1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.el;
18
19 import javax.servlet.jsp.el.ELException;
20 import javax.servlet.jsp.el.FunctionMapper;
21 import javax.servlet.jsp.el.VariableResolver;
22
23 /**
24 *
25 * <p>The abstract class from which all expression types
26 * derive.
27 *
28 * @author Nathan Abramson - Art Technology Group
29 * @author Shawn Bayern
30 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: bayard $
31 **/
32
33 public abstract class Expression
34 {
35 //-------------------------------------
36 // Member variables
37 //-------------------------------------
38
39 //-------------------------------------
40 /**
41 *
42 * Returns the expression in the expression language syntax
43 **/
44 public abstract String getExpressionString ();
45
46 //-------------------------------------
47 /**
48 *
49 * Evaluates the expression in the given context
50 **/
51 public abstract Object evaluate (VariableResolver pResolver, FunctionMapper functions)
52 throws ELException;
53
54 //-------------------------------------
55
56 /**
57 * Returns an expression with all <code>FunctionInvocation</code>s replaced by
58 * <code>BoundFunctionInvocation</code>s.
59 * @param functions the functions to use in this transformation
60 * @return an Expression identical to this expression except with all
61 * <code>FunctionInvocation</code>s replaced by
62 * <code>BoundFunctionInvocation</code>s.
63 * @throws ELException if any of the functions in this <code>Expression</code> are
64 * not present in <code>functions</code>
65 */
66 public abstract Expression bindFunctions(FunctionMapper functions)
67 throws ELException;
68
69 }