parse_numbers.h
Go to the documentation of this file.
// Components for compile-time parsing of numbers -*- C++ -*-
// Copyright (C) 2013-2019 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/>.
/** @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
limits
std::conditional_t
typename conditional< _Cond, _Iftrue, _Iffalse >::type conditional_t
Alias template for conditional.
Definition type_traits:2382
std::true_type
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition type_traits:75
std::false_type
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition type_traits:78
std
ISO C++ entities toplevel namespace is std.