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Java > Open Source Codes > org > apache > xpath > operations > Minus


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: Minus.java,v 1.8 2004/02/17 04:35:12 minchau Exp $
18  */
19 package org.apache.xpath.operations;
20
21 import org.apache.xpath.XPathContext;
22 import org.apache.xpath.objects.XNumber;
23 import org.apache.xpath.objects.XObject;
24
25 /**
26  * The binary '-' operation expression executer.
27  */
28 public class Minus extends Operation
29 {
30
31   /**
32    * Apply the operation to two operands, and return the result.
33    *
34    *
35    * @param left non-null reference to the evaluated left operand.
36    * @param right non-null reference to the evaluated right operand.
37    *
38    * @return non-null reference to the XObject that represents the
39    * result of the operation.
40    *
41    * @throws javax.xml.transform.TransformerException
42    */
43   public XObject operate(XObject left, XObject right)
44           throws javax.xml.transform.TransformerException JavaDoc
45   {
46     return new XNumber(left.num() - right.num());
47   }
48   
49   /**
50    * Evaluate this operation directly to a double.
51    *
52    * @param xctxt The runtime execution context.
53    *
54    * @return The result of the operation as a double.
55    *
56    * @throws javax.xml.transform.TransformerException
57    */
58   public double num(XPathContext xctxt)
59           throws javax.xml.transform.TransformerException JavaDoc
60   {
61
62     return (m_left.num(xctxt) - m_right.num(xctxt));
63   }
64
65 }
66
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