19f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson/* 29f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * Licensed to the Apache Software Foundation (ASF) under one 39f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * or more contributor license agreements. See the NOTICE file 49f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * distributed with this work for additional information 59f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * regarding copyright ownership. The ASF licenses this file 69f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * to you under the Apache License, Version 2.0 (the "License"); 79f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * you may not use this file except in compliance with the License. 89f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * You may obtain a copy of the License at 99f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * 109f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * http://www.apache.org/licenses/LICENSE-2.0 119f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * 129f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * Unless required by applicable law or agreed to in writing, software 139f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * distributed under the License is distributed on an "AS IS" BASIS, 149f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 159f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * See the License for the specific language governing permissions and 169f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * limitations under the License. 179f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson */ 189f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson/* 199f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * $Id: VariableSafeAbsRef.java 468655 2006-10-28 07:12:06Z minchau $ 209f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson */ 219f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonpackage org.apache.xpath.operations; 229f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson 239f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonimport org.apache.xml.dtm.DTMManager; 249f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonimport org.apache.xpath.Expression; 259f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonimport org.apache.xpath.XPathContext; 269f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonimport org.apache.xpath.objects.XNodeSet; 279f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonimport org.apache.xpath.objects.XObject; 289f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson 299f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson 309f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson/** 319f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * This is a "smart" variable reference that is used in situations where 329f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * an absolute path is optimized into a variable reference, but may 339f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * be used in some situations where the document context may have changed. 349f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * For instance, in select="document(doc/@href)//name[//salary > 7250]", the 359f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * root in the predicate will be different for each node in the set. While 369f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * this is easy to detect statically in this case, in other cases static 379f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * detection would be very hard or impossible. So, this class does a dynamic check 389f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * to make sure the document context of the referenced variable is the same as 399f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * the current document context, and, if it is not, execute the referenced variable's 409f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * expression with the current context instead. 419f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson */ 429f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilsonpublic class VariableSafeAbsRef extends Variable 439f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson{ 449f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson static final long serialVersionUID = -9174661990819967452L; 459f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson 469f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson /** 479f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * Dereference the variable, and return the reference value. Note that lazy 489f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * evaluation will occur. If a variable within scope is not found, a warning 499f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * will be sent to the error listener, and an empty nodeset will be returned. 509f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * 519f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * 529f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * @param xctxt The runtime execution context. 539f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * 549f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * @return The evaluated variable, or an empty nodeset if not found. 559f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * 569f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson * @throws javax.xml.transform.TransformerException 579f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson */ 589f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson public XObject execute(XPathContext xctxt, boolean destructiveOK) 599f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson throws javax.xml.transform.TransformerException 609f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson { 619f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson XNodeSet xns = (XNodeSet)super.execute(xctxt, destructiveOK); 629f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson DTMManager dtmMgr = xctxt.getDTMManager(); 639f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson int context = xctxt.getContextNode(); 649f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson if(dtmMgr.getDTM(xns.getRoot()).getDocument() != 659f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson dtmMgr.getDTM(context).getDocument()) 669f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson { 679f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson Expression expr = (Expression)xns.getContainedIter(); 689f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson xns = (XNodeSet)expr.asIterator(xctxt, context); 699f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson } 709f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson return xns; 719f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson } 729f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson 739f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson} 749f8118474e9513f7a5b7d2a05e4a0fb15d1a6569Jesse Wilson 75