+
+    assert_match_syntax_error("syntax error (line 7): Unknown tag 'error'", <<~LIQUID)
+    {{ test }}
+
+    {%-
+    liquid
+      for value in array
+
+        error no such tag
+      endfor
+    -%}
+    LIQUID
+
+    assert_match_syntax_error("syntax error (line 2): Unknown tag '!!! the guards are vigilant'", <<~LIQUID)
+    {%- liquid
+      !!! the guards are vigilant
+    -%}
+    LIQUID
+
+    assert_match_syntax_error("syntax error (line 4): 'for' tag was never closed", <<~LIQUID)
+    {%- liquid
+      for value in array
+        echo 'forgot to close the for tag'
+    -%}
+    LIQUID
+  end
+
+  def test_line_number_is_correct_after_a_blank_token
+    assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n\n error %}")
+    assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n  \n error %}")
+  end
+
+  def test_cannot_open_blocks_living_past_a_liquid_tag
+    assert_match_syntax_error("syntax error (line 3): 'if' tag was never closed", <<~LIQUID)
+    {%- liquid
+      if true
+    -%}
+    {%- endif -%}
+    LIQUID
+  end
+
+  def test_quirk_can_close_blocks_created_before_a_liquid_tag
+    assert_template_result("42", <<~LIQUID)
+    {%- if true -%}
+    42
+    {%- liquid endif -%}
+    LIQUID
+  end
+
+  def test_liquid_tag_in_raw
+    assert_template_result("{% liquid echo 'test' %}\n", <<~LIQUID)
+    {% raw %}{% liquid echo 'test' %}{% endraw %}
+    LIQUID
+  end
+end

test/integration/variable_test.rb

@@ -80,10 +80,7 @@ class VariableTest < Minitest::Test
     assigns['test'] = 'Tobi'
     assert_equal 'Hello Tobi', template.render!(assigns)
     assigns.delete('test')
-    e = assert_raises(RuntimeError) do
+    assert_equal "Hello ", template.render!(assigns)
-      template.render!(assigns)
-    end
-    assert_equal "Unknown variable 'test'", e.message
   end
 
   def test_multiline_variable

test/test_helper.rb

@@ -19,11 +19,6 @@ if ENV['LIQUID-C'] == '1'
   require 'liquid/c'
 end
 
-if ENV['SUPERFLUID'] == '1'
-  puts "-- SUPERFLUID"
-  require 'liquid/superfluid'
-end
-
 if Minitest.const_defined?('Test')
   # We're on Minitest 5+. Nothing to do here.
 else
@@ -42,18 +37,18 @@ module Minitest
     include Liquid
 
     def assert_template_result(expected, template, assigns = {}, message = nil)
-      assert_equal expected, Template.parse(template).render!(assigns), message
+      assert_equal expected, Template.parse(template, line_numbers: true).render!(assigns), message
     end
 
     def assert_template_result_matches(expected, template, assigns = {}, message = nil)
       return assert_template_result(expected, template, assigns, message) unless expected.is_a? Regexp
 
-      assert_match expected, Template.parse(template).render!(assigns), message
+      assert_match expected, Template.parse(template, line_numbers: true).render!(assigns), message
     end
 
     def assert_match_syntax_error(match, template, assigns = {})
       exception = assert_raises(Liquid::SyntaxError) do
-        Template.parse(template).render(assigns)
+        Template.parse(template, line_numbers: true).render(assigns)
       end
       assert_match match, exception.message
     end