Reorder classes

[phprus]

Prepare to PR #2586

class tm_writer must be declared before using in chrono formatters.
Therefore, the code related to tm_writer has been moved to the top.

[vitaut]

Could you clarify in the PR description why this reordering is needed?

[phprus]

@vitaut, PR description updated.

This PR move:

fmt/include/fmt/chrono.h

Lines 1355 to 1766 in 12b1d8b

	struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
	FMT_NORETURN void unsupported() { FMT_THROW(format_error("no format")); }
	template <typename Char>
	FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
	FMT_CONSTEXPR void on_year(numeric_system) {}
	FMT_CONSTEXPR void on_short_year(numeric_system) {}
	FMT_CONSTEXPR void on_offset_year() {}
	FMT_CONSTEXPR void on_century(numeric_system) {}
	FMT_CONSTEXPR void on_iso_week_based_year() {}
	FMT_CONSTEXPR void on_iso_week_based_short_year() {}
	FMT_CONSTEXPR void on_abbr_weekday() {}
	FMT_CONSTEXPR void on_full_weekday() {}
	FMT_CONSTEXPR void on_dec0_weekday(numeric_system) {}
	FMT_CONSTEXPR void on_dec1_weekday(numeric_system) {}
	FMT_CONSTEXPR void on_abbr_month() {}
	FMT_CONSTEXPR void on_full_month() {}
	FMT_CONSTEXPR void on_dec_month(numeric_system) {}
	FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) {}
	FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) {}
	FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) {}
	FMT_CONSTEXPR void on_day_of_year() {}
	FMT_CONSTEXPR void on_day_of_month(numeric_system) {}
	FMT_CONSTEXPR void on_day_of_month_space(numeric_system) {}
	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_CONSTEXPR void on_datetime(numeric_system) {}
	FMT_CONSTEXPR void on_loc_date(numeric_system) {}
	FMT_CONSTEXPR void on_loc_time(numeric_system) {}
	FMT_CONSTEXPR void on_us_date() {}
	FMT_CONSTEXPR void on_iso_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_utc_offset() {}
	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_;
	auto tm_sec() const noexcept -> int {
	FMT_ASSERT(tm_.tm_sec >= 0 && tm_.tm_sec <= 61, "");
	return tm_.tm_sec;
	}
	auto tm_min() const noexcept -> int {
	FMT_ASSERT(tm_.tm_min >= 0 && tm_.tm_min <= 59, "");
	return tm_.tm_min;
	}
	auto tm_hour() const noexcept -> int {
	FMT_ASSERT(tm_.tm_hour >= 0 && tm_.tm_hour <= 23, "");
	return tm_.tm_hour;
	}
	auto tm_mday() const noexcept -> int {
	FMT_ASSERT(tm_.tm_mday >= 1 && tm_.tm_mday <= 31, "");
	return tm_.tm_mday;
	}
	auto tm_mon() const noexcept -> int {
	FMT_ASSERT(tm_.tm_mon >= 0 && tm_.tm_mon <= 11, "");
	return tm_.tm_mon;
	}
	auto tm_year() const noexcept -> long long { return 1900ll + tm_.tm_year; }
	auto tm_wday() const noexcept -> int {
	FMT_ASSERT(tm_.tm_wday >= 0 && tm_.tm_wday <= 6, "");
	return tm_.tm_wday;
	}
	auto tm_yday() const noexcept -> int {
	FMT_ASSERT(tm_.tm_yday >= 0 && tm_.tm_yday <= 365, "");
	return tm_.tm_yday;
	}
	auto tm_hour12() const noexcept -> int {
	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
	// do if the year is negative or exceeds 9999. Use the convention that %C
	// concatenated with %y yields the same output as %Y, and that %Y contains at
	// least 4 characters, with more only if necessary.
	auto split_year_lower(long long year) const noexcept -> int {
	auto l = year % 100;
	if (l < 0) l = -l; // l in [0, 99]
	return static_cast<int>(l);
	}
	// Algorithm:
	// https://en.wikipedia.org/wiki/ISO_week_date#Calculating_the_week_number_from_a_month_and_day_of_the_month_or_ordinal_date
	auto iso_year_weeks(long long curr_year) const noexcept -> int {
	const auto prev_year = curr_year - 1;
	const auto curr_p =
	(curr_year + curr_year / 4 - curr_year / 100 + curr_year / 400) %
	days_per_week;
	const auto prev_p =
	(prev_year + prev_year / 4 - prev_year / 100 + prev_year / 400) %
	days_per_week;
	return 52 + ((curr_p == 4 || prev_p == 3) ? 1 : 0);
	}
	auto iso_week_num(int tm_yday, int tm_wday) const noexcept -> int {
	return (tm_yday + 11 - (tm_wday == 0 ? days_per_week : tm_wday)) /
	days_per_week;
	}
	auto tm_iso_week_year() const noexcept -> long long {
	const auto year = tm_year();
	const auto w = iso_week_num(tm_yday(), tm_wday());
	if (w < 1) return year - 1;
	if (w > iso_year_weeks(year)) return year + 1;
	return year;
	}
	auto tm_iso_week_of_year() const noexcept -> int {
	const auto year = tm_year();
	const auto w = iso_week_num(tm_yday(), tm_wday());
	if (w < 1) return iso_year_weeks(year - 1);
	if (w > iso_year_weeks(year)) return 1;
	return w;
	}
	void write1(int value) {
	*out_++ = static_cast<char>('0' + to_unsigned(value) % 10);
	}
	void write2(int value) {
	const char* d = digits2(to_unsigned(value) % 100);
	*out_++ = *d++;
	*out_++ = *d;
	}
	void write_year_extended(long long year) {
	// At least 4 characters.
	int width = 4;
	if (year < 0) {
	*out_++ = '-';
	year = 0 - year;
	--width;
	}
	uint32_or_64_or_128_t<long long> n = to_unsigned(year);
	const int num_digits = count_digits(n);
