time: d,c,dd,ddd,dddd pattern support for parse_format()

vlib/time/date_time_parser.v

@@ -101,14 +101,43 @@ fn (mut p DateTimeParser) must_be_valid_three_letter_month() !int {
 	return error_invalid_time(0, 'invalid three letter month, at: ${p.current_pos_datetime}')
 }
 
-fn (mut p DateTimeParser) must_be_valid_week_day(letters int) !string {
-	val := p.next(letters)!
+fn (mut p DateTimeParser) must_be_valid_week_day() !int {
 	for v in long_days {
-		if v[0..letters] == val {
-			return v
+		if p.current_pos_datetime + v.len < p.datetime.len {
+			weekday := p.datetime[p.current_pos_datetime..p.current_pos_datetime + v.len]
+			if v == weekday {
+				p.current_pos_datetime += v.len
+				return long_months.index(weekday) + 1
+			}
 		}
 	}
-	return error_invalid_time(0, 'invalid month name, at: ${p.current_pos_datetime}')
+	return error_invalid_time(0, 'invalid weekday, at: ${p.current_pos_datetime}')
+}
+
+fn (mut p DateTimeParser) must_be_valid_two_letter_week_day() !int {
+	if p.current_pos_datetime + 2 < p.datetime.len {
+		letters := p.datetime[p.current_pos_datetime..p.current_pos_datetime + 2]
+		for d := 1; d <= long_days.len; d++ {
+			if days_string[(d - 1) * 3..d * 3 - 1] == letters {
+				p.current_pos_datetime += 2
+				return d
+			}
+		}
+	}
+	return error_invalid_time(0, 'invalid two letter weekday, at: ${p.current_pos_datetime}')
+}
+
+fn (mut p DateTimeParser) must_be_valid_three_letter_week_day() !int {
+	if p.current_pos_datetime + 3 < p.datetime.len {
+		letters := p.datetime[p.current_pos_datetime..p.current_pos_datetime + 3]
+		for d := 1; d <= long_days.len; d++ {
+			if days_string[(d - 1) * 3..d * 3] == letters {
+				p.current_pos_datetime += 3
+				return d
+			}
+		}
+	}
+	return error_invalid_time(0, 'invalid three letter weekday, at: ${p.current_pos_datetime}')
 }
 
 fn extract_tokens(s string) ![]string {
@@ -133,9 +162,15 @@ fn extract_tokens(s string) ![]string {
 // YY - 2 digit year, 00..99
 // M - month, 1..12
 // MM - month, 2 digits, 01..12
+// MMM - month, three letters, Jan..Dec
 // MMMM - name of month
 // D - day of the month, 1..31
 // DD - day of the month, 01..31
+// d - day of week, 0..6
+// c - day of week, 1..7
+// dd - day of week, Su..Sa
+// ddd - day of week, Sun..Sat
+// dddd - day of week, Sunday..Saturday
 // H - hour, 0..23
 // HH - hour, 00..23
 // h - hour, 0..23
@@ -206,6 +241,21 @@ fn (mut p DateTimeParser) parse() !Time {
 					return error_invalid_time(0, 'day must be  between 01 and 31')
 				}
 			}
+			'd' {
+				p.must_be_int(1) or { return err }
+			}
+			'c' {
+				p.must_be_int(1) or { return err }
+			}
+			'dd' {
+				p.must_be_valid_two_letter_week_day() or { return err }
+			}
+			'ddd' {
+				p.must_be_valid_three_letter_week_day() or { return err }
+			}
+			'dddd' {
+				p.must_be_valid_week_day() or { return err }
+			}
 			'H' {
 				hour_ = p.must_be_int_with_minimum_length(1, 2, true) or {
 					return error_invalid_time(0, 'end of string reached before hours where specified')

vlib/time/parse.c.v

@@ -139,6 +139,11 @@ pub fn parse(s string) !Time {
 // MMMM - name of month
 // D - day of the month, 1..31
 // DD - day of the month, 01..31
+// d - day of week, 0..6
+// c - day of week, 1..7
+// dd - day of week, Su..Sa
+// ddd - day of week, Sun..Sat
+// dddd - day of week, Sunday..Saturday
 // H - hour, 0..23
 // HH - hour, 00..23
 // h - hour, 0..23

vlib/time/time_test.v

@@ -396,3 +396,43 @@ fn test_parse_three_letters_month() {
 	tm_tm := time.parse_format(tm_s, format)!
 	assert tm_tm.month == tm.month
 }
+
+fn test_parse_ordinal_weekday_d() {
+	format := 'd MMM DD HH:mm:ss YYYY'
+	dt := '0 Jan 01 00:00:00 1970'
+	tm := time.parse_format(dt, format)!
+	tm_s := tm.custom_format(format)
+	assert tm_s == '4 Jan 01 00:00:00 1970'
+}
+
+fn test_parse_ordinal_weekday_c() {
+	format := 'd MMM DD HH:mm:ss YYYY'
+	dt := '7 Jan 01 00:00:00 1970'
+	tm := time.parse_format(dt, format)!
+	tm_s := tm.custom_format(format)
+	assert tm_s == '4 Jan 01 00:00:00 1970'
+}
+
+fn test_parse_two_letters_weekday() {
+	format := 'dd MMM DD HH:mm:ss YYYY'
+	dt := 'Su Jan 01 00:00:00 1970'
+	tm := time.parse_format(dt, format)!
+	tm_s := tm.custom_format(format)
+	assert tm_s == 'Th Jan 01 00:00:00 1970'
+}
+
+fn test_parse_three_letters_weekday() {
+	format := 'ddd MMM DD HH:mm:ss YYYY'
+	dt := 'Sun Jan 01 00:00:00 1970'
+	tm := time.parse_format(dt, format)!
+	tm_s := tm.custom_format(format)
+	assert tm_s == 'Thu Jan 01 00:00:00 1970'
+}
+
+fn test_parse_weekday() {
+	format := 'dddd MMM DD HH:mm:ss YYYY'
+	dt := 'Sunday Jan 01 00:00:00 1970'
+	tm := time.parse_format(dt, format)!
+	tm_s := tm.custom_format(format)
+	assert tm_s == 'Thursday Jan 01 00:00:00 1970'
+}