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/*
* Copyright (C) 2003-2024 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#include "config.h"
#include <wtf/dtoa.h>
#include <wtf/dragonbox/dragonbox_to_chars.h>
namespace WTF {
NumberToStringSpan numberToStringAndSize(float number, NumberToStringBuffer& buffer)
{
static_assert(sizeof(buffer) >= (dragonbox::max_string_length<dragonbox::ieee754_binary32>() + 1));
auto* result = dragonbox::detail::to_chars_n<WTF::dragonbox::Mode::ToShortest>(number, buffer.data());
return std::span { buffer }.first(result - buffer.data());
}
NumberToStringSpan numberToStringAndSize(double number, NumberToStringBuffer& buffer)
{
static_assert(sizeof(buffer) >= (dragonbox::max_string_length<dragonbox::ieee754_binary64>() + 1));
auto* result = dragonbox::detail::to_chars_n<WTF::dragonbox::Mode::ToShortest>(number, buffer.data());
return std::span { buffer }.first(result - buffer.data());
}
NumberToStringSpan numberToStringWithTrailingPoint(double d, NumberToStringBuffer& buffer)
{
double_conversion::StringBuilder builder(std::span<char> { buffer });
auto& converter = double_conversion::DoubleToStringConverter::EcmaScriptConverterWithTrailingPoint();
converter.ToShortest(d, &builder);
return builder.Finalize();
}
static inline void truncateTrailingZeros(std::span<const char> buffer, double_conversion::StringBuilder& builder)
{
size_t length = builder.position();
size_t decimalPointPosition = 0;
for (; decimalPointPosition < length; ++decimalPointPosition) {
if (buffer[decimalPointPosition] == '.')
break;
}
// No decimal separator found, early exit.
if (decimalPointPosition == length)
return;
size_t pastMantissa = decimalPointPosition + 1;
for (; pastMantissa < length; ++pastMantissa) {
if (buffer[pastMantissa] == 'e')
break;
}
size_t truncatedLength = pastMantissa;
for (; truncatedLength > decimalPointPosition + 1; --truncatedLength) {
if (buffer[truncatedLength - 1] != '0')
break;
}
// No trailing zeros found to strip.
if (truncatedLength == pastMantissa)
return;
// If we removed all trailing zeros, remove the decimal point as well.
if (truncatedLength == decimalPointPosition + 1)
truncatedLength = decimalPointPosition;
// Truncate the mantissa, and return the final result.
builder.RemoveCharacters(truncatedLength, pastMantissa);
}
NumberToStringSpan numberToFixedPrecisionString(float number, unsigned significantFigures, NumberToStringBuffer& buffer, bool shouldTruncateTrailingZeros)
{
// For now, just call the double precision version.
// Do that here instead of at callers to pave the way to add a more efficient code path later.
return numberToFixedPrecisionString(static_cast<double>(number), significantFigures, buffer, shouldTruncateTrailingZeros);
}
NumberToStringSpan numberToFixedPrecisionString(double d, unsigned significantFigures, NumberToStringBuffer& buffer, bool shouldTruncateTrailingZeros)
{
// Mimic sprintf("%.[precision]g", ...).
// "g": Signed value printed in f or e format, whichever is more compact for the given value and precision.
// The e format is used only when the exponent of the value is less than –4 or greater than or equal to the
// precision argument. Trailing zeros are truncated, and the decimal point appears only if one or more digits follow it.
// "precision": The precision specifies the maximum number of significant digits printed.
double_conversion::StringBuilder builder(std::span<char> { buffer });
auto& converter = double_conversion::DoubleToStringConverter::EcmaScriptConverter();
converter.ToPrecision(d, significantFigures, &builder);
if (shouldTruncateTrailingZeros)
truncateTrailingZeros(std::span<const char> { buffer }, builder);
return builder.Finalize();
}
NumberToStringSpan numberToFixedWidthString(float number, unsigned decimalPlaces, NumberToStringBuffer& buffer)
{
// For now, just call the double precision version.
// Do that here instead of at callers to pave the way to add a more efficient code path later.
return numberToFixedWidthString(static_cast<double>(number), decimalPlaces, buffer);
}
NumberToStringSpan numberToFixedWidthString(double d, unsigned decimalPlaces, NumberToStringBuffer& buffer)
{
// Mimic sprintf("%.[precision]f", ...).
// "f": Signed value having the form [ – ]dddd.dddd, where dddd is one or more decimal digits.
// The number of digits before the decimal point depends on the magnitude of the number, and
// the number of digits after the decimal point depends on the requested precision.
// "precision": The precision value specifies the number of digits after the decimal point.
// If a decimal point appears, at least one digit appears before it.
// The value is rounded to the appropriate number of digits.
double_conversion::StringBuilder builder(std::span<char> { buffer });
auto& converter = double_conversion::DoubleToStringConverter::EcmaScriptConverter();
converter.ToFixed(d, decimalPlaces, &builder);
return builder.Finalize();
}
NumberToStringSpan numberToCSSString(double d, NumberToCSSStringBuffer& buffer)
{
// Mimic sprintf("%.[precision]f", ...).
// "f": Signed value having the form [ – ]dddd.dddd, where dddd is one or more decimal digits.
// The number of digits before the decimal point depends on the magnitude of the number, and
// the number of digits after the decimal point depends on the requested precision.
// "precision": The precision value specifies the number of digits after the decimal point.
// If a decimal point appears, at least one digit appears before it.
// The value is rounded to the appropriate number of digits.
double_conversion::StringBuilder builder(std::span<char> { buffer });
auto& converter = double_conversion::DoubleToStringConverter::CSSConverter();
converter.ToFixedUncapped(d, 6, &builder);
truncateTrailingZeros(std::span<const char> { buffer }, builder);
// If we've truncated the trailing zeros and a trailing decimal, we may have a -0. Remove the negative sign in this case.
if (builder.position() == 2 && buffer[0] == '-' && buffer[1] == '0')
builder.RemoveCharacters(0, 1);
return builder.Finalize();
}
} // namespace WTF
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