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 #if __cplusplus >= 201402L
33 #include <random>
34 #include <experimental/bits/lfts_config.h>
35 
36 namespace std {
37 _GLIBCXX_BEGIN_NAMESPACE_VERSION
38 
39 namespace experimental {
40 inline namespace fundamentals_v2 {
41 #define __cpp_lib_experimental_randint 201511
42 
43  inline std::default_random_engine&
44  _S_randint_engine()
45  {
46  static thread_local default_random_engine __eng{random_device{}()};
47  return __eng;
48  }
49 
50  // 13.2.2.1, Function template randint
51  template<typename _IntType>
52  inline _IntType
53  randint(_IntType __a, _IntType __b)
54  {
55  static_assert(is_integral<_IntType>::value && sizeof(_IntType) > 1,
56  "argument must be an integer type");
57  using _Dist = std::uniform_int_distribution<_IntType>;
58  // This relies on the fact our uniform_int_distribution is stateless,
59  // otherwise we'd need a static thread_local _Dist and pass it
60  // _Dist::param_type{__a, __b}.
61  return _Dist(__a, __b)(_S_randint_engine());
62  }
63 
64  inline void
65  reseed()
66  {
67  _S_randint_engine().seed(random_device{}());
68  }
69 
70  inline void
71  reseed(default_random_engine::result_type __value)
72  {
73  _S_randint_engine().seed(__value);
74  }
75 } // namespace fundamentals_v2
76 } // namespace experimental
77 
78 _GLIBCXX_END_NAMESPACE_VERSION
79 } // namespace std
80 
81 #endif // C++14
82 #endif // _GLIBCXX_EXPERIMENTAL_RANDOM