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AK: Add formatters for floating point numbers.

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asynts 2020-11-09 11:34:44 +01:00 • committed by Andreas Kling
parent 3b3edbc4d2
commit 32957745fb
3 changed files with 132 additions and 1 deletions
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73
AK/Format.cpp
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@ -384,6 +384,44 @@ void FormatBuilder::put_i64(
put_u64(static_cast<size_t>(value), base, prefix, upper_case, zero_pad, align, min_width, fill, sign_mode, is_negative);
}
#ifndef KERNEL
void FormatBuilder::put_f64(
double value,
u8 base,
bool upper_case,
Align align,
size_t min_width,
size_t precision,
char fill,
SignMode sign_mode)
{
StringBuilder string_builder;
FormatBuilder format_builder { string_builder };
format_builder.put_i64(static_cast<i64>(value), base, false, upper_case, false, Align::Right, 0, ' ', sign_mode);
string_builder.append('.');
if (precision > 0) {
// FIXME: This is a terrible approximation but doing it properly would be a lot of work. If someone is up for that, a good
// place to start would be the following video from CppCon 2019:
// https://youtu.be/4P_kbF0EbZM (Stephan T. Lavavej “Floating-Point <charconv>: Making Your Code 10x Faster With C++17's Final Boss”)
value -= static_cast<i64>(value);
if (value < 0)
value = -value;
for (u32 i = 0; i < precision; ++i)
value *= 10;
format_builder.put_u64(static_cast<u64>(value), base, false, upper_case, true, Align::Right, precision);
// FIXME: Cut off trailing zeroes by default?
}
put_string(string_builder.string_view(), align, min_width, NumericLimits<size_t>::max(), fill);
}
#endif
void vformat(StringBuilder& builder, StringView fmtstr, TypeErasedFormatParams params)
{
FormatBuilder fmtbuilder { builder };
@ -463,6 +501,12 @@ void StandardFormatter::parse(TypeErasedFormatParams& params, FormatParser& pars
m_mode = Mode::String;
else if (parser.consume_specific('p'))
m_mode = Mode::Pointer;
else if (parser.consume_specific('f'))
m_mode = Mode::Float;
else if (parser.consume_specific('a'))
m_mode = Mode::Hexfloat;
else if (parser.consume_specific('A'))
m_mode = Mode::HexfloatUppercase;
if (!parser.is_eof())
dbgln("{} did not consume '{}'", __PRETTY_FUNCTION__, parser.remaining());
@ -570,6 +614,35 @@ void Formatter<bool>::format(TypeErasedFormatParams& params, FormatBuilder& buil
return formatter.format(params, builder, value ? "true" : "false");
}
}
#ifndef KERNEL
void Formatter<double>::format(TypeErasedFormatParams& params, FormatBuilder& builder, double value)
{
u8 base;
bool upper_case;
if (m_mode == Mode::Default || m_mode == Mode::Float) {
base = 10;
upper_case = false;
} else if (m_mode == Mode::Hexfloat) {
base = 16;
upper_case = false;
} else if (m_mode == Mode::HexfloatUppercase) {
base = 16;
upper_case = true;
} else {
ASSERT_NOT_REACHED();
}
const auto width = params.decode(m_width);
const auto precision = params.decode(m_precision, 6);
builder.put_f64(value, base, upper_case, m_align, width, precision, m_fill, m_sign_mode);
}
void Formatter<float>::format(TypeErasedFormatParams& params, FormatBuilder& builder, float value)
{
Formatter<double> formatter { *this };
formatter.format(params, builder, value);
}
#endif
#ifndef KERNEL
void vout(FILE* file, StringView fmtstr, TypeErasedFormatParams params, bool newline)