/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package javax.servlet.jsp.jstl.core;
import javax.el.ValueExpression;
import javax.el.VariableMapper;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.IterationTag;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.tagext.TryCatchFinally;
import java.util.Collection;
import java.util.Map;
import java.util.Iterator;
import java.util.Enumeration;
abstract public class LoopTagSupport extends TagSupport
implements IterationTag, TryCatchFinally, LoopTag {
protected int begin;
protected boolean beginSpecified;
protected ValueExpression deferredExpression;
protected int end = -1;
protected boolean endSpecified;
protected int step = 1;
protected boolean stepSpecified;
protected String itemId;
protected String statusId;
private Object _initialVar;
private Object _current;
private LoopTagStatus _status;
private Object _oldStatus;
private int _index;
private int _count;
private ValueExpression _mapped;
/**
* Sets the var attribute.
*/
public void setVar(String id)
{
this.itemId = id;
}
/**
* Sets the var status attribute.
*/
public void setVarStatus(String id)
{
this.statusId = id;
}
/**
* Checks that the begin property makes sense.
*/
protected void validateBegin()
throws JspTagException
{
if (begin < 0)
throw new JspTagException("Invalid loop tag, 'begin' < 0.");
}
/**
* Checks that the end property makes sense.
*/
protected void validateEnd()
throws JspTagException
{
if (this.end < 0)
throw new JspTagException("Invalid loop tag, 'end' < 0.");
}
/**
* Checks that the step property makes sense.
*/
protected void validateStep()
throws JspTagException
{
if (step <= 0)
throw new JspTagException("Invalid loop tag, 'step' <= 0.");
}
/**
* Called before iteration starts
*/
protected abstract void prepare()
throws JspTagException;
/**
* Returns the next object for the tag.
*/
protected abstract Object next()
throws JspTagException;
/**
* Returns true if there are more values in the tag.
*/
protected abstract boolean hasNext()
throws JspTagException;
/**
* Returns the current object.
*/
public Object getCurrent()
{
return _current;
}
/**
* Returns the loop status.
*/
public LoopTagStatus getLoopStatus()
{
return _status;
}
private ValueExpression createIndexedExpression(int index)
throws JspTagException
{
Object items = deferredExpression.getValue(this.pageContext.getELContext());
if (items == null)
return deferredExpression;
else if (items instanceof Collection)
return new IndexedValueExpression(deferredExpression, index);
else if (items.getClass().isArray())
return new IndexedValueExpression(deferredExpression, index);
else if (items instanceof Map)
return new IteratedValueExpression(
new IteratedExpression(deferredExpression, null), index);
else if (items instanceof Iterator)
return new IteratedValueExpression(
new IteratedExpression(deferredExpression, null), index);
else if (items instanceof Enumeration)
return new IteratedValueExpression(
new IteratedExpression(deferredExpression, null), index);
else if (items instanceof String)
return new IteratedValueExpression(
new IteratedExpression(deferredExpression, getDelims()), index);
else
throw new JspTagException("unknown items value '" + items + "'");
}
/**
* Starts the iteration.
*/
public int doStartTag()
throws JspException
{
_index = 0;
_count = 0;
prepare();
if (this.itemId != null)
_initialVar = pageContext.getAttribute(itemId);
if (getLoopStatus() == null)
_status = new Status();
while (_index < begin && hasNext()) {
_index++;
next();
}
if (hasNext() && (end == -1 || _index <= end)) {
_count++;
_current = next();
if (itemId != null) {
if (deferredExpression != null) {
VariableMapper mapper = pageContext.getELContext()
.getVariableMapper();
_mapped = mapper.setVariable(itemId, createIndexedExpression(_index));
}
else
pageContext.setAttribute(itemId, _current);
}
if (statusId != null) {
_oldStatus = pageContext.getAttribute(statusId, PageContext.PAGE_SCOPE);
if (! (_oldStatus instanceof LoopTagStatus))
_oldStatus = null;
pageContext.setAttribute(statusId, getLoopStatus());
}
return EVAL_BODY_INCLUDE;
}
else
return SKIP_BODY;
}
public int doAfterBody() throws JspException
{
int stepCount;
if (! stepSpecified)
stepCount = 1;
else
stepCount = step;
for (; stepCount > 0; stepCount--) {
if (! hasNext()) {
if (this.itemId != null)
pageContext.setAttribute(itemId, _initialVar);
return SKIP_BODY;
}
_index++;
_current = next();
}
_count++;
if (end == -1 || _index <= end) {
if (itemId != null) {
if (deferredExpression != null) {
VariableMapper mapper = pageContext.getELContext().getVariableMapper();
mapper.setVariable(itemId, createIndexedExpression(_index));
}
else
pageContext.setAttribute(itemId, _current);
}
return EVAL_BODY_AGAIN;
}
else {
return SKIP_BODY;
}
}
public void doCatch(Throwable t) throws Throwable
{
throw t;
}
public void doFinally()
{
if (itemId != null) {
if (deferredExpression != null) {
VariableMapper mapper = pageContext.getELContext().getVariableMapper();
mapper.setVariable(itemId, _mapped);
}
else
pageContext.setAttribute(itemId, null);
}
if (statusId != null)
pageContext.setAttribute(statusId, _oldStatus);
_mapped = null;
deferredExpression = null;
}
protected String getDelims()
{
return ",";
}
private class Status implements LoopTagStatus {
/**
* Returns the current object.
*/
public Object getCurrent()
{
return _current;
}
/**
* Returns the index.
*/
public int getIndex()
{
return _index;
}
/**
* Returns the number of objects returned.
*/
public int getCount()
{
return _count;
}
/**
* Returns true if this is the first item.
*/
public boolean isFirst()
{
return _count == 1;
}
/**
* Returns true if this is the last item.
*/
public boolean isLast()
{
try {
if (! hasNext())
return true;
else if (endSpecified && step + _index > end)
return true;
else
return false;
} catch (Exception e) {
return false;
}
}
/**
* Returns the begin index.
*/
public Integer getBegin()
{
if (beginSpecified)
return new Integer(begin);
else
return null;
}
/**
* Returns the end index.
*/
public Integer getEnd()
{
if (endSpecified)
return new Integer(end);
else
return null;
}
/**
* Returns the step index.
*/
public Integer getStep()
{
if (stepSpecified)
return new Integer(step);
else
return null;
}
}
}