org.apache.commons.jexl.Expression 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 specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.jexl;
/**
*
* Represents a single JEXL expression. This simple interface
* provides access to the underlying expression through getExpression(),
* and it provides hooks to add a pre- and post- expression resolver.
*
*
*
* An expression is different than a script - it is simply a reference of
* an expression.
*
*
* @since 1.0
* @author Geir Magnusson Jr.
* @version $Id: Expression.java 480412 2006-11-29 05:11:23Z bayard $
*/
public interface Expression {
/**
* Evaluates the expression with the variables contained in the
* supplied {@link JexlContext}.
*
* @param context A JexlContext containing variables.
* @return The result of this evaluation
* @throws Exception on any error
*/
Object evaluate(JexlContext context) throws Exception;
/**
* Returns the JEXL expression this Expression was created with.
*
* @return The JEXL expression to be evaluated
*/
String getExpression();
/**
* Allows addition of a resolver to allow custom interdiction of
* expression evaluation.
*
* @param resolver resolver to be called before Jexl expression evaluated
*/
void addPreResolver(JexlExprResolver resolver);
/**
* Allows addition of a resolver to allow custom interdiction of
* expression evaluation.
*
* @param resolver resolver to be called if Jexl expression
* evaluated to null.
*/
void addPostResolver(JexlExprResolver resolver);
}