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Add initial support for weekday formatting

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This commit is contained in:
Victor Zverovich
2021-05-24 07:23:56 -07:00
parent 069131dc25
commit 1cd9899cf3
6 changed files with 157 additions and 33 deletions
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121
include/fmt/chrono.h
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@@ -683,34 +683,50 @@ FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
return ptr;
}
struct chrono_format_checker {
FMT_NORETURN void report_no_date() { FMT_THROW(format_error("no date")); }
template <typename Derived> struct null_chrono_spec_handler {
FMT_CONSTEXPR void unsupported() {
static_cast<Derived*>(this)->unsupported();
}
FMT_CONSTEXPR void on_abbr_weekday() { unsupported(); }
FMT_CONSTEXPR void on_full_weekday() { unsupported(); }
FMT_CONSTEXPR void on_dec0_weekday(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_dec1_weekday(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_abbr_month() { unsupported(); }
FMT_CONSTEXPR void on_full_month() { unsupported(); }
FMT_CONSTEXPR void on_24_hour(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_12_hour(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_minute(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_second(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_datetime(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_loc_date(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_loc_time(numeric_system) { unsupported(); }
FMT_CONSTEXPR void on_us_date() { unsupported(); }
FMT_CONSTEXPR void on_iso_date() { unsupported(); }
FMT_CONSTEXPR void on_12_hour_time() { unsupported(); }
FMT_CONSTEXPR void on_24_hour_time() { unsupported(); }
FMT_CONSTEXPR void on_iso_time() { unsupported(); }
FMT_CONSTEXPR void on_am_pm() { unsupported(); }
FMT_CONSTEXPR void on_duration_value() { unsupported(); }
FMT_CONSTEXPR void on_duration_unit() { unsupported(); }
FMT_CONSTEXPR void on_utc_offset() { unsupported(); }
FMT_CONSTEXPR void on_tz_name() { unsupported(); }
};
struct chrono_format_checker : null_chrono_spec_handler<chrono_format_checker> {
FMT_NORETURN void unsupported() { FMT_THROW(format_error("no date")); }
template <typename Char>
FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
FMT_NORETURN void on_abbr_weekday() { report_no_date(); }
FMT_NORETURN void on_full_weekday() { report_no_date(); }
FMT_NORETURN void on_dec0_weekday(numeric_system) { report_no_date(); }
FMT_NORETURN void on_dec1_weekday(numeric_system) { report_no_date(); }
FMT_NORETURN void on_abbr_month() { report_no_date(); }
FMT_NORETURN void on_full_month() { report_no_date(); }
FMT_CONSTEXPR void on_24_hour(numeric_system) {}
FMT_CONSTEXPR void on_12_hour(numeric_system) {}
FMT_CONSTEXPR void on_minute(numeric_system) {}
FMT_CONSTEXPR void on_second(numeric_system) {}
FMT_NORETURN void on_datetime(numeric_system) { report_no_date(); }
FMT_NORETURN void on_loc_date(numeric_system) { report_no_date(); }
FMT_NORETURN void on_loc_time(numeric_system) { report_no_date(); }
FMT_NORETURN void on_us_date() { report_no_date(); }
FMT_NORETURN void on_iso_date() { report_no_date(); }
FMT_CONSTEXPR void on_12_hour_time() {}
FMT_CONSTEXPR void on_24_hour_time() {}
FMT_CONSTEXPR void on_iso_time() {}
FMT_CONSTEXPR void on_am_pm() {}
FMT_CONSTEXPR void on_duration_value() {}
FMT_CONSTEXPR void on_duration_unit() {}
FMT_NORETURN void on_utc_offset() { report_no_date(); }
FMT_NORETURN void on_tz_name() { report_no_date(); }
};
template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
@@ -1080,6 +1096,81 @@ struct chrono_formatter {
FMT_END_DETAIL_NAMESPACE
#if defined(__cpp_lib_chrono) && __cpp_lib_chrono >= 201907
using weekday = std::chrono::weekday;
#else
// A fallback version of weekday.
class weekday {
private:
unsigned char value;
public:
weekday() = default;
explicit constexpr weekday(unsigned wd) noexcept
: value(static_cast<unsigned char>(wd != 7 ? wd : 0)) {}
constexpr unsigned c_encoding() const noexcept { return value; }
};
#endif
// A rudimentary weekday formatter.
template <> struct formatter<weekday> {
private:
bool localized = false;
public:
FMT_CONSTEXPR auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
auto begin = ctx.begin(), end = ctx.end();
if (begin != end && *begin == 'L') {
++begin;
localized = true;
}
return begin;
}
auto format(weekday wd, format_context& ctx) -> decltype(ctx.out()) {
auto tm = std::tm();
tm.tm_wday = static_cast<int>(wd.c_encoding());
auto&& os = std::ostringstream();
using iterator = std::ostreambuf_iterator<char>;
auto& loc = localized ? ctx.locale().template get<std::locale>()
: std::locale::classic();
const auto& tp = std::use_facet<std::time_put<char, iterator>>(loc);
auto fmt = string_view("%a");
auto end =
tp.put(iterator(os.rdbuf()), os, ' ', &tm, fmt.begin(), fmt.end());
if (end.failed()) FMT_THROW(format_error("failed to format time"));
auto s = os.str();
if (detail::is_utf8() && localized) {
// char16_t codecvt is broken in MSVC.
using code_unit = conditional_t<FMT_MSC_VER, wchar_t, char16_t>;
auto& f =
std::use_facet<std::codecvt<code_unit, char, std::mbstate_t>>(loc);
auto mb = std::mbstate_t();
const char* from_next = nullptr;
code_unit* to_next = nullptr;
constexpr size_t buf_size = 100;
code_unit buf[buf_size] = {};
auto result = f.in(mb, s.data(), s.data() + s.size(), from_next, buf,
buf + buf_size, to_next);
if (result != std::codecvt_base::ok)
FMT_THROW(format_error("failed to format time"));
s.clear();
for (code_unit* p = buf; p != to_next; ++p) {
code_unit c = *p;
if (c < 0x80) {
s.push_back(static_cast<char>(c));
} else if (c < 0x800) {
s.push_back(static_cast<char>(0xc0 | (c >> 6)));
s.push_back(static_cast<char>(0x80 | (c & 0x3f)));
} else {
FMT_THROW(format_error("failed to format time"));
}
}
}
return std::copy(s.begin(), s.end(), ctx.out());
}
};
template <typename Rep, typename Period, typename Char>
struct formatter<std::chrono::duration<Rep, Period>, Char> {
private: