fd33598558
This adds constexpr to 11 algorithms defined in <numeric> as per P1645R1. libstdc++-v3/ChangeLog: P1645R1 constexpr for <numeric> algorithms * include/bits/stl_numeric.h (iota, accumulate, inner_product, partial_sum, adjacent_difference): Make conditionally constexpr for C++20. * include/std/numeric (__cpp_lib_constexpr_numeric): Define this feature test macro. (reduce, transform_reduce, exclusive_scan, inclusive_scan, transform_exclusive_scan, transform_inclusive_scan): Make conditionally constexpr for C++20. * include/std/version (__cpp_lib_constexpr_numeric): Define. * testsuite/26_numerics/accumulate/constexpr.cc: New test. * testsuite/26_numerics/adjacent_difference/constexpr.cc: Likewise. * testsuite/26_numerics/exclusive_scan/constexpr.cc: Likewise. * testsuite/26_numerics/inclusive_scan/constexpr.cc: Likewise. * testsuite/26_numerics/inner_product/constexpr.cc: Likewise. * testsuite/26_numerics/iota/constexpr.cc: Likewise. * testsuite/26_numerics/partial_sum/constexpr.cc: Likewise. * testsuite/26_numerics/reduce/constexpr.cc: Likewise. * testsuite/26_numerics/transform_exclusive_scan/constexpr.cc: Likewise. * testsuite/26_numerics/transform_inclusive_scan/constexpr.cc: Likewise. * testsuite/26_numerics/transform_reduce/constexpr.cc: Likewise.
715 lines
24 KiB
C++
715 lines
24 KiB
C++
// <numeric> -*- C++ -*-
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// Copyright (C) 2001-2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/*
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*
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* Copyright (c) 1994
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* Hewlett-Packard Company
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Hewlett-Packard Company makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*
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* Copyright (c) 1996,1997
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file include/numeric
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* This is a Standard C++ Library header.
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*/
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#ifndef _GLIBCXX_NUMERIC
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#define _GLIBCXX_NUMERIC 1
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#pragma GCC system_header
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#include <bits/c++config.h>
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#include <bits/stl_iterator_base_types.h>
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#include <bits/stl_numeric.h>
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#ifdef _GLIBCXX_PARALLEL
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# include <parallel/numeric>
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#endif
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/**
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* @defgroup numerics Numerics
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*
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* Components for performing numeric operations. Includes support for
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* complex number types, random number generation, numeric (n-at-a-time)
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* arrays, generalized numeric algorithms, and mathematical special functions.
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*/
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#if __cplusplus >= 201402L
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#include <type_traits>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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namespace __detail
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{
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// std::abs is not constexpr and doesn't support unsigned integers.
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template<typename _Tp>
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constexpr
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enable_if_t<__and_<is_integral<_Tp>, is_signed<_Tp>>::value, _Tp>
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__abs_integral(_Tp __val)
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{ return __val < 0 ? -__val : __val; }
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template<typename _Tp>
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constexpr
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enable_if_t<__and_<is_integral<_Tp>, is_unsigned<_Tp>>::value, _Tp>
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__abs_integral(_Tp __val)
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{ return __val; }
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void __abs_integral(bool) = delete;
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template<typename _Mn, typename _Nn>
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constexpr common_type_t<_Mn, _Nn>
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__gcd(_Mn __m, _Nn __n)
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{
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return __m == 0 ? __detail::__abs_integral(__n)
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: __n == 0 ? __detail::__abs_integral(__m)
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: __detail::__gcd(__n, __m % __n);
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}
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/// Least common multiple
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template<typename _Mn, typename _Nn>
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constexpr common_type_t<_Mn, _Nn>
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__lcm(_Mn __m, _Nn __n)
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{
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return (__m != 0 && __n != 0)
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? (__detail::__abs_integral(__m) / __detail::__gcd(__m, __n))
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* __detail::__abs_integral(__n)
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: 0;
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}
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} // namespace __detail
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#if __cplusplus >= 201703L
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#define __cpp_lib_gcd_lcm 201606
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// These were used in drafts of SD-6:
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#define __cpp_lib_gcd 201606
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#define __cpp_lib_lcm 201606
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/// Greatest common divisor
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template<typename _Mn, typename _Nn>
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constexpr common_type_t<_Mn, _Nn>
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gcd(_Mn __m, _Nn __n)
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{
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static_assert(is_integral_v<_Mn>, "gcd arguments are integers");
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static_assert(is_integral_v<_Nn>, "gcd arguments are integers");
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static_assert(!is_same_v<remove_cv_t<_Mn>, bool>,
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"gcd arguments are not bools");
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static_assert(!is_same_v<remove_cv_t<_Nn>, bool>,
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"gcd arguments are not bools");
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return __detail::__gcd(__m, __n);
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}
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/// Least common multiple
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template<typename _Mn, typename _Nn>
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constexpr common_type_t<_Mn, _Nn>
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lcm(_Mn __m, _Nn __n)
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{
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static_assert(is_integral_v<_Mn>, "lcm arguments are integers");
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static_assert(is_integral_v<_Nn>, "lcm arguments are integers");
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static_assert(!is_same_v<remove_cv_t<_Mn>, bool>,
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"lcm arguments are not bools");
