1// <experimental/random> -*- C++ -*-
2
3// Copyright (C) 2015-2021 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 *  @ingroup libfund-ts
28 */
29
30#ifndef _GLIBCXX_EXPERIMENTAL_RANDOM
31#define _GLIBCXX_EXPERIMENTAL_RANDOM 1
32
33#if __cplusplus >= 201402L
34#include <random>
35#include <experimental/bits/lfts_config.h>
36
37namespace std {
38_GLIBCXX_BEGIN_NAMESPACE_VERSION
39
40namespace experimental {
41inline namespace fundamentals_v2 {
42#define __cpp_lib_experimental_randint 201511
43
44  inline std::default_random_engine&
45  _S_randint_engine()
46  {
47    static thread_local default_random_engine __eng{random_device{}()};
48    return __eng;
49  }
50
51  // 13.2.2.1, Function template randint
52  template<typename _IntType>
53    inline _IntType
54    randint(_IntType __a, _IntType __b)
55    {
56      static_assert(is_integral<_IntType>::value && sizeof(_IntType) > 1,
57		    "argument must be an integer type");
58      using _Dist = std::uniform_int_distribution<_IntType>;
59      // This relies on the fact our uniform_int_distribution is stateless,
60      // otherwise we'd need a static thread_local _Dist and pass it
61      // _Dist::param_type{__a, __b}.
62      return _Dist(__a, __b)(_S_randint_engine());
63    }
64
65  inline void
66  reseed()
67  {
68    _S_randint_engine().seed(random_device{}());
69  }
70
71  inline void
72  reseed(default_random_engine::result_type __value)
73  {
74    _S_randint_engine().seed(__value);
75  }
76} // namespace fundamentals_v2
77} // namespace experimental
78
79_GLIBCXX_END_NAMESPACE_VERSION
80} // namespace std
81
82#endif // C++14
83#endif // _GLIBCXX_EXPERIMENTAL_RANDOM
84