avoid allocating new empty array

propagate Environment on new Context creation

lib/liquid.rb

@@ -52,7 +52,6 @@ end
 require "liquid/version"
 require "liquid/deprecations"
 require "liquid/const"
-require "liquid/template/tag_registry"
 require 'liquid/standardfilters'
 require 'liquid/file_system'
 require 'liquid/parser_switching'

lib/liquid/context.rb

@@ -19,7 +19,7 @@ module Liquid
 
     # rubocop:disable Metrics/ParameterLists
     def self.build(environment: Environment.default, environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {}, &block)
-      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments, &block)
+      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments, environment, &block)
     end
 
     def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_environments = {}, environment = Environment.default)
@@ -143,6 +143,7 @@ module Liquid
       check_overflow
 
       self.class.build(
+        environment: @environment,
         resource_limits: resource_limits,
         static_environments: static_environments,
         registers: Registers.new(registers),

lib/liquid/environment.rb

@@ -41,7 +41,7 @@ module Liquid
       # @return [Environment] The new environment instance.
       def build(tags: nil, file_system: nil, error_mode: nil, exception_renderer: nil)
         ret = new
-        ret.tags = Template::TagRegistry.new(tags) if tags
+        ret.tags = tags if tags
         ret.file_system = file_system if file_system
         ret.error_mode = error_mode if error_mode
         ret.exception_renderer = exception_renderer if exception_renderer
@@ -74,7 +74,7 @@ module Liquid
     # Initializes a new environment instance.
     # @api private
     def initialize
-      @tags = Template::TagRegistry.new(Tags::STANDARD_TAGS)
+      @tags = Tags::STANDARD_TAGS.dup
       @error_mode = :lax
       @strainer_template = Class.new(StrainerTemplate).tap do |klass|
         klass.add_filter(StandardFilters)

lib/liquid/parse_tree_visitor.rb

@@ -36,7 +36,7 @@ module Liquid
     protected
 
     def children
-      @node.respond_to?(:nodelist) ? Array(@node.nodelist) : []
+      @node.respond_to?(:nodelist) ? Array(@node.nodelist) : Const::EMPTY_ARRAY
     end
   end
 end

lib/liquid/template/tag_registry.rb

@@ -1,44 +0,0 @@
-# frozen_string_literal: true
-
-module Liquid
-  class Template
-    class TagRegistry
-      include Enumerable
-
-      def initialize(tags = nil)
-        @tags  = {}
-        @cache = {}
-        tags.each { |tag_name, klass| self[tag_name] = klass }
-        Deprecations.warn("Template::TagRegistry", "Use a Environment instance with zeitwerk")
-      end
-
-      def [](tag_name)
-        return nil unless @tags.key?(tag_name)
-        return @cache[tag_name] if Liquid.cache_classes
-
-        lookup_class(@tags[tag_name]).tap { |o| @cache[tag_name] = o }
-      end
-
-      def delete(tag_name)
-        Deprecations.warn("Template::TagRegistry#delete", "Use a Environment instance with immutable tags")
-        @tags.delete(tag_name)
-        @cache.delete(tag_name)
-      end
-
-      def []=(tag_name, klass)
-        @tags[tag_name]  = klass.name
-        @cache[tag_name] = klass
-      end
-
-      def each(&block)
-        @tags.each(&block)
-      end
-
-      private
-
-      def lookup_class(name)
-        Object.const_get(name)
-      end
-    end
-  end
-end

lib/liquid/variable.rb

@@ -68,7 +68,7 @@ module Liquid
       @name = parse_context.parse_expression(p.expression)
       while p.consume?(:pipe)
         filtername = p.consume(:id)
-        filterargs = p.consume?(:colon) ? parse_filterargs(p) : []
+        filterargs = p.consume?(:colon) ? parse_filterargs(p) : Const::EMPTY_ARRAY
         @filters << parse_filter_expressions(filtername, filterargs)
       end
       p.consume(:end_of_string)

test/integration/context_test.rb

@@ -672,6 +672,21 @@ class ContextTest < Minitest::Test
     assert_includes(result, "unscoped_products_count: 5")
   end
 
+  def test_new_isolated_context_inherits_parent_environment
+    global_environment = Liquid::Environment.build(tags: {})
+    context = Context.build(environment: global_environment)
+
+    subcontext = context.new_isolated_subcontext
+    assert_equal(global_environment, subcontext.environment)
+  end
+
+  def test_newly_built_context_inherits_parent_environment
+    global_environment = Liquid::Environment.build(tags: {})
+    context = Context.build(environment: global_environment)
+    assert_equal(global_environment, context.environment)
+    assert(context.environment.tags.each.to_a.empty?)
+  end
+
   private
 
   def assert_no_object_allocations

test/unit/template_unit_test.rb

@@ -39,31 +39,12 @@ class TemplateUnitTest < Minitest::Test
     Liquid.cache_classes = original_cache_setting
   end
 
-  def test_without_cache_classes_tags_reloads_the_class
-    original_cache_setting = Liquid.cache_classes
-    Liquid.cache_classes   = false
-
-    original_klass = Class.new
-    Object.send(:const_set, :CustomTag, original_klass)
-    with_custom_tag('custom', CustomTag) do
-      Object.send(:remove_const, :CustomTag)
-
-      new_klass = Class.new
-      Object.send(:const_set, :CustomTag, new_klass)
-
-      assert(Template.tags['custom'].equal?(new_klass))
-    end
-  ensure
-    Object.send(:remove_const, :CustomTag)
-    Liquid.cache_classes = original_cache_setting
-  end
-
   class FakeTag; end
 
   def test_tags_can_be_looped_over
     with_custom_tag('fake', FakeTag) do
       result = Template.tags.map { |name, klass| [name, klass] }
-      assert(result.include?(["fake", "TemplateUnitTest::FakeTag"]))
+      assert(result.include?(["fake", TemplateUnitTest::FakeTag]))
     end
   end