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static_assert(!is_same_v<remove_cv_t<_Nn>, bool>,
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"lcm arguments are not bools");
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return __detail::__lcm(__m, __n);
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}
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#endif // C++17
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif // C++14
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#if __cplusplus > 201703L
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#include <limits>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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// midpoint
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# define __cpp_lib_interpolate 201902L
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template<typename _Tp>
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constexpr
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enable_if_t<__and_v<is_arithmetic<_Tp>, is_same<remove_cv_t<_Tp>, _Tp>,
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__not_<is_same<_Tp, bool>>>,
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_Tp>
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midpoint(_Tp __a, _Tp __b) noexcept
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{
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if constexpr (is_integral_v<_Tp>)
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{
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using _Up = make_unsigned_t<_Tp>;
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int __k = 1;
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_Up __m = __a;
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_Up __M = __b;
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if (__a > __b)
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{
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__k = -1;
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__m = __b;
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__M = __a;
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}
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return __a + __k * _Tp(_Up(__M - __m) / 2);
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}
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else // is_floating
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{
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constexpr _Tp __lo = numeric_limits<_Tp>::min() * 2;
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constexpr _Tp __hi = numeric_limits<_Tp>::max() / 2;
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const _Tp __abs_a = __a < 0 ? -__a : __a;
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const _Tp __abs_b = __b < 0 ? -__b : __b;
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if (__abs_a <= __hi && __abs_b <= __hi) [[likely]]
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return (__a + __b) / 2; // always correctly rounded
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if (__abs_a < __lo) // not safe to halve __a
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return __a + __b/2;
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if (__abs_b < __lo) // not safe to halve __b
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return __a/2 + __b;
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return __a/2 + __b/2; // otherwise correctly rounded
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}
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}
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template<typename _Tp>
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constexpr enable_if_t<is_object_v<_Tp>, _Tp*>
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midpoint(_Tp* __a, _Tp* __b) noexcept
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{
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static_assert( sizeof(_Tp) != 0, "type must be complete" );
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return __a + (__b - __a) / 2;
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif // C++20
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#if __cplusplus > 201402L
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#include <bits/stl_function.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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#if __cplusplus > 201703L
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#define __cpp_lib_constexpr_numeric 201911L
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#endif
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/// @addtogroup numeric_ops
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/// @{
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/**
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* @brief Calculate reduction of values in a range.
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*
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* @param __first Start of range.
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* @param __last End of range.
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* @param __init Starting value to add other values to.
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* @param __binary_op A binary function object.
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* @return The final sum.
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*
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* Reduce the values in the range `[first,last)` using a binary operation.
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* The initial value is `init`. The values are not necessarily processed
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* in order.
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*
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* This algorithm is similar to `std::accumulate` but is not required to
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* perform the operations in order from first to last. For operations
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* that are commutative and associative the result will be the same as
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* for `std::accumulate`, but for other operations (such as floating point
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* arithmetic) the result can be different.
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*/
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template<typename _InputIterator, typename _Tp, typename _BinaryOperation>
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_GLIBCXX20_CONSTEXPR
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_Tp
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reduce(_InputIterator __first, _InputIterator __last, _Tp __init,
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_BinaryOperation __binary_op)
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{
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using value_type = typename iterator_traits<_InputIterator>::value_type;
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static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, _Tp&, _Tp&>);
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static_assert(is_convertible_v<value_type, _Tp>);
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if constexpr (__is_random_access_iter<_InputIterator>::value)
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{
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while ((__last - __first) >= 4)
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{
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_Tp __v1 = __binary_op(__first[0], __first[1]);
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_Tp __v2 = __binary_op(__first[2], __first[3]);
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_Tp __v3 = __binary_op(__v1, __v2);
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__init = __binary_op(__init, __v3);
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__first += 4;
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}
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}
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for (; __first != __last; ++__first)
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__init = __binary_op(__init, *__first);
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return __init;
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}
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/**
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* @brief Calculate reduction of values in a range.
