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.config;
22:
23: /**
24: * This class provides static constants for the query evaluation
25: * modes that db4o supports.
26: * <br><br><b>For detailed documentation please see
27: * {@link QueryConfiguration#evaluationMode(QueryEvaluationMode)}</b>
28: */
29: public class QueryEvaluationMode {
30:
31: private final String _id;
32:
33: private QueryEvaluationMode(String id) {
34: _id = id;
35: }
36:
37: /**
38: * Constant for immediate query evaluation. The query is executed fully
39: * when Query#execute() is called.
40: * <br><br><b>For detailed documentation please see
41: * {@link QueryConfiguration#evaluationMode(QueryEvaluationMode)}</b>
42: */
43: public static final QueryEvaluationMode IMMEDIATE = new QueryEvaluationMode(
44: "IMMEDIATE");
45:
46: /**
47: * Constant for snapshot query evaluation. When Query#execute() is called,
48: * the query processor chooses the best indexes, does all index processing
49: * and creates a snapshot of the index at this point in time. Non-indexed
50: * constraints are evaluated lazily when the application iterates through
51: * the {@link com.db4o.ObjectSet} resultset of the query.
52: * <br><br><b>For detailed documentation please see
53: * {@link QueryConfiguration#evaluationMode(QueryEvaluationMode)}</b>
54: */
55: public static final QueryEvaluationMode SNAPSHOT = new QueryEvaluationMode(
56: "SNAPSHOT");
57:
58: /**
59: * Constant for lazy query evaluation. When Query#execute() is called, the
60: * query processor only chooses the best index and creates an iterator on
61: * this index. Indexes and constraints are evaluated lazily when the
62: * application iterates through the {@link com.db4o.ObjectSet} resultset of the query.
63: * <br><br><b>For detailed documentation please see
64: * {@link QueryConfiguration#evaluationMode(QueryEvaluationMode)}</b>
65: */
66: public static final QueryEvaluationMode LAZY = new QueryEvaluationMode(
67: "LAZY");
68:
69: private static final QueryEvaluationMode[] MODES = new QueryEvaluationMode[] {
70: QueryEvaluationMode.IMMEDIATE,
71: QueryEvaluationMode.SNAPSHOT, QueryEvaluationMode.LAZY, };
72:
73: /**
74: * internal method, ignore please.
75: */
76: public int asInt() {
77: for (int i = 0; i < MODES.length; i++) {
78: if (MODES[i] == this ) {
79: return i;
80: }
81: }
82: throw new IllegalStateException();
83: }
84:
85: /**
86: * internal method, ignore please.
87: */
88: public static QueryEvaluationMode fromInt(int i) {
89: return MODES[i];
90: }
91:
92: public String toString() {
93: return _id;
94: }
95: }
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