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Replacing strftime with std::time_put (#2550)

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* Fix unicode test

* Add xchar support to chrono formatter

* Replace strftime with std::time_put

* Add std::locale support to std::tm formatter

* Use predefined names and formats for C-locale

* Performance improvement

* Make locale-independent and C locale formats consistent among platforms
This commit is contained in:
Vladislav Shchapov
2021-10-30 20:25:45 +05:00
committed by GitHub
parent 90034e4c4b
commit 1031eedf27
4 changed files with 247 additions and 141 deletions
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295
include/fmt/chrono.h
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@@ -289,84 +289,95 @@ inline null<> localtime_s(...) { return null<>(); }
inline null<> gmtime_r(...) { return null<>(); }
inline null<> gmtime_s(...) { return null<>(); }
template <typename Char>
inline auto do_write(const std::tm& time, const std::locale& loc, char format,
char modifier) -> std::string {
auto&& os = std::ostringstream();
char modifier) -> std::basic_string<Char> {
auto&& os = std::basic_ostringstream<Char>();
os.imbue(loc);
using iterator = std::ostreambuf_iterator<char>;
const auto& facet = std::use_facet<std::time_put<char, iterator>>(loc);
auto end = facet.put(os, os, ' ', &time, format, modifier);
using iterator = std::ostreambuf_iterator<Char>;
const auto& facet = std::use_facet<std::time_put<Char, iterator>>(loc);
auto end = facet.put(os, os, Char(' '), &time, format, modifier);
if (end.failed()) FMT_THROW(format_error("failed to format time"));
auto str = os.str();
if (!detail::is_utf8() || loc == std::locale::classic()) return str;
return std::move(os).str();
}
template <typename Char, typename OutputIt,
FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
auto write(OutputIt out, const std::tm& time, const std::locale& loc,
char format, char modifier = 0) -> OutputIt {
auto str = do_write<Char>(time, loc, format, modifier);
return std::copy(str.begin(), str.end(), out);
}
template <typename Char, typename OutputIt,
FMT_ENABLE_IF(std::is_same<Char, char>::value)>
auto write(OutputIt out, const std::tm& time, const std::locale& loc,
char format, char modifier = 0) -> OutputIt {
auto str = do_write<char>(time, loc, format, modifier);
if (detail::is_utf8() && loc != std::locale::classic()) {
// char16_t and char32_t codecvts are broken in MSVC (linkage errors) and
// gcc-4.
#if FMT_MSC_VER != 0 || \
(defined(__GLIBCXX__) && !defined(_GLIBCXX_USE_DUAL_ABI))
// The _GLIBCXX_USE_DUAL_ABI macro is always defined in libstdc++ from gcc-5
// and newer.
using code_unit = wchar_t;
// The _GLIBCXX_USE_DUAL_ABI macro is always defined in libstdc++ from gcc-5
// and newer.
using code_unit = wchar_t;
#else
using code_unit = char32_t;
using code_unit = char32_t;
#endif
using codecvt = std::codecvt<code_unit, char, std::mbstate_t>;
using codecvt = std::codecvt<code_unit, char, std::mbstate_t>;
#if FMT_CLANG_VERSION
# pragma clang diagnostic push
# pragma clang diagnostic ignored "-Wdeprecated"
auto& f = std::use_facet<codecvt>(loc);
auto& f = std::use_facet<codecvt>(loc);
# pragma clang diagnostic pop
#else
auto& f = std::use_facet<codecvt>(loc);
auto& f = std::use_facet<codecvt>(loc);
#endif
auto mb = std::mbstate_t();
const char* from_next = nullptr;
code_unit* to_next = nullptr;
constexpr size_t buf_size = 32;
code_unit buf[buf_size] = {};
auto result = f.in(mb, str.data(), str.data() + str.size(), from_next, buf,
buf + buf_size, to_next);
if (result != std::codecvt_base::ok)
FMT_THROW(format_error("failed to format time"));
str.clear();
for (code_unit* p = buf; p != to_next; ++p) {
