    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.runtime;
    014
    015import org.apache.tapestry5.MarkupWriter;
    016
    017/**
    018 * A command used during rendering of a page.
    019 */
    020public interface RenderCommand
    021{
    022    /**
    023     * Invoked on an object to request that it render itself. This involves a mix of invoking methods on the writer, and
    024     * queueing up additional commands (often, representing children of the object that was invoked) to perform
    025     * additional rendering.
    026     *
    027     * In this way, rendering is a tail recursive algorithm, but is not implemented using tail recursion.
    028     */
    029    void render(MarkupWriter writer, RenderQueue queue);
    030}