com.sun.org.apache.xpath.internal.operations.VariableSafeAbsRef Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of jaxp-ri Show documentation
Java API for XML Processing Reference Implementation
The newest version!
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 *
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *
 * 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: VariableSafeAbsRef.java,v 1.8 2010-11-01 04:35:17 joehw Exp $
 */
package com.sun.org.apache.xpath.internal.operations;

import com.sun.org.apache.xml.internal.dtm.DTMManager;
import com.sun.org.apache.xpath.internal.Expression;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.objects.XNodeSet;
import com.sun.org.apache.xpath.internal.objects.XObject;


/**
 * This is a "smart" variable reference that is used in situations where 
 * an absolute path is optimized into a variable reference, but may 
 * be used in some situations where the document context may have changed.
 * For instance, in select="document(doc/@href)//name[//salary > 7250]", the 
 * root in the predicate will be different for each node in the set.  While 
 * this is easy to detect statically in this case, in other cases static 
 * detection would be very hard or impossible.  So, this class does a dynamic check 
 * to make sure the document context of the referenced variable is the same as 
 * the current document context, and, if it is not, execute the referenced variable's 
 * expression with the current context instead.
 */
public class VariableSafeAbsRef extends Variable
{
    static final long serialVersionUID = -9174661990819967452L;
	
  /**
   * Dereference the variable, and return the reference value.  Note that lazy 
   * evaluation will occur.  If a variable within scope is not found, a warning 
   * will be sent to the error listener, and an empty nodeset will be returned.
   *
   *
   * @param xctxt The runtime execution context.
   *
   * @return The evaluated variable, or an empty nodeset if not found.
   *
   * @throws javax.xml.transform.TransformerException
   */
  public XObject execute(XPathContext xctxt, boolean destructiveOK) 
  	throws javax.xml.transform.TransformerException
  {
  	XNodeSet xns = (XNodeSet)super.execute(xctxt, destructiveOK);
  	DTMManager dtmMgr = xctxt.getDTMManager();
  	int context = xctxt.getContextNode();
  	if(dtmMgr.getDTM(xns.getRoot()).getDocument() != 
  	   dtmMgr.getDTM(context).getDocument())
  	{
  		Expression expr = (Expression)xns.getContainedIter();
  		xns = (XNodeSet)expr.asIterator(xctxt, context);
  	}
  	return xns;
  }

}