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Fix errors in ISO week-base-year formatter

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Vladislav Shchapov 2021-10-14 17:50:16 +05:00 committed by Victor Zverovich
parent 218cecb6d1
commit 2754546080
2 changed files with 42 additions and 28 deletions
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45
include/fmt/chrono.h
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@ -1412,11 +1412,11 @@ template <typename FormatContext, typename OutputIt> struct tm_formatter {
// do if the year is negative or exceeds 9999. Use the convention that %C // 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 // concatenated with %y yields the same output as %Y, and that %Y contains at
// least 4 bytes, with more only if necessary. // least 4 bytes, with more only if necessary.
struct split_year { struct split_year_result {
int upper; int upper;
int lower; int lower;
}; };
auto tm_split_year(int year) const -> split_year { auto split_year(int year) const -> split_year_result {
auto q = year / 100; auto q = year / 100;
auto r = year % 100; auto r = year % 100;
if (r < 0) { if (r < 0) {
@ -1428,23 +1428,28 @@ template <typename FormatContext, typename OutputIt> struct tm_formatter {
// Algorithm: // Algorithm:
// https://en.wikipedia.org/wiki/ISO_week_date#Calculating_the_week_number_from_a_month_and_day_of_the_month_or_ordinal_date // https://en.wikipedia.org/wiki/ISO_week_date#Calculating_the_week_number_from_a_month_and_day_of_the_month_or_ordinal_date
struct iso_weak { struct iso_week_result {
int year; int year;
int woy; int woy;
}; };
auto tm_iso_year_weaks(int year) -> int { auto iso_year_weeks(const int curr_year) -> int {
int p = (year + year / 4 - year / 100 + year / 400) % daysperweek; const int prev_year = curr_year - 1;
int year_1 = year - 1; const int curr_p =
int p_1 = (year_1 + year_1 / 4 - year_1 / 100 + year_1 / 400) % daysperweek; (curr_year + curr_year / 4 - curr_year / 100 + curr_year / 400) %
return 52 + ((p == 4 || p_1 == 3) ? 1 : 0); daysperweek;
const int prev_p =
(prev_year + prev_year / 4 - prev_year / 100 + prev_year / 400) %
daysperweek;
return 52 + ((curr_p == 4 || prev_p == 3) ? 1 : 0);
} }
auto tm_iso_weak() -> iso_weak { auto tm_iso_week() -> iso_week_result {
auto year = tm_year(); const auto year = tm_year();
int w = (tm.tm_yday + 10 - (tm.tm_wday == 0 ? daysperweek : tm.tm_wday)) / const int w =
daysperweek; (tm.tm_yday + 11 - (tm.tm_wday == 0 ? daysperweek : tm.tm_wday)) /
daysperweek;
if (w < 1) { if (w < 1) {
return {year - 1, tm_iso_year_weaks(year - 1)}; return {year - 1, iso_year_weeks(year - 1)};
} else if (w > tm_iso_year_weaks(year)) { } else if (w > iso_year_weeks(year)) {
return {year + 1, 1}; return {year + 1, 1};
} else { } else {
return {year, w}; return {year, w};
@ -1537,7 +1542,7 @@ template <typename FormatContext, typename OutputIt> struct tm_formatter {
detail::write_digit2_separated( detail::write_digit2_separated(
buf, detail::to_unsigned(tm.tm_mon + 1), buf, detail::to_unsigned(tm.tm_mon + 1),
detail::to_unsigned(tm.tm_mday), detail::to_unsigned(tm.tm_mday),
detail::to_unsigned(tm_split_year(tm_year()).lower), '/'); detail::to_unsigned(split_year(tm_year()).lower), '/');
out = detail::copy_str<char_type>(std::begin(buf), std::end(buf), out); out = detail::copy_str<char_type>(std::begin(buf), std::end(buf), out);
} }
void on_iso_date() { void on_iso_date() {
@ -1568,7 +1573,7 @@ template <typename FormatContext, typename OutputIt> struct tm_formatter {
