01: /*
02: * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
03: *
04: * This file is part of Resin(R) Open Source
05: *
06: * Each copy or derived work must preserve the copyright notice and this
07: * notice unmodified.
08: *
09: * 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;
35: import java.sql.SQLException;
36: import java.util.logging.Logger;
37:
38: class RowIterateExpr extends Expr {
39: private static final Logger log = Log.open(RowIterateExpr.class);
40:
41: /**
42: * Sets the initial row.
43: */
44: boolean init(QueryContext context, TableIterator rowIter)
45: throws SQLException, IOException {
46: rowIter.init(context);
47:
48: return nextBlock(context, rowIter);
49: }
50:
51: /**
52: * Initializes the current row.
53: */
54: boolean initRow(QueryContext context, TableIterator rowIter)
55: throws SQLException, IOException {
56: rowIter.initRow();
57:
58: return rowIter.nextRow();
59: }
60:
61: /**
62: * Returns the next row.
63: */
64: boolean nextRow(QueryContext context, TableIterator rowIter)
65: throws IOException, SQLException {
66: return rowIter.nextRow();
67: }
68:
69: /**
70: * Returns true if shifing the child rows will make a difference.
71: */
72: boolean allowChildRowShift(QueryContext context,
73: TableIterator rowIter) {
74: return true;
75: }
76:
77: /**
78: * Returns the next block.
79: */
80: boolean nextBlock(QueryContext context, TableIterator rowIter)
81: throws IOException, SQLException {
82: context.unlock();
83:
84: while (rowIter.nextBlock()) {
85: context.lock();
86:
87: rowIter.initRow();
88:
89: if (rowIter.nextRow())
90: return true;
91:
92: context.unlock();
93: }
94:
95: return false;
96: }
97: }
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