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}