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Get rid of float_writer

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This commit is contained in:
Victor Zverovich 2020-10-04 16:17:45 -07:00 committed by Victor Zverovich
parent b4b64b9cce
commit b91d39f20b
1 changed files with 87 additions and 107 deletions
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194
include/fmt/format.h
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@ -1310,109 +1310,6 @@ template <typename Char, typename It> It write_exponent(int exp, It it) {
return it;
}
template <typename OutputIt, typename Char>
OutputIt write_float(OutputIt it, const buffer<char>& significand, int exp,
float_specs specs, Char decimal_point) {
const char* digits = significand.data();
int num_digits = static_cast<int>(significand.size());
int full_exp = exp + num_digits;
auto format = specs.format;
if (format == float_format::general &&
!(full_exp >= -3 &&
full_exp < (specs.precision > 0 ? specs.precision : 16) + 1)) {
format = float_format::exp;
}
const Char zero = static_cast<Char>('0');
if (format == float_format::exp) {
// Insert a decimal point after the first digit and add an exponent.
*it++ = static_cast<Char>(*digits);
int num_zeros = specs.precision - num_digits;
if (num_digits > 1 || specs.showpoint) *it++ = decimal_point;
it = copy_str<Char>(digits + 1, digits + num_digits, it);
if (num_zeros > 0 && specs.showpoint) it = std::fill_n(it, num_zeros, zero);
*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, zero);
if (specs.showpoint) {
*it++ = decimal_point;
int num_zeros = specs.precision - full_exp;
if (num_zeros <= 0) {
if (format != float_format::fixed) *it++ = zero;
return it;
}
#ifdef FMT_FUZZ
if (num_zeros > 5000)
throw std::runtime_error("fuzz mode - avoiding excessive cpu use");
#endif
it = std::fill_n(it, num_zeros, zero);
}
} else if (full_exp > 0) {
// 1234e-2 -> 12.34[0+]
it = copy_str<Char>(digits, digits + full_exp, it);
if (!specs.showpoint) {
if (num_digits != full_exp) *it++ = decimal_point;
return copy_str<Char>(digits + full_exp, digits + num_digits, it);
}
*it++ = decimal_point;
it = copy_str<Char>(digits + full_exp, digits + num_digits, it);
if (specs.precision > num_digits) {
// Add trailing zeros.
int num_zeros = specs.precision - num_digits;
it = std::fill_n(it, num_zeros, zero);
}
} else {
// 1234e-6 -> 0.001234
*it++ = zero;
int num_zeros = -full_exp;
if (num_digits == 0 && specs.precision >= 0 &&
specs.precision < num_zeros) {
num_zeros = specs.precision;
}
if (num_zeros != 0 || num_digits != 0 || specs.showpoint) {
*it++ = decimal_point;
it = std::fill_n(it, num_zeros, zero);
it = copy_str<Char>(digits, digits + num_digits, it);
}
}
return it;
}
template <typename Char> class float_writer {
private:
// The number is given as v = significand_ * pow(10, exp_).
const buffer<char>& significand_;
int exp_;
size_t size_;
float_specs specs_;
Char decimal_point_;
template <typename It> It prettify(It it) const {
return write_float(it, significand_, exp_, specs_, decimal_point_);
}
public:
float_writer(const buffer<char>& significand, int exp, float_specs specs,
Char decimal_point)
: significand_(significand),
exp_(exp),
specs_(specs),
decimal_point_(decimal_point) {
size_ = prettify(counting_iterator()).count();
size_ += specs.sign ? 1 : 0;
}
size_t size() const { return size_; }
template <typename It> It operator()(It it) const {
if (specs_.sign) *it++ = static_cast<Char>(data::signs[specs_.sign]);
return prettify(it);
}
};
template <typename T>
int format_float(T value, int precision, float_specs specs, buffer<char>& buf);
@ -1827,6 +1724,90 @@ OutputIt write_nonfinite(OutputIt out, bool isinf,
});
}
template <typename OutputIt, typename Char>
OutputIt write_float(OutputIt out, const buffer<char>& significand, int exp,
float_specs specs, Char decimal_point) {
const char* digits = significand.data();
int num_digits = static_cast<int>(significand.size());
int full_exp = exp + num_digits;
auto format = specs.format;
if (format == float_format::general &&
!(full_exp >= -3 &&
full_exp < (specs.precision > 0 ? specs.precision : 16) + 1)) {
format = float_format::exp;
}
const Char zero = static_cast<Char>('0');
if (format == float_format::exp) {
// Insert a decimal point after the first digit and add an exponent.
