/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * Portions Copyright Apache Software Foundation.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 * 
 * Contributor(s):
 * 
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

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

import java.util.StringTokenizer;
import javax.el.ValueExpression;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.jstl.core.LoopTagSupport;
import org.apache.taglibs.standard.resources.Resources;

/**
 * <p>Support for tag handlers for <forTokens>, the tokenizing
 * iteration tag in JSTL 1.0.  This class extends LoopTagSupport and
 * provides ForTokens-specific functionality.  The rtexprvalue and
 * expression-evaluating libraries each have handlers that extend this
 * class.</p>
 *
 * @see javax.servlet.jsp.jstl.core.LoopTagSupport
 * @author Shawn Bayern
 */

public abstract class ForTokensSupport extends LoopTagSupport {

    //*********************************************************************
    // Implementation overview

    /*
     * This handler simply constructs a StringTokenizer based on its input
     * and relays tokens to the iteration implementation that it inherits.
     * The 'items' and 'delims' attributes are expected to be provided by
     * a subtag (presumably in the rtexprvalue or expression-evaluating
     * versions of the JSTL library).
     */


    //*********************************************************************
    // ForEachTokens-specific state (protected)

    protected Object items;                       // 'items' attribute
    protected String delims;                      // 'delims' attribute
    protected StringTokenizer st;                 // digested tokenizer


    //*********************************************************************
    // Iteration control methods

    /*
     * These just create and use a StringTokenizer.
     * We inherit semantics and Javadoc from LoopTagSupport.
     */

    protected void prepare() throws JspTagException {
        if (items instanceof ValueExpression) {
            deferredExpression = (ValueExpression) items;
            items = deferredExpression.getValue(pageContext.getELContext());
        }
        if (!(items instanceof String)) {
            throw new JspTagException(
                Resources.getMessage("FORTOKENS_BAD_ITEMS"));
        }
        st = new StringTokenizer((String)items, delims);
    }

    protected boolean hasNext() throws JspTagException {
        return st.hasMoreElements();
    }

    protected Object next() throws JspTagException {
        return st.nextElement();
    }

    protected String getDelims() {
        return delims;
    }

    //*********************************************************************
    // Tag logic and lifecycle management


    // Releases any resources we may have (or inherit)
    public void release() {
        super.release();
        items = delims = null;
        st = null;
        deferredExpression = null;
    }

}