org.apache.xml.dtm.ref.DTMNodeIterator 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
* regarding copyright ownership. The ASF licenses this file
* 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,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* $Id: DTMNodeIterator.java 468653 2006-10-28 07:07:05Z minchau $
*/
package org.apache.xml.dtm.ref;
import org.apache.xml.dtm.DTM;
import org.apache.xml.dtm.DTMDOMException;
import org.apache.xml.dtm.DTMIterator;
import org.w3c.dom.DOMException;
import org.w3c.dom.Node;
import org.w3c.dom.traversal.NodeFilter;
/**
* DTMNodeIterator gives us an implementation of the
* DTMNodeIterator which returns DOM nodes.
*
* Please note that this is not necessarily equivlaent to a DOM
* NodeIterator operating over the same document. In particular:
*
*
* - If there are several Text nodes in logical succession (ie,
* across CDATASection and EntityReference boundaries), we will return
* only the first; the caller is responsible for stepping through
* them.
* (%REVIEW% Provide a convenience routine here to assist, pending
* proposed DOM Level 3 getAdjacentText() operation?)
*
* - Since the whole XPath/XSLT architecture assumes that the source
* document is not altered while we're working with it, we do not
* promise to implement the DOM NodeIterator's "maintain current
* position" response to document mutation.
*
* - Since our design for XPath NodeIterators builds a stateful
* filter directly into the traversal object, getNodeFilter() is not
* supported.
*
*
*
* State: In progress!!
* */
public class DTMNodeIterator implements org.w3c.dom.traversal.NodeIterator
{
private DTMIterator dtm_iter;
private boolean valid=true;
//================================================================
// Methods unique to this class
/** Public constructor: Wrap a DTMNodeIterator around an existing
* and preconfigured DTMIterator
* */
public DTMNodeIterator(DTMIterator dtmIterator)
{
try
{
dtm_iter=(DTMIterator)dtmIterator.clone();
}
catch(CloneNotSupportedException cnse)
{
throw new org.apache.xml.utils.WrappedRuntimeException(cnse);
}
}
/** Access the wrapped DTMIterator. I'm not sure whether anyone will
* need this or not, but let's write it and think about it.
* */
public DTMIterator getDTMIterator()
{
return dtm_iter;
}
//================================================================
// org.w3c.dom.traversal.NodeFilter API follows
/** Detaches the NodeIterator from the set which it iterated over,
* releasing any computational resources and placing the iterator in
* the INVALID state.
* */
public void detach()
{
// Theoretically, we could release dtm_iter at this point. But
// some of the operations may still want to consult it even though
// navigation is now invalid.
valid=false;
}
/** The value of this flag determines whether the children
* of entity reference nodes are visible to the iterator.
*
* @return false, always (the DTM model flattens entity references)
* */
public boolean getExpandEntityReferences()
{
return false;
}
/** Return a handle to the filter used to screen nodes.
*
* This is ill-defined in Xalan's usage of Nodeiterator, where we have
* built stateful XPath-based filtering directly into the traversal
* object. We could return something which supports the NodeFilter interface
* and allows querying whether a given node would be permitted if it appeared
* as our next node, but in the current implementation that would be very
* complex -- and just isn't all that useful.
*
* @throws DOMException -- NOT_SUPPORTED_ERROR because I can't think
* of anything more useful to do in this case
* */
public NodeFilter getFilter()
{
throw new DTMDOMException(DOMException.NOT_SUPPORTED_ERR);
}
/** @return The root node of the NodeIterator, as specified
* when it was created.
* */
public Node getRoot()
{
int handle=dtm_iter.getRoot();
return dtm_iter.getDTM(handle).getNode(handle);
}
/** Return a mask describing which node types are presented via the
* iterator.
**/
public int getWhatToShow()
{
return dtm_iter.getWhatToShow();
}
/** @return the next node in the set and advance the position of the
* iterator in the set.
*
* @throws DOMException - INVALID_STATE_ERR Raised if this method is
* called after the detach method was invoked.
* */
public Node nextNode() throws DOMException
{
if(!valid)
throw new DTMDOMException(DOMException.INVALID_STATE_ERR);
int handle=dtm_iter.nextNode();
if (handle==DTM.NULL)
return null;
return dtm_iter.getDTM(handle).getNode(handle);
}
/** @return the next previous in the set and advance the position of the
* iterator in the set.
*
* @throws DOMException - INVALID_STATE_ERR Raised if this method is
* called after the detach method was invoked.
* */
public Node previousNode()
{
if(!valid)
throw new DTMDOMException(DOMException.INVALID_STATE_ERR);
int handle=dtm_iter.previousNode();
if (handle==DTM.NULL)
return null;
return dtm_iter.getDTM(handle).getNode(handle);
}
}