001    // Copyright 2004, 2005 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.tapestry.contrib.components;
016    
017    import org.apache.tapestry.IRender;
018    import org.apache.tapestry.IRequestCycle;
019    import org.apache.tapestry.components.Conditional;
020    
021    /**
022     * This component is a container for {@link When} or Otherwise components; it
023     * provides the context for mutually exclusive conditional evaluation. [<a
024     * href="../../../../../../ComponentReference/contrib.Choose.html">Component
025     * Reference</a>]
026     * 
027     * @author David Solis
028     */
029    public abstract class Choose extends Conditional
030    {
031    
032        public void addBody(IRender element)
033        {
034            super.addBody(element);
035            if (element instanceof When) ((When) element).setChoose(this);
036        }
037    
038        protected void cleanupAfterRender(IRequestCycle cycle)
039        {
040            setConditionMet(false);
041            super.cleanupAfterRender(cycle);
042        }
043    
044        protected boolean evaluateCondition()
045        {
046            return getCondition();
047        }
048    
049        public boolean getInvert()
050        {
051            // This component doesn't require invert parameter.
052            return false;
053        }
054    
055        public abstract boolean getCondition();
056    
057        public abstract boolean isConditionMet();
058    
059        public abstract void setConditionMet(boolean value);
060    }