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LibCore: Add a way to parse a DateTime from a string
DateTime can now be parsed from a string. Implements the same formatters as strptime: https://linux.die.net/man/3/strptime (Well, some of them at least).
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x-yl
Ali Mohammad Pur
parent
cbd7437d40
commit
904322e754
2 changed files with 282 additions and 0 deletions
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@ -4,9 +4,11 @@
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/CharacterTypes.h>
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#include <AK/StringBuilder.h>
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#include <AK/Time.h>
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#include <LibCore/DateTime.h>
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#include <errno.h>
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#include <sys/time.h>
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#include <time.h>
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@ -228,4 +230,283 @@ String DateTime::to_string(const String& format) const
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return builder.build();
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}
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Optional<DateTime> DateTime::parse(const String& format, const String& string)
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{
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unsigned format_pos = 0;
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unsigned string_pos = 0;
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struct tm tm = {};
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const StringView wday_short_names[7] = {
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"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
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};
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const StringView wday_long_names[7] = {
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"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
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};
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const StringView mon_short_names[12] = {
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"Jan", "Feb", "Mar", "Apr", "May", "Jun",
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"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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};
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const StringView mon_long_names[12] = {
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"January", "February", "March", "April", "May", "June",
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"July", "August", "September", "October", "November", "December"
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};
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auto parsing_failed = false;
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auto parse_number = [&] {
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if (string_pos >= string.length()) {
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parsing_failed = true;
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return 0;
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}
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char* end_ptr = nullptr;
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errno = 0;
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int number = strtol(string.characters() + string_pos, &end_ptr, 10);
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auto chars_parsed = end_ptr - (string.characters() + string_pos);
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if (chars_parsed == 0 || errno != 0)
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parsing_failed = true;
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else
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string_pos += chars_parsed;
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return number;
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};
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auto consume = [&](char x) {
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if (string_pos >= string.length()) {
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parsing_failed = true;
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return;
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}
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if (string[string_pos] != x)
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parsing_failed = true;
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else
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string_pos++;
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};
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while (format_pos < format.length() && string_pos < string.length()) {
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if (format[format_pos] != '%') {
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if (format[format_pos] != string[string_pos]) {
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return {};
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}
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format_pos++;
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string_pos++;
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continue;
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}
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format_pos++;
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if (format_pos == format.length()) {
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return {};
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}
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switch (format[format_pos]) {
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case 'a': {
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auto wday = 0;
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for (auto name : wday_short_names) {
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if (string.substring_view(string_pos).starts_with(name, AK::CaseSensitivity::CaseInsensitive)) {
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string_pos += name.length();
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tm.tm_wday = wday;
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break;
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}
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++wday;
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}
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if (wday == 7)
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return {};
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break;
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}
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case 'A': {
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auto wday = 0;
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for (auto name : wday_long_names) {
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if (string.substring_view(string_pos).starts_with(name, AK::CaseSensitivity::CaseInsensitive)) {
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string_pos += name.length();
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tm.tm_wday = wday;
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break;
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}
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++wday;
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}
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if (wday == 7)
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return {};
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break;
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}
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case 'h':
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case 'b': {
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auto mon = 0;
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for (auto name : mon_short_names) {
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if (string.substring_view(string_pos).starts_with(name, AK::CaseSensitivity::CaseInsensitive)) {
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string_pos += name.length();
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tm.tm_mon = mon;
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break;
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}
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++mon;
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}
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if (mon == 12)
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return {};
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break;
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}
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case 'B': {
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auto mon = 0;
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for (auto name : mon_long_names) {
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if (string.substring_view(string_pos).starts_with(name, AK::CaseSensitivity::CaseInsensitive)) {
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string_pos += name.length();
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tm.tm_mon = mon;
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break;
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}
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++mon;
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}
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if (mon == 12)
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return {};
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break;
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}
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case 'C': {
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int num = parse_number();
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tm.tm_year = (num - 19) * 100;
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break;
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}
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case 'd': {
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tm.tm_mday = parse_number();
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break;
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}
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case 'D': {
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int mon = parse_number();
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consume('/');
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int day = parse_number();
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consume('/');
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int year = parse_number();
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tm.tm_mon = mon + 1;
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tm.tm_mday = day;
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tm.tm_year = (year + 1900) % 100;
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break;
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}
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case 'e': {
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tm.tm_mday = parse_number();
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break;
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}
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case 'H': {
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tm.tm_hour = parse_number();
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break;
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}
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case 'I': {
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int num = parse_number();
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tm.tm_hour = num % 12;
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break;
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}
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case 'j': {
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// a little trickery here... we can get mktime() to figure out mon and mday using out of range values.
