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Java > Open Source Codes > org > apache > commons > jxpath > ri > compiler > CoreOperationNegate


1 /*
2  * Copyright 2002-2004 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.jxpath.ri.compiler;
17
18 import org.apache.commons.jxpath.ri.EvalContext;
19 import org.apache.commons.jxpath.ri.InfoSetUtil;
20
21 /**
22  * Implementation of Expression for the operation unary "-".
23  *
24  * @author Dmitri Plotnikov
25  * @version $Revision: 1.3 $ $Date: 2004/02/29 14:17:39 $
26  */
27 public class CoreOperationNegate extends CoreOperation {
28
29     public CoreOperationNegate(Expression arg) {
30         super(new Expression[] { arg });
31     }
32
33     public Object JavaDoc computeValue(EvalContext context) {
34         double a = InfoSetUtil.doubleValue(args[0].computeValue(context));
35         return new Double JavaDoc(-a);
36     }
37     
38     protected int getPrecedence() {
39         return 6;
40     }
41
42     protected boolean isSymmetric() {
43         return false;
44     }
45     
46     public String JavaDoc getSymbol() {
47         return "-";
48     }
49 }
50
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