/*
* Copyright 1999,2004 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.taglibs.standard.tag.common.core;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.jstl.core.ConditionalTagSupport;
import javax.servlet.jsp.tagext.Tag;
import org.apache.taglibs.standard.resources.Resources;
/**
* <p>WhenTagSupport is an abstract class that facilitates
* implementation of <when>-style tags in both the rtexprvalue
* and expression-evaluating libraries. It also supports
* <otherwise>.</p>
*
* <p>In particular, this base class does the following:</p>
*
* <ul>
* <li> overrides ConditionalTagSupport.doStartTag() to implement the
* appropriate semantics of subtags of <choose> </li>
* </ul>
*
* @author Shawn Bayern
*/
public abstract class WhenTagSupport extends ConditionalTagSupport
{
//*********************************************************************
// Implementation of exclusive-conditional behavior
/*
* Includes its body if condition() evalutes to true AND its parent
* ChooseTag wants it to do so. The condition will not even be
* evaluated if ChooseTag instructs us not to run.
*/
public int doStartTag() throws JspException {
Tag parent;
// make sure we're contained properly
if (!((parent = getParent()) instanceof ChooseTag))
throw new JspTagException(
Resources.getMessage("WHEN_OUTSIDE_CHOOSE"));
// make sure our parent wants us to continue
if (!((ChooseTag) parent).gainPermission())
return SKIP_BODY; // we've been reeled in
// handle conditional behavior
if (condition()) {
((ChooseTag) parent).subtagSucceeded();
return EVAL_BODY_INCLUDE;
} else
return SKIP_BODY;
}
}