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gnss-sim/3rdparty/boost/charconv/detail/from_chars_integer_impl.hpp

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// Copyright 2023 Matt Borland
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
#ifndef BOOST_CHARCONV_DETAIL_FROM_CHARS_INTEGER_IMPL_HPP
#define BOOST_CHARCONV_DETAIL_FROM_CHARS_INTEGER_IMPL_HPP
#include <boost/charconv/detail/apply_sign.hpp>
#include <boost/charconv/detail/config.hpp>
#include <boost/charconv/detail/from_chars_result.hpp>
#include <boost/charconv/detail/emulated128.hpp>
#include <boost/charconv/detail/type_traits.hpp>
#include <boost/charconv/config.hpp>
#include <boost/config.hpp>
#include <system_error>
#include <type_traits>
#include <limits>
#include <cstdlib>
#include <cerrno>
#include <cstddef>
#include <cstdint>
namespace boost { namespace charconv { namespace detail {
static constexpr unsigned char uchar_values[] =
{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
255, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 255, 255, 255, 255, 255,
255, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255};
static_assert(sizeof(uchar_values) == 256, "uchar_values should represent all 256 values of unsigned char");
static constexpr double log_2_table[] =
{
0.0,
0.0,
1.0,
0.630929753571,
0.5,
0.430676558073,
0.386852807235,
0.356207187108,
0.333333333333,
0.315464876786,
0.301029995664,
0.289064826318,
0.278942945651,
0.270238154427,
0.262649535037,
0.255958024810,
0.25,
0.244650542118,
0.239812466568,
0.235408913367,
0.231378213160,
0.227670248697,
0.224243824218,
0.221064729458,
0.218104291986,
0.215338279037,
0.212746053553,
0.210309917857,
0.208014597677,
0.205846832460,
0.203795047091,
0.201849086582,
0.2,
0.198239863171,
0.196561632233,
0.194959021894,
0.193426403617
};
// Convert characters for 0-9, A-Z, a-z to 0-35. Anything else is 255
constexpr unsigned char digit_from_char(char val) noexcept
{
return uchar_values[static_cast<unsigned char>(val)];
}
#ifdef BOOST_MSVC
# pragma warning(push)
# pragma warning(disable: 4146) // unary minus operator applied to unsigned type, result still unsigned
# pragma warning(disable: 4189) // 'is_negative': local variable is initialized but not referenced
#elif defined(__clang__)
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wconstant-conversion"
#elif defined(__GNUC__) && (__GNUC__ < 7)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Woverflow"
# pragma GCC diagnostic ignored "-Wconversion"
# pragma GCC diagnostic ignored "-Wsign-conversion"
#elif defined(__GNUC__) && (__GNUC__ >= 7)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
# pragma GCC diagnostic ignored "-Wconversion"
#endif
template <typename Integer, typename Unsigned_Integer>
BOOST_CXX14_CONSTEXPR from_chars_result from_chars_integer_impl(const char* first, const char* last, Integer& value, int base) noexcept
{
Unsigned_Integer result = 0;
Unsigned_Integer overflow_value = 0;
Unsigned_Integer max_digit = 0;
// Check pre-conditions
if (!((first <= last) && (base >= 2 && base <= 36)))
{
return {first, std::errc::invalid_argument};
}
const auto unsigned_base = static_cast<Unsigned_Integer>(base);
// Strip sign if the type is signed
// Negative sign will be appended at the end of parsing
BOOST_ATTRIBUTE_UNUSED bool is_negative = false;
auto next = first;
BOOST_CHARCONV_IF_CONSTEXPR (is_signed<Integer>::value)
{
if (next != last)
{
if (*next == '-')
{
is_negative = true;
++next;
}
else if (*next == '+' || *next == ' ')
{
return {next, std::errc::invalid_argument};
}
}
#ifdef BOOST_CHARCONV_HAS_INT128
BOOST_IF_CONSTEXPR (std::is_same<Integer, boost::int128_type>::value)
{
overflow_value = BOOST_CHARCONV_INT128_MAX;
max_digit = BOOST_CHARCONV_INT128_MAX;
}
else
#endif
{
overflow_value = (std::numeric_limits<Integer>::max)();
max_digit = (std::numeric_limits<Integer>::max)();
}
if (is_negative)
{
++overflow_value;
++max_digit;
}
}
else
{
if (next != last && (*next == '-' || *next == '+' || *next == ' '))
{
return {first, std::errc::invalid_argument};
}
#ifdef BOOST_CHARCONV_HAS_INT128
