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 17 namespace std { 18 namespace experimental { 19 inline 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 51 template <typename _Result, typename _Source, bool _IsSigned = is_signed<_Source>::value> struct __abs; 52 53 template <typename _Result, typename _Source> 54 struct __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 64 template <typename _Result, typename _Source> 65 struct __abs<_Result, _Source, false> { 66 _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY 67 _Result operator()(_Source __t) const noexcept { return __t; } 68 }; 69 70 71 template<class _Tp> 72 _LIBCPP_CONSTEXPR _LIBCPP_HIDDEN 73 inline _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 80 template<class _Tp, class _Up> 81 _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY 82 common_type_t<_Tp,_Up> 83 gcd(_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 95 template<class _Tp, class _Up> 96 _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY 97 common_type_t<_Tp,_Up> 98 lcm(_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
