001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 /*
019 * $Id: AbsPathChecker.java 468643 2006-10-28 06:56:03Z minchau $
020 */
021 package org.apache.xalan.templates;
022
023 import org.apache.xpath.ExpressionOwner;
024 import org.apache.xpath.XPathVisitor;
025 import org.apache.xpath.axes.LocPathIterator;
026 import org.apache.xpath.functions.FuncCurrent;
027 import org.apache.xpath.functions.FuncExtFunction;
028 import org.apache.xpath.functions.Function;
029 import org.apache.xpath.operations.Variable;
030
031 /**
032 * This class runs over a path expression that is assumed to be absolute, and
033 * checks for variables and the like that may make it context dependent.
034 */
035 public class AbsPathChecker extends XPathVisitor
036 {
037 private boolean m_isAbs = true;
038
039 /**
040 * Process the LocPathIterator to see if it contains variables
041 * or functions that may make it context dependent.
042 * @param path LocPathIterator that is assumed to be absolute, but needs checking.
043 * @return true if the path is confirmed to be absolute, false if it
044 * may contain context dependencies.
045 */
046 public boolean checkAbsolute(LocPathIterator path)
047 {
048 m_isAbs = true;
049 path.callVisitors(null, this);
050 return m_isAbs;
051 }
052
053 /**
054 * Visit a function.
055 * @param owner The owner of the expression, to which the expression can
056 * be reset if rewriting takes place.
057 * @param func The function reference object.
058 * @return true if the sub expressions should be traversed.
059 */
060 public boolean visitFunction(ExpressionOwner owner, Function func)
061 {
062 if((func instanceof FuncCurrent) ||
063 (func instanceof FuncExtFunction))
064 m_isAbs = false;
065 return true;
066 }
067
068 /**
069 * Visit a variable reference.
070 * @param owner The owner of the expression, to which the expression can
071 * be reset if rewriting takes place.
072 * @param var The variable reference object.
073 * @return true if the sub expressions should be traversed.
074 */
075 public boolean visitVariableRef(ExpressionOwner owner, Variable var)
076 {
077 m_isAbs = false;
078 return true;
079 }
080 }
081