http://xml.apache.org/xalan-j/: Serializer to write out XML, HTML etc. as a stream of characters from an input DOM or from input SAX events. (The Apache Software Foundation) 
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 * distributed under the License is distributed on an "AS IS" BASIS,
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/*
 * $Id: DTMAxisTraverser.java 468653 2006-10-28 07:07:05Z minchau $
 */
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.

A DTMAxisTraverser can probably not traverse a reverse axis in
document order.


Typical usage:



for(int nodeHandle=myTraverser.first(myContext);
    nodeHandle!=DTM.NULL;
    nodeHandle=myTraverser.next(myContext,nodeHandle))
{ ... processing for node indicated by nodeHandle goes here ... }



Author:Scott Boag
/**
 * 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.

This method needs to be overloaded only by those axis that process
the self node. <\p>

Params:
  • context – The context node of this traversal. This is the point
that the traversal starts from.
Returns:the first node in the traversal.
/**
   * 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.

This method needs to be overloaded only by those axis that process
the self node. <\p>

Params:
  • context – The context node of this traversal. This is the point
of origin for the traversal -- its "root node" or starting point.
  • extendedTypeID – The extended type ID that must match.
Returns:the first node in the traversal.
/**
   * 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.

Params:
  • context – The context node of this traversal. This is the point
of origin for the traversal -- its "root node" or starting point.
  • 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.
See Also:
Returns:the next node in the iteration, or DTM.NULL.
/**
   * 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.

Params:
  • context – The context node of this traversal. This is the point
of origin for the traversal -- its "root node" or starting point.
  • 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.
  • extendedTypeID – The extended type ID that must match.
See Also:
Returns:the next node in the iteration, or DTM.NULL.
/**
   * 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);
}