uint32_t c = static_cast<uint32_t>(*p);
if (sizeof(code_unit) == 2 && c >= 0xd800 && c <= 0xdfff) {
// surrogate pair
++p;
if (p == to_next || (c & 0xfc00) != 0xd800 || (*p & 0xfc00) != 0xdc00) {
auto mb = std::mbstate_t();
const char* from_next = nullptr;
code_unit* to_next = nullptr;
constexpr size_t buf_size = 32;
code_unit buf[buf_size] = {};
auto result = f.in(mb, str.data(), str.data() + str.size(), from_next, buf,
buf + buf_size, to_next);
if (result != std::codecvt_base::ok)
FMT_THROW(format_error("failed to format time"));
str.clear();
for (code_unit* p = buf; p != to_next; ++p) {
uint32_t c = static_cast<uint32_t>(*p);
if (sizeof(code_unit) == 2 && c >= 0xd800 && c <= 0xdfff) {
// surrogate pair
++p;
if (p == to_next || (c & 0xfc00) != 0xd800 || (*p & 0xfc00) != 0xdc00) {
FMT_THROW(format_error("failed to format time"));
}
c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
}
if (c < 0x80) {
str.push_back(static_cast<char>(c));
} else if (c < 0x800) {
str.push_back(static_cast<char>(0xc0 | (c >> 6)));
str.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else if ((c >= 0x800 && c <= 0xd7ff) || (c >= 0xe000 && c <= 0xffff)) {
str.push_back(static_cast<char>(0xe0 | (c >> 12)));
str.push_back(static_cast<char>(0x80 | ((c & 0xfff) >> 6)));
str.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else if (c >= 0x10000 && c <= 0x10ffff) {
str.push_back(static_cast<char>(0xf0 | (c >> 18)));
str.push_back(static_cast<char>(0x80 | ((c & 0x3ffff) >> 12)));
str.push_back(static_cast<char>(0x80 | ((c & 0xfff) >> 6)));
str.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else {
FMT_THROW(format_error("failed to format time"));
}
c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
}
if (c < 0x80) {
str.push_back(static_cast<char>(c));
} else if (c < 0x800) {
str.push_back(static_cast<char>(0xc0 | (c >> 6)));
str.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else if ((c >= 0x800 && c <= 0xd7ff) || (c >= 0xe000 && c <= 0xffff)) {
str.push_back(static_cast<char>(0xe0 | (c >> 12)));
str.push_back(static_cast<char>(0x80 | ((c & 0xfff) >> 6)));
str.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else if (c >= 0x10000 && c <= 0x10ffff) {
str.push_back(static_cast<char>(0xf0 | (c >> 18)));
str.push_back(static_cast<char>(0x80 | ((c & 0x3ffff) >> 12)));
str.push_back(static_cast<char>(0x80 | ((c & 0xfff) >> 6)));
str.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else {
FMT_THROW(format_error("failed to format time"));
}
}
return str;
}
template <typename OutputIt>
auto write(OutputIt out, const std::tm& time, const std::locale& loc,
char format, char modifier = 0) -> OutputIt {
auto str = do_write(time, loc, format, modifier);
return std::copy(str.begin(), str.end(), out);
}
} // namespace detail
FMT_MODULE_EXPORT_BEGIN
@@ -464,25 +475,6 @@ inline std::tm gmtime(
FMT_BEGIN_DETAIL_NAMESPACE
inline size_t strftime(char* str, size_t count, const char* format,
const std::tm* time) {
// Assign to a pointer to suppress GCCs -Wformat-nonliteral
// First assign the nullptr to suppress -Wsuggest-attribute=format
std::size_t (*strftime)(char*, std::size_t, const char*, const std::tm*) =
nullptr;
strftime = std::strftime;
return strftime(str, count, format, time);
}
inline size_t strftime(wchar_t* str, size_t count, const wchar_t* format,
const std::tm* time) {
// See above
std::size_t (*wcsftime)(wchar_t*, std::size_t, const wchar_t*,
const std::tm*) = nullptr;
wcsftime = std::wcsftime;
return wcsftime(str, count, format, time);
}
// Writes two-digit numbers a, b and c separated by sep to buf.
// The method by Pavel Novikov based on
// https://johnnylee-sde.github.io/Fast-unsigned-integer-to-time-string/.
