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.foundation.*;
24:
25: /**
26: * @exclude
27: */
28: class QOrder extends Tree {
29:
30: static int equalityIDGenerator = 1;
31:
32: final QConObject _constraint;
33: final QCandidate _candidate;
34:
35: private int _equalityID;
36:
37: QOrder(QConObject a_constraint, QCandidate a_candidate) {
38: _constraint = a_constraint;
39: _candidate = a_candidate;
40: }
41:
42: public boolean isEqual(QOrder other) {
43: if (other == null) {
44: return false;
45: }
46: return _equalityID != 0 && _equalityID == other._equalityID;
47: }
48:
49: public int compare(Tree a_to) {
50: int res = internalCompare();
51: if (res != 0) {
52: return res;
53: }
54: QOrder other = (QOrder) a_to;
55: int equalityID = _equalityID;
56: if (equalityID == 0) {
57: if (other._equalityID != 0) {
58: equalityID = other._equalityID;
59: }
60: }
61: if (equalityID == 0) {
62: equalityID = generateEqualityID();
63: }
64: _equalityID = equalityID;
65: other._equalityID = equalityID;
66: return res;
67: }
68:
69: private int internalCompare() {
70: int comparisonResult = _constraint.i_comparator
71: .compareTo(_candidate.value());
72: if (comparisonResult < 0) {
73: return -_constraint.ordering();
74: }
75: if (comparisonResult == 0) {
76: return 0;
77: }
78: return _constraint.ordering();
79: }
80:
81: public Object shallowClone() {
82: QOrder order = new QOrder(_constraint, _candidate);
83: super .shallowCloneInternal(order);
84: return order;
85: }
86:
87: public Object key() {
88: throw new NotImplementedException();
89: }
90:
91: private static int generateEqualityID() {
92: equalityIDGenerator++;
93: if (equalityIDGenerator < 1) {
94: equalityIDGenerator = 1;
95: }
96: return equalityIDGenerator;
97: }
98:
99: }
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