| // Copyright 2004, 2005 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry.script; |
| |
| import org.apache.hivemind.Location; |
| import org.apache.tapestry.IRequestCycle; |
| |
| /** |
| * Writes out its child tokens only the first time it executes |
| * (with a given tag). Uses |
| * {@link org.apache.tapestry.IRequestCycle#setAttribute(String, Object)} |
| * to identify whether a particular block has rendered yet. |
| * |
| * @author Howard Lewis Ship |
| * @since 3.0 |
| */ |
| |
| class UniqueToken extends AbstractToken |
| { |
| public UniqueToken(Location location) |
| { |
| super(location); |
| } |
| |
| public void write(StringBuffer buffer, ScriptSession session) |
| { |
| IRequestCycle cycle = session.getRequestCycle(); |
| |
| Location location = getLocation(); |
| String tag = "<unique> " + location.toString(); |
| |
| if (cycle.getAttribute(tag) != null) |
| return; |
| |
| cycle.setAttribute(tag, Boolean.TRUE); |
| |
| writeChildren(buffer, session); |
| } |
| |
| } |