From bd33df09de271541b4186caa1e84863e436a18a1 Mon Sep 17 00:00:00 2001
From: Dylan Thacker-Smith <Dylan.Smith@shopify.com>
Date: Mon, 31 Aug 2020 17:28:26 -0400
Subject: [PATCH 1/4] Provide Block#new_body so that liquid-c can override it

This way liquid-c can return a body of a different class that wraps
a C implementation.
---
 lib/liquid/block.rb     | 10 ++++++++--
 lib/liquid/tags/case.rb |  6 +++---
 lib/liquid/tags/for.rb  |  4 ++--
 lib/liquid/tags/if.rb   |  2 +-
 4 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/lib/liquid/block.rb b/lib/liquid/block.rb
index 9d7b752..b3a982e 100644
--- a/lib/liquid/block.rb
+++ b/lib/liquid/block.rb
@@ -10,7 +10,7 @@ module Liquid
     end
 
     def parse(tokens)
-      @body = BlockBody.new
+      @body = new_body
       while parse_body(@body, tokens)
       end
     end
@@ -55,8 +55,14 @@ module Liquid
       @block_delimiter ||= "end#{block_name}"
     end
 
-    protected
+    private
 
+    # @api public
+    def new_body
+      BlockBody.new
+    end
+
+    # @api public
     def parse_body(body, tokens)
       if parse_context.depth >= MAX_DEPTH
         raise StackLevelError, "Nesting too deep"
diff --git a/lib/liquid/tags/case.rb b/lib/liquid/tags/case.rb
index f6e0e70..0b48bf1 100644
--- a/lib/liquid/tags/case.rb
+++ b/lib/liquid/tags/case.rb
@@ -19,7 +19,7 @@ module Liquid
     end
 
     def parse(tokens)
-      body = BlockBody.new
+      body = new_body
       body = @blocks.last.attachment while parse_body(body, tokens)
       if blank?
         @blocks.each { |condition| condition.attachment.remove_blank_strings }
@@ -59,7 +59,7 @@ module Liquid
     private
 
     def record_when_condition(markup)
-      body = BlockBody.new
+      body = new_body
 
       while markup
         unless markup =~ WhenSyntax
@@ -80,7 +80,7 @@ module Liquid
       end
 
       block = ElseCondition.new
-      block.attach(BlockBody.new)
+      block.attach(new_body)
       @blocks << block
     end
 
diff --git a/lib/liquid/tags/for.rb b/lib/liquid/tags/for.rb
index bb03392..6f66ebd 100644
--- a/lib/liquid/tags/for.rb
+++ b/lib/liquid/tags/for.rb
@@ -54,7 +54,7 @@ module Liquid
       super
       @from = @limit = nil
       parse_with_selected_parser(markup)
-      @for_block = BlockBody.new
+      @for_block = new_body
       @else_block = nil
     end
 
@@ -74,7 +74,7 @@ module Liquid
 
     def unknown_tag(tag, markup, tokens)
       return super unless tag == 'else'
-      @else_block = BlockBody.new
+      @else_block = new_body
     end
 
     def render_to_output_buffer(context, output)
diff --git a/lib/liquid/tags/if.rb b/lib/liquid/tags/if.rb
index 43c8b0a..1b4de55 100644
--- a/lib/liquid/tags/if.rb
+++ b/lib/liquid/tags/if.rb
@@ -64,7 +64,7 @@ module Liquid
       end
 
       @blocks.push(block)
-      block.attach(BlockBody.new)
+      block.attach(new_body)
     end
 
     def lax_parse(markup)

From 037b6036031802cf38f7360dda9071666c5a8474 Mon Sep 17 00:00:00 2001
From: Dylan Thacker-Smith <Dylan.Smith@shopify.com>
Date: Tue, 1 Sep 2020 14:38:40 -0400
Subject: [PATCH 2/4] Turn some Liquid::BlockBody methods into class methods
 for liquid-c

So they can be used from a Liquid::C::BlockBody
---
 lib/liquid/block_body.rb | 41 ++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/lib/liquid/block_body.rb b/lib/liquid/block_body.rb
index 18b3062..e2ebf7a 100644
--- a/lib/liquid/block_body.rb
+++ b/lib/liquid/block_body.rb
@@ -58,6 +58,28 @@ module Liquid
       Block.raise_unknown_tag(tag, 'liquid', '%}', parse_context)
     end
 
+    # @api private
+    def self.raise_missing_tag_terminator(token, parse_context)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_termination", token: token, tag_end: TagEnd.inspect)
+    end
+
+    # @api private
+    def self.raise_missing_variable_terminator(token, parse_context)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.variable_termination", token: token, tag_end: VariableEnd.inspect)
+    end
+
+    # @api private
+    def self.render_node(context, output, node)
+      node.render_to_output_buffer(context, output)
+    rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
+      context.handle_error(e, node.line_number)
+    rescue MemoryError
+      raise
+    rescue ::StandardError => e
+      line_number = node.is_a?(String) ? nil : node.line_number
+      output << context.handle_error(e, line_number)
+    end
+
     private def parse_liquid_tag(markup, parse_context)
       liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)
       parse_for_liquid_tag(liquid_tag_tokenizer, parse_context) do |end_tag_name, _end_tag_markup|
@@ -74,7 +96,7 @@ module Liquid
         when token.start_with?(TAGSTART)
           whitespace_handler(token, parse_context)
           unless token =~ FullToken
-            raise_missing_tag_terminator(token, parse_context)
+            BlockBody.raise_missing_tag_terminator(token, parse_context)
           end
           tag_name = Regexp.last_match(2)
           markup   = Regexp.last_match(4)
@@ -179,14 +201,7 @@ module Liquid
     private
 
