01: /*
02: * $Id: LazyRow.java,v 1.4 2005/12/22 09:02:30 ahimanikya Exp $
03: * =======================================================================
04: * Copyright (c) 2002 Axion Development Team. All rights reserved.
05: *
06: * Redistribution and use in source and binary forms, with or without
07: * modification, are permitted provided that the following conditions
08: * are met:
09: *
10: * 1. Redistributions of source code must retain the above
11: * copyright notice, this list of conditions and the following
12: * disclaimer.
13: *
14: * 2. Redistributions in binary form must reproduce the above copyright
15: * notice, this list of conditions and the following disclaimer in
16: * the documentation and/or other materials provided with the
17: * distribution.
18: *
19: * 3. The names "Tigris", "Axion", nor the names of its contributors may
20: * not be used to endorse or promote products derived from this
21: * software without specific prior written permission.
22: *
23: * 4. Products derived from this software may not be called "Axion", nor
24: * may "Tigris" or "Axion" appear in their names without specific prior
25: * written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
30: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
32: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
33: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38: * =======================================================================
39: */
40:
41: package org.axiondb.engine.rows;
42:
43: import org.axiondb.AxionException;
44: import org.axiondb.Row;
45: import org.axiondb.RowSource;
46: import org.axiondb.util.ExceptionConverter;
47:
48: /**
49: * A {@link Row}which loads data from a {@link RowSource}as needed.
50: *
51: * @version $Revision: 1.4 $ $Date: 2005/12/22 09:02:30 $
52: * @author Rodney Waldhoff
53: */
54: public class LazyRow extends BaseRow implements Row {
55: public LazyRow(RowSource source, int id) {
56: this (source, id, -1, null);
57: }
58:
59: public LazyRow(RowSource source, int id, int col, Object value) {
60: super .setIdentifier(id);
61: _source = source;
62: _knownColumnIndex = col;
63: _knownValue = value;
64: }
65:
66: public Object get(int i) {
67: if (i == _knownColumnIndex) {
68: return _knownValue;
69: }
70: Row row = getRow();
71: return row != null ? row.get(i) : null;
72: }
73:
74: public void set(int i, Object val)
75: throws UnsupportedOperationException {
76: getRow().set(i, val);
77: _hash = 0;
78: }
79:
80: public int size() {
81: return _source.getColumnCount();
82: }
83:
84: private Row getRow() {
85: if (null == _row) {
86: try {
87: _row = _source.getRow(getIdentifier());
88: } catch (AxionException e) {
89: throw ExceptionConverter.convertToRuntimeException(e);
90: }
91: }
92: return _row;
93: }
94:
95: private Row _row;
96: private RowSource _source;
97: private int _knownColumnIndex = -1;
98: private Object _knownValue;
99: }
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