Rails でめっちゃ雑に TypedCoffeeScript 使う

typed_coffee_script.rb

require 'open3'

module TypedCoffeeScript
  class Error < StandardError
  end

  class NotInstalled < Error
  end

  class Template < Tilt::Template
    self.default_mime_type = 'application/javascript'

    def self.engine_initialized?
      _, _, status = Open3.capture3('which tcoffee')
      status.success?
    end

    def initialize_engine
      raise NotInstalled, 'TypedCoffeeScript not installed'
    end

    def prepare
    end

    def evaluate(scope, locals, &block)
      out, err, status = Open3.capture3("tcoffee -c #{file}", chdir: Dir.tmpdir)
      if status.success?
        filename = out.chomp.split(' ').last
        IO.read(File.join(Dir.tmpdir, filename))
      else
        raise Error, remove_ansi_escape_sequence(err)
      end
    end

    def allow_script?
      false
    end

    private

    def remove_ansi_escape_sequence(text)
      text.gsub(/\x1B\[[0-9;]*[mK]/, '')
    end
  end
end

Rails.configuration.after_initialize do
  Sprockets::Rails::Helper.assets.register_engine('.tcoffee', TypedCoffeeScript::Template)
end