charconv
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// Primitive numeric conversions (to_chars and from_chars) -*- C++ -*-
// Copyright (C) 2017-2021 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 include/charconv
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_CHARCONV
#define _GLIBCXX_CHARCONV 1
#pragma GCC system_header
// As an extension we support <charconv> in C++14, but this header should not
// be included by any other library headers in C++14 mode. This ensures that
// the names defined in this header are not added to namespace std unless a
// user explicitly includes <charconv> in C++14 code.
#if __cplusplus >= 201402L
#include <type_traits>
#include <bit> // for __bit_width
#include <cctype> // for isdigit
#include <bits/charconv.h> // for __to_chars_len, __to_chars_10_impl
#include <bits/error_constants.h> // for std::errc
#include <ext/numeric_traits.h>
#if _GLIBCXX_HAVE_USELOCALE
# define __cpp_lib_to_chars 201611L
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Result type of std::to_chars
struct to_chars_result
{
char* ptr;
errc ec;
#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
friend bool
operator==(const to_chars_result&, const to_chars_result&) = default;
#endif
};
/// Result type of std::from_chars
struct from_chars_result
{
const char* ptr;
errc ec;
#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
friend bool
operator==(const from_chars_result&, const from_chars_result&) = default;
#endif
};
namespace __detail
{
template<typename _Tp>
using __integer_to_chars_result_type
= enable_if_t<__or_<__is_signed_integer<_Tp>,
__is_unsigned_integer<_Tp>,
is_same<char, remove_cv_t<_Tp>>>::value,
to_chars_result>;
// Pick an unsigned type of suitable size. This is used to reduce the
// number of specializations of __to_chars_len, __to_chars etc. that
// get instantiated. For example, to_chars<char> and to_chars<short>
// and to_chars<unsigned> will all use the same code, and so will
// to_chars<long> when sizeof(int) == sizeof(long).
template<typename _Tp>
struct __to_chars_unsigned_type : __make_unsigned_selector_base
{
using _UInts = _List<unsigned int, unsigned long, unsigned long long
#if _GLIBCXX_USE_INT128
, unsigned __int128
#endif
>;
using type = typename __select<sizeof(_Tp), _UInts>::__type;
};
template<typename _Tp>
using __unsigned_least_t = typename __to_chars_unsigned_type<_Tp>::type;
// Generic implementation for arbitrary bases.
// Defined in <bits/charconv.h>.
template<typename _Tp>
constexpr unsigned
__to_chars_len(_Tp __value, int __base /* = 10 */) noexcept;
template<typename _Tp>
constexpr unsigned
__to_chars_len_2(_Tp __value) noexcept
{ return std::__bit_width(__value); }
// Generic implementation for arbitrary bases.
template<typename _Tp>
to_chars_result
__to_chars(char* __first, char* __last, _Tp __val, int __base) noexcept
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
to_chars_result __res;
const unsigned __len = __to_chars_len(__val, __base);
if (__builtin_expect((__last - __first) < __len, 0))
{
__res.ptr = __last;
__res.ec = errc::value_too_large;
return __res;
}
unsigned __pos = __len - 1;
static constexpr char __digits[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z'
};
while (__val >= (unsigned)__base)
{
auto const __quo = __val / __base;
auto const __rem = __val % __base;
__first[__pos--] = __digits[__rem];
__val = __quo;
}
*__first = __digits[__val];
__res.ptr = __first + __len;
__res.ec = {};
return __res;
}
template<typename _Tp>
__integer_to_chars_result_type<_Tp>
__to_chars_16(char* __first, char* __last, _Tp __val) noexcept
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
to_chars_result __res;
const unsigned __len = (__to_chars_len_2(__val) + 3) / 4;
if (__builtin_expect((__last - __first) < __len, 0))
{
__res.ptr = __last;
__res.ec = errc::value_too_large;
return __res;
}
static constexpr char __digits[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'
};
unsigned __pos = __len - 1;
while (__val >= 0x100)
{
auto __num = __val & 0xF;
__val >>= 4;
__first[__pos] = __digits[__num];
__num = __val & 0xF;
__val >>= 4;
__first[__pos - 1] = __digits[__num];
__pos -= 2;
}
if (__val >= 0x10)
{
const auto __num = __val & 0xF;
__val >>= 4;
__first[1] = __digits[__num];
__first[0] = __digits[__val];
}
else
__first[0] = __digits[__val];
__res.ptr = __first + __len;
__res.ec = {};
return __res;
}
template<typename _Tp>
inline __integer_to_chars_result_type<_Tp>
__to_chars_10(char* __first, char* __last, _Tp __val) noexcept
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
to_chars_result __res;
