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Java > Open Source Codes > com > sun > org > apache > xpath > internal > operations > Neg


1 /*
2  * Copyright 1999-2004 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 /*
17  * $Id: Neg.java,v 1.8 2004/02/17 04:35:12 minchau Exp $
18  */
19 package com.sun.org.apache.xpath.internal.operations;
20
21 import com.sun.org.apache.xpath.internal.XPathContext;
22 import com.sun.org.apache.xpath.internal.objects.XNumber;
23 import com.sun.org.apache.xpath.internal.objects.XObject;
24
25 /**
26  * The unary '-' operation expression executer.
27  */
28 public class Neg extends UnaryOperation
29 {
30
31   /**
32    * Apply the operation to two operands, and return the result.
33    *
34    *
35    * @param right non-null reference to the evaluated right operand.
36    *
37    * @return non-null reference to the XObject that represents the result of the operation.
38    *
39    * @throws javax.xml.transform.TransformerException
40    */
41   public XObject operate(XObject right) throws javax.xml.transform.TransformerException JavaDoc
42   {
43     return new XNumber(-right.num());
44   }
45   
46   /**
47    * Evaluate this operation directly to a double.
48    *
49    * @param xctxt The runtime execution context.
50    *
51    * @return The result of the operation as a double.
52    *
53    * @throws javax.xml.transform.TransformerException
54    */
55   public double num(XPathContext xctxt)
56           throws javax.xml.transform.TransformerException JavaDoc
57   {
58
59     return -(m_right.num(xctxt));
60   }
61
62 }
63
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