Skip to content

Commit

Permalink
Move snprintf_float to format.h
Browse files Browse the repository at this point in the history
  • Loading branch information
@vitaut
vitaut committed Mar 18, 2022
1 parent 0419d23 commit c076a54
Show file tree
Hide file tree
Showing 3 changed files with 118 additions and 131 deletions.
128 changes: 11 additions & 117 deletions include/fmt/format-inl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,19 +44,6 @@ FMT_FUNC void throw_format_error(const char* message) {
FMT_THROW(format_error(message));
}

#ifndef _MSC_VER
# define FMT_SNPRINTF snprintf
#else // _MSC_VER
inline int fmt_snprintf(char* buffer, size_t size, const char* format, ...) {
va_list args;
va_start(args, format);
int result = vsnprintf_s(buffer, size, _TRUNCATE, format, args);
va_end(args);
return result;
}
# define FMT_SNPRINTF fmt_snprintf
#endif // _MSC_VER

FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
string_view message) noexcept {
// Report error code making sure that the output fits into
Expand Down Expand Up @@ -2174,6 +2161,17 @@ FMT_CONSTEXPR20 inline void format_dragon(fp value, bool is_predecessor_closer,
buf[num_digits - 1] = static_cast<char>('0' + digit);
}

#ifdef _MSC_VER
FMT_FUNC auto fmt_snprintf(char* buf, size_t size, const char* fmt, ...)
-> int {
auto args = va_list();
va_start(args, fmt);
int result = vsnprintf_s(buf, size, _TRUNCATE, fmt, args);
va_end(args);
return result;
}
#endif

template <typename Float>
FMT_HEADER_ONLY_CONSTEXPR20 int format_float(Float value, int precision,
float_specs specs,
Expand Down Expand Up @@ -2251,110 +2249,6 @@ FMT_HEADER_ONLY_CONSTEXPR20 int format_float(Float value, int precision,
}
return exp;
}

template <typename T>
int snprintf_float(T value, int precision, float_specs specs,
buffer<char>& buf) {
// Buffer capacity must be non-zero, otherwise MSVC's vsnprintf_s will fail.
FMT_ASSERT(buf.capacity() > buf.size(), "empty buffer");
static_assert(!std::is_same<T, float>::value, "");

// Subtract 1 to account for the difference in precision since we use %e for
// both general and exponent format.
if (specs.format == float_format::general ||
specs.format == float_format::exp)
precision = (precision >= 0 ? precision : 6) - 1;

// Build the format string.
enum { max_format_size = 7 }; // The longest format is "%#.*Le".
char format[max_format_size];
char* format_ptr = format;
*format_ptr++ = '%';
if (specs.showpoint && specs.format == float_format::hex) *format_ptr++ = '#';
if (precision >= 0) {
*format_ptr++ = '.';
*format_ptr++ = '*';
}
if (std::is_same<T, long double>()) *format_ptr++ = 'L';
*format_ptr++ = specs.format != float_format::hex
? (specs.format == float_format::fixed ? 'f' : 'e')
: (specs.upper ? 'A' : 'a');
*format_ptr = '\0';

// Format using snprintf.
auto offset = buf.size();
for (;;) {
auto begin = buf.data() + offset;
auto capacity = buf.capacity() - offset;
#ifdef FMT_FUZZ
if (precision > 100000)
throw std::runtime_error(
"fuzz mode - avoid large allocation inside snprintf");
#endif
// Suppress the warning about a nonliteral format string.
// Cannot use auto because of a bug in MinGW (#1532).
int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
int result = precision >= 0
? snprintf_ptr(begin, capacity, format, precision, value)
: snprintf_ptr(begin, capacity, format, value);
if (result < 0) {
// The buffer will grow exponentially.
buf.try_reserve(buf.capacity() + 1);
continue;
}
auto size = to_unsigned(result);
// Size equal to capacity means that the last character was truncated.
if (size >= capacity) {
buf.try_reserve(size + offset + 1); // Add 1 for the terminating '\0'.
continue;
}
auto is_digit = [](char c) { return c >= '0' && c <= '9'; };
if (specs.format == float_format::fixed) {
if (precision == 0) {
buf.try_resize(size);
return 0;
}
// Find and remove the decimal point.
auto end = begin + size, p = end;
do {
--p;
} while (is_digit(*p));
int fraction_size = static_cast<int>(end - p - 1);
std::memmove(p, p + 1, to_unsigned(fraction_size));
buf.try_resize(size - 1);
return -fraction_size;
}
if (specs.format == float_format::hex) {
buf.try_resize(size + offset);
return 0;
}
// Find and parse the exponent.
auto end = begin + size, exp_pos = end;
do {
--exp_pos;
} while (*exp_pos != 'e');
char sign = exp_pos[1];
FMT_ASSERT(sign == '+' || sign == '-', "");
int exp = 0;
auto p = exp_pos + 2; // Skip 'e' and sign.
do {
FMT_ASSERT(is_digit(*p), "");
exp = exp * 10 + (*p++ - '0');
} while (p != end);
if (sign == '-') exp = -exp;
int fraction_size = 0;
if (exp_pos != begin + 1) {
// Remove trailing zeros.
auto fraction_end = exp_pos - 1;
while (*fraction_end == '0') --fraction_end;
// Move the fractional part left to get rid of the decimal point.
fraction_size = static_cast<int>(fraction_end - begin - 1);
std::memmove(begin + 1, begin + 2, to_unsigned(fraction_size));
}
buf.try_resize(to_unsigned(fraction_size) + offset + 1);
return exp - fraction_size;
}
}
} // namespace detail

template <> struct formatter<detail::bigint> {
Expand Down
116 changes: 107 additions & 9 deletions include/fmt/format.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1325,10 +1325,116 @@ FMT_HEADER_ONLY_CONSTEXPR20 auto format_float(T value, int precision,
float_specs specs,
buffer<char>& buf) -> int;