@@ -1067,7 +1059,7 @@ struct chrono_formatter {
if (isnan(val)) return write_nan();
const auto& loc = localized ? context.locale().template get<std::locale>()
: std::locale::classic();
out = detail::write(out, time, loc, format, modifier);
out = detail::write<char_type>(out, time, loc, format, modifier);
}
void on_text(const char_type* begin, const char_type* end) {
@@ -1215,12 +1207,13 @@ class year_month_day {};
#endif
// A rudimentary weekday formatter.
template <> struct formatter<weekday> {
template <typename Char> struct formatter<weekday, Char> {
private:
bool localized = false;
public:
FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
-> decltype(ctx.begin()) {
auto begin = ctx.begin(), end = ctx.end();
if (begin != end && *begin == 'L') {
++begin;
@@ -1229,12 +1222,13 @@ template <> struct formatter<weekday> {
return begin;
}
auto format(weekday wd, format_context& ctx) -> decltype(ctx.out()) {
template <typename FormatContext>
auto format(weekday wd, FormatContext& ctx) const -> decltype(ctx.out()) {
auto time = std::tm();
time.tm_wday = static_cast<int>(wd.c_encoding());
const auto& loc = localized ? ctx.locale().template get<std::locale>()
: std::locale::classic();
return detail::write(ctx.out(), time, loc, 'a');
return detail::write<Char>(ctx.out(), time, loc, 'a');
}
};
@@ -1399,10 +1393,38 @@ struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
FMT_CONSTEXPR void on_tz_name() {}
};
inline const char* tm_wday_full_name(int wday) {
static constexpr const char* full_name_list[] = {
"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"};
return wday >= 0 && wday <= 6 ? full_name_list[wday] : "?";
}
inline const char* tm_wday_short_name(int wday) {
static constexpr const char* short_name_list[] = {"Sun", "Mon", "Tue", "Wed",
"Thu", "Fri", "Sat"};
return wday >= 0 && wday <= 6 ? short_name_list[wday] : "???";
}
inline const char* tm_mon_full_name(int mon) {
static constexpr const char* full_name_list[] = {
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"};
return mon >= 0 && mon <= 11 ? full_name_list[mon] : "?";
}
inline const char* tm_mon_short_name(int mon) {
static constexpr const char* short_name_list[] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
};
return mon >= 0 && mon <= 11 ? short_name_list[mon] : "???";
}
template <typename OutputIt, typename Char> class tm_writer {
private:
static constexpr int days_per_week = 7;
const std::locale& loc_;
const bool is_classic_;
OutputIt out_;
const std::tm& tm_;
@@ -1437,8 +1459,9 @@ template <typename OutputIt, typename Char> class tm_writer {
}
auto tm_hour12() const noexcept -> int {
auto hour = tm_hour() % 12;
return hour == 0 ? 12 : hour;
const auto h = tm_hour();
const auto z = h < 12 ? h : h - 12;
return z == 0 ? 12 : z;
}
// POSIX and the C Standard are unclear or inconsistent about what %C and %y
@@ -1514,34 +1537,15 @@ template <typename OutputIt, typename Char> class tm_writer {
}
void format_localized(char format, char modifier = 0) {
// By prepending an extra space we can distinguish an empty result that
// indicates insufficient buffer size from a guaranteed non-empty result
// https://github.com/fmtlib/fmt/issues/2238
Char tm_format[5] = {' ', '%', 'x', '\0', '\0'};
if (modifier) {
tm_format[2] = modifier;
tm_format[3] = format;
} else {
tm_format[2] = format;
}
basic_memory_buffer<Char> buf;
for (;;) {
size_t size = buf.capacity();
size_t count = detail::strftime(buf.data(), size, tm_format, &tm_);
if (count != 0) {
buf.resize(count);
break;
}
const size_t min_growth = 10;
buf.reserve(buf.capacity() + (size > min_growth ? size : min_growth));
}
// Remove the extra space.
out_ = copy_str<Char>(buf.begin() + 1, buf.end(), out_);
