libstdc++-v3/include/std/numeric

// <numeric> -*- C++ -*-

// Copyright (C) 2001-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1996,1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/** @file include/numeric
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_NUMERIC
#define _GLIBCXX_NUMERIC 1

#pragma GCC system_header

#include <bits/c++config.h>
#include <bits/stl_iterator_base_types.h>
#include <bits/stl_numeric.h>
#include <ext/numeric_traits.h>

#ifdef _GLIBCXX_PARALLEL
# include <parallel/numeric>
#endif

/**
 * @defgroup numerics Numerics
 *
 * Components for performing numeric operations. Includes support for
 * for complex number types, random number generation, numeric
 * (n-at-a-time) arrays, generalized numeric algorithms, and special
 * math functions.
 */

#if __cplusplus >= 201402L
#include <type_traits>

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace __detail
{
  // std::abs is not constexpr, doesn't support unsigned integers,
  // and std::abs(std::numeric_limits<T>::min()) is undefined.
  template<typename _Up, typename _Tp>
    constexpr _Up
    __absu(_Tp __val)
    {
      static_assert(is_unsigned<_Up>::value, "result type must be unsigned");
      static_assert(sizeof(_Up) >= sizeof(_Tp),
	  "result type must be at least as wide as the input type");
      return __val < 0 ? -(_Up)__val : (_Up)__val;
    }

  template<typename _Up> void __absu(bool) = delete;

  // GCD implementation
  template<typename _Tp>
    constexpr _Tp
    __gcd(_Tp __m, _Tp __n)
    {
      static_assert(is_unsigned<_Tp>::value, "type must be unsigned");
      return __m == 0 ? __n
	: __n == 0 ? __m
	: __detail::__gcd(__n, _Tp(__m % __n));
    }

  // LCM implementation
  template<typename _Tp>
    constexpr _Tp
    __lcm(_Tp __m, _Tp __n)
    {
      return (__m != 0 && __n != 0)
	? (__m / __detail::__gcd(__m, __n)) * __n
	: 0;
    }
} // namespace __detail

#if __cplusplus > 201402L

#define __cpp_lib_gcd_lcm 201606
// These were used in drafts of SD-6:
#define __cpp_lib_gcd 201606
#define __cpp_lib_lcm 201606

  /// Greatest common divisor
  template<typename _Mn, typename _Nn>
    constexpr common_type_t<_Mn, _Nn>
    gcd(_Mn __m, _Nn __n) noexcept
    {
      static_assert(is_integral_v<_Mn>, "std::gcd arguments must be integers");
      static_assert(is_integral_v<_Nn>, "std::gcd arguments must be integers");
      static_assert(_Mn(2) != _Mn(1), "std::gcd arguments must not be bool");
      static_assert(_Nn(2) != _Nn(1), "std::gcd arguments must not be bool");
      using _Up = make_unsigned_t<common_type_t<_Mn, _Nn>>;
      return __detail::__gcd(__detail::__absu<_Up>(__m),
			     __detail::__absu<_Up>(__n));
    }

  /// Least common multiple
  template<typename _Mn, typename _Nn>
    constexpr common_type_t<_Mn, _Nn>
    lcm(_Mn __m, _Nn __n) noexcept
    {
      static_assert(is_integral_v<_Mn>, "std::lcm arguments must be integers");
      static_assert(is_integral_v<_Nn>, "std::lcm arguments must be integers");
      static_assert(_Mn(2) == 2, "std::lcm arguments must not be bool");
      static_assert(_Nn(2) == 2, "std::lcm arguments must not be bool");
      using _Up = make_unsigned_t<common_type_t<_Mn, _Nn>>;
      return __detail::__lcm(__detail::__absu<_Up>(__m),
			     __detail::__absu<_Up>(__n));
    }

#endif // C++17

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++14


#endif /* _GLIBCXX_NUMERIC */