/*
* Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
*
* This software is open source.
* See the bottom of this file for the licence.
*/
package org.dom4j.io;
import org.dom4j.
Element;
import org.dom4j.
ElementHandler;
/**
* <p>
* <code>PruningElementStack</code> is a stack of {@link Element}instances
* which will prune the tree when a path expression is reached. This is useful
* for parsing very large documents where children of the root element can be
* processed individually rather than keeping them all in memory at the same
* time.
* </p>
*
* @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
* @version $Revision: 1.11 $
*/
class
PruningElementStack extends
ElementStack {
/** ElementHandler to call when pruning occurs */
private
ElementHandler elementHandler;
/**
* the element name path which denotes the node to remove from its parent
* when it is complete (i.e. when it is popped from the stack). The first
* entry in the path will be a child of the root node
*/
private
String[]
path;
/**
* The level at which a path match can occur. We match when we have popped
* the selected node so the and the lastElementIndex points to its parent so
* this value should be path.length - 2
*/
private int
matchingElementIndex;
public
PruningElementStack(
String[]
path,
ElementHandler elementHandler) {
this.
path =
path;
this.
elementHandler =
elementHandler;
checkPath();
}
public
PruningElementStack(
String[]
path,
ElementHandler elementHandler,
int
defaultCapacity) {
super(
defaultCapacity);
this.
path =
path;
this.
elementHandler =
elementHandler;
checkPath();
}
public
Element popElement() {
Element answer = super.popElement();
if ((
lastElementIndex ==
matchingElementIndex)
&& (
lastElementIndex >= 0)) {
// we are popping the correct level in the tree
// lets check if the path fits
//
// NOTE: this is an inefficient way of doing it - we could
// maintain a history of which parts matched?
if (
validElement(
answer,
lastElementIndex + 1)) {
Element parent = null;
for (int
i = 0;
i <=
lastElementIndex;
i++) {
parent =
stack[
i];
if (!
validElement(
parent,
i)) {
parent = null;
break;
}
}
if (
parent != null) {
pathMatches(
parent,
answer);
}
}
}
return
answer;
}
protected void
pathMatches(
Element parent,
Element selectedNode) {
elementHandler.
onEnd(this);
parent.
remove(
selectedNode);
}
protected boolean
validElement(
Element element, int
index) {
String requiredName =
path[
index];
String name =
element.
getName();
if (
requiredName ==
name) {
return true;
}
if ((
requiredName != null) && (
name != null)) {
return
requiredName.
equals(
name);
}
return false;
}
private void
checkPath() {
if (
path.length < 2) {
throw new
RuntimeException("Invalid path of length: " +
path.length
+ " it must be greater than 2");
}
matchingElementIndex =
path.length - 2;
}
}
/*
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided that the
* following conditions are met:
*
* 1. Redistributions of source code must retain copyright statements and
* notices. Redistributions must also contain a copy of this document.
*
* 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 name "DOM4J" must not be used to endorse or promote products derived
* from this Software without prior written permission of MetaStuff, Ltd. For
* written permission, please contact dom4j-info@metastuff.com.
*
* 4. Products derived from this Software may not be called "DOM4J" nor may
* "DOM4J" appear in their names without prior written permission of MetaStuff,
* Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
*
* 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
*
* THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``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 METASTUFF, LTD. 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 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.
*
* Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
*/