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	/*
	* reserved comment block
	* DO NOT REMOVE OR ALTER!
	*/
	/*
	* 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.
	*/

	package com.sun.org.apache.xpath.internal;

	import com.sun.org.apache.xpath.internal.axes.LocPathIterator;
	import com.sun.org.apache.xpath.internal.axes.UnionPathIterator;
	import com.sun.org.apache.xpath.internal.functions.Function;
	import com.sun.org.apache.xpath.internal.objects.XNumber;
	import com.sun.org.apache.xpath.internal.objects.XString;
	import com.sun.org.apache.xpath.internal.operations.Operation;
	import com.sun.org.apache.xpath.internal.operations.UnaryOperation;
	import com.sun.org.apache.xpath.internal.operations.Variable;
	import com.sun.org.apache.xpath.internal.patterns.NodeTest;
	import com.sun.org.apache.xpath.internal.patterns.StepPattern;
	import com.sun.org.apache.xpath.internal.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;
	}


	}

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