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// yday is not used so setting it is pointless.
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tm.tm_mday = parse_number();
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tm.tm_mon = 0;
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mktime(&tm);
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break;
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}
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case 'm': {
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int num = parse_number();
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tm.tm_mon = num - 1;
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break;
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}
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case 'M': {
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tm.tm_min = parse_number();
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break;
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}
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case 'n':
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case 't':
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while (is_ascii_blank(string[string_pos])) {
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string_pos++;
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}
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break;
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case 'p': {
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auto ampm = string.substring_view(string_pos, 4);
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if (ampm == "p.m." && tm.tm_hour < 12) {
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tm.tm_hour += 12;
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}
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string_pos += 4;
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break;
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}
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case 'r': {
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auto ampm = string.substring_view(string_pos, 4);
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if (ampm == "p.m." && tm.tm_hour < 12) {
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tm.tm_hour += 12;
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}
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string_pos += 4;
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break;
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}
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case 'R': {
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tm.tm_hour = parse_number();
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consume(':');
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tm.tm_min = parse_number();
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break;
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}
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case 'S':
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tm.tm_sec = parse_number();
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break;
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case 'T':
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tm.tm_hour = parse_number();
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consume(':');
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tm.tm_min = parse_number();
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consume(':');
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tm.tm_sec = parse_number();
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break;
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case 'w':
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tm.tm_wday = parse_number();
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break;
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case 'y': {
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int year = parse_number();
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tm.tm_year = year <= 99 && year > 69 ? 1900 + year : 2000 + year;
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break;
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}
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case 'Y': {
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int year = parse_number();
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tm.tm_year = year - 1900;
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break;
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}
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case 'z': {
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if (string[string_pos] == 'Z') {
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// UTC time
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string_pos++;
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break;
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}
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int sign;
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if (string[string_pos] == '+')
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sign = -1;
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else if (string[string_pos] == '-')
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sign = +1;
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else
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return {};
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string_pos++;
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auto hours = parse_number();
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int minutes;
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if (string_pos < string.length() && string[string_pos] == ':') {
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string_pos++;
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minutes = parse_number();
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} else {
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minutes = hours % 100;
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hours = hours / 100;
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}
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tm.tm_hour += sign * hours;
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tm.tm_min += sign * minutes;
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break;
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}
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case '%':
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if (string[string_pos] != '%') {
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return {};
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}
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string_pos += 1;
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break;
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default:
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parsing_failed = true;
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break;
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}
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if (parsing_failed) {
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return {};
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}
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format_pos++;
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}
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if (string_pos != string.length() || format_pos != format.length()) {
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return {};
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}
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return DateTime::from_timestamp(mktime(&tm));
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}
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}
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@ -35,6 +35,7 @@ public:
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static DateTime create(unsigned year, unsigned month = 1, unsigned day = 0, unsigned hour = 0, unsigned minute = 0, unsigned second = 0);
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static DateTime now();
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static DateTime from_timestamp(time_t);
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static Optional<DateTime> parse(const String& format, const String& string);
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bool operator<(const DateTime& other) const { return m_timestamp < other.m_timestamp; }
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