/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Xalan" and "Apache Software Foundation" must
* not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
* ITS 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
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* 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 Apache Software Foundation and was
* originally based on software copyright (c) 1999, Lotus
* Development Corporation., http://www.lotus.com. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.xml.dtm;
/**
* A class that implements traverses DTMAxisTraverser interface can traverse
* a set of nodes, usually as defined by an XPath axis. It is different from
* an iterator, because it does not need to hold state, and, in fact, must not
* hold any iteration-based state. It is meant to be implemented as an inner
* class of a DTM, and returned by the getAxisTraverser(final int axis)
* function.
*
* <p>A DTMAxisTraverser can probably not traverse a reverse axis in
* document order.</p>
*
* <p>Typical usage:</p>
* <pre><code>
* for(int nodeHandle=myTraverser.first(myContext);
* nodeHandle!=DTM.NULL;
* nodeHandle=myTraverser.next(myContext,nodeHandle))
* { ... processing for node indicated by nodeHandle goes here ... }
* </code></pre>
*
* @author Scott Boag
*/
public abstract class DTMAxisTraverser
{
/**
* By the nature of the stateless traversal, the context node can not be
* returned or the iteration will go into an infinate loop. So to traverse
* an axis, the first function must be used to get the first node.
*
* <p>This method needs to be overloaded only by those axis that process
* the self node. <\p>
*
* @param context The context node of this traversal. This is the point
* that the traversal starts from.
* @return the first node in the traversal.
*/
public int first(int context)
{
return next(context, context);
}
/**
* By the nature of the stateless traversal, the context node can not be
* returned or the iteration will go into an infinate loop. So to traverse
* an axis, the first function must be used to get the first node.
*
* <p>This method needs to be overloaded only by those axis that process
* the self node. <\p>
*
* @param context The context node of this traversal. This is the point
* of origin for the traversal -- its "root node" or starting point.
* @param extendedTypeID The extended type ID that must match.
*
* @return the first node in the traversal.
*/
public int first(int context, int extendedTypeID)
{
return next(context, context, extendedTypeID);
}
/**
* Traverse to the next node after the current node.
*
* @param context The context node of this traversal. This is the point
* of origin for the traversal -- its "root node" or starting point.
* @param current The current node of the traversal. This is the last known
* location in the traversal, typically the node-handle returned by the
* previous traversal step. For the first traversal step, context
* should be set equal to current. Note that in order to test whether
* context is in the set, you must use the first() method instead.
*
* @return the next node in the iteration, or DTM.NULL.
* @see first(int)
*/
public abstract int next(int context, int current);
/**
* Traverse to the next node after the current node that is matched
* by the extended type ID.
*
* @param context The context node of this traversal. This is the point
* of origin for the traversal -- its "root node" or starting point.
* @param current The current node of the traversal. This is the last known
* location in the traversal, typically the node-handle returned by the
* previous traversal step. For the first traversal step, context
* should be set equal to current. Note that in order to test whether
* context is in the set, you must use the first() method instead.
* @param extendedTypeID The extended type ID that must match.
*
* @return the next node in the iteration, or DTM.NULL.
* @see first(int,int)
*/
public abstract int next(int context, int current, int extendedTypeID);
}