/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.util.StringTokenizer;
import javax.el.ValueExpression;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.jstl.core.IteratedExpression;
import javax.servlet.jsp.jstl.core.IteratedValueExpression;
import javax.servlet.jsp.jstl.core.LoopTagSupport;
/**
* <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>
*
* @author Shawn Bayern
* @see javax.servlet.jsp.jstl.core.LoopTagSupport
*/
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
protected int currentIndex;
private IteratedExpression itemsValueIteratedExpression;
//*********************************************************************
// Iteration control methods
/*
* These just create and use a StringTokenizer.
* We inherit semantics and Javadoc from LoopTagSupport.
*/
@Override
protected void prepare() throws JspTagException {
if (items instanceof ValueExpression) {
deferredExpression = (ValueExpression) items;
itemsValueIteratedExpression = new IteratedExpression(deferredExpression, getDelims());
currentIndex = 0;
Object originalValue = deferredExpression.getValue(pageContext.getELContext());
if (originalValue instanceof String) {
st = new StringTokenizer((String) originalValue, delims);
} else {
throw new JspTagException();
}
} else {
st = new StringTokenizer((String) items, delims);
}
}
@Override
protected boolean hasNext() throws JspTagException {
return st.hasMoreElements();
}
@Override
protected Object next() throws JspTagException {
if (deferredExpression != null) {
st.nextElement();
return new IteratedValueExpression(itemsValueIteratedExpression, currentIndex++);
} else {
return st.nextElement();
}
}
//*********************************************************************
// Tag logic and lifecycle management
// Releases any resources we may have (or inherit)
@Override
public void release() {
super.release();
items = delims = null;
st = null;
}
/**
* Get the delimiter for string tokens. Used only for constructing
* the deferred expression for it.
*/
@Override
protected String getDelims() {
return delims;
}
}