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Java > Open Source Codes > org > apache > commons > jxpath > ri > compiler > Constant


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 package org.apache.commons.jxpath.ri.compiler;
17
18 import org.apache.commons.jxpath.ri.EvalContext;
19
20 /**
21  * A compile tree element containing a constant number or string.
22  *
23  * @author Dmitri Plotnikov
24  * @version $Revision: 1.8 $ $Date: 2004/02/29 14:17:39 $
25  */
26 public class Constant extends Expression {
27
28     private Object JavaDoc value;
29
30     public Constant(Number JavaDoc number) {
31         this.value = number;
32     }
33
34     public Constant(String JavaDoc string) {
35         this.value = string;
36     }
37
38     public Object JavaDoc compute(EvalContext context) {
39         return value;
40     }
41
42     /**
43      * Returns the value of the constant.
44      */
45     public Object JavaDoc computeValue(EvalContext context) {
46         return value;
47     }
48
49     /**
50      * Returns false
51      */
52     public boolean isContextDependent() {
53         return false;
54     }
55
56     /**
57      * Returns false
58      */
59     public boolean computeContextDependent() {
60         return false;
61     }
62
63     public String JavaDoc toString() {
64         if (value instanceof Number JavaDoc) {
65             double doubleValue = ((Number JavaDoc) value).doubleValue();
66             long longValue = ((Number JavaDoc) value).longValue();
67             if (doubleValue == longValue) {
68                 return String.valueOf(longValue);
69             }
70             else {
71                 return String.valueOf(doubleValue);
72             }
73         }
74         else {
75             return "'" + value + "'";
76         }
77     }
78 }
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