| /* |
| * 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: XPathVisitor.java 468655 2006-10-28 07:12:06Z minchau $ |
| */ |
| package org.apache.xpath; |
| |
| import org.apache.xpath.axes.LocPathIterator; |
| import org.apache.xpath.axes.UnionPathIterator; |
| import org.apache.xpath.functions.Function; |
| import org.apache.xpath.objects.XNumber; |
| import org.apache.xpath.objects.XString; |
| import org.apache.xpath.operations.Operation; |
| import org.apache.xpath.operations.UnaryOperation; |
| import org.apache.xpath.operations.Variable; |
| import org.apache.xpath.patterns.NodeTest; |
| import org.apache.xpath.patterns.StepPattern; |
| import org.apache.xpath.patterns.UnionPattern; |
| |
| /** |
| * A derivation from this class can be passed to a class that implements |
| * the XPathVisitable interface, to have the appropriate method called |
| * for each component of the XPath. Aside from possible other uses, the |
| * main intention is to provide a reasonable means to perform expression |
| * rewriting. |
| * |
| * <p>Each method has the form |
| * <code>boolean visitComponentType(ExpressionOwner owner, ComponentType compType)</code>. |
| * The ExpressionOwner argument is the owner of the component, and can |
| * be used to reset the expression for rewriting. If a method returns |
| * false, the sub hierarchy will not be traversed.</p> |
| * |
| * <p>This class is meant to be a base class that will be derived by concrete classes, |
| * and doesn't much except return true for each method.</p> |
| */ |
| public class XPathVisitor |
| { |
| /** |
| * Visit a LocationPath. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param path The LocationPath object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitLocationPath(ExpressionOwner owner, LocPathIterator path) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a UnionPath. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param path The UnionPath object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitUnionPath(ExpressionOwner owner, UnionPathIterator path) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a step within a location path. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param step The Step object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitStep(ExpressionOwner owner, NodeTest step) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a predicate within a location path. Note that there isn't a |
| * proper unique component for predicates, and that the expression will |
| * be called also for whatever type Expression is. |
| * |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param pred The predicate object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitPredicate(ExpressionOwner owner, Expression pred) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a binary operation. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param op The operation object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitBinaryOperation(ExpressionOwner owner, Operation op) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a unary operation. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param op The operation object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitUnaryOperation(ExpressionOwner owner, UnaryOperation op) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a variable reference. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param var The variable reference object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitVariableRef(ExpressionOwner owner, Variable var) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a function. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param func The function reference object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitFunction(ExpressionOwner owner, Function func) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a match pattern. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param pattern The match pattern object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitMatchPattern(ExpressionOwner owner, StepPattern pattern) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a union pattern. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param pattern The union pattern object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitUnionPattern(ExpressionOwner owner, UnionPattern pattern) |
| { |
| return true; |
| } |
| |
| /** |
| * Visit a string literal. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param str The string literal object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitStringLiteral(ExpressionOwner owner, XString str) |
| { |
| return true; |
| } |
| |
| |
| /** |
| * Visit a number literal. |
| * @param owner The owner of the expression, to which the expression can |
| * be reset if rewriting takes place. |
| * @param num The number literal object. |
| * @return true if the sub expressions should be traversed. |
| */ |
| public boolean visitNumberLiteral(ExpressionOwner owner, XNumber num) |
| { |
| return true; |
| } |
| |
| |
| } |
| |