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*
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* @param __first Start of range.
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* @param __last End of range.
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* @param __init Starting value to add other values to.
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* @return The final sum.
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*
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* Reduce the values in the range `[first,last)` using addition.
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* Equivalent to calling `std::reduce(first, last, init, std::plus<>())`.
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*/
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template<typename _InputIterator, typename _Tp>
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_GLIBCXX20_CONSTEXPR
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inline _Tp
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reduce(_InputIterator __first, _InputIterator __last, _Tp __init)
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{ return std::reduce(__first, __last, std::move(__init), plus<>()); }
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/**
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* @brief Calculate reduction of values in a range.
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*
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* @param __first Start of range.
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* @param __last End of range.
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* @return The final sum.
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*
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* Reduce the values in the range `[first,last)` using addition, with
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* an initial value of `T{}`, where `T` is the iterator's value type.
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* Equivalent to calling `std::reduce(first, last, T{}, std::plus<>())`.
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*/
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template<typename _InputIterator>
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_GLIBCXX20_CONSTEXPR
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inline typename iterator_traits<_InputIterator>::value_type
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reduce(_InputIterator __first, _InputIterator __last)
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{
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using value_type = typename iterator_traits<_InputIterator>::value_type;
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return std::reduce(__first, __last, value_type{}, plus<>());
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}
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/**
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* @brief Combine elements from two ranges and reduce
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*
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* @param __first1 Start of first range.
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* @param __last1 End of first range.
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* @param __first2 Start of second range.
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* @param __init Starting value to add other values to.
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* @param __binary_op1 The function used to perform reduction.
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* @param __binary_op2 The function used to combine values from the ranges.
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* @return The final sum.
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*
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* Call `binary_op2(first1[n],first2[n])` for each `n` in `[0,last1-first1)`
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* and then use `binary_op1` to reduce the values returned by `binary_op2`
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* to a single value of type `T`.
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*
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* The range beginning at `first2` must contain at least `last1-first1`
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* elements.
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*/
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template<typename _InputIterator1, typename _InputIterator2, typename _Tp,
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typename _BinaryOperation1, typename _BinaryOperation2>
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_GLIBCXX20_CONSTEXPR
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_Tp
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transform_reduce(_InputIterator1 __first1, _InputIterator1 __last1,
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_InputIterator2 __first2, _Tp __init,
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_BinaryOperation1 __binary_op1,
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_BinaryOperation2 __binary_op2)
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{
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if constexpr (__and_v<__is_random_access_iter<_InputIterator1>,
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__is_random_access_iter<_InputIterator2>>)
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{
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while ((__last1 - __first1) >= 4)
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{
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_Tp __v1 = __binary_op1(__binary_op2(__first1[0], __first2[0]),
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__binary_op2(__first1[1], __first2[1]));
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_Tp __v2 = __binary_op1(__binary_op2(__first1[2], __first2[2]),
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__binary_op2(__first1[3], __first2[3]));
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_Tp __v3 = __binary_op1(__v1, __v2);
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__init = __binary_op1(__init, __v3);
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__first1 += 4;
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__first2 += 4;
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}
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}
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for (; __first1 != __last1; ++__first1, (void) ++__first2)
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__init = __binary_op1(__init, __binary_op2(*__first1, *__first2));
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return __init;
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}
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/**
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* @brief Combine elements from two ranges and reduce
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*
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* @param __first1 Start of first range.
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* @param __last1 End of first range.
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* @param __first2 Start of second range.
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* @param __init Starting value to add other values to.
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* @return The final sum.
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*
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* Call `first1[n]*first2[n]` for each `n` in `[0,last1-first1)` and then
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* use addition to sum those products to a single value of type `T`.
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*
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* The range beginning at `first2` must contain at least `last1-first1`
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* elements.
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*/
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template<typename _InputIterator1, typename _InputIterator2, typename _Tp>
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_GLIBCXX20_CONSTEXPR
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inline _Tp
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transform_reduce(_InputIterator1 __first1, _InputIterator1 __last1,
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_InputIterator2 __first2, _Tp __init)
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{
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return std::transform_reduce(__first1, __last1, __first2,
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std::move(__init),
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plus<>(), multiplies<>());
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}
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/**
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* @brief Transform the elements of a range and reduce
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*
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* @param __first Start of range.
