288 lines
6.3 KiB
Go
288 lines
6.3 KiB
Go
package txt
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import (
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"fmt"
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"regexp"
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"strings"
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"time"
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)
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// Go regular expression tester: https://regoio.herokuapp.com/
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var DateRegexp = regexp.MustCompile("\\D\\d{4}[\\-_]\\d{2}[\\-_]\\d{2,}")
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var DatePathRegexp = regexp.MustCompile("\\D\\d{4}/\\d{1,2}/?\\d*")
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var DateTimeRegexp = regexp.MustCompile("\\D\\d{4}[\\-_]\\d{2}[\\-_]\\d{2}.{1,4}\\d{2}\\D\\d{2}\\D\\d{2,}")
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var DateIntRegexp = regexp.MustCompile("\\d{1,4}")
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var YearRegexp = regexp.MustCompile("\\d{4,5}")
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var IsDateRegexp = regexp.MustCompile("\\d{4}[\\-_]?\\d{2}[\\-_]?\\d{2}")
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var IsDateTimeRegexp = regexp.MustCompile("\\d{4}[\\-_]?\\d{2}[\\-_]?\\d{2}.{1,4}\\d{2}\\D?\\d{2}\\D?\\d{2}")
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var ExifDateTimeRegexp = regexp.MustCompile("((?P<year>\\d{4})|\\D{4})\\D((?P<month>\\d{2})|\\D{2})\\D((?P<day>\\d{2})|\\D{2})\\D((?P<h>\\d{2})|\\D{2})\\D((?P<m>\\d{2})|\\D{2})\\D((?P<s>\\d{2})|\\D{2})(\\.(?P<subsec>\\d+))?(?P<z>\\D)?(?P<zh>\\d{2})?\\D?(?P<zm>\\d{2})?")
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var ExifDateTimeMatch = make(map[string]int)
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func init() {
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names := ExifDateTimeRegexp.SubexpNames()
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for i := 0; i < len(names); i++ {
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if name := names[i]; name != "" {
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ExifDateTimeMatch[name] = i
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}
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}
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}
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var (
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YearMin = 1990
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YearMax = time.Now().Year() + 3
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)
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const (
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MonthMin = 1
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MonthMax = 12
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DayMin = 1
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DayMax = 31
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HourMin = 0
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HourMax = 24
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MinMin = 0
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MinMax = 59
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SecMin = 0
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SecMax = 59
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)
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// DateTime parses a string and returns a valid Exif timestamp if possible.
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func DateTime(s, timeZone string) (t time.Time) {
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defer func() {
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if r := recover(); r != nil {
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// Panic? Return unknown time.
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t = time.Time{}
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}
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}()
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// Empty timestamp? Return unknown time.
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if s == "" {
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return time.Time{}
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}
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s = strings.TrimLeft(s, " ")
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// Timestamp too short?
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if len(s) < 4 {
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return time.Time{}
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} else if len(s) > 50 {
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// Clip to max length.
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s = s[:50]
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}
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// Pad short timestamp with whitespace at the end.
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s = fmt.Sprintf("%-19s", s)
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v := ExifDateTimeMatch
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m := ExifDateTimeRegexp.FindStringSubmatch(s)
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// Pattern doesn't match? Return unknown time.
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if len(m) == 0 {
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return time.Time{}
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}
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// Default to UTC.
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tz := time.UTC
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// Local time zone currently not supported (undefined).
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if timeZone == time.Local.String() {
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timeZone = ""
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}
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// Set time zone.
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loc, err := time.LoadLocation(timeZone)
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// Location found?
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if err == nil && timeZone != "" && tz != time.Local {
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tz = loc
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timeZone = tz.String()
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} else {
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timeZone = ""
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}
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// Does the timestamp contain a time zone offset?
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z := m[v["z"]] // Supported values, if not empty: Z, +, -
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zh := IntVal(m[v["zh"]], 0, 23, 0) // Hours.
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zm := IntVal(m[v["zm"]], 0, 59, 0) // Minutes.
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// Valid time zone offset found?
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if offset := (zh*60 + zm) * 60; offset > 0 && offset <= 86400 {
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// Offset timezone name example: UTC+03:30
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if z == "+" {
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// Positive offset relative to UTC.
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tz = time.FixedZone(fmt.Sprintf("UTC+%02d:%02d", zh, zm), offset)
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} else if z == "-" {
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// Negative offset relative to UTC.
