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Java > Open Source Codes > org > apache > slide > search > basic > expression > IsDefinedExpression


1 /*
2  * $Header: /home/cvs/jakarta-slide/src/share/org/apache/slide/search/basic/expression/IsDefinedExpression.java,v 1.4 2004/07/28 09:34:50 ib Exp $
3  * $Revision: 1.4 $
4  * $Date: 2004/07/28 09:34:50 $
5  *
6  * ====================================================================
7  *
8  * Copyright 1999-2002 The Apache Software Foundation
9  *
10  * Licensed under the Apache License, Version 2.0 (the "License");
11  * you may not use this file except in compliance with the License.
12  * You may obtain a copy of the License at
13  *
14  * http://www.apache.org/licenses/LICENSE-2.0
15  *
16  * Unless required by applicable law or agreed to in writing, software
17  * distributed under the License is distributed on an "AS IS" BASIS,
18  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19  * See the License for the specific language governing permissions and
20  * limitations under the License.
21  *
22  */
23
24 package org.apache.slide.search.basic.expression;
25
26 import org.apache.slide.search.InvalidQueryException;
27 import org.apache.slide.search.basic.ComparableResource;
28 import org.apache.slide.search.basic.ComparableResourcesPool;
29 import org.apache.slide.search.basic.Literals;
30 import org.jdom.Element;
31
32 /**
33  * Represents an isdefined expression.
34  *
35  * @version $Revision: 1.4 $
36  */
37 public class IsDefinedExpression extends ComparePropertyExpression {
38     
39     /**
40      * Creates an isdefined expression according to Element e
41      *
42      * @param e jdom element, that describes the expression
43      * @param requestedResourcesPool the pool of resources to apply the expression to.
44      */
45     public IsDefinedExpression (Element e, ComparableResourcesPool requestedResourcesPool) throws InvalidQueryException {
46         super(e, requestedResourcesPool, false);
47         comparedProperty.setLiteral("");
48     }
49     
50     /**
51      * Checks if property is defined in the resource
52      *
53      * @param item a RequestedResource
54      *
55      * @return a boolean
56      *
57      */
58     protected boolean compare (ComparableResource item) {
59         return item.isDefined (comparedProperty.getProperty(),
60                                comparedProperty.getPropNamespace());
61     }
62     
63     
64     /**
65      * For debugging purpose.
66      *
67      * @return This expression as string
68      *
69      */
70     public String JavaDoc toString () {
71         return (Literals.ISDEFINED + " (" + comparedProperty.getProperty () + ")");
72     }
73 }
74
75
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