const unsigned __len = __to_chars_len(__val, 10);
if (__builtin_expect((__last - __first) < __len, 0))
{
__res.ptr = __last;
__res.ec = errc::value_too_large;
return __res;
}
__detail::__to_chars_10_impl(__first, __len, __val);
__res.ptr = __first + __len;
__res.ec = {};
return __res;
}
template<typename _Tp>
__integer_to_chars_result_type<_Tp>
__to_chars_8(char* __first, char* __last, _Tp __val) noexcept
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
to_chars_result __res;
unsigned __len;
if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Tp>::__digits <= 16)
{
__len = __val > 077777u ? 6u
: __val > 07777u ? 5u
: __val > 0777u ? 4u
: __val > 077u ? 3u
: __val > 07u ? 2u
: 1u;
}
else
__len = (__to_chars_len_2(__val) + 2) / 3;
if (__builtin_expect((__last - __first) < __len, 0))
{
__res.ptr = __last;
__res.ec = errc::value_too_large;
return __res;
}
unsigned __pos = __len - 1;
while (__val >= 0100)
{
auto __num = __val & 7;
__val >>= 3;
__first[__pos] = '0' + __num;
__num = __val & 7;
__val >>= 3;
__first[__pos - 1] = '0' + __num;
__pos -= 2;
}
if (__val >= 010)
{
auto const __num = __val & 7;
__val >>= 3;
__first[1] = '0' + __num;
__first[0] = '0' + __val;
}
else
__first[0] = '0' + __val;
__res.ptr = __first + __len;
__res.ec = {};
return __res;
}
template<typename _Tp>
__integer_to_chars_result_type<_Tp>
__to_chars_2(char* __first, char* __last, _Tp __val) noexcept
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
to_chars_result __res;
const unsigned __len = __to_chars_len_2(__val);
if (__builtin_expect((__last - __first) < __len, 0))
{
__res.ptr = __last;
__res.ec = errc::value_too_large;
return __res;
}
unsigned __pos = __len - 1;
while (__pos)
{
__first[__pos--] = '0' + (__val & 1);
__val >>= 1;
}
// First digit is always '1' because __to_chars_len_2 skips
// leading zero bits and std::to_chars handles zero values
// directly.
__first[0] = '1';
__res.ptr = __first + __len;
__res.ec = {};
return __res;
}
} // namespace __detail
template<typename _Tp>
__detail::__integer_to_chars_result_type<_Tp>
__to_chars_i(char* __first, char* __last, _Tp __value, int __base = 10)
{
__glibcxx_assert(2 <= __base && __base <= 36);
using _Up = __detail::__unsigned_least_t<_Tp>;
_Up __unsigned_val = __value;
if (__first == __last) [[__unlikely__]]
return { __last, errc::value_too_large };
if (__value == 0)
{
*__first = '0';
return { __first + 1, errc{} };
}
else if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value)
if (__value < 0)
{
*__first++ = '-';
__unsigned_val = _Up(~__value) + _Up(1);
}
switch (__base)
{
case 16:
return __detail::__to_chars_16(__first, __last, __unsigned_val);
case 10:
return __detail::__to_chars_10(__first, __last, __unsigned_val);
case 8:
return __detail::__to_chars_8(__first, __last, __unsigned_val);
case 2:
return __detail::__to_chars_2(__first, __last, __unsigned_val);
default:
return __detail::__to_chars(__first, __last, __unsigned_val, __base);
}
}
#define _GLIBCXX_TO_CHARS(T) \
inline to_chars_result \
to_chars(char* __first, char* __last, T __value, int __base = 10) \
{ return std::__to_chars_i<T>(__first, __last, __value, __base); }
_GLIBCXX_TO_CHARS(char)
_GLIBCXX_TO_CHARS(signed char)
_GLIBCXX_TO_CHARS(unsigned char)
_GLIBCXX_TO_CHARS(signed short)
_GLIBCXX_TO_CHARS(unsigned short)
_GLIBCXX_TO_CHARS(signed int)
_GLIBCXX_TO_CHARS(unsigned int)
_GLIBCXX_TO_CHARS(signed long)
_GLIBCXX_TO_CHARS(unsigned long)
_GLIBCXX_TO_CHARS(signed long long)
_GLIBCXX_TO_CHARS(unsigned long long)
#if defined(__GLIBCXX_TYPE_INT_N_0)
_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_0)
_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_0)
#endif
#if defined(__GLIBCXX_TYPE_INT_N_1)
_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_1)
_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_1)
#endif
#if defined(__GLIBCXX_TYPE_INT_N_2)
_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_2)
_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_2)
#endif
#if defined(__GLIBCXX_TYPE_INT_N_3)
_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_3)
_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_3)
#endif
#undef _GLIBCXX_TO_CHARS
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 3266. to_chars(bool) should be deleted
to_chars_result to_chars(char*, char*, bool, int = 10) = delete;
namespace __detail
{
template<typename _Tp>
bool
__raise_and_add(_Tp& __val, int __base, unsigned char __c)
{
if (__builtin_mul_overflow(__val, __base, &__val)
|| __builtin_add_overflow(__val, __c, &__val))
return false;
return true;
}
/// std::from_chars implementation for integers in base 2.
