org.apache.xpath.XPathVisitor Maven / Gradle / Ivy
/*
* 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.
*
* Each method has the form
* boolean visitComponentType(ExpressionOwner owner, ComponentType compType).
* 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.
*
* 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.
*/
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;
}
}