| // Copyright 2004 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.components; |
| |
| import org.apache.tapestry.AbstractComponent; |
| import org.apache.tapestry.IMarkupWriter; |
| import org.apache.tapestry.IRequestCycle; |
| import org.apache.tapestry.Tapestry; |
| |
| /** |
| * A conditional element on a page which will render its wrapped elements |
| * zero or one times. |
| * |
| * [<a href="../../../../../ComponentReference/Conditional.html">Component Reference</a>] |
| * |
| * @author Howard Lewis Ship, David Solis |
| * @version $Id$ |
| * |
| **/ |
| |
| public abstract class Conditional extends AbstractComponent |
| { |
| /** |
| * Renders its wrapped components only if the condition is true (technically, |
| * if condition matches invert). |
| * Additionally, if element is specified, can emulate that HTML element if condition is met |
| * |
| **/ |
| |
| protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle) |
| { |
| if (evaluateCondition()) |
| { |
| String element = getElement(); |
| |
| boolean render = !cycle.isRewinding() && Tapestry.isNonBlank(element); |
| |
| if (render) |
| { |
| writer.begin(element); |
| renderInformalParameters(writer, cycle); |
| } |
| |
| renderBody(writer, cycle); |
| |
| if (render) |
| writer.end(element); |
| } |
| } |
| |
| protected boolean evaluateCondition() |
| { |
| return getCondition() != getInvert(); |
| } |
| |
| public abstract boolean getCondition(); |
| public abstract boolean getInvert(); |
| |
| public abstract String getElement(); |
| } |