	if (width > num_digits) out_ = std::fill_n(out_, width - num_digits, '0');
	out_ = format_decimal<Char>(out_, n, num_digits).end;
	}
	void write_year(long long year) {
	if (year >= 0 && year < 10000) {
	write2(static_cast<int>(year / 100));
	write2(static_cast<int>(year % 100));
	} else {
	write_year_extended(year);
	}
	}
	void format_localized(char format, char modifier = 0) {
	out_ = write<Char>(out_, tm_, loc_, format, modifier);
	}
	public:
	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_; }
	FMT_CONSTEXPR void on_text(const Char* begin, const Char* end) {
	out_ = copy_str<Char>(begin, end, out_);
	}
	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());
	}
	void on_dec1_weekday(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('u', 'O');
	auto wday = tm_wday();
	write1(wday == 0 ? days_per_week : wday);
	}
	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) {
	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) {
	if (is_classic_)
	on_us_date();
	else
	format_localized('x', ns == numeric_system::standard ? '\0' : 'E');
	}
	void on_loc_time(numeric_system ns) {
	if (is_classic_)
	on_iso_time();
	else
	format_localized('X', ns == numeric_system::standard ? '\0' : 'E');
	}
	void on_us_date() {
	char buf[8];
	write_digit2_separated(buf, to_unsigned(tm_mon() + 1),
	to_unsigned(tm_mday()),
	to_unsigned(split_year_lower(tm_year())), '/');
	out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
	}
	void on_iso_date() {
	auto year = tm_year();
	char buf[10];
	size_t offset = 0;
	if (year >= 0 && year < 10000) {
	copy2(buf, digits2(to_unsigned(year / 100)));
	} else {
	offset = 4;
	write_year_extended(year);
	year = 0;
	}
	write_digit2_separated(buf + 2, static_cast<unsigned>(year % 100),
	to_unsigned(tm_mon() + 1), to_unsigned(tm_mday()),
	'-');
	out_ = copy_str<Char>(std::begin(buf) + offset, std::end(buf), out_);
	}
	void on_utc_offset() { format_localized('z'); }
	void on_tz_name() { format_localized('Z'); }
	void on_year(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('Y', 'E');
	write_year(tm_year());
	}
	void on_short_year(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('y', 'O');
	write2(split_year_lower(tm_year()));
	}
	void on_offset_year() { format_localized('y', 'E'); }
	void on_century(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('C', 'E');
	auto year = tm_year();
	auto upper = year / 100;
	if (year >= -99 && year < 0) {
	// Zero upper on negative year.
	*out_++ = '-';
	*out_++ = '0';
	} else if (upper >= 0 && upper < 100) {
	write2(static_cast<int>(upper));
	} else {
	out_ = write<Char>(out_, upper);
	}
	}
	void on_dec_month(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('m', 'O');
	write2(tm_mon() + 1);
	}
	void on_dec0_week_of_year(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('U', 'O');
	write2((tm_yday() + days_per_week - tm_wday()) / days_per_week);
	}
	void on_dec1_week_of_year(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('W', 'O');
	auto wday = tm_wday();
	write2((tm_yday() + days_per_week -
	(wday == 0 ? (days_per_week - 1) : (wday - 1))) /
	days_per_week);
	}
	void on_iso_week_of_year(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('V', 'O');
	write2(tm_iso_week_of_year());
	}
	void on_iso_week_based_year() { write_year(tm_iso_week_year()); }
	void on_iso_week_based_short_year() {
	write2(split_year_lower(tm_iso_week_year()));
	}
	void on_day_of_year() {
	auto yday = tm_yday() + 1;
	write1(yday / 100);
	write2(yday % 100);
	}
	void on_day_of_month(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('d', 'O');
	write2(tm_mday());
	}
	void on_day_of_month_space(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('e', 'O');
	auto mday = to_unsigned(tm_mday()) % 100;
	const char* d2 = digits2(mday);
	*out_++ = mday < 10 ? ' ' : d2[0];
	*out_++ = d2[1];
	}
	void on_24_hour(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('H', 'O');
	write2(tm_hour());
	}
	void on_12_hour(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('I', 'O');
	write2(tm_hour12());
	}
	void on_minute(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('M', 'O');
	write2(tm_min());
	}
	void on_second(numeric_system ns) {
	if (ns != numeric_system::standard) return format_localized('S', 'O');
	write2(tm_sec());
	}
	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_++ = ':';
	write2(tm_min());
	}
	void on_iso_time() {
	char buf[8];
	write_digit2_separated(buf, to_unsigned(tm_hour()), to_unsigned(tm_min()),
	to_unsigned(tm_sec()), ':');
	out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
	}
	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() {}
	void on_duration_unit() {}
	};

before:

fmt/include/fmt/chrono.h

Lines 802 to 803 in 12b1d8b

	struct chrono_format_checker : null_chrono_spec_handler<chrono_format_checker> {
	FMT_NORETURN void unsupported() { FMT_THROW(format_error("no date")); }

[phprus]

@vitaut, PR rebased.

[vitaut]

Merged, thanks