    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
    015    package org.apache.tapestry5.runtime;
    016
    017    import org.apache.tapestry5.MarkupWriter;
    018
    019    /**
    020     * A command used during rendering of a page.
    021     */
    022    public 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    }