template<typename _Tp>
bool
__from_chars_binary(const char*& __first, const char* __last, _Tp& __val)
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
const ptrdiff_t __len = __last - __first;
ptrdiff_t __i = 0;
while (__i < __len && __first[__i] == '0')
++__i;
const ptrdiff_t __leading_zeroes = __i;
while (__i < __len)
{
const unsigned char __c = (unsigned)__first[__i] - '0';
if (__c < 2)
__val = (__val << 1) | __c;
else
break;
__i++;
}
__first += __i;
return (__i - __leading_zeroes) <= __gnu_cxx::__int_traits<_Tp>::__digits;
}
/// std::from_chars implementation for integers in bases 3 to 10.
template<typename _Tp>
bool
__from_chars_digit(const char*& __first, const char* __last, _Tp& __val,
int __base)
{
static_assert(is_integral<_Tp>::value, "implementation bug");
static_assert(is_unsigned<_Tp>::value, "implementation bug");
auto __matches = [__base](char __c) {
return '0' <= __c && __c <= ('0' + (__base - 1));
};
while (__first != __last)
{
const char __c = *__first;
if (__matches(__c))
{
if (!__raise_and_add(__val, __base, __c - '0'))
{
while (++__first != __last && __matches(*__first))
;
return false;
}
__first++;
}
else
return true;
}
return true;
}
constexpr unsigned char
__from_chars_alpha_to_num(char __c)
{
switch (__c)
{
case 'a':
case 'A':
return 10;
case 'b':
case 'B':
return 11;
case 'c':
case 'C':
return 12;
case 'd':
case 'D':
return 13;
case 'e':
case 'E':
return 14;
case 'f':
case 'F':
return 15;
case 'g':
case 'G':
return 16;
case 'h':
case 'H':
return 17;
case 'i':
case 'I':
return 18;
case 'j':
case 'J':
return 19;
case 'k':
case 'K':
return 20;
case 'l':
case 'L':
return 21;
case 'm':
case 'M':
return 22;
case 'n':
case 'N':
return 23;
case 'o':
case 'O':
return 24;
case 'p':
case 'P':
return 25;
case 'q':
case 'Q':
return 26;
case 'r':
case 'R':
return 27;
case 's':
case 'S':
return 28;
case 't':
case 'T':
return 29;
case 'u':
case 'U':
return 30;
case 'v':
case 'V':
return 31;
case 'w':
case 'W':
return 32;
case 'x':
case 'X':
return 33;
case 'y':
case 'Y':
return 34;
case 'z':
case 'Z':
return 35;
}
return __gnu_cxx::__int_traits<unsigned char>::__max;
}
/// std::from_chars implementation for integers in bases 11 to 26.
template<typename _Tp>
bool
__from_chars_alnum(const char*& __first, const char* __last, _Tp& __val,
int __base)
{
bool __valid = true;
while (__first != __last)
{
unsigned char __c = *__first;
if (std::isdigit(__c))
__c -= '0';
else
{
__c = __from_chars_alpha_to_num(__c);
if (__c >= __base)
break;
}
if (__builtin_expect(__valid, 1))
__valid = __raise_and_add(__val, __base, __c);
__first++;
}
return __valid;
}
template<typename _Tp>
using __integer_from_chars_result_type
= enable_if_t<__or_<__is_signed_integer<_Tp>,
__is_unsigned_integer<_Tp>,
is_same<char, remove_cv_t<_Tp>>>::value,
from_chars_result>;
} // namespace __detail
/// std::from_chars for integral types.
