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/**

 * Extends and based on Apache Struts source code.

 *

 * Copyleft Anatoli Klassen (anatoli@aksoft.net)

 */

package ak.strutsx.taglib;

import java.util.Iterator;

import java.util.Collection;

import java.util.Map;

import javax.servlet.jsp.JspException;

import org.apache.struts.util.RequestUtils;

import org.apache.struts.taglib.logic.ConditionalTagBase;

public class EmptyTag

	extends ConditionalTagBase

{

    protected boolean condition()

    	throws JspException

    {

        return condition(true);

    }

    protected boolean condition(boolean desired)

    	throws JspException

    {

		if(this.name == null) {

			JspException e = new JspException(messages.getMessage("empty.noNameAttribute"));

			RequestUtils.saveException(pageContext, e);

			throw e;

		}

		boolean empty = true;

		Object value = null;

		if(this.property == null)

			value = RequestUtils.lookup(pageContext, name, scope);

		else

			value = RequestUtils.lookup(pageContext, name, property, scope);

		if(value != null) {

			if(value instanceof String)

				empty = (((String)value).length() < 1);

			else if(value instanceof Collection)

				empty = ((Collection)value).isEmpty();

			else if(value instanceof Map)

				empty = ((Map)value).isEmpty();

			else if(value instanceof Iterator)

				empty = !((Iterator)value).hasNext();

			else

				empty = false;

		}

		return (empty == desired);

    }

}