/*
* 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.
*/
package org.apache.excalibur.xml.xpath;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.TransformerFactory;
import org.apache.avalon.framework.thread.ThreadSafe;
import com.icl.saxon.Context;
import com.icl.saxon.TransformerFactoryImpl;
import com.icl.saxon.tinytree.TinyBuilder;
import com.icl.saxon.expr.Expression;
import com.icl.saxon.expr.StandaloneContext;
import com.icl.saxon.expr.Value;
import com.icl.saxon.expr.XPathException;
import com.icl.saxon.expr.NodeSetValue;
import com.icl.saxon.om.DocumentInfo;
import com.icl.saxon.om.NamePool;
import com.icl.saxon.om.NodeInfo;
import com.icl.saxon.om.NodeEnumeration;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
/**
* This class defines the implementation of the {@link XPathProcessor}
* component. This implementation depends on Saxon 6.X XSLT processor.
* This implementation was tested with Saxon 6.5.2 release.
*
* To configure it, add the following lines in the
* <file>cocoon.xconf</file> file:
*
* <pre>
* <xpath-processor class="org.apache.cocoon.components.xpath.Saxon6ProcessorImpl">
* </xpath-processor>
* </pre>
*
* @author <a href="mailto:dev@avalon.apache.org">Avalon Development Team</a>
* @version CVS $Revision: 1.4 $ $Date: 2004/02/28 11:47:15 $ $Author: cziegeler $
*/
public class Saxon6ProcessorImpl
extends AbstractProcessorImpl
implements ThreadSafe
{
private static final TransformerFactory factory = new TransformerFactoryImpl();
/**
* Evaluate XPath expression within a context.
*
* @param contextNode The context node.
* @param str A valid XPath string.
* @param resolver a PrefixResolver, used for resolving namespace prefixes
* @return expression result as boolean.
*/
public boolean evaluateAsBoolean(Node contextNode, String str, PrefixResolver resolver)
{
try
{
Value value = evaluate(contextNode, str, resolver);
if (value == null)
{
return false;
}
return value.asBoolean();
}
catch (final Exception e)
{
if (getLogger().isDebugEnabled()) {
getLogger().debug("Failed to evaluate '" + str + "'", e);
}
// ignore it
return false;
}
}
/**
* Evaluate XPath expression within a context.
*
* @param contextNode The context node.
* @param str A valid XPath string.
* @param resolver a PrefixResolver, used for resolving namespace prefixes
* @return expression result as number.
*/
public Number evaluateAsNumber(Node contextNode, String str, PrefixResolver resolver)
{
try
{
Value value = evaluate(contextNode, str, resolver);
if (value == null)
{
return null;
}
return new Double(value.asNumber());
}
catch (final Exception e)
{
if (getLogger().isDebugEnabled()) {
getLogger().debug("Failed to evaluate '" + str + "'", e);
}
// ignore it
return null;
}
}
/**
* Evaluate XPath expression within a context.
*
* @param contextNode The context node.
* @param str A valid XPath string.
* @param resolver a PrefixResolver, used for resolving namespace prefixes
* @return expression result as string.
*/
public String evaluateAsString(Node contextNode, String str, PrefixResolver resolver) {
try
{
Value value = evaluate(contextNode, str, resolver);
if (value == null)
{
return null;
}
return value.asString();
}
catch (final Exception e)
{
if (getLogger().isDebugEnabled()) {
getLogger().debug("Failed to evaluate '" + str + "'", e);
}
// ignore it
return null;
}
}
public Node selectSingleNode(Node contextNode, String str, PrefixResolver resolver)
{
try
{
Value value = evaluate(contextNode, str, resolver);
if (value == null || value.getDataType() != Value.NODESET)
{
return null;
}
return (Node)((NodeSetValue)value).getFirst();
}
catch (final Exception e)
{
if (getLogger().isDebugEnabled()) {
getLogger().debug("Failed to evaluate '" + str + "'", e);
}
// ignore it
return null;
}
}
public NodeList selectNodeList(Node contextNode, String str, PrefixResolver resolver)
{
try
{
Value value = evaluate(contextNode, str, resolver);
if (value.getDataType() != Value.NODESET)
{
return null;
}
NodeSetValue nodeset = (NodeSetValue)value;
NodeEnumeration enumeration = nodeset.enumerate();
Node[] nodes = new Node[nodeset.getCount()];
for (int i = 0; i < nodes.length; i++)
{
nodes[i] = (Node)enumeration.nextElement();
}
return new NodeListImpl(nodes);
} catch (final Exception e) {
if (getLogger().isDebugEnabled()) {
getLogger().debug("Failed to evaluate '" + str + "'", e);
}
// ignore it
return null;
}
}
private Value evaluate(Node contextNode, String str, PrefixResolver resolver)
{
try
{
if (!(contextNode instanceof NodeInfo))
{
getLogger().debug("Input tree is not SAXON TinyTree, converting");
DOMSource source = new DOMSource(contextNode);
TinyBuilder result = new TinyBuilder();
factory.newTransformer().transform(source, result);
contextNode = (Node)result.getCurrentDocument();
}
DocumentInfo doc = ((NodeInfo)contextNode).getDocumentRoot();
NamePool pool = doc.getNamePool();
if (pool == null)
{
pool = NamePool.getDefaultNamePool();
doc.setNamePool(pool);
}
Expression expression = Expression.make(str, new Saxon6Context(pool, resolver));
Context context = new Context();
context.setContextNode((NodeInfo)contextNode);
context.setPosition(1);
context.setLast(1);
return expression.evaluate(context);
}
catch (final Exception e)
{
if (getLogger().isDebugEnabled()) {
getLogger().debug("Failed to evaluate '" + str + "'", e);
}
// ignore it
return null;
}
}
private class Saxon6Context extends StandaloneContext
{
private final PrefixResolver resolver;
public Saxon6Context(NamePool namePool, PrefixResolver resolver)
{
super(namePool);
this.resolver = resolver;
}
public String getURIForPrefix(String prefix) throws XPathException
{
return resolver.prefixToNamespace(prefix);
}
}
}