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Java > Open Source Codes > org > sapia > util > cursor > impl > BatchImpl


1 package org.sapia.util.cursor.impl;
2
3 import org.sapia.util.cursor.Batch;
4 import org.sapia.util.cursor.CursorException;
5 import org.sapia.util.cursor.CursorListener;
6
7 /**
8  * @author Yanick Duchesne
9  *
10  * <dl>
11  * <dt><b>Copyright:</b><dd>Copyright &#169; 2002-2004 <a HREF="http://www.sapia-oss.org">Sapia Open Source Software</a>. All Rights Reserved.</dd></dt>
12  * <dt><b>License:</b><dd>Read the license.txt file of the jar or visit the
13  * <a HREF="http://www.sapia-oss.org/license.html">license page</a> at the Sapia OSS web site</dd></dt>
14  * </dl>
15  */
16 public class BatchImpl implements Batch{
17   
18   private Object JavaDoc[] _items;
19   private int _count, _index;
20   private CursorListener _listener;
21   private int _pos;
22   
23   /**
24    * @param items the array of objects that this instance will wrap.
25    * @param listener a <code>CursorListener</code>, or <code>null</code> if none is provided.
26    * @param count the number of actual items in the array.
27    * @param absoluteIndex the index of this instance, relative to its cursor.
28    */
29   public BatchImpl(Object JavaDoc[] items, CursorListener listener, int count, int absoluteIndex){
30     _items = items;
31     _listener = listener;
32     _count = count;
33     _index = absoluteIndex;
34   }
35   
36   /**
37    * @see Batch#getCount()
38    */
39   public int getCount(){
40     return _count;
41   }
42   
43   /**
44    * @see Batch#getAbsolutePos()
45    */
46   public int getAbsolutePos(){
47     return _index + _pos;
48   }
49   
50   /**
51    * @see Batch#getPos()
52    */
53   public int getPos(){
54     return _pos;
55   }
56   
57   /**
58    * @see Batch#setPos(int)
59    */
60   public void setPos(int pos){
61     if(_count == 0 || pos < 0 || pos >= _count){
62       throw new IndexOutOfBoundsException JavaDoc(""+pos);
63     }
64     _pos = pos;
65   }
66   
67   /**
68    * @see Batch#toFirst()
69    */
70   public Batch toFirst(){
71     _pos = 0;
72     return this;
73   }
74   
75   /**
76    * @see Batch#toLast()
77    */
78   public Batch toLast(){
79     _pos = _count - 1;
80     return this;
81   }
82   
83   /**
84    * @see Batch#getItemAt(int)
85    */
86   public Object JavaDoc getItemAt(int index){
87     if(index < 0 || index >= _count){
88       throw new java.lang.IndexOutOfBoundsException JavaDoc(""+index);
89     }
90     return _items[index];
91   }
92   
93   /**
94    * @see Batch#hasNext()
95    */
96   public boolean hasNext(){
97     return _pos < _count;
98   }
99   
100   /**
101    * @see Batch#next()
102    */
103   public Object JavaDoc next(){
104     if(_pos >= _count){
105       throw new java.util.NoSuchElementException JavaDoc();
106     }
107     if(_listener != null){
108       try{
109         Object JavaDoc next = (_items[_pos++]);
110         _listener.onNext(next);
111         return next;
112       }catch(Exception JavaDoc e){
113         throw new CursorException("Error handing next object to cursor listener", e);
114       }
115     }
116     return _items[_pos++];
117   }
118   
119   /**
120    * @see Batch#hasPrevious()
121    */
122   public boolean hasPrevious(){
123     return _pos > 0;
124   }
125   
126   /**
127    * @see Batch#previous()
128    */
129   public Object JavaDoc previous(){
130     if(_pos <= 0){
131       throw new java.util.NoSuchElementException JavaDoc();
132     }
133     return _items[_pos--];
134   }
135     
136   
137   /**
138    * @see BatchImpl#getIterator()
139    */
140   public java.util.Iterator JavaDoc getIterator(){
141     return new BatchIterator(this, false);
142   }
143   
144   /**
145    * @see BatchImpl#getReverseIterator()
146    */
147   public java.util.Iterator JavaDoc getReverseIterator(){
148     return new BatchIterator(this, true);
149   }
150   
151   ////////////////// INNER CLASSES /////////////////
152
153   public static class BatchIterator implements java.util.Iterator JavaDoc{
154     
155     private Batch _batch;
156     private boolean _reverse;
157     
158     BatchIterator(Batch batch, boolean reverse){
159       _batch = batch;
160       _reverse = reverse;
161     }
162     
163     public boolean hasNext(){
164       if(_reverse){
165         return _batch.hasPrevious();
166       }
167       return _batch.hasNext();
168     }
169     
170     public Object JavaDoc next(){
171       if(_reverse){
172         return _batch.previous();
173       }
174       return _batch.next();
175     }
176     
177     public void remove(){
178       throw new UnsupportedOperationException JavaDoc();
179     }
180   }
181 }
182
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