configure_rdoc_files

# File railties/lib/rails/api/task.rb, line 148
      def configure_rdoc_files
        RDOC_FILES.each do |component, cfg|
          cdr = component_root_dir(component)

          Array(cfg[:include]).each do |pattern|
            rdoc_files.include("#{cdr}/#{pattern}")
          end

          Array(cfg[:exclude]).each do |pattern|
            rdoc_files.exclude("#{cdr}/#{pattern}")
          end
        end

        # Only generate documentation for files that have been
        # changed since the API was generated.
        timestamp_path = "#{api_dir}/created.rid"
        if File.exist?(timestamp_path) && !File.zero?(timestamp_path) && !ENV["ALL"]
          last_generation = DateTime.rfc2822(File.open(timestamp_path, &:readline))

          rdoc_files.keep_if do |file|
            File.mtime(file).to_datetime > last_generation
          end

          # Nothing to do
          exit(0) if rdoc_files.empty?
        end

        # This must come after the mtime comparison to ensure the main page is not excluded.
        rdoc_files.include(api_main)
      end