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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 computeValue(EvalContext context) {
34          double a = InfoSetUtil.doubleValue(args[0].computeValue(context));
35          return new Double(-a);
36      }
37      
38      protected int getPrecedence() {
39          return 6;
40      }
41  
42      protected boolean isSymmetric() {
43          return false;
44      }
45      
46      public String getSymbol() {
47          return "-";
48      }
49  }