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* @param __last End of range.
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* @param __init Starting value to add other values to.
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* @param __binary_op The function used to perform reduction.
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* @param __unary_op The function used to transform values from the range.
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* @return The final sum.
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*
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* Call `unary_op(first[n])` for each `n` in `[0,last-first)` and then
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* use `binary_op` to reduce the values returned by `unary_op`
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* to a single value of type `T`.
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*/
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template<typename _InputIterator, typename _Tp,
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typename _BinaryOperation, typename _UnaryOperation>
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_GLIBCXX20_CONSTEXPR
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_Tp
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transform_reduce(_InputIterator __first, _InputIterator __last, _Tp __init,
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_BinaryOperation __binary_op, _UnaryOperation __unary_op)
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{
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if constexpr (__is_random_access_iter<_InputIterator>::value)
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{
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while ((__last - __first) >= 4)
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{
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_Tp __v1 = __binary_op(__unary_op(__first[0]),
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__unary_op(__first[1]));
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_Tp __v2 = __binary_op(__unary_op(__first[2]),
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__unary_op(__first[3]));
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_Tp __v3 = __binary_op(__v1, __v2);
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__init = __binary_op(__init, __v3);
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__first += 4;
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}
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}
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for (; __first != __last; ++__first)
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__init = __binary_op(__init, __unary_op(*__first));
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return __init;
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}
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/** @brief Output the cumulative sum of one range to a second range
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*
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* @param __first Start of input range.
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* @param __last End of input range.
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* @param __result Start of output range.
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* @param __init Initial value.
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* @param __binary_op Function to perform summation.
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* @return The end of the output range.
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*
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* Write the cumulative sum (aka prefix sum, aka scan) of the input range
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* to the output range. Each element of the output range contains the
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* running total of all earlier elements (and the initial value),
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* using `binary_op` for summation.
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*
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* This function generates an "exclusive" scan, meaning the Nth element
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* of the output range is the sum of the first N-1 input elements,
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* so the Nth input element is not included.
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*/
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template<typename _InputIterator, typename _OutputIterator, typename _Tp,
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typename _BinaryOperation>
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_GLIBCXX20_CONSTEXPR
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_OutputIterator
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exclusive_scan(_InputIterator __first, _InputIterator __last,
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_OutputIterator __result, _Tp __init,
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_BinaryOperation __binary_op)
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{
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while (__first != __last)
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{
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auto __v = __init;
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__init = __binary_op(__init, *__first);
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++__first;
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*__result++ = std::move(__v);
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}
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return __result;
|
|
}
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @param __init Initial value.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements (and the initial value),
|
|
* using `std::plus<>` for summation.
|
|
*
|
|
* This function generates an "exclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N-1 input elements,
|
|
* so the Nth input element is not included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator, typename _Tp>
|
|
_GLIBCXX20_CONSTEXPR
|
|
inline _OutputIterator
|
|
exclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result, _Tp __init)
|
|
{
|
|
return std::exclusive_scan(__first, __last, __result, std::move(__init),
|
|
plus<>());
|
|
}
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @param __binary_op Function to perform summation.
|
|
* @param __init Initial value.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements (and the initial value),
|
|
* using `binary_op` for summation.
|
|
*
|
|
* This function generates an "inclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N input elements,
|
|
* so the Nth input element is included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator,
|
|
typename _BinaryOperation, typename _Tp>
|
|
_GLIBCXX20_CONSTEXPR
|
|
_OutputIterator
|
|
inclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result, _BinaryOperation __binary_op,
|
|
_Tp __init)
|
|
{
|
|
for (; __first != __last; ++__first)
|
|
*__result++ = __init = __binary_op(__init, *__first);
|
|
return __result;
|
|
}
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @param __binary_op Function to perform summation.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements, using `binary_op` for summation.
|
|
*
|
|
* This function generates an "inclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N input elements,
|
|
* so the Nth input element is included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator,
|
|
typename _BinaryOperation>
|
|
_GLIBCXX20_CONSTEXPR
|
|
_OutputIterator
|
|
inclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result, _BinaryOperation __binary_op)
|
|
{
|
|
if (__first != __last)
|
|
{
|
|
auto __init = *__first;
|
|
*__result++ = __init;
|
|
++__first;
|
|
if (__first != __last)
|
|
__result = std::inclusive_scan(__first, __last, __result,
|
|
__binary_op, std::move(__init));
|
|
}
|
|
return __result;
|
|
}
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements, using `std::plus<>` for summation.
