KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > caucho > db > sql > RowIterateExpr


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  * Free SoftwareFoundation, Inc.
23  * 59 Temple Place, Suite 330
24  * Boston, MA 02111-1307 USA
25  *
26  * @author Scott Ferguson
27  */
28
29 package com.caucho.db.sql;
30
31 import com.caucho.db.table.TableIterator;
32 import com.caucho.log.Log;
33
34 import java.io.IOException JavaDoc;
35 import java.sql.SQLException JavaDoc;
36 import java.util.logging.Logger JavaDoc;
37
38 class RowIterateExpr extends Expr {
39   private static final Logger JavaDoc log = Log.open(RowIterateExpr.class);
40   
41   /**
42    * Sets the initial row.
43    */
44   boolean init(QueryContext context, TableIterator rowIter)
45     throws SQLException JavaDoc, IOException JavaDoc
46   {
47     rowIter.init(context);
48
49     return nextBlock(context, rowIter);
50   }
51
52   /**
53    * Initializes the current row.
54    */
55   boolean initRow(QueryContext context, TableIterator rowIter)
56     throws SQLException JavaDoc, IOException JavaDoc
57   {
58     rowIter.initRow();
59
60     return rowIter.nextRow();
61   }
62
63   /**
64    * Returns the next row.
65    */
66   boolean nextRow(QueryContext context, TableIterator rowIter)
67     throws IOException JavaDoc, SQLException JavaDoc
68   {
69     return rowIter.nextRow();
70   }
71
72   /**
73    * Returns true if shifing the child rows will make a difference.
74    */
75   boolean allowChildRowShift(QueryContext context, TableIterator rowIter)
76   {
77     return true;
78   }
79
80   /**
81    * Returns the next block.
82    */
83   boolean nextBlock(QueryContext context, TableIterator rowIter)
84     throws IOException JavaDoc, SQLException JavaDoc
85   {
86     context.unlock();
87     
88     while (rowIter.nextBlock()) {
89       context.lock();
90
91       rowIter.initRow();
92
93       if (rowIter.nextRow())
94     return true;
95       
96       context.unlock();
97     }
98     
99     return false;
100   }
101 }
102
Popular Tags