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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;
}
}