libstdc++: numeric Source File

libstdc++

experimental/numeric
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1// <experimental/numeric> -*- C++ -*-
2
3// Copyright (C) 2015-2026 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/numeric
26 * This is a TS C++ Library header.
27 * @ingroup libfund-ts
28 */
29
30//
31// N4336 Working Draft, C++ Extensions for Library Fundamentals, Version 2
32//
33
34#ifndef _GLIBCXX_EXPERIMENTAL_NUMERIC
35#define _GLIBCXX_EXPERIMENTAL_NUMERIC 1
36
37#ifdef _GLIBCXX_SYSHDR
38#pragma GCC system_header
39#endif
40
41#include <bits/requires_hosted.h> // experimental is currently omitted
42
43#if __cplusplus >= 201402L
44
45#include <numeric>
46#include <experimental/type_traits>
47
48namespace std _GLIBCXX_VISIBILITY(default)
49{
50_GLIBCXX_BEGIN_NAMESPACE_VERSION
51
52namespace experimental
53{
54inline namespace fundamentals_v2
55{
56#define __cpp_lib_experimental_gcd_lcm 201411
57
58 /// Greatest common divisor
59 template<typename _Mn, typename _Nn>
60 constexpr common_type_t<_Mn, _Nn>
61 gcd(_Mn __m, _Nn __n) noexcept
62 {
63 static_assert(is_integral_v<_Mn> && is_integral_v<_Nn>,
64 "std::experimental::gcd arguments must be integers");
65 static_assert(_Mn(2) == 2 && _Nn(2) == 2,
66 "std::experimental::gcd arguments must not be bool");
67 namespace __detail = std::__detail;
68 using _Ct = common_type_t<_Mn, _Nn>;
69 const _Ct __m2 = __detail::__abs_r<_Ct>(__m);
70 const _Ct __n2 = __detail::__abs_r<_Ct>(__n);
71 return __detail::__gcd<make_unsigned_t<_Ct>>(__m2, __n2);
72 }
73
74 /// Least common multiple
75 template<typename _Mn, typename _Nn>
76 constexpr common_type_t<_Mn, _Nn>
77 lcm(_Mn __m, _Nn __n)
78 {
79 static_assert(is_integral_v<_Mn> && is_integral_v<_Nn>,
80 "std::experimental::lcm arguments must be integers");
81 static_assert(_Mn(2) == 2 && _Nn(2) == 2,
82 "std::experimental::lcm arguments must not be bool");
83 namespace __detail = std::__detail;
84 using _Ct = common_type_t<_Mn, _Nn>;
85 const _Ct __m2 = __detail::__abs_r<_Ct>(__m);
86 const _Ct __n2 = __detail::__abs_r<_Ct>(__n);
87 if (__m2 == 0 || __n2 == 0)
88 return 0;
89 _Ct __r = __m2 / __detail::__gcd<make_unsigned_t<_Ct>>(__m2, __n2);
90
91#pragma GCC diagnostic push
92#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr
93 if constexpr (is_signed_v<_Ct>)
94 if (__is_constant_evaluated())
95 return __r * __n2; // constant evaluation can detect overflow here.
96#pragma GCC diagnostic pop
97
98 bool __overflow = __builtin_mul_overflow(__r, __n2, &__r);
99 __glibcxx_assert(!__overflow);
100 return __r;
101 }
102} // namespace fundamentals_v2
103} // namespace experimental
104
105_GLIBCXX_END_NAMESPACE_VERSION
106} // namespace std
107
108#endif // __cplusplus <= 201103L
109
110#endif // _GLIBCXX_EXPERIMENTAL_NUMERIC
requires_hosted.h
std::common_type_t
typename common_type< _Tp... >::type common_type_t
Alias template for common_type.
Definition type_traits:2977
std
ISO C++ entities toplevel namespace is std.
std::__detail
Implementation details not part of the namespace std interface.
std::experimental
Namespace for features defined in ISO Technical Specifications.
std::experimental::fundamentals_v2::lcm
constexpr common_type_t< _Mn, _Nn > lcm(_Mn __m, _Nn __n)
Least common multiple.
Definition experimental/numeric:77
std::experimental::fundamentals_v2::gcd
constexpr common_type_t< _Mn, _Nn > gcd(_Mn __m, _Nn __n) noexcept
Greatest common divisor.
Definition experimental/numeric:61
numeric
type_traits