01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o.internal.query.processor;
22:
23: import com.db4o.internal.*;
24: import com.db4o.internal.handlers.*;
25: import com.db4o.types.Unversioned;
26:
27: /**
28: * Query Evaluator - Represents such things as >, >=, <, <=, EQUAL, LIKE, etc.
29: *
30: * @exclude
31: */
32: public class QE implements Unversioned {
33:
34: static final QE DEFAULT = new QE();
35:
36: public static final int NULLS = 0;
37: public static final int SMALLER = 1;
38: public static final int EQUAL = 2;
39: public static final int GREATER = 3;
40:
41: QE add(QE evaluator) {
42: return evaluator;
43: }
44:
45: public boolean identity() {
46: return false;
47: }
48:
49: boolean isDefault() {
50: return true;
51: }
52:
53: boolean evaluate(QConObject constraint, QCandidate candidate,
54: Object obj) {
55: Comparable4 comparator = constraint.getComparator(candidate);
56: if (obj == null) {
57: return comparator instanceof Null;
58: }
59: if (comparator instanceof ArrayHandler) {
60: return ((ArrayHandler) comparator).isEqual(obj);
61: }
62: return comparator.compareTo(obj) == 0;
63: }
64:
65: public boolean equals(Object obj) {
66: return obj != null && obj.getClass() == this .getClass();
67: }
68:
69: public int hashCode() {
70: return getClass().hashCode();
71: }
72:
73: // overridden in QENot
74: boolean not(boolean res) {
75: return res;
76: }
77:
78: /**
79: * Specifies which part of the index to take.
80: * Array elements:
81: * [0] - smaller
82: * [1] - equal
83: * [2] - greater
84: * [3] - nulls
85: *
86: *
87: * @param bits
88: */
89: public void indexBitMap(boolean[] bits) {
90: bits[QE.EQUAL] = true;
91: }
92:
93: public boolean supportsIndex() {
94: return true;
95: }
96:
97: }
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