ministd.callable source code

1 /*
2  * Copyright (C) 2023 Mai-Lapyst
3  * 
4  * This program is free software: you can redistribute it and/or modify
5  * it under the terms of the GNU Affero General Public License as published by
6  * the Free Software Foundation, either version 3 of the License, or
7  * (at your option) any later version.
8  * 
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU Affero General Public License for more details.
13  * 
14  * You should have received a copy of the GNU Affero General Public License
15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
16  */
17 
18 /** 
19  * Module to provide callables for dlang.
20  * 
21  * License:   $(HTTP https://www.gnu.org/licenses/agpl-3.0.html, AGPL 3.0).
22  * Copyright: Copyright (C) 2023 Mai-Lapyst
23  * Authors:   $(HTTP codeark.it/Mai-Lapyst, Mai-Lapyst)
24  */
25 module ministd.callable;
26 
27 /// A struct that makes holding any function and/or delegate a breeze!
28 struct Callable(RetT, ParamsT...) {
29     this(RetT function(ParamsT) fn) pure nothrow @nogc @safe {
30         () @trusted { this.fn = fn; }();
31         this.kind = Kind.FN;
32     }
33     this(RetT delegate(ParamsT) dg) pure nothrow @nogc @safe {
34         () @trusted { this.dg = dg; }();
35         this.kind = Kind.DG;
36     }
37 
38     RetT opCall(ParamsT params) {
39         final switch (this.kind) {
40             case Kind.FN: return fn(params);
41             case Kind.DG: return dg(params);
42             case Kind.NO: throw new Exception("Called uninitialzed Callable!");
43         }
44     }
45 
46 private:
47     enum Kind { NO, FN, DG }
48     Kind kind = Kind.NO;
49     union {
50         RetT function(ParamsT) fn;
51         RetT delegate(ParamsT) dg;
52     }
53 }
54 
55 unittest {
56     auto adder = Callable!(int, int, int)( (int a, int b) => a + b );
57     assert( adder(12, 34) == (12 + 34) );
58 }