middleman/middleman-core/lib/middleman-core/renderers/coffee_script.rb

# Require gem
require 'coffee_script'

module Middleman
  module Renderers
    # CoffeeScript Renderer
    module CoffeeScript
      # Setup extension
      class << self
        # Once registered
        def registered(app)
          # Tell Tilt to use it as well (for inline scss blocks)
          ::Tilt.register 'coffee', DebuggingCoffeeScriptTemplate
          ::Tilt.prefer(DebuggingCoffeeScriptTemplate)

          app.before_configuration do
            DebuggingCoffeeScriptTemplate.middleman_app = self
          end
        end
        alias_method :included, :registered
      end

      # A Template for Tilt which outputs debug messages
      class DebuggingCoffeeScriptTemplate < ::Tilt::CoffeeScriptTemplate
        # Make the current Middleman app accessible to the template
        cattr_accessor :middleman_app

        # Add exception messaging
        # @param [Class] context
        # @param [Hash] locals
        # @return [String]
        def evaluate(context, locals, &block)
          return super unless middleman_app.server?

          begin
            super
          rescue ::ExecJS::RuntimeError => e
            e.to_s
          rescue => e
            e.to_s
          end
        end
      end
    end
  end
end