org.htmlunit.xpath.xml.dtm.DTMAxisTraverser Maven / Gradle / Ivy
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* 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
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.htmlunit.xpath.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
*/
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.
*
* @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(final 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.
*
* @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(final int context, final 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);
}