#ifndef _MSC_VER
# define FMT_SNPRINTF snprintf
#else
FMT_API auto fmt_snprintf(char* buf, size_t size, const char* fmt, ...) -> int;
# define FMT_SNPRINTF fmt_snprintf
#endif // _MSC_VER

// Formats a floating-point number with snprintf.
template <typename T>
auto snprintf_float(T value, int precision, float_specs specs,
buffer<char>& buf) -> int;
buffer<char>& buf) -> int {
// Buffer capacity must be non-zero, otherwise MSVC's vsnprintf_s will fail.
FMT_ASSERT(buf.capacity() > buf.size(), "empty buffer");
static_assert(!std::is_same<T, float>::value, "");

// Subtract 1 to account for the difference in precision since we use %e for
// both general and exponent format.
if (specs.format == float_format::general ||
specs.format == float_format::exp) {
precision = (precision >= 0 ? precision : 6) - 1;
}

// Build the format string.
char format[7]; // The longest format is "%#.*Le".
char* format_ptr = format;
*format_ptr++ = '%';
if (specs.showpoint && specs.format == float_format::hex) *format_ptr++ = '#';
if (precision >= 0) {
*format_ptr++ = '.';
*format_ptr++ = '*';
}
if (std::is_same<T, long double>()) *format_ptr++ = 'L';
*format_ptr++ = specs.format != float_format::hex
? (specs.format == float_format::fixed ? 'f' : 'e')
: (specs.upper ? 'A' : 'a');
*format_ptr = '\0';

// Format using snprintf.
auto offset = buf.size();
for (;;) {
auto begin = buf.data() + offset;
auto capacity = buf.capacity() - offset;
#ifdef FMT_FUZZ
if (precision > 100000)
throw std::runtime_error("fuzz mode: avoid large allocation in snprintf");
#endif
// Suppress the warning about a nonliteral format string.
// Cannot use auto because of a bug in MinGW (#1532).
int (*snprintf_ptr)(char*, size_t, const char*, ...) = FMT_SNPRINTF;
int result = precision >= 0
? snprintf_ptr(begin, capacity, format, precision, value)
: snprintf_ptr(begin, capacity, format, value);
if (result < 0) {
// The buffer will grow exponentially.
buf.try_reserve(buf.capacity() + 1);
continue;
}
auto size = to_unsigned(result);
// Size equal to capacity means that the last character was truncated.
if (size >= capacity) {
buf.try_reserve(size + offset + 1); // Add 1 for the terminating '\0'.
continue;
}
auto is_digit = [](char c) { return c >= '0' && c <= '9'; };
if (specs.format == float_format::fixed) {
if (precision == 0) {
buf.try_resize(size);
return 0;
}
// Find and remove the decimal point.
auto end = begin + size, p = end;
do {
--p;
} while (is_digit(*p));
int fraction_size = static_cast<int>(end - p - 1);
std::memmove(p, p + 1, to_unsigned(fraction_size));
buf.try_resize(size - 1);
return -fraction_size;
}
if (specs.format == float_format::hex) {
buf.try_resize(size + offset);
return 0;
}
// Find and parse the exponent.
auto end = begin + size, exp_pos = end;
do {
--exp_pos;
} while (*exp_pos != 'e');
char sign = exp_pos[1];
FMT_ASSERT(sign == '+' || sign == '-', "");
int exp = 0;
auto p = exp_pos + 2; // Skip 'e' and sign.
do {
FMT_ASSERT(is_digit(*p), "");
exp = exp * 10 + (*p++ - '0');
} while (p != end);
if (sign == '-') exp = -exp;
int fraction_size = 0;
if (exp_pos != begin + 1) {
// Remove trailing zeros.
auto fraction_end = exp_pos - 1;
while (*fraction_end == '0') --fraction_end;
// Move the fractional part left to get rid of the decimal point.
fraction_size = static_cast<int>(fraction_end - begin - 1);
std::memmove(begin + 1, begin + 2, to_unsigned(fraction_size));
}
buf.try_resize(to_unsigned(fraction_size) + offset + 1);
return exp - fraction_size;
}
}

template <typename T>
using convert_float_result =
Expand Down Expand Up @@ -3203,14 +3309,6 @@ extern template auto format_float<double>(double value, int precision,
extern template auto format_float<long double>(long double value, int precision,
float_specs specs,
buffer<char>& buf) -> int;
void snprintf_float(float, int, float_specs, buffer<char>&) = delete;
extern template auto snprintf_float<double>(double value, int precision,
float_specs specs,
buffer<char>& buf) -> int;
extern template auto snprintf_float<long double>(long double value,
int precision,
float_specs specs,
buffer<char>& buf) -> int;
#endif // FMT_HEADER_ONLY

FMT_END_DETAIL_NAMESPACE
Expand Down
5 changes: 0 additions & 5 deletions src/format.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -100,11 +100,6 @@ template FMT_API void detail::vformat_to(
detail::buffer<char>&, string_view,
basic_format_args<FMT_BUFFER_CONTEXT(char)>, detail::locale_ref);

template FMT_API int detail::snprintf_float(double, int, detail::float_specs,
detail::buffer<char>&);
template FMT_API int detail::snprintf_float(long double, int,
detail::float_specs,
detail::buffer<char>&);
template FMT_API int detail::format_float(double, int, detail::float_specs,
detail::buffer<char>&);
template FMT_API int detail::format_float(long double, int, detail::float_specs,
Expand Down

0 comments on commit c076a54

Please sign in to comment.