kaorukobo/implement-capture-haml-in-haml6.md

## implement-capture-haml-in-haml6.md

      
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              implement-capture-haml-in-haml6.md
            
          
    The capture_haml method has been removed as of HAML 6.0.0:

https://github.com/haml/haml/blob/main/CHANGELOG.md#600
Most Haml helpers are removed.
For helpers generating general HTML tags, also consider using what your framework provides, e.g. Rails content_tag. Same applies to capture_haml, e.g. Rails capture.

This change is breaking for the code that works outside of Rails.
So I have implemented capture_haml for Haml 6
Note that this does not work with block capturing support so you need to set the option {disable_capture: true}.

  
## implement-capture-haml-in-haml6.rb
require "bundler/inline"

gemfile(false) do
  source "https://rubygems.org"
  gem "haml"
  gem "temple"
  gem "rspec"
end

require "haml"
require "temple/html/safe"

module Haml
  module Capture
    module HelperExtension
      def capture_haml(&block)
        with_buf =
          begin
            buf = Haml::Capture.buffer_stack.last
            if buf
              buf.method(:then)
            else
              Haml::Capture.method(:with_new_buffer)
            end
          end

        with_buf.call { |buf|
          length_before_capture = buf.length
          begin
            block.call(buf)
            buf[length_before_capture..-1].html_safe
          ensure
            buf.slice!(length_before_capture..-1)
          end
        }
      end
    end

    module BufferExtension
      def create_buffer
        "Haml::Capture.with_new_buffer do |#{buffer}|;"
      end

      def return_buffer
        "#{buffer.to_s};end;"
      end
    end

    ::Haml::Helpers.prepend(HelperExtension)
    ::Temple::Generators::StringBuffer.prepend(BufferExtension)

    class << self
      # @return [Array<String>]
      def buffer_stack
        th = Thread.current
        th.thread_variable_get(:capture_haml_buffer_stack) ||
          [].tap { |v|
            th.thread_variable_set(:capture_haml_buffer_stack, v)
          }
      end

      def with_new_buffer(&block)
        buf = ''.dup
        buffer_stack << buf
        begin
          yield buf
        ensure
          last_buf = buffer_stack.pop
          unless last_buf.equal?(buf)
            raise StandardError, "inconsistent buffer stack push/pop"
          end
        end
      end
    end
  end
end

require "rspec/autorun"
RSpec.describe "capture_haml for Haml6+ outside Rails" do
  let :context do
    Object.new
  end

  it "allows us to define a helper Proc that returns HAML output" do
    haml = <<~HAML
      - @fragment = -> do
        - capture_haml do
          %div fragment
      %body= @fragment.call
    HAML

    expect(render(haml)).to eq(<<~HTML)
      <body><div>fragment</div>\n</body>
    HTML
  end

  it "allows us to define a method that returns HAML output" do
    haml = <<~HAML
      - def self.fragment
        - capture_haml do |_buf|  # needs to initialize `_buf` variable
          %div fragment
    HAML

    render(haml)
    expect(context.fragment).to eq(<<~HTML)
      <div>fragment</div>
    HTML
  end

  def render(haml)
    template = Haml::Template.new(use_html_safe: true) { haml }
    # decomment to print the generated code:
    #   puts template.send(:precompiled, {})
    template.render(context)
  end
end
	require "bundler/inline"

	gemfile(false) do
	source "https://rubygems.org"
	gem "haml"
	gem "temple"
	gem "rspec"
	end

	require "haml"
	require "temple/html/safe"

	module Haml
	module Capture
	module HelperExtension
	def capture_haml(&block)
	with_buf =
	begin
	buf = Haml::Capture.buffer_stack.last
	if buf
	buf.method(:then)
	else
	Haml::Capture.method(:with_new_buffer)
	end
	end

	with_buf.call { \|buf\|
	length_before_capture = buf.length
	begin
	block.call(buf)
	buf[length_before_capture..-1].html_safe
	ensure
	buf.slice!(length_before_capture..-1)
	end
	}
	end
	end

	module BufferExtension
	def create_buffer
	"Haml::Capture.with_new_buffer do \|#{buffer}\|;"
	end

	def return_buffer
	"#{buffer.to_s};end;"
	end
	end

	::Haml::Helpers.prepend(HelperExtension)
	::Temple::Generators::StringBuffer.prepend(BufferExtension)

	class << self
	# @return [Array<String>]
	def buffer_stack
	th = Thread.current
	th.thread_variable_get(:capture_haml_buffer_stack) \|\|
	[].tap { \|v\|
	th.thread_variable_set(:capture_haml_buffer_stack, v)
	}
	end

	def with_new_buffer(&block)
	buf = ''.dup
	buffer_stack << buf
	begin
	yield buf
	ensure
	last_buf = buffer_stack.pop
	unless last_buf.equal?(buf)
	raise StandardError, "inconsistent buffer stack push/pop"
	end
	end
	end
	end
	end
	end

	require "rspec/autorun"
	RSpec.describe "capture_haml for Haml6+ outside Rails" do
	let :context do
	Object.new
	end

	it "allows us to define a helper Proc that returns HAML output" do
	haml = <<~HAML
	- @fragment = -> do
	- capture_haml do
	%div fragment
	%body= @fragment.call
	HAML

	expect(render(haml)).to eq(<<~HTML)
	<body><div>fragment</div>\n</body>
	HTML
	end

	it "allows us to define a method that returns HAML output" do
	haml = <<~HAML
	- def self.fragment
	- capture_haml do \|_buf\| # needs to initialize `_buf` variable
	%div fragment
	HAML

	render(haml)
	expect(context.fragment).to eq(<<~HTML)
	<div>fragment</div>
	HTML
	end

	def render(haml)
	template = Haml::Template.new(use_html_safe: true) { haml }
	# decomment to print the generated code:
	# puts template.send(:precompiled, {})
	template.render(context)
	end
	end