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Refactor floating-point formatting

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This commit is contained in:
Victor Zverovich 2019-11-27 07:32:29 -08:00
parent c68703c9f4
commit c3be0f593d
3 changed files with 35 additions and 37 deletions
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2
include/fmt/format-inl.h
View File

@ -1128,7 +1128,7 @@ int snprintf_float(T value, int precision, float_specs specs,
char format[max_format_size];
char* format_ptr = format;
*format_ptr++ = '%';
if (specs.alt) *format_ptr++ = '#';
if (specs.trailing_zeros) *format_ptr++ = '#';
if (precision >= 0) {
*format_ptr++ = '.';
*format_ptr++ = '*';

68
include/fmt/format.h
View File

@ -1076,7 +1076,6 @@ struct float_specs {
bool upper : 1;
bool locale : 1;
bool percent : 1;
bool alt : 1;
bool binary32 : 1;
bool use_grisu : 1;
bool trailing_zeros : 1;
@ -1110,32 +1109,32 @@ template <typename Char> class float_writer {
int num_digits_;
int exp_;
size_t size_;
float_specs params_;
float_specs specs_;
Char decimal_point_;
template <typename It> It prettify(It it) const {
// pow(10, full_exp - 1) <= v <= pow(10, full_exp).
int full_exp = num_digits_ + exp_;
if (params_.format == float_format::exp) {
if (specs_.format == float_format::exp) {
// Insert a decimal point after the first digit and add an exponent.
*it++ = static_cast<Char>(*digits_);
if (num_digits_ > 1) *it++ = decimal_point_;
it = copy_str<Char>(digits_ + 1, digits_ + num_digits_, it);
int num_zeros = params_.precision - num_digits_;
if (num_zeros > 0 && params_.trailing_zeros)
int num_zeros = specs_.precision - num_digits_;
if (num_zeros > 0 && specs_.trailing_zeros)
it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
*it++ = static_cast<Char>(params_.upper ? 'E' : 'e');
*it++ = static_cast<Char>(specs_.upper ? 'E' : 'e');
return write_exponent<Char>(full_exp - 1, it);
}
if (num_digits_ <= full_exp) {
// 1234e7 -> 12340000000[.0+]
it = copy_str<Char>(digits_, digits_ + num_digits_, it);
it = std::fill_n(it, full_exp - num_digits_, static_cast<Char>('0'));
if (params_.trailing_zeros) {
if (specs_.trailing_zeros) {
*it++ = decimal_point_;
int num_zeros = params_.precision - full_exp;
int num_zeros = specs_.precision - full_exp;
if (num_zeros <= 0) {
if (params_.format != float_format::fixed)
if (specs_.format != float_format::fixed)
*it++ = static_cast<Char>('0');
return it;
}
@ -1148,7 +1147,7 @@ template <typename Char> class float_writer {
} else if (full_exp > 0) {
// 1234e-2 -> 12.34[0+]
it = copy_str<Char>(digits_, digits_ + full_exp, it);
if (!params_.trailing_zeros) {
if (!specs_.trailing_zeros) {
// Remove trailing zeros.
int num_digits = num_digits_;
while (num_digits > full_exp && digits_[num_digits - 1] == '0')
@ -1158,19 +1157,19 @@ template <typename Char> class float_writer {
}
*it++ = decimal_point_;
it = copy_str<Char>(digits_ + full_exp, digits_ + num_digits_, it);
if (params_.precision > num_digits_) {
if (specs_.precision > num_digits_) {
// Add trailing zeros.
int num_zeros = params_.precision - num_digits_;
int num_zeros = specs_.precision - num_digits_;
it = std::fill_n(it, num_zeros, static_cast<Char>('0'));
}
} else {
// 1234e-6 -> 0.001234
*it++ = static_cast<Char>('0');
int num_zeros = -full_exp;
if (params_.precision >= 0 && params_.precision < num_zeros)
num_zeros = params_.precision;
if (specs_.precision >= 0 && specs_.precision < num_zeros)
num_zeros = specs_.precision;
int num_digits = num_digits_;
if (!params_.trailing_zeros)
if (!specs_.trailing_zeros)
while (num_digits > 0 && digits_[num_digits - 1] == '0') --num_digits;
if (num_zeros != 0 || num_digits != 0) {
*it++ = decimal_point_;
@ -1187,13 +1186,13 @@ template <typename Char> class float_writer {
: digits_(digits),
num_digits_(num_digits),
exp_(exp),
params_(specs),
specs_(specs),
decimal_point_(decimal_point) {
int full_exp = num_digits + exp - 1;
int precision = specs.precision > 0 ? specs.precision : 16;
if (params_.format == float_format::general &&
if (specs_.format == float_format::general &&
