rails--rails/actionpack/lib/action_view/renderer/abstract_renderer.rb

module ActionView
  class AbstractRenderer #:nodoc:
    delegate :find_template, :template_exists?, :with_fallbacks, :with_layout_format, :formats, :to => :@lookup_context

    def initialize(lookup_context)
      @lookup_context = lookup_context
    end

    def render
      raise NotImplementedError
    end

    protected

    def extract_details(options)
      @lookup_context.registered_details.each_with_object({}) do |key, details|
        next unless value = options[key]
        details[key] = Array(value)
      end
    end

    def instrument(name, options={})
      ActiveSupport::Notifications.instrument("render_#{name}.action_view", options){ yield }
    end

    def prepend_formats(formats)
      formats = Array(formats)
      return if formats.empty? || @lookup_context.html_fallback_for_js
      @lookup_context.formats = formats | @lookup_context.formats
    end
  end
end