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Java > Open Source Codes > com > sleepycat > persist > BasicIterator


1 /*-
2  * See the file LICENSE for redistribution information.
3  *
4  * Copyright (c) 2002,2006 Oracle. All rights reserved.
5  *
6  * $Id: BasicIterator.java,v 1.7 2006/10/30 21:14:30 bostic Exp $
7  */
8
9 package com.sleepycat.persist;
10
11 import java.util.Iterator JavaDoc;
12 import java.util.NoSuchElementException JavaDoc;
13
14 import com.sleepycat.je.DatabaseException;
15 import com.sleepycat.je.LockMode;
16 import com.sleepycat.util.RuntimeExceptionWrapper;
17
18 /**
19  * Implements Iterator for an arbitrary EntityCursor.
20  *
21  * @author Mark Hayes
22  */
23 class BasicIterator<V> implements Iterator JavaDoc<V> {
24
25     private EntityCursor<V> entityCursor;
26     private ForwardCursor<V> forwardCursor;
27     private LockMode lockMode;
28     private V nextValue;
29
30     /**
31      * An EntityCursor is given and the remove() method is supported.
32      */
33     BasicIterator(EntityCursor<V> entityCursor, LockMode lockMode) {
34         this.entityCursor = entityCursor;
35         this.forwardCursor = entityCursor;
36         this.lockMode = lockMode;
37     }
38
39     /**
40      * A ForwardCursor is given and the remove() method is not supported.
41      */
42     BasicIterator(ForwardCursor<V> forwardCursor, LockMode lockMode) {
43         this.forwardCursor = forwardCursor;
44         this.lockMode = lockMode;
45     }
46
47     public boolean hasNext() {
48         if (nextValue == null) {
49             try {
50                 nextValue = forwardCursor.next(lockMode);
51             } catch (DatabaseException e) {
52                 throw new RuntimeExceptionWrapper(e);
53             }
54             return nextValue != null;
55         } else {
56             return true;
57         }
58     }
59
60     public V next() {
61         if (hasNext()) {
62             V v = nextValue;
63             nextValue = null;
64             return v;
65         } else {
66             throw new NoSuchElementException JavaDoc();
67         }
68     }
69
70     public void remove() {
71         if (entityCursor == null) {
72             throw new UnsupportedOperationException JavaDoc();
73         }
74         try {
75             if (!entityCursor.delete()) {
76                 throw new IllegalStateException JavaDoc
77                     ("Record at cursor position is already deleted");
78             }
79         } catch (DatabaseException e) {
80             throw new RuntimeExceptionWrapper(e);
81         }
82     }
83 }
84
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