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Java > Open Source Codes > edu > neu > ccs > jmk > Expression


1 // $Id: Expression.java,v 1.2 2001/12/07 11:41:24 ramsdell Exp $
2
3 // Expressions
4
5 /*
6  * Copyright 1999 by John D. Ramsdell
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public License
10  * as published by the Free Software Foundation; either version 2
11  * of the License, or (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21  */
22
23 package edu.neu.ccs.jmk;
24
25 /**
26  * Expressions.
27  * This is the base class of all classes that
28  * implement expression evaluation.
29  * @version May 1999
30  * @author John D. Ramsdell
31  */
32 abstract class Expression
33 {
34   /*
35    * Evaluate expression.
36    * @param env run time environment
37    * @param a string list
38    * @return result of invocation appended to the list
39    * (if list is non-null, result must be a string list)
40    * @exception Exception if evaluation failed
41    */
42   abstract Value eval(Environment env, StringList list)
43        throws Exception JavaDoc;
44 }
45
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