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Java > Open Source Codes > org > apache > xerces > jaxp > validation > WeakReferenceXMLSchema


1 /*
2  * Copyright 2005 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 package org.apache.xerces.jaxp.validation;
18
19 import java.lang.ref.WeakReference JavaDoc;
20
21 import org.apache.xerces.xni.grammars.XMLGrammarPool;
22
23 /**
24  * <p>An implementation of Schema for W3C XML Schemas
25  * that keeps a weak reference to its grammar pool. If
26  * no validators currently have a reference to the
27  * grammar pool, the garbage collector is free to reclaim
28  * its memory.</p>
29  *
30  * @author Michael Glavassevich, IBM
31  * @version $Id: WeakReferenceXMLSchema.java,v 1.1 2005/05/14 20:37:18 mrglavas Exp $
32  */
33 final class WeakReferenceXMLSchema extends AbstractXMLSchema {
34     
35     /** Weak reference to grammar pool. */
36     private WeakReference JavaDoc fGrammarPool = new WeakReference JavaDoc(null);
37
38     public WeakReferenceXMLSchema() {}
39     
40     /*
41      * XSGrammarPoolContainer methods
42      */
43
44     public synchronized XMLGrammarPool getGrammarPool() {
45         XMLGrammarPool grammarPool = (XMLGrammarPool) fGrammarPool.get();
46         // If there's no grammar pool then either we haven't created one
47 // yet or the garbage collector has already cleaned out the previous one.
48 if (grammarPool == null) {
49             grammarPool = new SoftReferenceGrammarPool();
50             fGrammarPool = new WeakReference JavaDoc(grammarPool);
51         }
52         return grammarPool;
53     }
54
55     public boolean isFullyComposed() {
56         return false;
57     }
58
59 } // WeakReferenceXMLSchema
60
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