Remove blank nodes from AST with omit_blank_nodes option

History.md

@@ -1,12 +1,15 @@
 # Liquid Change Log
 
+## 5.6.1 2025-01-07
+
+Add `omit_blank_nodes` parse option to skip blank nodes in the AST (#1870) [Michael Go]
+
 ## 5.6.0 (unreleased)
 
 ### Fixes
 
 * Fix Tokenizer to handle null source value (#1873) [Bahar Pourazar]
 
-
 ## 5.5.0 2024-03-21
 
 Please reference the GitHub release for more information.

lib/liquid/block_body.rb

@@ -58,6 +58,9 @@ def freeze
             return yield tag_name, markup
           end
           new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+
+          next if parse_context.omit_blank_nodes && blank_node?(new_tag)
+
           @blank &&= new_tag.blank?
           @nodelist << new_tag
         end
@@ -153,6 +156,9 @@ def self.rescue_render_node(context, output, line_number, exc, blank_tag)
             return yield tag_name, markup
           end
           new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+
+          next if parse_context.omit_blank_nodes && blank_node?(new_tag)
+
           @blank &&= new_tag.blank?
           @nodelist << new_tag
         when token.start_with?(VARSTART)
@@ -269,5 +275,18 @@ def raise_missing_tag_terminator(token, parse_context)
     def raise_missing_variable_terminator(token, parse_context)
       BlockBody.raise_missing_variable_terminator(token, parse_context)
     end
+
+    def blank_node?(node)
+      case node
+      when Comment
+        true
+      when BlockBody
+        true if node.nodelist.empty?
+      when Tag
+        node.nodelist.all? { |n| blank_node?(n) }
+      else
+        false
+      end
+    end
   end
 end

lib/liquid/parse_context.rb

@@ -3,7 +3,7 @@
 module Liquid
   class ParseContext
     attr_accessor :locale, :line_number, :trim_whitespace, :depth
-    attr_reader :partial, :warnings, :error_mode, :environment
+    attr_reader :partial, :warnings, :error_mode, :environment, :omit_blank_nodes
 
     def initialize(options = Const::EMPTY_HASH)
       @environment = options.fetch(:environment, Environment.default)
@@ -12,6 +12,10 @@ def initialize(options = Const::EMPTY_HASH)
       @locale   = @template_options[:locale] ||= I18n.new
       @warnings = []
 
+      # remove blank nodes such as
+      # comment tags, empty if tags, etc from the AST
+      @omit_blank_nodes = options.fetch(:omit_blank_nodes, false)
+
       self.depth   = 0
       self.partial = false
     end

lib/liquid/version.rb

@@ -2,5 +2,5 @@
 # frozen_string_literal: true
 
 module Liquid
-  VERSION = "5.6.0"
+  VERSION = "5.6.1"
 end

performance/tests/tribble/404.liquid

@@ -1,4 +1,3 @@
-  <div id="page" class="innerpage clearfix">
 
     <div id="text-page">
       <div class="entry">

test/unit/block_unit_test.rb

@@ -53,8 +53,103 @@ def test_with_block
     assert_equal(3, template.root.nodelist.size)
   end
 
+  def test_remove_empty_for_blocks_with_optimization_option
+    source = <<~LIQUID.chomp
+      {% for i in (1..1000000) %}
+      {% endfor %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% for i in (1..1000000) %}
+      {% else %}
+      {% endfor %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% for i in list %}
+        i
+      {% endfor %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 1, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% for i in list %}
+      {% else %}
+        1
+      {% endfor %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 1, omit_blank_nodes: true)
+  end
+
+  def test_remove_comment_nodes_with_optimization_option
+    source = <<~LIQUID.chomp
+      {% comment %}
+        {% if true %}
+        {% endif %}
+      {% endcomment %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% liquid
+        comment
+          if true
+          endif
+        endcomment
+      %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+  end
+
+  def test_remove_if_nodes_with_optimization_option
+    source = <<~LIQUID.chomp
+      {% if true %}
+      {% endif %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% unless true %}
+      {% endunless %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% if false %}
+      {% else %}
+      {% endif %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 0, omit_blank_nodes: true)
+
+    source = <<~LIQUID.chomp
+      {% if false %}
+      {% else %}
+        Hello!
+      {% endif %}
+    LIQUID
+
+    assert_root_nodelist_size(source, 1, omit_blank_nodes: true)
+  end
+
   private
 
+  def assert_root_nodelist_size(source, expected_size, parse_options = {})
+    template = Liquid::Template.parse(source, parse_options)
+
+    assert_equal(expected_size, template.root.nodelist.size)
+  end
+
   def block_types(nodelist)
     nodelist.collect(&:class)
   end

test/unit/template_unit_test.rb

@@ -7,13 +7,13 @@ class TemplateUnitTest < Minitest::Test
 
   def test_sets_default_localization_in_document
     t = Template.new
-    t.parse('{%comment%}{%endcomment%}')
+    t.parse('{%raw%}{%endraw%}')
     assert_instance_of(I18n, t.root.nodelist[0].options[:locale])
   end
 
   def test_sets_default_localization_in_context_with_quick_initialization
     t = Template.new
-    t.parse('{%comment%}{%endcomment%}', locale: I18n.new(fixture("en_locale.yml")))
+    t.parse('{%raw%}{%endraw%}', locale: I18n.new(fixture("en_locale.yml")))
 
     locale = t.root.nodelist[0].options[:locale]
     assert_instance_of(I18n, locale)