BOOST_IF_CONSTEXPR (std::is_same<Integer, boost::uint128_type>::value)
{
overflow_value = BOOST_CHARCONV_UINT128_MAX;
max_digit = BOOST_CHARCONV_UINT128_MAX;
}
else
#endif
{
overflow_value = (std::numeric_limits<Unsigned_Integer>::max)();
max_digit = (std::numeric_limits<Unsigned_Integer>::max)();
}
}
#ifdef BOOST_CHARCONV_HAS_INT128
BOOST_IF_CONSTEXPR (std::is_same<Integer, boost::int128_type>::value)
{
overflow_value /= unsigned_base;
max_digit %= unsigned_base;
#ifndef __GLIBCXX_TYPE_INT_N_0
if (base != 10)
{
// Overflow value would cause INT128_MIN in non-base10 to fail
overflow_value *= static_cast<Unsigned_Integer>(2);
}
#endif
}
else
#endif
{
overflow_value /= unsigned_base;
max_digit %= unsigned_base;
}
// If the only character was a sign abort now
if (next == last)
{
return {first, std::errc::invalid_argument};
}
bool overflowed = false;
const std::ptrdiff_t nc = last - next;
// In non-GNU mode on GCC numeric limits may not be specialized
#if defined(BOOST_CHARCONV_HAS_INT128) && !defined(__GLIBCXX_TYPE_INT_N_0)
constexpr std::ptrdiff_t nd_2 = std::is_same<Integer, boost::int128_type>::value ? 127 :
std::is_same<Integer, boost::uint128_type>::value ? 128 :
std::numeric_limits<Integer>::digits10;
#else
constexpr std::ptrdiff_t nd_2 = std::numeric_limits<Integer>::digits;
#endif
const auto nd = static_cast<std::ptrdiff_t>(nd_2 * log_2_table[static_cast<std::size_t>(unsigned_base)]);
{
// Check that the first character is valid before proceeding
const unsigned char first_digit = digit_from_char(*next);
if (first_digit >= unsigned_base)
{
return {first, std::errc::invalid_argument};
}
result = static_cast<Unsigned_Integer>(result * unsigned_base + first_digit);
++next;
std::ptrdiff_t i = 1;
for( ; i < nd && i < nc; ++i )
{
// overflow is not possible in the first nd characters
const unsigned char current_digit = digit_from_char(*next);
if (current_digit >= unsigned_base)
{
break;
}
result = static_cast<Unsigned_Integer>(result * unsigned_base + current_digit);
++next;
}
for( ; i < nc; ++i )
{
const unsigned char current_digit = digit_from_char(*next);
if (current_digit >= unsigned_base)
{
break;
}
if (result < overflow_value || (result == overflow_value && current_digit <= max_digit))
{
result = static_cast<Unsigned_Integer>(result * unsigned_base + current_digit);
}
else
{
// Required to keep updating the value of next, but the result is garbage
overflowed = true;
}
++next;
}
}
// Return the parsed value, adding the sign back if applicable
// If we have overflowed then we do not return the result
if (overflowed)
{
return {next, std::errc::result_out_of_range};
}
value = static_cast<Integer>(result);
BOOST_IF_CONSTEXPR (is_signed<Integer>::value)
{
if (is_negative)
{
value = static_cast<Integer>(-(static_cast<Unsigned_Integer>(value)));
}
}
return {next, std::errc()};
}
#ifdef BOOST_MSVC
# pragma warning(pop)
#elif defined(__clang__)
# pragma clang diagnostic pop
#elif defined(__GNUC__)
# pragma GCC diagnostic pop
#endif
// Only from_chars for integer types is constexpr (as of C++23)
template <typename Integer>
BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars(const char* first, const char* last, Integer& value, int base = 10) noexcept
{
using Unsigned_Integer = typename std::make_unsigned<Integer>::type;
return detail::from_chars_integer_impl<Integer, Unsigned_Integer>(first, last, value, base);
}
#ifdef BOOST_CHARCONV_HAS_INT128
template <typename Integer>
BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars128(const char* first, const char* last, Integer& value, int base = 10) noexcept
{
using Unsigned_Integer = boost::uint128_type;
return detail::from_chars_integer_impl<Integer, Unsigned_Integer>(first, last, value, base);
}
#endif
BOOST_CHARCONV_GCC5_CONSTEXPR from_chars_result from_chars128(const char* first, const char* last, uint128& value, int base = 10) noexcept
{
return from_chars_integer_impl<uint128, uint128>(first, last, value, base);
}
}}} // Namespaces
#endif // BOOST_CHARCONV_DETAIL_FROM_CHARS_INTEGER_IMPL_HPP
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