01: /*
02: * Copyright 2002-2004 The Apache Software Foundation
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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 computeValue(EvalContext context) {
34: double a = InfoSetUtil.doubleValue(args[0]
35: .computeValue(context));
36: return new Double(-a);
37: }
38:
39: protected int getPrecedence() {
40: return 6;
41: }
42:
43: protected boolean isSymmetric() {
44: return false;
45: }
46:
47: public String getSymbol() {
48: return "-";
49: }
50: }
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