    001// Copyright 2006 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007//     http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.runtime;
    016
    017import org.apache.tapestry5.MarkupWriter;
    018
    019/**
    020 * A command used during rendering of a page.
    021 */
    022public interface RenderCommand
    023{
    024    /**
    025     * Invoked on an object to request that it render itself. This involves a mix of invoking methods on the writer, and
    026     * queueing up additional commands (often, representing children of the object that was invoked) to perform
    027     * additional rendering.
    028     * <p/>
    029     * In this way, rendering is a tail recursive algorithm, but is not implemented using tail recursion.
    030     */
    031    void render(MarkupWriter writer, RenderQueue queue);
    032}