gcc/libstdc++-v3/include/std/numeric

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

// Copyright (C) 2001-2019 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>

#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 and doesn't support unsigned integers.
  template<typename _Tp>
    constexpr
    enable_if_t<__and_<is_integral<_Tp>, is_signed<_Tp>>::value, _Tp>
    __abs_integral(_Tp __val)
    { return __val < 0 ? -__val : __val; }

  template<typename _Tp>
    constexpr
    enable_if_t<__and_<is_integral<_Tp>, is_unsigned<_Tp>>::value, _Tp>
    __abs_integral(_Tp __val)
    { return __val; }

  void __abs_integral(bool) = delete;

  template<typename _Mn, typename _Nn>
    constexpr common_type_t<_Mn, _Nn>
    __gcd(_Mn __m, _Nn __n)
    {
      return __m == 0 ? __detail::__abs_integral(__n)
	: __n == 0 ? __detail::__abs_integral(__m)
	: __detail::__gcd(__n, __m % __n);
    }

  /// Least common multiple
  template<typename _Mn, typename _Nn>
    constexpr common_type_t<_Mn, _Nn>
    __lcm(_Mn __m, _Nn __n)
    {
      return (__m != 0 && __n != 0)
	? (__detail::__abs_integral(__m) / __detail::__gcd(__m, __n))
	  * __detail::__abs_integral(__n)
	: 0;
    }
} // namespace __detail

#if __cplusplus >= 201703L

#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)
    {
      static_assert(is_integral_v<_Mn>, "gcd arguments are integers");
      static_assert(is_integral_v<_Nn>, "gcd arguments are integers");
      static_assert(!is_same_v<remove_cv_t<_Mn>, bool>,
		    "gcd arguments are not bools");
      static_assert(!is_same_v<remove_cv_t<_Nn>, bool>,
		    "gcd arguments are not bools");
      return __detail::__gcd(__m, __n);
    }

  /// Least common multiple
  template<typename _Mn, typename _Nn>
    constexpr common_type_t<_Mn, _Nn>
    lcm(_Mn __m, _Nn __n)
    {
      static_assert(is_integral_v<_Mn>, "lcm arguments are integers");
      static_assert(is_integral_v<_Nn>, "lcm arguments are integers");
      static_assert(!is_same_v<remove_cv_t<_Mn>, bool>,
		    "lcm arguments are not bools");
      static_assert(!is_same_v<remove_cv_t<_Nn>, bool>,
		    "lcm arguments are not bools");
      return __detail::__lcm(__m, __n);
    }

#endif // C++17

#if __cplusplus > 201703L
  // midpoint
# define __cpp_lib_interpolate 201902L

template<typename _Tp>
    constexpr
    enable_if_t<__and_<is_arithmetic<_Tp>, is_same<remove_cv_t<_Tp>, _Tp>,
		       __not_<is_same<_Tp, bool>>>::value,
		_Tp>
    midpoint(_Tp __a, _Tp __b) noexcept
    {
      if constexpr (is_integral_v<_Tp>)
	{
	  using _Up = make_unsigned_t<_Tp>;

	  int __k = 1;
	  _Up __m = __a;
	  _Up __M = __b;
	  if (__a > __b)
	    {
	      __k = -1;
	      __m = __b;
	      __M = __a;
	    }
	  return __a + __k * _Tp(_Up(__M - __m) / 2);
	}
      else
	{
	  return __builtin_isnormal(__a) && __builtin_isnormal(__b)
	    ? __a / 2 + __b / 2
	    : (__a + __b) / 2;
	}
    }

  template<typename _Tp>
    constexpr
    enable_if_t<__and_<is_object<_Tp>, bool_constant<sizeof(_Tp) != 0>>::value,
		_Tp*>
    midpoint(_Tp* __a, _Tp* __b) noexcept
    {
      return __a > __b ? __b + (__a - __b) / 2 : __a + (__b - __a) / 2;
    }
#endif // C++20

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++14

#if __cplusplus > 201402L
// Parallel STL algorithms
# if __PSTL_EXECUTION_POLICIES_DEFINED
// If <execution> has already been included, pull in implementations
#  include <pstl/glue_numeric_impl.h>
# else
// Otherwise just pull in forward declarations
#  include <pstl/glue_numeric_defs.h>
#  define __PSTL_NUMERIC_FORWARD_DECLARED 1
# endif

// Feature test macro for parallel algorithms
# define __cpp_lib_parallel_algorithm 201703L
#endif // C++17

#endif /* _GLIBCXX_NUMERIC */