Mercurial > hg > truffle
annotate truffle/com.oracle.truffle.sl/src/com/oracle/truffle/sl/runtime/SLNull.java @ 21997:c07e64ecb528
Update SL copyright headers to use UPL
author | Gilles Duboscq <gilles.m.duboscq@oracle.com> |
---|---|
date | Thu, 16 Jul 2015 15:50:46 +0200 |
parents | 9c8c0937da41 |
children | 503529c65456 |
rev | line source |
---|---|
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
1 /* |
13821
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
2 * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved. |
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
4 * |
21997
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
5 * The Universal Permissive License (UPL), Version 1.0 |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
6 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
7 * Subject to the condition set forth below, permission is hereby granted to any |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
8 * person obtaining a copy of this software, associated documentation and/or |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
9 * data (collectively the "Software"), free of charge and under any and all |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
10 * copyright rights in the Software, and any and all patent rights owned or |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
11 * freely licensable by each licensor hereunder covering either (i) the |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
12 * unmodified Software as contributed to or provided by such licensor, or (ii) |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
13 * the Larger Works (as defined below), to deal in both |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
14 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
15 * (a) the Software, and |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
16 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
17 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
18 * one is included with the Software each a "Larger Work" to which the Software |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
19 * is contributed by such licensors), |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
20 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
21 * without restriction, including without limitation the rights to copy, create |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
22 * derivative works of, display, perform, and distribute the Software and make, |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
23 * use, sell, offer for sale, import, export, have made, and have sold the |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
24 * Software and the Larger Work(s), and to sublicense the foregoing rights on |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
25 * either these or other terms. |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
26 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
27 * This license is subject to the following condition: |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
28 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
29 * The above copyright notice and either this complete permission notice or at a |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
30 * minimum a reference to the UPL must be included in all copies or substantial |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
31 * portions of the Software. |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
32 * |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
33 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
34 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
35 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
36 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
37 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
38 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
c07e64ecb528
Update SL copyright headers to use UPL
Gilles Duboscq <gilles.m.duboscq@oracle.com>
parents:
21951
diff
changeset
|
39 * SOFTWARE. |
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
40 */ |
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
41 package com.oracle.truffle.sl.runtime; |
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
42 |
21770
c76742cc2c6f
Polishing inter-operability APIs: Exposing only Message, TruffleObject and ForeignAccess-related classes.
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
21689
diff
changeset
|
43 import com.oracle.truffle.api.interop.ForeignAccess; |
21689
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
44 import com.oracle.truffle.api.interop.TruffleObject; |
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
45 |
13821
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
46 /** |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
47 * The SL type for a {@code null} (i.e., undefined) value. In Truffle, it is generally discouraged |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
48 * to use the Java {@code null} value to represent the guest language {@code null} value. It is not |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
49 * possible to specialize on Java {@code null} (since you cannot ask it for the Java class), and |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
50 * there is always the danger of a spurious {@link NullPointerException}. Representing the guest |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
51 * language {@code null} as a singleton, as in {@link #SINGLETON this class}, is the recommended |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
52 * practice. |
15404
1d3c23e675ed
fixed some minor javadoc formatting issues
Doug Simon <doug.simon@oracle.com>
parents:
13821
diff
changeset
|
53 */ |
21689
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
54 public final class SLNull implements TruffleObject { |
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
55 |
13821
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
56 /** |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
57 * The canonical value to represent {@code null} in SL. |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
58 */ |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
59 public static final SLNull SINGLETON = new SLNull(); |
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
60 |
13821
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
61 /** |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
62 * Disallow instantiation from outside to ensure that the {@link #SINGLETON} is the only |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
63 * instance. |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
64 */ |
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
65 private SLNull() { |
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
66 } |
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
67 |
13821
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
68 /** |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
69 * This method is, e.g., called when using the {@code null} value in a string concatenation. So |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
70 * changing it has an effect on SL programs. |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
71 */ |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
72 @Override |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
73 public String toString() { |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
74 return "null"; |
b16ec83edc73
Documentation and more refactoring of Simple Language
Christian Wimmer <christian.wimmer@oracle.com>
parents:
12752
diff
changeset
|
75 } |
21689
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
76 |
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
77 @Override |
21770
c76742cc2c6f
Polishing inter-operability APIs: Exposing only Message, TruffleObject and ForeignAccess-related classes.
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
21689
diff
changeset
|
78 public ForeignAccess getForeignAccess() { |
21689
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
79 return SLFunctionForeignAccess.INSTANCE; |
ed234a3178af
Behavior of null-like values is now part of the TCK
Jaroslav Tulach <jaroslav.tulach@oracle.com>
parents:
15404
diff
changeset
|
80 } |
12752
71991b7a0f14
SL: Enhanced SimpleLanguage with support for if statements, function calls, function caching + inlining and builtins.
Christian Humer <christian.humer@gmail.com>
parents:
diff
changeset
|
81 } |