out_ = write<Char>(out_, tm_, loc_, format, modifier);
}
public:
explicit tm_writer(OutputIt out, const std::tm& tm) : out_(out), tm_(tm) {}
explicit tm_writer(const std::locale& loc, OutputIt out, const std::tm& tm)
: loc_(loc),
is_classic_(loc_ == std::locale::classic()),
out_(out),
tm_(tm) {}
OutputIt out() const { return out_; }
@@ -1549,8 +1553,18 @@ template <typename OutputIt, typename Char> class tm_writer {
out_ = copy_str<Char>(begin, end, out_);
}
void on_abbr_weekday() { format_localized('a'); }
void on_full_weekday() { format_localized('A'); }
void on_abbr_weekday() {
if (is_classic_)
out_ = write(out_, tm_wday_short_name(tm_wday()));
else
format_localized('a');
}
void on_full_weekday() {
if (is_classic_)
out_ = write(out_, tm_wday_full_name(tm_wday()));
else
format_localized('A');
}
void on_dec0_weekday(numeric_system ns) {
if (ns != numeric_system::standard) return format_localized('w', 'O');
write1(tm_wday());
@@ -1561,17 +1575,45 @@ template <typename OutputIt, typename Char> class tm_writer {
write1(wday == 0 ? days_per_week : wday);
}
void on_abbr_month() { format_localized('b'); }
void on_full_month() { format_localized('B'); }
void on_abbr_month() {
if (is_classic_)
out_ = write(out_, tm_mon_short_name(tm_mon()));
else
format_localized('b');
}
void on_full_month() {
if (is_classic_)
out_ = write(out_, tm_mon_full_name(tm_mon()));
else
format_localized('B');
}
void on_datetime(numeric_system ns) {
format_localized('c', ns == numeric_system::standard ? '\0' : 'E');
if (is_classic_) {
on_abbr_weekday();
*out_++ = ' ';
on_abbr_month();
*out_++ = ' ';
on_day_of_month_space(numeric_system::standard);
*out_++ = ' ';
on_iso_time();
*out_++ = ' ';
on_year(numeric_system::standard);
} else {
format_localized('c', ns == numeric_system::standard ? '\0' : 'E');
}
}
void on_loc_date(numeric_system ns) {
format_localized('x', ns == numeric_system::standard ? '\0' : 'E');
if (is_classic_)
on_us_date();
else
format_localized('x', ns == numeric_system::standard ? '\0' : 'E');
}
void on_loc_time(numeric_system ns) {
format_localized('X', ns == numeric_system::standard ? '\0' : 'E');
if (is_classic_)
on_iso_time();
else
format_localized('X', ns == numeric_system::standard ? '\0' : 'E');
}
void on_us_date() {
char buf[8];
@@ -1685,7 +1727,18 @@ template <typename OutputIt, typename Char> class tm_writer {
write2(tm_sec());
}
void on_12_hour_time() { format_localized('r'); }
void on_12_hour_time() {
if (is_classic_) {
char buf[8];
write_digit2_separated(buf, to_unsigned(tm_hour12()),
to_unsigned(tm_min()), to_unsigned(tm_sec()), ':');
out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
*out_++ = ' ';
on_am_pm();
} else {
format_localized('r');
}
}
void on_24_hour_time() {
write2(tm_hour());
*out_++ = ':';
@@ -1698,7 +1751,14 @@ template <typename OutputIt, typename Char> class tm_writer {
out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
}
void on_am_pm() { format_localized('p'); }
void on_am_pm() {
if (is_classic_) {
*out_++ = tm_hour() < 12 ? 'A' : 'P';
*out_++ = 'M';
} else {
format_localized('p');
}
}
// These apply to chrono durations but not tm.
void on_duration_value() {}
@@ -1771,7 +1831,10 @@ template <typename Char> struct formatter<std::tm, Char> {
template <typename FormatContext>
auto format(const std::tm& tm, FormatContext& ctx) const
-> decltype(ctx.out()) {
auto w = detail::tm_writer<decltype(ctx.out()), Char>(ctx.out(), tm);
const auto& loc_ref = ctx.locale();
const auto& loc =
loc_ref ? loc_ref.template get<std::locale>() : std::locale::classic();
auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), tm);
if (spec_ == spec::year_month_day)
w.on_iso_date();
else if (spec_ == spec::hh_mm_ss)