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Implement locale-specific integer formatting

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This commit is contained in:
vitaut
2016-04-17 19:06:03 -07:00
parent 581afee039
commit f68771abe4
2 changed files with 62 additions and 7 deletions
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54
cppformat/format.h
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@@ -29,6 +29,7 @@
#define FMT_FORMAT_H_
#include <cassert>
#include <clocale>
#include <cmath>
#include <cstdio>
#include <cstring>
@@ -871,9 +872,38 @@ inline unsigned count_digits(uint32_t n) {
}
#endif
// A functor that doesn't add a thousands separator.
struct NoThousandsSep {
template <typename Char>
void operator()(Char *) {}
};
// A functor that adds a thousands separator.
class ThousandsSep {
private:
fmt::StringRef sep_;
// Index of a decimal digit with the least significant digit having index 0.
unsigned digit_index_;
public:
explicit ThousandsSep(fmt::StringRef sep) : sep_(sep), digit_index_(0) {}
template <typename Char>
void operator()(Char *&buffer) {
if (++digit_index_ % 3 != 0)
return;
buffer -= sep_.size();
std::uninitialized_copy(sep_.data(), sep_.data() + sep_.size(), buffer);
}
};
// Formats a decimal unsigned integer value writing into buffer.
template <typename UInt, typename Char>
inline void format_decimal(Char *buffer, UInt value, unsigned num_digits) {
// thousands_sep is a functor that is called after writing each char to
// add a thousands separator if necessary.
template <typename UInt, typename Char, typename ThousandsSep>
inline void format_decimal(Char *buffer, UInt value, unsigned num_digits,
ThousandsSep thousands_sep) {
buffer += num_digits;
while (value >= 100) {
// Integer division is slow so do it for a group of two digits instead
@@ -882,7 +912,9 @@ inline void format_decimal(Char *buffer, UInt value, unsigned num_digits) {
unsigned index = static_cast<unsigned>((value % 100) * 2);
value /= 100;
*--buffer = Data::DIGITS[index + 1];
thousands_sep(buffer);
*--buffer = Data::DIGITS[index];
thousands_sep(buffer);
}
if (value < 10) {
*--buffer = static_cast<char>('0' + value);
@@ -893,6 +925,11 @@ inline void format_decimal(Char *buffer, UInt value, unsigned num_digits) {
*--buffer = Data::DIGITS[index];
}
template <typename UInt, typename Char>
inline void format_decimal(Char *buffer, UInt value, unsigned num_digits) {
return format_decimal(buffer, value, num_digits, NoThousandsSep());
}
#ifndef _WIN32
# define FMT_USE_WINDOWS_H 0
#elif !defined(FMT_USE_WINDOWS_H)
@@ -2627,9 +2664,8 @@ void BasicWriter<Char>::write_int(T value, Spec spec) {
switch (spec.type()) {
case 0: case 'd': {
unsigned num_digits = internal::count_digits(abs_value);
CharPtr p = prepare_int_buffer(
num_digits, spec, prefix, prefix_size) + 1 - num_digits;
internal::format_decimal(get(p), abs_value, num_digits);
CharPtr p = prepare_int_buffer(num_digits, spec, prefix, prefix_size) + 1;
internal::format_decimal(get(p), abs_value, 0);
break;
}
case 'x': case 'X': {
@@ -2684,6 +2720,14 @@ void BasicWriter<Char>::write_int(T value, Spec spec) {
} while ((n >>= 3) != 0);
break;
}
case 'n': {
unsigned num_digits = internal::count_digits(abs_value);
fmt::StringRef sep = std::localeconv()->thousands_sep;
std::size_t size = num_digits + sep.size() * (num_digits - 1) / 3;
CharPtr p = prepare_int_buffer(size, spec, prefix, prefix_size) + 1;
internal::format_decimal(get(p), abs_value, 0, internal::ThousandsSep(sep));
break;
}
default:
internal::report_unknown_type(
spec.type(), spec.flag(CHAR_FLAG) ? "char" : "integer");