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package internal
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import (
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	"fmt"
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	"time"
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)
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//go:generate stringer -type=TimeFormatType
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type TimeFormatType int
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const (
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	TimeFormatNoTimezone TimeFormatType = iota
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	TimeFormatNamedTimezone
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	TimeFormatNumericTimezone
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	TimeFormatNumericAndNamedTimezone
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	TimeFormatTimeOnly
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)
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type TimeFormat struct {
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	Format string
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	Typ    TimeFormatType
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}
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func (f TimeFormat) HasTimezone() bool {
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	// We don't include the formats with only named timezones, see
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	// https://github.com/golang/go/issues/19694#issuecomment-289103522
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	return f.Typ >= TimeFormatNumericTimezone && f.Typ <= TimeFormatNumericAndNamedTimezone
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}
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var TimeFormats = []TimeFormat{
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	// Keep common formats at the top.
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	{"2006-01-02", TimeFormatNoTimezone},
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	{time.RFC3339, TimeFormatNumericTimezone},
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	{"2006-01-02T15:04:05", TimeFormatNoTimezone}, // iso8601 without timezone
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	{time.RFC1123Z, TimeFormatNumericTimezone},
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	{time.RFC1123, TimeFormatNamedTimezone},
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	{time.RFC822Z, TimeFormatNumericTimezone},
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	{time.RFC822, TimeFormatNamedTimezone},
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	{time.RFC850, TimeFormatNamedTimezone},
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	{"2006-01-02 15:04:05.999999999 -0700 MST", TimeFormatNumericAndNamedTimezone}, // Time.String()
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	{"2006-01-02T15:04:05-0700", TimeFormatNumericTimezone},                        // RFC3339 without timezone hh:mm colon
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	{"2006-01-02 15:04:05Z0700", TimeFormatNumericTimezone},                        // RFC3339 without T or timezone hh:mm colon
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	{"2006-01-02 15:04:05", TimeFormatNoTimezone},
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	{time.ANSIC, TimeFormatNoTimezone},
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	{time.UnixDate, TimeFormatNamedTimezone},
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	{time.RubyDate, TimeFormatNumericTimezone},
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	{"2006-01-02 15:04:05Z07:00", TimeFormatNumericTimezone},
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	{"02 Jan 2006", TimeFormatNoTimezone},
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	{"2006-01-02 15:04:05 -07:00", TimeFormatNumericTimezone},
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	{"2006-01-02 15:04:05 -0700", TimeFormatNumericTimezone},
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	{time.Kitchen, TimeFormatTimeOnly},
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	{time.Stamp, TimeFormatTimeOnly},
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	{time.StampMilli, TimeFormatTimeOnly},
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	{time.StampMicro, TimeFormatTimeOnly},
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	{time.StampNano, TimeFormatTimeOnly},
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}
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func ParseDateWith(s string, location *time.Location, formats []TimeFormat) (d time.Time, e error) {
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	for _, format := range formats {
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		if d, e = time.Parse(format.Format, s); e == nil {
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			// Some time formats have a zone name, but no offset, so it gets
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			// put in that zone name (not the default one passed in to us), but
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			// without that zone's offset. So set the location manually.
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			if format.Typ <= TimeFormatNamedTimezone {
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				if location == nil {
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					location = time.Local
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				}
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				year, month, day := d.Date()
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				hour, min, sec := d.Clock()
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				d = time.Date(year, month, day, hour, min, sec, d.Nanosecond(), location)
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			}
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			return
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		}
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	}
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	return d, fmt.Errorf("unable to parse date: %s", s)
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}
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