*out++ = static_cast<Char>(*digits);
int num_zeros = specs.precision - num_digits;
if (num_digits > 1 || specs.showpoint) *out++ = decimal_point;
out = copy_str<Char>(digits + 1, digits + num_digits, out);
if (num_zeros > 0 && specs.showpoint)
out = std::fill_n(out, num_zeros, zero);
*out++ = static_cast<Char>(specs.upper ? 'E' : 'e');
return write_exponent<Char>(full_exp - 1, out);
}
if (num_digits <= full_exp) {
// 1234e7 -> 12340000000[.0+]
out = copy_str<Char>(digits, digits + num_digits, out);
out = std::fill_n(out, full_exp - num_digits, zero);
if (specs.showpoint) {
*out++ = decimal_point;
int num_zeros = specs.precision - full_exp;
if (num_zeros <= 0) {
if (format != float_format::fixed) *out++ = zero;
return out;
}
#ifdef FMT_FUZZ
if (num_zeros > 5000)
throw std::runtime_error("fuzz mode - avoiding excessive cpu use");
#endif
out = std::fill_n(out, num_zeros, zero);
}
} else if (full_exp > 0) {
// 1234e-2 -> 12.34[0+]
out = copy_str<Char>(digits, digits + full_exp, out);
if (!specs.showpoint) {
if (num_digits != full_exp) *out++ = decimal_point;
return copy_str<Char>(digits + full_exp, digits + num_digits, out);
}
*out++ = decimal_point;
out = copy_str<Char>(digits + full_exp, digits + num_digits, out);
// Add trailing zeros.
if (specs.precision > num_digits)
out = std::fill_n(out, specs.precision - num_digits, zero);
} else {
// 1234e-6 -> 0.001234
*out++ = zero;
int num_zeros = -full_exp;
if (num_digits == 0 && specs.precision >= 0 && specs.precision < num_zeros)
num_zeros = specs.precision;
if (num_zeros != 0 || num_digits != 0 || specs.showpoint) {
*out++ = decimal_point;
out = std::fill_n(out, num_zeros, zero);
out = copy_str<Char>(digits, digits + num_digits, out);
}
}
return out;
}
// The number is given as v = significand * pow(10, exp).
template <typename OutputIt, typename Char>
OutputIt write_float(OutputIt out, const buffer<char>& significand, int exp,
const basic_format_specs<Char>& specs, float_specs fspecs,
Char decimal_point) {
auto size =
write_float(counting_iterator(), significand, exp, fspecs, decimal_point)
.count();
size += fspecs.sign ? 1 : 0;
using iterator = remove_reference_t<decltype(reserve(out, 0))>;
return write_padded<align::right>(out, specs, size, [&](iterator it) {
if (fspecs.sign) *it++ = static_cast<Char>(data::signs[fspecs.sign]);
return write_float(it, significand, exp, fspecs, decimal_point);
});
}
template <typename Char, typename OutputIt, typename T,
FMT_ENABLE_IF(std::is_floating_point<T>::value)>
OutputIt write(OutputIt out, T value, basic_format_specs<Char> specs,
@ -1871,8 +1852,7 @@ OutputIt write(OutputIt out, T value, basic_format_specs<Char> specs,
fspecs.precision = precision;
Char point =
fspecs.locale ? decimal_point<Char>(loc) : static_cast<Char>('.');
float_writer<Char> w(buffer, exp, fspecs, point);
return write_padded<align::right>(out, specs, w.size(), w);
return write_float(out, buffer, exp, specs, fspecs, point);
}
template <
@ -1894,8 +1874,8 @@ OutputIt write(OutputIt out, T value) {
auto dec = dragonbox::to_decimal(static_cast<type>(value));
memory_buffer buf;
write<char>(buffer_appender<char>(buf), dec.significand);
float_writer<Char> w(buf, dec.exponent, fspecs, static_cast<Char>('.'));
return base_iterator(out, w(reserve(out, w.size())));
return write_float(out, buf, dec.exponent, specs, fspecs,
static_cast<Char>('.'));
}
template <typename Char, typename OutputIt, typename T,