libstdc++
experimental/random
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1 // <experimental/random> -*- C++ -*-
2 
3 // Copyright (C) 2015-2018 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file experimental/random
26  * This is a TS C++ Library header.
27  */
28 
29 #ifndef _GLIBCXX_EXPERIMENTAL_RANDOM
30 #define _GLIBCXX_EXPERIMENTAL_RANDOM 1
31 
32 #include <random>
33 #include <experimental/bits/lfts_config.h>
34 
35 namespace std {
36 _GLIBCXX_BEGIN_NAMESPACE_VERSION
37 
38 namespace experimental {
39 inline namespace fundamentals_v2 {
40 #define __cpp_lib_experimental_randint 201511
41 
42  inline std::default_random_engine&
43  _S_randint_engine()
44  {
45  static thread_local default_random_engine __eng{random_device{}()};
46  return __eng;
47  }
48 
49  // 13.2.2.1, Function template randint
50  template<typename _IntType>
51  inline _IntType
52  randint(_IntType __a, _IntType __b)
53  {
54  static_assert(is_integral<_IntType>::value && sizeof(_IntType) > 1,
55  "argument must be an integer type");
56  using _Dist = std::uniform_int_distribution<_IntType>;
57  // This relies on the fact our uniform_int_distribution is stateless,
58  // otherwise we'd need a static thread_local _Dist and pass it
59  // _Dist::param_type{__a, __b}.
60  return _Dist(__a, __b)(_S_randint_engine());
61  }
62 
63  inline void
64  reseed()
65  {
66  _S_randint_engine().seed(random_device{}());
67  }
68 
69  inline void
70  reseed(default_random_engine::result_type __value)
71  {
72  _S_randint_engine().seed(__value);
73  }
74 } // namespace fundamentals_v2
75 } // namespace experimental
76 
77 _GLIBCXX_END_NAMESPACE_VERSION
78 } // namespace std
79 
80 #endif