     def render_node(context, output, node)
-      node.render_to_output_buffer(context, output)
-    rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
-      context.handle_error(e, node.line_number)
-    rescue MemoryError
-      raise
-    rescue ::StandardError => e
-      line_number = node.is_a?(String) ? nil : node.line_number
-      output << context.handle_error(e, line_number)
+      BlockBody.render_node(context, output, node)
     end
 
     def create_variable(token, parse_context)
@@ -194,15 +209,17 @@ module Liquid
         markup = content.first
         return Variable.new(markup, parse_context)
       end
-      raise_missing_variable_terminator(token, parse_context)
+      BlockBody.raise_missing_variable_terminator(token, parse_context)
     end
 
+    # @deprecated Use {.raise_missing_tag_terminator} instead
     def raise_missing_tag_terminator(token, parse_context)
-      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_termination", token: token, tag_end: TagEnd.inspect)
+      BlockBody.raise_missing_tag_terminator(token, parse_context)
     end
 
+    # @deprecated Use {.raise_missing_variable_terminator} instead
     def raise_missing_variable_terminator(token, parse_context)
-      raise SyntaxError, parse_context.locale.t("errors.syntax.variable_termination", token: token, tag_end: VariableEnd.inspect)
+      BlockBody.raise_missing_variable_terminator(token, parse_context)
     end
 
     def registered_tags

From dfbbf87ba9f02c0ca439a79f6eb7e475cd9bf84e Mon Sep 17 00:00:00 2001
From: Dylan Thacker-Smith <Dylan.Smith@shopify.com>
Date: Wed, 2 Sep 2020 09:32:19 -0400
Subject: [PATCH 3/4] Use BlockBody from Document using composition rather than
 inheritence

This way liquid-c can more cleanly use a Liquid::C::BlockBody object
for the block body by overriding Liquid::Document#new_body.
---
 lib/liquid/document.rb | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/lib/liquid/document.rb b/lib/liquid/document.rb
index e160886..8338b06 100644
--- a/lib/liquid/document.rb
+++ b/lib/liquid/document.rb
@@ -1,15 +1,26 @@
 # frozen_string_literal: true
 
 module Liquid
-  class Document < BlockBody
+  class Document
     def self.parse(tokens, parse_context)
-      doc = new
+      doc = new(parse_context)
       doc.parse(tokens, parse_context)
       doc
     end
 
+    attr_reader :parse_context, :body
+
+    def initialize(parse_context)
+      @parse_context = parse_context
+      @body = new_body
+    end
+
+    def nodelist
+      @body.nodelist
+    end
+
     def parse(tokens, parse_context)
-      super do |end_tag_name, _end_tag_params|
+      @body.parse(tokens, parse_context) do |end_tag_name, _end_tag_params|
         unknown_tag(end_tag_name, parse_context) if end_tag_name
       end
     rescue SyntaxError => e
@@ -25,5 +36,19 @@ module Liquid
         raise SyntaxError, parse_context.locale.t("errors.syntax.unknown_tag", tag: tag)
       end
     end
+
+    def render_to_output_buffer(context, output)
+      @body.render_to_output_buffer(context, output)
+    end
+
+    def render(context)
+      @body.render(context)
+    end
+
+    private
+
+    def new_body
+      Liquid::BlockBody.new
+    end
   end
 end

From bbc56f35ecd6e68f6d6a31246ea59ded5028c4a0 Mon Sep 17 00:00:00 2001
From: Dylan Thacker-Smith <Dylan.Smith@shopify.com>
Date: Wed, 9 Sep 2020 12:25:35 -0400
Subject: [PATCH 4/4] Add ParseContext#new_block_body to centralize the
 liquid-c override point

---
 lib/liquid/block.rb         | 2 +-
 lib/liquid/document.rb      | 2 +-
 lib/liquid/parse_context.rb | 4 ++++
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/liquid/block.rb b/lib/liquid/block.rb
index b3a982e..e0ad332 100644
--- a/lib/liquid/block.rb
+++ b/lib/liquid/block.rb
@@ -59,7 +59,7 @@ module Liquid
 
     # @api public
     def new_body
-      BlockBody.new
+      parse_context.new_block_body
     end
 
     # @api public
diff --git a/lib/liquid/document.rb b/lib/liquid/document.rb
index 8338b06..e0818ec 100644
--- a/lib/liquid/document.rb
+++ b/lib/liquid/document.rb
@@ -48,7 +48,7 @@ module Liquid
     private
 
     def new_body
-      Liquid::BlockBody.new
+      parse_context.new_block_body
     end
   end
 end
diff --git a/lib/liquid/parse_context.rb b/lib/liquid/parse_context.rb
index 83d4e0f..4724ec2 100644
--- a/lib/liquid/parse_context.rb
+++ b/lib/liquid/parse_context.rb
@@ -19,6 +19,10 @@ module Liquid
       @options[option_key]
     end
 
+    def new_block_body
+      Liquid::BlockBody.new
+    end
+
     def partial=(value)
       @partial = value
       @options = value ? partial_options : @template_options