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/*
* Copyright (C) 2023-2024 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* License header from dragonbox
* https://github.com/jk-jeon/dragonbox/blob/master/LICENSE-Boost
* https://github.com/jk-jeon/dragonbox/blob/master/LICENSE-Apache2-LLVM
*/
#pragma once
#include <wtf/dragonbox/dragonbox.h>
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace WTF {
namespace dragonbox {
namespace detail {
template <class Float, class FloatTraits, Mode mode, PrintTrailingZero print_trailing_zero>
WTF_EXPORT_PRIVATE extern char* to_chars_impl(typename FloatTraits::carrier_uint significand, int32_t exponent, char* buffer);
WTF_EXPORT_PRIVATE extern char* to_shortest(const uint64_t significand, int32_t exponent, char* buffer);
template <>
WTF_EXPORT_PRIVATE char* to_chars_impl<double, default_float_traits<double>, Mode::ToExponential, PrintTrailingZero::No>(uint64_t significand, int32_t exponent, char* buffer);
template <>
WTF_EXPORT_PRIVATE char* to_chars_impl<float, default_float_traits<float>, Mode::ToExponential, PrintTrailingZero::No>(uint32_t significand, int32_t exponent, char* buffer);
// Avoid needless ABI overhead incurred by tag dispatch.
template<Mode mode, class PolicyHolder, class Float, class FloatTraits>
char* to_chars_n_impl(float_bits<Float, FloatTraits> br, char* buffer) noexcept
{
auto const exponent_bits = br.extract_exponent_bits();
auto const s = br.remove_exponent_bits(exponent_bits);
if (br.is_finite(exponent_bits)) {
if (s.is_negative() && br.is_nonzero()) {
*buffer = '-';
++buffer;
}
if (br.is_nonzero()) {
auto result = to_decimal<Float, FloatTraits>(s,
exponent_bits,
policy::sign::ignore,
policy::trailing_zero::ignore,
typename PolicyHolder::decimal_to_binary_rounding_policy { },
typename PolicyHolder::binary_to_decimal_rounding_policy { },
typename PolicyHolder::cache_policy { });
switch (mode) {
case Mode::ToShortest:
return to_shortest(result.significand, result.exponent, buffer);
case Mode::ToExponential:
return to_chars_impl<Float, FloatTraits, Mode::ToExponential, PrintTrailingZero::No>(result.significand, result.exponent, buffer);
default:
return nullptr;
}
} else {
switch (mode) {
case Mode::ToShortest:
*buffer++ = '0';
return buffer;
case Mode::ToExponential:
memcpy(buffer, "0e+0", 4);
return buffer + 4;
default:
return nullptr;
}
}
} else {
if (s.has_all_zero_significand_bits()) {
if (s.is_negative()) {
*buffer = '-';
++buffer;
}
memcpy(buffer, "Infinity", 8);
return buffer + 8;
}
memcpy(buffer, "NaN", 3);
return buffer + 3;
}
}
// Returns the next-to-end position
template<Mode mode, class Float, class FloatTraits = default_float_traits<Float>, class... Policies>
char* to_chars_n(Float x, char* buffer, Policies... policies) noexcept
{
// using namespace detail::policy_impl;
using policy_holder = decltype(make_policy_holder(
policy_impl::base_default_pair_list<policy_impl::base_default_pair<policy_impl::decimal_to_binary_rounding::base, policy_impl::decimal_to_binary_rounding::nearest_to_even>,
policy_impl::base_default_pair<policy_impl::binary_to_decimal_rounding::base, policy_impl::binary_to_decimal_rounding::to_even>,
policy_impl::base_default_pair<policy_impl::cache::base, policy_impl::cache::full>> { },
policies...));
return to_chars_n_impl<mode, policy_holder>(float_bits<Float, FloatTraits>(x), buffer);
}
// Null-terminate and bypass the return value of fp_to_chars_n
template<Mode mode, class Float, class FloatTraits = default_float_traits<Float>, class... Policies>
char* to_chars(Float x, char* buffer, Policies... policies) noexcept
{
auto ptr = to_chars_n<mode, Float, FloatTraits>(x, buffer, policies...);
*ptr = '\0';
return ptr;
}
} // namespace detail
typedef WTF::double_conversion::StringBuilder StringBuilder;
// See `ToExponential` in double-conversion.h for detailed definitons.
template<class Float>
void ToExponential(Float value, StringBuilder* result_builder)
{
static_assert(std::is_same_v<Float, double> || std::is_same_v<Float, float>);
constexpr size_t buffer_length = 1 + (std::is_same<Float, float>::value ? to_exponential_max_string_length<ieee754_binary32>() : to_exponential_max_string_length<ieee754_binary64>());
char buffer[buffer_length];
auto* cursor = detail::to_chars_n<Mode::ToExponential>(value, buffer);
result_builder->AddSubstring(buffer, cursor - buffer);
}
// See `ToShortest` in double-conversion.h for detailed definitons.
template<class Float>
void ToShortest(Float value, StringBuilder* result_builder)
{
static_assert(std::is_same_v<Float, double> || std::is_same_v<Float, float>);
constexpr size_t buffer_length = 1 + (std::is_same<Float, float>::value ? max_string_length<ieee754_binary32>() : max_string_length<ieee754_binary64>());
char buffer[buffer_length];
auto* cursor = detail::to_chars_n<Mode::ToShortest>(value, buffer);
result_builder->AddSubstring(buffer, cursor - buffer);
}
} // namespace dragonbox
} // namespace WTF
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
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