1// -*- C++ -*-
2//===--------------------------- numeric ----------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10
11#ifndef _LIBCPP_EXPERIMENTAL_NUMERIC
12#define _LIBCPP_EXPERIMENTAL_NUMERIC
13/*
14    experimental/numeric synopsis
15
16// C++1z
17namespace std {
18namespace experimental {
19inline namespace fundamentals_v2 {
20
21  // 13.1.2, Greatest common divisor
22  template<class M, class N>
23  constexpr common_type_t<M,N> gcd(M m, N n);
24
25  // 13.1.3, Least common multiple
26  template<class M, class N>
27  constexpr common_type_t<M,N> lcm(M m, N n);
28
29} // namespace fundamentals_v2
30} // namespace experimental
31} // namespace std
32
33 */
34
35#include <experimental/__config>
36#include <numeric>
37#include <type_traits>              // is_integral
38#include <limits>                   // numeric_limits
39
40#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
41#pragma GCC system_header
42#endif
43
44_LIBCPP_PUSH_MACROS
45#include <__undef_macros>
46
47#if _LIBCPP_STD_VER > 11
48
49_LIBCPP_BEGIN_NAMESPACE_LFTS_V2
50
51template <typename _Result, typename _Source, bool _IsSigned = is_signed<_Source>::value> struct __abs;
52
53template <typename _Result, typename _Source>
54struct __abs<_Result, _Source, true> {
55    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
56    _Result operator()(_Source __t) const noexcept
57    {
58    if (__t >= 0) return __t;
59    if (__t == numeric_limits<_Source>::min()) return -static_cast<_Result>(__t);
60    return -__t;
61    }
62};
63
64template <typename _Result, typename _Source>
65struct __abs<_Result, _Source, false> {
66    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
67    _Result operator()(_Source __t) const noexcept { return __t; }
68};
69
70
71template<class _Tp>
72_LIBCPP_CONSTEXPR _LIBCPP_HIDDEN
73inline _Tp __gcd(_Tp __m, _Tp __n)
74{
75    static_assert((!is_signed<_Tp>::value), "" );
76    return __n == 0 ? __m : _VSTD_LFTS_V2::__gcd<_Tp>(__n, __m % __n);
77}
78
79
80template<class _Tp, class _Up>
81_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
82common_type_t<_Tp,_Up>
83gcd(_Tp __m, _Up __n)
84{
85    static_assert((is_integral<_Tp>::value && is_integral<_Up>::value), "Arguments to gcd must be integer types");
86    static_assert((!is_same<typename remove_cv<_Tp>::type, bool>::value), "First argument to gcd cannot be bool" );
87    static_assert((!is_same<typename remove_cv<_Up>::type, bool>::value), "Second argument to gcd cannot be bool" );
88    using _Rp = common_type_t<_Tp,_Up>;
89    using _Wp = make_unsigned_t<_Rp>;
90    return static_cast<_Rp>(_VSTD_LFTS_V2::__gcd(
91      static_cast<_Wp>(__abs<_Rp, _Tp>()(__m)),
92      static_cast<_Wp>(__abs<_Rp, _Up>()(__n))));
93}
94
95template<class _Tp, class _Up>
96_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
97common_type_t<_Tp,_Up>
98lcm(_Tp __m, _Up __n)
99{
100    static_assert((is_integral<_Tp>::value && is_integral<_Up>::value), "Arguments to lcm must be integer types");
101    static_assert((!is_same<typename remove_cv<_Tp>::type, bool>::value), "First argument to lcm cannot be bool" );
102    static_assert((!is_same<typename remove_cv<_Up>::type, bool>::value), "Second argument to lcm cannot be bool" );
103    if (__m == 0 || __n == 0)
104        return 0;
105
106    using _Rp = common_type_t<_Tp,_Up>;
107    _Rp __val1 = __abs<_Rp, _Tp>()(__m) / _VSTD_LFTS_V2::gcd(__m, __n);
108    _Rp __val2 = __abs<_Rp, _Up>()(__n);
109    _LIBCPP_ASSERT((numeric_limits<_Rp>::max() / __val1 > __val2), "Overflow in lcm");
110    return __val1 * __val2;
111}
112
113_LIBCPP_END_NAMESPACE_LFTS_V2
114
115#endif /* _LIBCPP_STD_VER > 11 */
116
117_LIBCPP_POP_MACROS
118
119#endif /* _LIBCPP_EXPERIMENTAL_NUMERIC */
120