|
|
*
|
|
* This function generates an "inclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N input elements,
|
|
* so the Nth input element is included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator>
|
|
_GLIBCXX20_CONSTEXPR
|
|
inline _OutputIterator
|
|
inclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result)
|
|
{ return std::inclusive_scan(__first, __last, __result, plus<>()); }
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @param __init Initial value.
|
|
* @param __binary_op Function to perform summation.
|
|
* @param __unary_op Function to transform elements of the input range.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements (and the initial value),
|
|
* using `__unary_op` to transform the input elements
|
|
* and using `__binary_op` for summation.
|
|
*
|
|
* This function generates an "exclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N-1 input elements,
|
|
* so the Nth input element is not included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator, typename _Tp,
|
|
typename _BinaryOperation, typename _UnaryOperation>
|
|
_GLIBCXX20_CONSTEXPR
|
|
_OutputIterator
|
|
transform_exclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result, _Tp __init,
|
|
_BinaryOperation __binary_op,
|
|
_UnaryOperation __unary_op)
|
|
{
|
|
while (__first != __last)
|
|
{
|
|
auto __v = __init;
|
|
__init = __binary_op(__init, __unary_op(*__first));
|
|
++__first;
|
|
*__result++ = std::move(__v);
|
|
}
|
|
return __result;
|
|
}
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @param __binary_op Function to perform summation.
|
|
* @param __unary_op Function to transform elements of the input range.
|
|
* @param __init Initial value.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements (and the initial value),
|
|
* using `__unary_op` to transform the input elements
|
|
* and using `__binary_op` for summation.
|
|
*
|
|
* This function generates an "inclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N input elements,
|
|
* so the Nth input element is included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator,
|
|
typename _BinaryOperation, typename _UnaryOperation, typename _Tp>
|
|
_GLIBCXX20_CONSTEXPR
|
|
_OutputIterator
|
|
transform_inclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result,
|
|
_BinaryOperation __binary_op,
|
|
_UnaryOperation __unary_op,
|
|
_Tp __init)
|
|
{
|
|
for (; __first != __last; ++__first)
|
|
*__result++ = __init = __binary_op(__init, __unary_op(*__first));
|
|
return __result;
|
|
}
|
|
|
|
/** @brief Output the cumulative sum of one range to a second range
|
|
*
|
|
* @param __first Start of input range.
|
|
* @param __last End of input range.
|
|
* @param __result Start of output range.
|
|
* @param __binary_op Function to perform summation.
|
|
* @param __unary_op Function to transform elements of the input range.
|
|
* @return The end of the output range.
|
|
*
|
|
* Write the cumulative sum (aka prefix sum, aka scan) of the input range
|
|
* to the output range. Each element of the output range contains the
|
|
* running total of all earlier elements,
|
|
* using `__unary_op` to transform the input elements
|
|
* and using `__binary_op` for summation.
|
|
*
|
|
* This function generates an "inclusive" scan, meaning the Nth element
|
|
* of the output range is the sum of the first N input elements,
|
|
* so the Nth input element is included.
|
|
*/
|
|
template<typename _InputIterator, typename _OutputIterator,
|
|
typename _BinaryOperation, typename _UnaryOperation>
|
|
_GLIBCXX20_CONSTEXPR
|
|
_OutputIterator
|
|
transform_inclusive_scan(_InputIterator __first, _InputIterator __last,
|
|
_OutputIterator __result,
|
|
_BinaryOperation __binary_op,
|
|
_UnaryOperation __unary_op)
|
|
{
|
|
if (__first != __last)
|
|
{
|
|
auto __init = __unary_op(*__first);
|
|
*__result++ = __init;
|
|
++__first;
|
|
if (__first != __last)
|
|
__result = std::transform_inclusive_scan(__first, __last, __result,
|
|
__binary_op, __unary_op,
|
|
std::move(__init));
|
|
}
|
|
return __result;
|
|
}
|
|
|
|
// @} group numeric_ops
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace std
|
|
|
|
// 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 201603L
|
|
#endif // C++17
|
|
|
|
#endif /* _GLIBCXX_NUMERIC */
|