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1 | /* | |
2 | This module is based on code in the std.typecons module in the standard library of the D programming language. The authors of std.typecons deserve credit and thanks, and are listed at the top of the source code for the module, which is available here: | |
3 | ||
4 | https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d | |
5 | ||
6 | Copyright (c) 2013, w0rp <moebiuspersona@gmail.com> | |
7 | All rights reserved. | |
8 | ||
9 | Redistribution and use in source and binary forms, with or without | |
10 | modification, are permitted provided that the following conditions are met: | |
11 | ||
12 | 1. Redistributions of source code must retain the above copyright notice, this | |
13 | list of conditions and the following disclaimer. | |
14 | 2. Redistributions in binary form must reproduce the above copyright notice, | |
15 | this list of conditions and the following disclaimer in the documentation | |
16 | and/or other materials provided with the distribution. | |
17 | ||
18 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND | |
19 | ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | |
20 | WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
21 | DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR | |
22 | ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
23 | (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
24 | LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND | |
25 | ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
26 | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |
27 | SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
28 | */ | |
29 | ||
30 | import std.exception; | |
31 | import std.typecons; | |
32 | ||
33 | module option; | |
34 | ||
35 | struct Option(T) if(is(T == class)) { | |
36 | private T _value; | |
37 | ||
38 | this(T value) { | |
39 | _value = value; | |
40 | } | |
41 | ||
42 | this(Nullable!T value) { | |
43 | if (!value.isNull) | |
44 | { | |
45 | _value = value; | |
46 | } | |
47 | } | |
48 | ||
49 | @property @safe const pure nothrow | |
50 | bool isNull() { | |
51 | return _value is null; | |
52 | } | |
53 | ||
54 | @safe pure nothrow | |
55 | void opAssign(T value) { | |
56 | _value = value; | |
57 | } | |
58 | ||
59 | @safe pure | |
60 | void opAssign(Nullable!T value) { | |
61 | if (!value.isNull) | |
62 | { | |
63 | _value = value; | |
64 | } | |
65 | } | |
66 | ||
67 | @safe pure nothrow nullify() { | |
68 | _value = null; | |
69 | } | |
70 | ||
71 | @property @safe pure nothrow inout(T) get() inout { | |
72 | enum message = "Called `get' on null Option!" ~ T.stringof ~ "."; | |
73 | assert(_value !is null, message); | |
74 | return _value; | |
75 | } | |
76 | ||
77 | alias get this; | |
78 | } | |
79 | ||
80 | struct Option(T) if(!is(T == class)) { | |
81 | private T _value; | |
82 | private bool _isNull = true; | |
83 | ||
84 | this(T value) { | |
85 | _value = value; | |
86 | _isNull = false; | |
87 | } | |
88 | ||
89 | this(Nullable!T value) { | |
90 | if (!value.isNull) { | |
91 | _value = value; | |
92 | _isNull = false; | |
93 | } | |
94 | } | |
95 | ||
96 | @property @safe const pure nothrow | |
97 | bool isNull() { | |
98 | return _isNull; | |
99 | } | |
100 | ||
101 | @safe pure nothrow | |
102 | void opAssign(T value) { | |
103 | _value = value; | |
104 | _isNull = false; | |
105 | } | |
106 | ||
107 | @safe pure | |
108 | void opAssign(Nullable!T value) { | |
109 | if (!value.isNull) { | |
110 | _value = value; | |
111 | _isNull = false; | |
112 | } | |
113 | } | |
114 | ||
115 | @safe pure nothrow nullify() { | |
116 | _value = T.init; | |
117 | _isNull = true; | |
118 | } | |
119 | ||
120 | @property @safe pure nothrow | |
121 | inout(T) get() inout { | |
122 | enum message = "Called `get' on null Option!" ~ T.stringof ~ "."; | |
123 | assert(!_isNull, message); | |
124 | return _value; | |
125 | } | |
126 | ||
127 | alias get this; | |
128 | } | |
129 | ||
130 | // Test that Option works for classes. | |
131 | unittest { | |
132 | class MyClass { } | |
133 | ||
134 | Option!MyClass test = null; | |
135 | assert(test.isNull); | |
136 | assertThrown!Throwable(test.get); | |
137 | } | |
138 | ||
139 | unittest { | |
140 | class MyClass { } | |
141 | ||
142 | Option!MyClass test = new MyClass(); | |
143 | test = null; | |
144 | ||
145 | assert(test.isNull); | |
146 | assertThrown!Throwable(test.get); | |
147 | } | |
148 | ||
149 | unittest { | |
150 | class MyClass { } | |
151 | ||
152 | Option!MyClass test = new MyClass(); | |
153 | assert(!test.isNull); | |
154 | assertNotThrown!Throwable(test.get); | |
155 | } | |
156 | ||
157 | unittest { | |
158 | class MyClass { } | |
159 | ||
160 | Option!MyClass test; | |
161 | test = new MyClass(); | |
162 | assert(!test.isNull); | |
163 | assertNotThrown!Throwable(test.get); | |
164 | } | |
165 | ||
166 | // Test that option works for primitives. | |
167 | unittest { | |
168 | Option!int test; | |
169 | assert(test.isNull); | |
170 | assertThrown!Throwable(test.get); | |
171 | } | |
172 | ||
173 | unittest { | |
174 | Option!int test = 3; | |
175 | test.nullify(); | |
176 | assert(test.isNull); | |
177 | assertThrown!Throwable(test.get); | |
178 | } | |
179 | ||
180 | unittest { | |
181 | Option!int test = 4; | |
182 | assert(!test.isNull); | |
183 | assertNotThrown!Throwable(test.get); | |
184 | } | |
185 | ||
186 | unittest { | |
187 | Option!int test; | |
188 | test = 4; | |
189 | assert(!test.isNull); | |
190 | assertNotThrown!Throwable(test.get); | |
191 | } | |
192 | ||
193 | // Test that option supports Nullable for classes. | |
194 | unittest { | |
195 | class MyClass { } | |
196 | ||
197 | Nullable!MyClass nullableInstance; | |
198 | Option!MyClass optInstance = nullableInstance; | |
199 | ||
200 | assert(optInstance.isNull); | |
201 | assertThrown!Throwable(optInstance.get); | |
202 | } | |
203 | ||
204 | unittest { | |
205 | class MyClass { } | |
206 | ||
207 | MyClass instance = new MyClass(); | |
208 | ||
209 | Nullable!MyClass nullableInstance = instance; | |
210 | Option!MyClass optInstance = nullableInstance; | |
211 | ||
212 | assert(!optInstance.isNull); | |
213 | assertNotThrown!Throwable(optInstance.get); | |
214 | assert(optInstance == instance); | |
215 | } | |
216 | ||
217 | // Test that option supports Nullable for primitives. | |
218 | unittest { | |
219 | Nullable!int nullableInt; | |
220 | Option!int optInt = nullableInt; | |
221 | ||
222 | assert(optInt.isNull); | |
223 | assertThrown!Throwable(optInt.get); | |
224 | } | |
225 | ||
226 | unittest { | |
227 | Nullable!int nullableInt = 3; | |
228 | Option!int optInt = nullableInt; | |
229 | ||
230 | assert(!optInt.isNull); | |
231 | assertNotThrown!Throwable(optInt.get); | |
232 | assert(optInt == 3); | |
233 | } |