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LazyRandomEngine.hxx
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1 /*
2 * Copyright 2003-2017 The Music Player Daemon Project
3 * http://www.musicpd.org
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #ifndef MPD_LAZY_RANDOM_ENGINE_HXX
21 #define MPD_LAZY_RANDOM_ENGINE_HXX
22
23 #include "check.h"
24
25 #include <random>
26
27 #include <assert.h>
28
32 class LazyRandomEngine {
33 std::mt19937 *engine;
34
35 public:
36 typedef std::mt19937::result_type result_type;
37
38 LazyRandomEngine():engine(nullptr) {}
39 ~LazyRandomEngine() {
40 delete engine;
41 }
42
43 LazyRandomEngine(const LazyRandomEngine &other) = delete;
44 LazyRandomEngine &operator=(const LazyRandomEngine &other) = delete;
45
50 void AutoCreate();
51
52 static constexpr result_type min() {
53 return std::mt19937::min();
54 }
55
56 static constexpr result_type max() {
57 return std::mt19937::max();
58 }
59
60 result_type operator()() {
61 assert(engine != nullptr);
62
63 return engine->operator()();
64 }
65 };
66
67 #endif
check.h
LazyRandomEngine::AutoCreate
void AutoCreate()
Create and seed the real engine.
LazyRandomEngine::~LazyRandomEngine
~LazyRandomEngine()
Definition: LazyRandomEngine.hxx:39
LazyRandomEngine::max
static constexpr result_type max()
Definition: LazyRandomEngine.hxx:56
LazyRandomEngine::LazyRandomEngine
LazyRandomEngine()
Definition: LazyRandomEngine.hxx:38
LazyRandomEngine::operator()
result_type operator()()
Definition: LazyRandomEngine.hxx:60
LazyRandomEngine::operator=
LazyRandomEngine & operator=(const LazyRandomEngine &other)=delete
LazyRandomEngine::min
static constexpr result_type min()
Definition: LazyRandomEngine.hxx:52
LazyRandomEngine::result_type
std::mt19937::result_type result_type
Definition: LazyRandomEngine.hxx:36
LazyRandomEngine
A random engine that will be created and seeded on demand.
Definition: LazyRandomEngine.hxx:32