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Editing: parse_numbers.h
// Components for compile-time parsing of numbers -*- C++ -*- // Copyright (C) 2013-2018 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/>. /** @file bits/parse_numbers.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{chrono} */ #ifndef _GLIBCXX_PARSE_NUMBERS_H #define _GLIBCXX_PARSE_NUMBERS_H 1 #pragma GCC system_header // From n3642.pdf except I added binary literals and digit separator '\''. #if __cplusplus > 201103L #include <limits> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace __parse_int { template<unsigned _Base, char _Dig> struct _Digit; template<unsigned _Base> struct _Digit<_Base, '0'> : integral_constant<unsigned, 0> { using __valid = true_type; }; template<unsigned _Base> struct _Digit<_Base, '1'> : integral_constant<unsigned, 1> { using __valid = true_type; }; template<unsigned _Base, unsigned _Val> struct _Digit_impl : integral_constant<unsigned, _Val> { static_assert(_Base > _Val, "invalid digit"); using __valid = true_type; }; template<unsigned _Base> struct _Digit<_Base, '2'> : _Digit_impl<_Base, 2> { }; template<unsigned _Base> struct _Digit<_Base, '3'> : _Digit_impl<_Base, 3> { }; template<unsigned _Base> struct _Digit<_Base, '4'> : _Digit_impl<_Base, 4> { }; template<unsigned _Base> struct _Digit<_Base, '5'> : _Digit_impl<_Base, 5> { }; template<unsigned _Base> struct _Digit<_Base, '6'> : _Digit_impl<_Base, 6> { }; template<unsigned _Base> struct _Digit<_Base, '7'> : _Digit_impl<_Base, 7> { }; template<unsigned _Base> struct _Digit<_Base, '8'> : _Digit_impl<_Base, 8> { }; template<unsigned _Base> struct _Digit<_Base, '9'> : _Digit_impl<_Base, 9> { }; template<unsigned _Base> struct _Digit<_Base, 'a'> : _Digit_impl<_Base, 0xa> { }; template<unsigned _Base> struct _Digit<_Base, 'A'> : _Digit_impl<_Base, 0xa> { }; template<unsigned _Base> struct _Digit<_Base, 'b'> : _Digit_impl<_Base, 0xb> { }; template<unsigned _Base> struct _Digit<_Base, 'B'> : _Digit_impl<_Base, 0xb> { }; template<unsigned _Base> struct _Digit<_Base, 'c'> : _Digit_impl<_Base, 0xc> { }; template<unsigned _Base> struct _Digit<_Base, 'C'> : _Digit_impl<_Base, 0xc> { }; template<unsigned _Base> struct _Digit<_Base, 'd'> : _Digit_impl<_Base, 0xd> { }; template<unsigned _Base> struct _Digit<_Base, 'D'> : _Digit_impl<_Base, 0xd> { }; template<unsigned _Base> struct _Digit<_Base, 'e'> : _Digit_impl<_Base, 0xe> { }; template<unsigned _Base> struct _Digit<_Base, 'E'> : _Digit_impl<_Base, 0xe> { }; template<unsigned _Base> struct _Digit<_Base, 'f'> : _Digit_impl<_Base, 0xf> { }; template<unsigned _Base> struct _Digit<_Base, 'F'> : _Digit_impl<_Base, 0xf> { }; // Digit separator template<unsigned _Base> struct _Digit<_Base, '\''> : integral_constant<unsigned, 0> { using __valid = false_type; }; //------------------------------------------------------------------------------ template<unsigned long long _Val> using __ull_constant = integral_constant<unsigned long long, _Val>; template<unsigned _Base, char _Dig, char... _Digs> struct _Power_help { using __next = typename _Power_help<_Base, _Digs...>::type; using __valid_digit = typename _Digit<_Base, _Dig>::__valid; using type = __ull_constant<__next::value * (__valid_digit{} ? _Base : 1ULL)>; }; template<unsigned _Base, char _Dig> struct _Power_help<_Base, _Dig> { using __valid_digit = typename _Digit<_Base, _Dig>::__valid; using type = __ull_constant<__valid_digit::value>; }; template<unsigned _Base, char... _Digs> struct _Power : _Power_help<_Base, _Digs...>::type { }; template<unsigned _Base> struct _Power<_Base> : __ull_constant<0> { }; //------------------------------------------------------------------------------ template<unsigned _Base, unsigned long long _Pow, char _Dig, char... _Digs> struct _Number_help { using __digit = _Digit<_Base, _Dig>; using __valid_digit = typename __digit::__valid; using __next = _Number_help<_Base, __valid_digit::value ? _Pow / _Base : _Pow, _Digs...>; using type = __ull_constant<_Pow * __digit::value + __next::type::value>; static_assert((type::value / _Pow) == __digit::value, "integer literal does not fit in unsigned long long"); }; // Skip past digit separators: template<unsigned _Base, unsigned long long _Pow, char _Dig, char..._Digs> struct _Number_help<_Base, _Pow, '\'', _Dig, _Digs...> : _Number_help<_Base, _Pow, _Dig, _Digs...> { }; // Terminating case for recursion: template<unsigned _Base, char _Dig> struct _Number_help<_Base, 1ULL, _Dig> { using type = __ull_constant<_Digit<_Base, _Dig>::value>; }; template<unsigned _Base, char... _Digs> struct _Number : _Number_help<_Base, _Power<_Base, _Digs...>::value, _Digs...>::type { }; template<unsigned _Base> struct _Number<_Base> : __ull_constant<0> { }; //------------------------------------------------------------------------------ template<char... _Digs> struct _Parse_int; template<char... _Digs> struct _Parse_int<'0', 'b', _Digs...> : _Number<2U, _Digs...>::type { }; template<char... _Digs> struct _Parse_int<'0', 'B', _Digs...> : _Number<2U, _Digs...>::type { }; template<char... _Digs> struct _Parse_int<'0', 'x', _Digs...> : _Number<16U, _Digs...>::type { }; template<char... _Digs> struct _Parse_int<'0', 'X', _Digs...> : _Number<16U, _Digs...>::type { }; template<char... _Digs> struct _Parse_int<'0', _Digs...> : _Number<8U, _Digs...>::type { }; template<char... _Digs> struct _Parse_int : _Number<10U, _Digs...>::type { }; } // namespace __parse_int namespace __select_int { template<unsigned long long _Val, typename... _Ints> struct _Select_int_base; template<unsigned long long _Val, typename _IntType, typename... _Ints> struct _Select_int_base<_Val, _IntType, _Ints...> : conditional_t<(_Val <= std::numeric_limits<_IntType>::max()), integral_constant<_IntType, _Val>, _Select_int_base<_Val, _Ints...>> { }; template<unsigned long long _Val> struct _Select_int_base<_Val> { }; template<char... _Digs> using _Select_int = typename _Select_int_base< __parse_int::_Parse_int<_Digs...>::value, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long >::type; } // namespace __select_int _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif // __cplusplus > 201103L #endif // _GLIBCXX_PARSE_NUMBERS_H
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