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Java > Open Source Codes > org > apache > commons > jexl > JexlExprResolver


1 /*
2  * Copyright 2002-2006 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.jexl;
17
18 /**
19  * A Resolver allows custom resolution of the expression, and can be
20  * added in front of the jexl engine, or after in the evaluation.
21  *
22  * @todo This needs to be explained in detail. Why do this?
23  * @since 1.0
24  * @author <a HREF="mailto:geirm@adeptra.com">Geir Magnusson Jr.</a>
25  * @version $Id: JexlExprResolver.java 397092 2006-04-26 05:11:28Z dion $
26  */
27 public interface JexlExprResolver {
28     /** represents an expression result of no value. */
29     Object JavaDoc NO_VALUE = new Object JavaDoc();
30
31     /**
32      * Evaluates an expression against the context.
33      *
34      * @todo Must detail the expectations and effects of this resolver.
35      * @param context current data context
36      * @param expression expression to evauluate
37      * @return value (may be null) or the NO_VALUE object to
38      * indicate no resolution.
39      */
40     Object JavaDoc evaluate(JexlContext context, String JavaDoc expression);
41 }
42
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