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package org.apache.taglibs.standard.tag.common.core;

import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.tagext.TryCatchFinally;

/**
 * <p>Tag handler for <catch> in JSTL 1.0.</p>
 * 
 * <p><catch> simply catches any Throwables that occur in its body
 * and optionally exposes them.
 *
 * @author Shawn Bayern
 */

public class CatchTag extends TagSupport implements TryCatchFinally {

    /*
     * If all tags that I proposed were this simple, people might
     * think I was just trying to avoid work.  :-)
     */

    //*********************************************************************
    // Constructor and lifecycle management

    // initialize inherited and local state
    public CatchTag() {
        super();
        init();
    }

    // Releases any resources we may have (or inherit)
    public void release() {
        super.release();
        init();
    }

    private void init() {
        var = null;
    }


    //*********************************************************************
    // Private state

    private String var;                                 // tag attribute
    private boolean caught;                             // internal status


    //*********************************************************************
    // Tag logic

    public int doStartTag() {
        caught = false;
	return EVAL_BODY_INCLUDE;
    }

    public void doCatch(Throwable t) {
        if (var != null)
            pageContext.setAttribute(var, t, PageContext.PAGE_SCOPE);
        caught = true;
    }

    public void doFinally() {
        if (var != null && !caught)
            pageContext.removeAttribute(var, PageContext.PAGE_SCOPE);
    }


    //*********************************************************************
    // Attribute accessors

    public void setVar(String var) {
        this.var = var;
    }

}