org.apache.openjpa.kernel.exps.ExpressionVisitor Maven / Gradle / Ivy
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* 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
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* under the License.
*/
package org.apache.openjpa.kernel.exps;
/**
* Visits nodes of a query expression tree.
*
* @author Abe White
*/
public interface ExpressionVisitor {
/**
* Enter an expression. The expression will then invoke visits on its
* components.
*/
void enter(Expression exp);
/**
* Leave an expression.
*/
void exit(Expression exp);
/**
* Enter a value. The value will then invoke visits on its components.
*/
void enter(Value val);
/**
* Leave a value.
*/
void exit(Value val);
}