package org.jaxen.util;
/*
* $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/util/PrecedingAxisIterator.java,v 1.11 2006/11/13 22:10:09 elharo Exp $
* $Revision: 1.11 $
* $Date: 2006/11/13 22:10:09 $
*
* ====================================================================
*
* Copyright 2000-2005 bob mcwhirter & James Strachan.
* All rights reserved.
*
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of the Jaxen Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ====================================================================
* This software consists of voluntary contributions made by many
* individuals on behalf of the Jaxen Project and was originally
* created by bob mcwhirter <bob@werken.com> and
* James Strachan <jstrachan@apache.org>. For more information on the
* Jaxen Project, please see <http://www.jaxen.org/>.
*
* $Id: PrecedingAxisIterator.java,v 1.11 2006/11/13 22:10:09 elharo Exp $
*/
import org.jaxen.JaxenConstants;
import org.jaxen.JaxenRuntimeException;
import org.jaxen.Navigator;
import org.jaxen.UnsupportedAxisException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;
/**
* <p>
* Represents the XPath <code>preceding</code> axis.
* The "<code>preceding</code> axis contains all nodes in the same document as the context
* node that are before the context node in document order, excluding any ancestors
* and excluding attribute nodes and namespace nodes."
*
* <p>
* This implementation of '<code>preceding</code>' works like so:
* the <code>preceding</code> axis includes preceding siblings of this node and
* their descendants. Also, for each ancestor node of this node, it includes
* all preceding siblings of that ancestor, and their descendants. Finally, it
* includes the ancestor nodes themselves.
* </p>
*
* <p>
* The reversed <code>descendant-or-self</code> axes that are required are calculated using a
* stack of reversed 'child-or-self' axes. When asked for a node, it is always taken
* from a child-or-self axis. If it was the last node on that axis, the node is returned.
* Otherwise, this axis is pushed on the stack, and the process is repeated with the child-or-self
* of the node. Eventually this recurses down to the last descendant of any node, then works
* back up to the root.
* </p>
*
* <p>
* Most object models could provide a faster implementation of the reversed
* 'children-or-self' used here.</p>
*
* @version 1.2b12
*/
public class PrecedingAxisIterator implements Iterator
{
private Iterator ancestorOrSelf;
private Iterator precedingSibling;
private ListIterator childrenOrSelf;
private ArrayList stack;
private Navigator navigator;
/**
* Create a new <code>preceding</code> axis iterator.
*
* @param contextNode the node to start from
* @param navigator the object model specific navigator
*/
public PrecedingAxisIterator(Object contextNode,
Navigator navigator) throws UnsupportedAxisException
{
this.navigator = navigator;
this.ancestorOrSelf = navigator.getAncestorOrSelfAxisIterator(contextNode);
this.precedingSibling = JaxenConstants.EMPTY_ITERATOR;
this.childrenOrSelf = JaxenConstants.EMPTY_LIST_ITERATOR;
this.stack = new ArrayList();
}
/**
* Returns true if there are any preceding nodes remaining; false otherwise.
*
* @return true if any preceding nodes remain; false otherwise
*
* @see java.util.Iterator#hasNext()
*/
public boolean hasNext()
{
try
{
while (!childrenOrSelf.hasPrevious())
{
if (stack.isEmpty())
{
while (!precedingSibling.hasNext())
{
if (!ancestorOrSelf.hasNext())
{
return false;
}
Object contextNode = ancestorOrSelf.next();
precedingSibling = new PrecedingSiblingAxisIterator(contextNode, navigator);
}
Object node = precedingSibling.next();
childrenOrSelf = childrenOrSelf(node);
}
else
{
childrenOrSelf = (ListIterator) stack.remove(stack.size()-1);
}
}
return true;
}
catch (UnsupportedAxisException e)
{
throw new JaxenRuntimeException(e);
}
}
private ListIterator childrenOrSelf(Object node)
{
try
{
ArrayList reversed = new ArrayList();
reversed.add(node);
Iterator childAxisIterator = navigator.getChildAxisIterator(node);
if (childAxisIterator != null)
{
while (childAxisIterator.hasNext())
{
reversed.add(childAxisIterator.next());
}
}
return reversed.listIterator(reversed.size());
}
catch (UnsupportedAxisException e)
{
throw new JaxenRuntimeException(e);
}
}
/**
* Returns the next preceding node.
*
* @return the next preceding node
*
* @throws NoSuchElementException if no preceding nodes remain
*
* @see java.util.Iterator#next()
*/
public Object next() throws NoSuchElementException
{
if (!hasNext())
{
throw new NoSuchElementException();
}
while (true)
{
Object result = childrenOrSelf.previous();
if (childrenOrSelf.hasPrevious())
{
// if this isn't 'self' construct 'descendant-or-self'
stack.add(childrenOrSelf);
childrenOrSelf = childrenOrSelf(result);
continue;
}
return result;
}
}
/**
* This operation is not supported.
*
* @throws UnsupportedOperationException always
*/
public void remove() throws UnsupportedOperationException
{
throw new UnsupportedOperationException();
}
}