template<typename _Tp>
__detail::__integer_from_chars_result_type<_Tp>
from_chars(const char* __first, const char* __last, _Tp& __value,
int __base = 10)
{
__glibcxx_assert(2 <= __base && __base <= 36);
from_chars_result __res{__first, {}};
int __sign = 1;
if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value)
if (__first != __last && *__first == '-')
{
__sign = -1;
++__first;
}
using _Up = __detail::__unsigned_least_t<_Tp>;
_Up __val = 0;
const auto __start = __first;
bool __valid;
if (__base == 2)
__valid = __detail::__from_chars_binary(__first, __last, __val);
else if (__base <= 10)
__valid = __detail::__from_chars_digit(__first, __last, __val, __base);
else
__valid = __detail::__from_chars_alnum(__first, __last, __val, __base);
if (__builtin_expect(__first == __start, 0))
__res.ec = errc::invalid_argument;
else
{
__res.ptr = __first;
if (!__valid)
__res.ec = errc::result_out_of_range;
else
{
if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value)
{
_Tp __tmp;
if (__builtin_mul_overflow(__val, __sign, &__tmp))
__res.ec = errc::result_out_of_range;
else
__value = __tmp;
}
else
{
if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Up>::__max
> __gnu_cxx::__int_traits<_Tp>::__max)
{
if (__val > __gnu_cxx::__int_traits<_Tp>::__max)
__res.ec = errc::result_out_of_range;
else
__value = __val;
}
else
__value = __val;
}
}
}
return __res;
}
/// floating-point format for primitive numerical conversion
enum class chars_format
{
scientific = 1, fixed = 2, hex = 4, general = fixed | scientific
};
constexpr chars_format
operator|(chars_format __lhs, chars_format __rhs) noexcept
{ return (chars_format)((unsigned)__lhs | (unsigned)__rhs); }
constexpr chars_format
operator&(chars_format __lhs, chars_format __rhs) noexcept
{ return (chars_format)((unsigned)__lhs & (unsigned)__rhs); }
constexpr chars_format
operator^(chars_format __lhs, chars_format __rhs) noexcept
{ return (chars_format)((unsigned)__lhs ^ (unsigned)__rhs); }
constexpr chars_format
operator~(chars_format __fmt) noexcept
{ return (chars_format)~(unsigned)__fmt; }
constexpr chars_format&
operator|=(chars_format& __lhs, chars_format __rhs) noexcept
{ return __lhs = __lhs | __rhs; }
constexpr chars_format&
operator&=(chars_format& __lhs, chars_format __rhs) noexcept
{ return __lhs = __lhs & __rhs; }
constexpr chars_format&
operator^=(chars_format& __lhs, chars_format __rhs) noexcept
{ return __lhs = __lhs ^ __rhs; }
#if _GLIBCXX_HAVE_USELOCALE
from_chars_result
from_chars(const char* __first, const char* __last, float& __value,
chars_format __fmt = chars_format::general) noexcept;
from_chars_result
from_chars(const char* __first, const char* __last, double& __value,
chars_format __fmt = chars_format::general) noexcept;
from_chars_result
from_chars(const char* __first, const char* __last, long double& __value,
chars_format __fmt = chars_format::general) noexcept;
#endif
#if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \
&& __SIZE_WIDTH__ >= 32
// Floating-point std::to_chars
// Overloads for float.
to_chars_result to_chars(char* __first, char* __last, float __value) noexcept;
to_chars_result to_chars(char* __first, char* __last, float __value,
chars_format __fmt) noexcept;
to_chars_result to_chars(char* __first, char* __last, float __value,
chars_format __fmt, int __precision) noexcept;
// Overloads for double.
to_chars_result to_chars(char* __first, char* __last, double __value) noexcept;
to_chars_result to_chars(char* __first, char* __last, double __value,
chars_format __fmt) noexcept;
to_chars_result to_chars(char* __first, char* __last, double __value,
chars_format __fmt, int __precision) noexcept;
// Overloads for long double.
to_chars_result to_chars(char* __first, char* __last, long double __value)
noexcept;
to_chars_result to_chars(char* __first, char* __last, long double __value,
chars_format __fmt) noexcept;
to_chars_result to_chars(char* __first, char* __last, long double __value,
chars_format __fmt, int __precision) noexcept;
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++14
#endif // _GLIBCXX_CHARCONV