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comparison graal/com.oracle.jvmci.meta/src/com/oracle/jvmci/meta/TriState.java @ 21556:48c1ebd24120

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renamed com.oracle.graal.api[meta|code] modules to com.oracle.jvmci.[meta|code] (JBS:GRAAL-53)
author Doug Simon <doug.simon@oracle.com>
date Wed, 27 May 2015 00:36:16 +0200
parents graal/com.oracle.graal.api.meta/src/com/oracle/graal/api/meta/TriState.java@758c2bd9bc0d
children
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21555:d12eaef9af72 21556:48c1ebd24120
1 /*
2 * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 package com.oracle.jvmci.meta;
24
25 /**
26 * Represents a logic value that can be either {@link #TRUE}, {@link #FALSE}, or {@link #UNKNOWN}.
27 */
28 public enum TriState {
29 TRUE,
30 FALSE,
31 UNKNOWN;
32
33 public static TriState get(boolean value) {
34 return value ? TRUE : FALSE;
35 }
36
37 /**
38 * This is optimistic about {@link #UNKNOWN} (it prefers known values over {@link #UNKNOWN}) and
39 * pesimistic about known (it perfers {@link #TRUE} over {@link #FALSE}).
40 */
41 public static TriState merge(TriState a, TriState b) {
42 if (a == TRUE || b == TRUE) {
43 return TRUE;
44 }
45 if (a == FALSE || b == FALSE) {
46 return FALSE;
47 }
48 assert a == UNKNOWN && b == UNKNOWN;
49 return UNKNOWN;
50 }
51
52 public boolean isTrue() {
53 return this == TRUE;
54 }
55
56 public boolean isFalse() {
57 return this == FALSE;
58 }
59
60 public boolean isUnknown() {
61 return this == UNKNOWN;
62 }
63
64 public boolean isKnown() {
65 return this != UNKNOWN;
66 }
67
68 public boolean toBoolean() {
69 if (isTrue()) {
70 return true;
71 } else if (isFalse()) {
72 return false;
73 } else {
74 throw new IllegalStateException("Cannot convert to boolean, TriState is in an unknown state");
75 }
76 }
77 }