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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.jxpath.ri.compiler;
18  
19  import org.apache.commons.jxpath.ri.EvalContext;
20  import org.apache.commons.jxpath.ri.InfoSetUtil;
21  
22  /**
23   * Implementation of {@link Expression} for the operation unary "-".
24   *
25   * @author Dmitri Plotnikov
26   * @version $Revision: 652845 $ $Date: 2008-05-02 13:46:46 -0400 (Fri, 02 May 2008) $
27   */
28  public class CoreOperationNegate extends CoreOperation {
29  
30      /**
31       * Create a new CoreOperationNegate.
32       * @param arg the Expression to negate
33       */
34      public CoreOperationNegate(Expression arg) {
35          super(new Expression[] { arg });
36      }
37  
38      public Object computeValue(EvalContext context) {
39          double a = InfoSetUtil.doubleValue(args[0].computeValue(context));
40          return new Double(-a);
41      }
42  
43      protected int getPrecedence() {
44          return NEGATE_PRECEDENCE;
45      }
46  
47      protected boolean isSymmetric() {
48          return false;
49      }
50  
51      public String getSymbol() {
52          return "-";
53      }
54  }