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tz = time.FixedZone(fmt.Sprintf("UTC-%02d:%02d", zh, zm), -1*offset)
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}
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}
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var nsec int
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if subsec := m[v["subsec"]]; subsec != "" {
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nsec = Int(subsec + strings.Repeat("0", 9-len(subsec)))
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} else {
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nsec = 0
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}
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// Create rounded timestamp from parsed input values.
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t = time.Date(
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IntVal(m[v["year"]], 1, YearMax, time.Now().Year()),
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time.Month(IntVal(m[v["month"]], 1, 12, 1)),
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IntVal(m[v["day"]], 1, 31, 1),
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IntVal(m[v["h"]], 0, 23, 0),
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IntVal(m[v["m"]], 0, 59, 0),
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IntVal(m[v["s"]], 0, 59, 0),
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nsec,
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tz)
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if timeZone != "" && loc != nil && loc != tz {
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return t.In(loc)
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}
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return t
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}
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// DateFromFilePath returns a string as time or the zero time instant in case it can not be converted.
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func DateFromFilePath(s string) (result time.Time) {
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defer func() {
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if r := recover(); r != nil {
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result = time.Time{}
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}
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}()
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if len(s) < 6 {
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return time.Time{}
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}
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if !strings.HasPrefix(s, "/") {
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s = "/" + s
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}
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b := []byte(s)
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if found := DateTimeRegexp.Find(b); len(found) > 0 { // Is it a date with time like "2020-01-30_09-57-18"?
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n := DateIntRegexp.FindAll(found, -1)
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if len(n) != 6 {
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return result
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}
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year := Int(string(n[0]))
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month := Int(string(n[1]))
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day := Int(string(n[2]))
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hour := Int(string(n[3]))
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min := Int(string(n[4]))
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sec := Int(string(n[5]))
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if year < YearMin || year > YearMax || month < MonthMin || month > MonthMax || day < DayMin || day > DayMax {
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return result
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}
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if hour < HourMin || hour > HourMax || min < MinMin || min > MinMax || sec < SecMin || sec > SecMax {
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return result
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}
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result = time.Date(
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year,
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time.Month(month),
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day,
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hour,
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min,
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sec,
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0,
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time.UTC)
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} else if found := DateRegexp.Find(b); len(found) > 0 { // Is it a date only like "2020-01-30"?
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n := DateIntRegexp.FindAll(found, -1)
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if len(n) != 3 {
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return result
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}
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year := Int(string(n[0]))
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month := Int(string(n[1]))
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day := Int(string(n[2]))
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if year < YearMin || year > YearMax || month < MonthMin || month > MonthMax || day < DayMin || day > DayMax {
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return result
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}
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result = time.Date(
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year,
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time.Month(month),
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day,
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0,
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0,
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0,
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0,
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time.UTC)
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} else if found := DatePathRegexp.Find(b); len(found) > 0 { // Is it a date path like "2020/01/03"?
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n := DateIntRegexp.FindAll(found, -1)
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if len(n) < 2 || len(n) > 3 {
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return result
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}
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year := Int(string(n[0]))
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month := Int(string(n[1]))
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if year < YearMin || year > YearMax || month < MonthMin || month > MonthMax {
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return result
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}
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if len(n) == 2 {
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result = time.Date(
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year,
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time.Month(month),
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1,
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0,
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0,
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0,
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0,
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time.UTC)
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} else if day := Int(string(n[2])); day >= DayMin && day <= DayMax {
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result = time.Date(
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year,
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time.Month(month),
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day,
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0,
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0,
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0,
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0,
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time.UTC)
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}
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}
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return result.UTC()
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}
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// IsTime tests if the string looks like a date and/or time.
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func IsTime(s string) bool {
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if s == "" {
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return false
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} else if m := IsDateRegexp.FindString(s); m == s {
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return true
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} else if m := IsDateTimeRegexp.FindString(s); m == s {
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return true
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}
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return false
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}
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// Year tries to find a matching year for a given string e.g. from a file oder directory name.
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func Year(s string) int {
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b := []byte(s)
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found := YearRegexp.FindAll(b, -1)
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for _, match := range found {
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year := Int(string(match))
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if year > YearMin && year < YearMax {
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return year
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}
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}
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return 0
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}
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