!(full_exp >= -4 && full_exp < precision)) {
params_.format = float_format::exp;
specs_.format = float_format::exp;
}
size_ = prettify(counting_iterator()).count();
size_ += specs.sign ? 1 : 0;
@ -1203,7 +1202,7 @@ template <typename Char> class float_writer {
size_t width() const { return size(); }
template <typename It> void operator()(It&& it) {
if (params_.sign) *it++ = static_cast<Char>(data::signs[params_.sign]);
if (specs_.sign) *it++ = static_cast<Char>(data::signs[specs_.sign]);
it = prettify(it);
}
};
@ -1245,15 +1244,19 @@ FMT_CONSTEXPR void handle_int_type_spec(char spec, Handler&& handler) {
}
}
template <typename ErrorHandler = error_handler>
FMT_CONSTEXPR float_specs parse_float_type_spec(char spec,
ErrorHandler&& eh = {}) {
template <typename ErrorHandler = error_handler, typename Char>
FMT_CONSTEXPR float_specs parse_float_type_spec(
const basic_format_specs<Char>& specs, ErrorHandler&& eh = {}) {
auto result = float_specs();
switch (spec) {
result.trailing_zeros = specs.alt;
switch (specs.type) {
case 0:
result.format = float_format::general;
result.trailing_zeros |= specs.precision != 0;
break;
case 'G':
result.upper = true;
FMT_FALLTHROUGH;
case 0:
case 'g':
result.format = float_format::general;
break;
@ -1262,12 +1265,14 @@ FMT_CONSTEXPR float_specs parse_float_type_spec(char spec,
FMT_FALLTHROUGH;
case 'e':
result.format = float_format::exp;
result.trailing_zeros |= specs.precision != 0;
break;
case 'F':
result.upper = true;
FMT_FALLTHROUGH;
case 'f':
result.format = float_format::fixed;
result.trailing_zeros |= specs.precision != 0;
break;
#if FMT_DEPRECATED_PERCENT
case '%':
@ -1378,7 +1383,7 @@ void arg_map<Context>::init(const basic_format_args<Context>& args) {
}
}
template <typename Char> struct inf_or_nan_writer {
template <typename Char> struct nonfinite_writer {
sign_t sign;
const char* str;
static constexpr size_t str_size = 3;
@ -1691,7 +1696,7 @@ template <typename Range> class basic_writer {
template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
void write(T value, format_specs specs = {}) {
float_specs fspecs = parse_float_type_spec(specs.type);
float_specs fspecs = parse_float_type_spec(specs);
fspecs.sign = specs.sign;
if (std::signbit(value)) { // value < 0 is false for NaN so use signbit.
fspecs.sign = sign::minus;
@ -1703,8 +1708,7 @@ template <typename Range> class basic_writer {
if (!std::isfinite(value)) {
auto str = std::isinf(value) ? (fspecs.upper ? "INF" : "inf")
: (fspecs.upper ? "NAN" : "nan");
return write_padded(specs,
inf_or_nan_writer<char_type>{fspecs.sign, str});
return write_padded(specs, nonfinite_writer<char_type>{fspecs.sign, str});
}
if (specs.align == align::none) {
@ -1722,18 +1726,12 @@ template <typename Range> class basic_writer {
memory_buffer buffer;
if (fspecs.format == float_format::hex) {
if (fspecs.sign) buffer.push_back(data::signs[fspecs.sign]);
fspecs.alt = specs.alt;
snprintf_float(promote_float(value), specs.precision, fspecs, buffer);
write_padded(specs, str_writer<char>{buffer.data(), buffer.size()});
return;
}
int precision = specs.precision >= 0 || !specs.type ? specs.precision : 6;
if (fspecs.format == float_format::exp) ++precision;
fspecs.trailing_zeros =
(precision != 0 &&
(!specs.type || fspecs.format == float_format::fixed ||
fspecs.format == float_format::exp)) ||
specs.alt;
if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
fspecs.use_grisu = use_grisu<T>();
if (const_check(FMT_DEPRECATED_PERCENT) && fspecs.percent) value *= 100;
@ -2956,7 +2954,7 @@ struct formatter<T, Char,
case internal::float_type:
case internal::double_type:
case internal::long_double_type:
internal::parse_float_type_spec(specs_.type, eh);
internal::parse_float_type_spec(specs_, eh);
break;
case internal::cstring_type:
internal::handle_cstring_type_spec(

2
test/format
View File

@ -666,7 +666,7 @@ struct formatter {
break;
case internal::double_type:
case internal::long_double_type:
internal::parse_float_type_spec(type_spec, eh);
internal::parse_float_type_spec(specs_, eh);
break;
case internal::cstring_type:
internal::handle_cstring_type_spec(