Page MenuHomePhabricator

Please use GitHub pull requests for new patches. Avoid migrating existing patches. Phabricator shutdown timeline

Differential D145590 Diff 505163 libcxx/include/__charconv/traits.h

Changeset View

Standalone View

View Options

libcxx/include/__charconv/traits.h

  • This file was added.
// -*- C++ -*-
//===----------------------------------------------------------------------===//
philnikUnsubmitted
Done
ReplyInline Actions

FWIW I'd be fine with formatting the files in this patch.

philnik: FWIW I'd be fine with formatting the files in this patch.
MordanteAuthorUnsubmitted
Done
ReplyInline Actions

I really prefer to do it separately. I also want to format the other headers in this directory.
(I will only make a draft of it to test the CI and land it so no additional reviewing is required.)

Mordante: I really prefer to do it separately. I also want to format the other headers in this directory.
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___CHARCONV_TRAITS
#define _LIBCPP___CHARCONV_TRAITS
#include <__bit/countl.h>
#include <__charconv/tables.h>
#include <__charconv/to_chars_base_10.h>
#include <__config>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_unsigned.h>
#include <cstdint>
#include <limits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 17
namespace __itoa
{
template <typename _Tp, typename = void>
struct _LIBCPP_HIDDEN __traits_base;
template <typename _Tp>
struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) <= sizeof(uint32_t)>>
{
using type = uint32_t;
/// The width estimation using a log10 algorithm.
///
/// The algorithm is based on
/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
/// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
/// function requires its input to have at least one bit set the value of
/// zero is set to one. This means the first element of the lookup table is
/// zero.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v)
{
auto __t = (32 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
return __t - (__v < __itoa::__pow10_32[__t]) + 1;
}
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v)
{
return __itoa::__base_10_u32(__p, __v);
}
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_32)& __pow() { return __itoa::__pow10_32; }
};
template <typename _Tp>
struct _LIBCPP_HIDDEN
__traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(uint64_t)>> {
using type = uint64_t;
/// The width estimation using a log10 algorithm.
///
/// The algorithm is based on
/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
/// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
/// function requires its input to have at least one bit set the value of
/// zero is set to one. This means the first element of the lookup table is
/// zero.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
auto __t = (64 - std::__libcpp_clz(static_cast<type>(__v | 1))) * 1233 >> 12;
return __t - (__v < __itoa::__pow10_64[__t]) + 1;
}
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) { return __itoa::__base_10_u64(__p, __v); }
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_64)& __pow() { return __itoa::__pow10_64; }
};
# ifndef _LIBCPP_HAS_NO_INT128
template <typename _Tp>
struct _LIBCPP_HIDDEN
__traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(__uint128_t)> > {
using type = __uint128_t;
/// The width estimation using a log10 algorithm.
///
/// The algorithm is based on
/// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
/// Instead of using IntegerLogBase2 it uses __libcpp_clz. Since that
/// function requires its input to have at least one bit set the value of
/// zero is set to one. This means the first element of the lookup table is
/// zero.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {
_LIBCPP_ASSERT(__v > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fail when this isn't true.");
// There's always a bit set in the upper 64-bits.
auto __t = (128 - std::__libcpp_clz(static_cast<uint64_t>(__v >> 64))) * 1233 >> 12;
_LIBCPP_ASSERT(__t >= __itoa::__pow10_128_offset, "Index out of bounds");
// __t is adjusted since the lookup table misses the lower entries.
return __t - (__v < __itoa::__pow10_128[__t - __itoa::__pow10_128_offset]) + 1;
}
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) { return __itoa::__base_10_u128(__p, __v); }
// TODO FMT This pow function should get an index.
// By moving this to its own header it can be reused by the pow function in to_chars_base_10.
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_128)& __pow() { return __itoa::__pow10_128; }
};
#endif
template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__mul_overflowed(unsigned char __a, _Tp __b, unsigned char& __r)
{
auto __c = __a * __b;
__r = __c;
return __c > numeric_limits<unsigned char>::max();
}
template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__mul_overflowed(unsigned short __a, _Tp __b, unsigned short& __r)
{
auto __c = __a * __b;
__r = __c;
return __c > numeric_limits<unsigned short>::max();
}
template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
__mul_overflowed(_Tp __a, _Tp __b, _Tp& __r)
{
static_assert(is_unsigned<_Tp>::value, "");
return __builtin_mul_overflow(__a, __b, &__r);
}
template <typename _Tp, typename _Up>
inline _LIBCPP_HIDE_FROM_ABI bool
_LIBCPP_CONSTEXPR_SINCE_CXX23 __mul_overflowed(_Tp __a, _Up __b, _Tp& __r)
{
return __itoa::__mul_overflowed(__a, static_cast<_Tp>(__b), __r);
}
template <typename _Tp>
struct _LIBCPP_HIDDEN __traits : __traits_base<_Tp>
{
static constexpr int digits = numeric_limits<_Tp>::digits10 + 1;
using __traits_base<_Tp>::__pow;
using typename __traits_base<_Tp>::type;
// precondition: at least one non-zero character available
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char const*
__read(char const* __p, char const* __ep, type& __a, type& __b)
{
type __cprod[digits];
int __j = digits - 1;
int __i = digits;
do
{
if (*__p < '0' || *__p > '9')
break;
__cprod[--__i] = *__p++ - '0';
} while (__p != __ep && __i != 0);
__a = __inner_product(__cprod + __i + 1, __cprod + __j, __pow() + 1,
__cprod[__i]);
if (__itoa::__mul_overflowed(__cprod[__j], __pow()[__j - __i], __b))
--__p;
return __p;
}
template <typename _It1, typename _It2, class _Up>
static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _Up
__inner_product(_It1 __first1, _It1 __last1, _It2 __first2, _Up __init)
{
for (; __first1 < __last1; ++__first1, ++__first2)
__init = __init + *__first1 * *__first2;
return __init;
}
};
} // namespace __itoa
template <typename _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _Tp
__complement(_Tp __x)
{
static_assert(is_unsigned<_Tp>::value, "cast to unsigned first");
return _Tp(~__x + 1);
}
#endif // _LIBCPP_STD_VER >= 17
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___CHARCONV_TRAITS