} }
void on_last2_year(numeric_system ns) { void on_last2_year(numeric_system ns) {
if (ns == numeric_system::standard) { if (ns == numeric_system::standard) {
write2(detail::to_unsigned(tm_split_year(tm_year()).lower)); write2(detail::to_unsigned(split_year(tm_year()).lower));
} else { } else {
format_localized('y', 'O'); format_localized('y', 'O');
} }
@ -1576,7 +1581,7 @@ template <typename FormatContext, typename OutputIt> struct tm_formatter {
void on_offset_year() { format_localized('y', 'E'); } void on_offset_year() { format_localized('y', 'E'); }
void on_base_year(numeric_system ns) { void on_base_year(numeric_system ns) {
if (ns == numeric_system::standard) { if (ns == numeric_system::standard) {
auto split = tm_split_year(tm_year()); auto split = split_year(tm_year());
if (split.upper >= 0 && split.upper < 100) { if (split.upper >= 0 && split.upper < 100) {
write2(detail::to_unsigned(split.upper)); write2(detail::to_unsigned(split.upper));
} else { } else {
@ -1613,14 +1618,14 @@ template <typename FormatContext, typename OutputIt> struct tm_formatter {
} }
void on_iso_week_of_year(numeric_system ns) { void on_iso_week_of_year(numeric_system ns) {
if (ns == numeric_system::standard) { if (ns == numeric_system::standard) {
write2(detail::to_unsigned(tm_iso_weak().woy)); write2(detail::to_unsigned(tm_iso_week().woy));
} else { } else {
format_localized('V', 'O'); format_localized('V', 'O');
} }
} }
void on_iso_week_based_year() { write_year(tm_iso_weak().year); } void on_iso_week_based_year() { write_year(tm_iso_week().year); }
void on_iso_week_based_year_last2() { void on_iso_week_based_year_last2() {
write2(detail::to_unsigned(tm_split_year(tm_iso_weak().year).lower)); write2(detail::to_unsigned(split_year(tm_iso_week().year).lower));
} }
void on_day_of_year() { void on_day_of_year() {
auto yday = tm.tm_yday + 1; auto yday = tm.tm_yday + 1;

25
test/chrono-test.cc
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@ -85,10 +85,10 @@ TEST(chrono_test, format_tm) {
"2000-01-02", // W52 "2000-01-02", // W52
"2000-01-03", // W1 "2000-01-03", // W1
}; };
std::vector<std::string> spec_list = {"%G", "%g", "%V"}; const std::string iso_week_spec = "%Y-%m-%d: %G %g %V";
for (const auto& str_tm : str_tm_list) { for (const auto& str_tm : str_tm_list) {
tm = std::tm(); tm = std::tm();
// GCC 4 does not support std::get_time // GCC 4 does not support std::get_time
// MSVC dows not support POSIX strptime // MSVC dows not support POSIX strptime
#ifdef _WIN32 #ifdef _WIN32
@ -102,12 +102,21 @@ TEST(chrono_test, format_tm) {
std::time_t t = std::mktime(&tm); std::time_t t = std::mktime(&tm);
tm = *std::localtime(&t); tm = *std::localtime(&t);
for (const auto& spec : spec_list) { char output[256] = {};
char output[256] = {}; std::strftime(output, sizeof(output), iso_week_spec.c_str(), &tm);
std::strftime(output, sizeof(output), spec.c_str(), &tm); auto fmt_spec = std::string("{:").append(iso_week_spec).append("}");
auto fmt_spec = std::string("{:").append(spec).append("}"); EXPECT_EQ(output, fmt::format(fmt::runtime(fmt_spec), tm));
EXPECT_EQ(output, fmt::format(fmt::runtime(fmt_spec), tm)); }
}
// Every day from 1970-01-01
std::time_t time_now = std::time(nullptr);
for (std::time_t t = 6 * 3600; t < time_now; t += 86400) {
tm = *std::localtime(&t);
char output[256] = {};
std::strftime(output, sizeof(output), iso_week_spec.c_str(), &tm);
auto fmt_spec = std::string("{:").append(iso_week_spec).append("}");
EXPECT_EQ(output, fmt::format(fmt::runtime(fmt_spec), tm));
} }
} }