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gotosocial/vendor/github.com/ncruces/go-strftime/strftime.go

325 lines
7.0 KiB
Go

package strftime
import (
"bytes"
"strconv"
"time"
)
// Format returns a textual representation of the time value
// formatted according to the strftime format specification.
func Format(fmt string, t time.Time) string {
buf := buffer(fmt)
return string(AppendFormat(buf, fmt, t))
}
// AppendFormat is like Format, but appends the textual representation
// to dst and returns the extended buffer.
func AppendFormat(dst []byte, fmt string, t time.Time) []byte {
var parser parser
parser.literal = func(b byte) error {
dst = append(dst, b)
return nil
}
parser.format = func(spec, flag byte) error {
switch spec {
case 'A':
dst = append(dst, t.Weekday().String()...)
return nil
case 'a':
dst = append(dst, t.Weekday().String()[:3]...)
return nil
case 'B':
dst = append(dst, t.Month().String()...)
return nil
case 'b', 'h':
dst = append(dst, t.Month().String()[:3]...)
return nil
case 'm':
dst = appendInt2(dst, int(t.Month()), flag)
return nil
case 'd':
dst = appendInt2(dst, int(t.Day()), flag)
return nil
case 'e':
dst = appendInt2(dst, int(t.Day()), ' ')
return nil
case 'I':
dst = append12Hour(dst, t, flag)
return nil
case 'l':
dst = append12Hour(dst, t, ' ')
return nil
case 'H':
dst = appendInt2(dst, t.Hour(), flag)
return nil
case 'k':
dst = appendInt2(dst, t.Hour(), ' ')
return nil
case 'M':
dst = appendInt2(dst, t.Minute(), flag)
return nil
case 'S':
dst = appendInt2(dst, t.Second(), flag)
return nil
case 'L':
dst = append(dst, t.Format(".000")[1:]...)
return nil
case 'f':
dst = append(dst, t.Format(".000000")[1:]...)
return nil
case 'N':
dst = append(dst, t.Format(".000000000")[1:]...)
return nil
case 'y':
dst = t.AppendFormat(dst, "06")
return nil
case 'Y':
dst = t.AppendFormat(dst, "2006")
return nil
case 'C':
dst = t.AppendFormat(dst, "2006")
dst = dst[:len(dst)-2]
return nil
case 'U':
dst = appendWeekNumber(dst, t, flag, true)
return nil
case 'W':
dst = appendWeekNumber(dst, t, flag, false)
return nil
case 'V':
_, w := t.ISOWeek()
dst = appendInt2(dst, w, flag)
return nil
case 'g':
y, _ := t.ISOWeek()
dst = year(y).AppendFormat(dst, "06")
return nil
case 'G':
y, _ := t.ISOWeek()
dst = year(y).AppendFormat(dst, "2006")
return nil
case 's':
dst = strconv.AppendInt(dst, t.Unix(), 10)
return nil
case 'Q':
dst = strconv.AppendInt(dst, t.UnixMilli(), 10)
return nil
case 'w':
w := t.Weekday()
dst = appendInt1(dst, int(w))
return nil
case 'u':
if w := t.Weekday(); w == 0 {
dst = append(dst, '7')
} else {
dst = appendInt1(dst, int(w))
}
return nil
case 'j':
if flag == '-' {
dst = strconv.AppendInt(dst, int64(t.YearDay()), 10)
} else {
dst = t.AppendFormat(dst, "002")
}
return nil
}
if layout := goLayout(spec, flag, false); layout != "" {
dst = t.AppendFormat(dst, layout)
return nil
}
dst = append(dst, '%')
if flag != 0 {
dst = append(dst, flag)
}
dst = append(dst, spec)
return nil
}
parser.parse(fmt)
return dst
}
// Parse converts a textual representation of time to the time value it represents
// according to the strptime format specification.
func Parse(fmt, value string) (time.Time, error) {
pattern, err := layout(fmt, true)
if err != nil {
return time.Time{}, err
}
return time.Parse(pattern, value)
}
// Layout converts a strftime format specification
// to a Go time pattern specification.
func Layout(fmt string) (string, error) {
return layout(fmt, false)
}
func layout(fmt string, parsing bool) (string, error) {
dst := buffer(fmt)
var parser parser
parser.literal = func(b byte) error {
if '0' <= b && b <= '9' {
return literalErr(b)
}
dst = append(dst, b)
if b == 'M' || b == 'T' || b == 'm' || b == 'n' {
switch {
case bytes.HasSuffix(dst, []byte("Jan")):
return literalErr("Jan")
case bytes.HasSuffix(dst, []byte("Mon")):
return literalErr("Mon")
case bytes.HasSuffix(dst, []byte("MST")):
return literalErr("MST")
case bytes.HasSuffix(dst, []byte("PM")):
return literalErr("PM")
case bytes.HasSuffix(dst, []byte("pm")):
return literalErr("pm")
}
}
return nil
}
parser.format = func(spec, flag byte) error {
if layout := goLayout(spec, flag, parsing); layout != "" {
dst = append(dst, layout...)
return nil
}
switch spec {
default:
return formatError{}
case 'L', 'f', 'N':
if bytes.HasSuffix(dst, []byte(".")) || bytes.HasSuffix(dst, []byte(",")) {
switch spec {
default:
dst = append(dst, "000"...)
case 'f':
dst = append(dst, "000000"...)
case 'N':
dst = append(dst, "000000000"...)
}
return nil
}
return formatError{message: "must follow '.' or ','"}
}
}
if err := parser.parse(fmt); err != nil {
return "", err
}
return string(dst), nil
}
// UTS35 converts a strftime format specification
// to a Unicode Technical Standard #35 Date Format Pattern.
func UTS35(fmt string) (string, error) {
const quote = '\''
var quoted bool
dst := buffer(fmt)
var parser parser
parser.literal = func(b byte) error {
if b == quote {
dst = append(dst, quote, quote)
return nil
}
if !quoted && ('a' <= b && b <= 'z' || 'A' <= b && b <= 'Z') {
dst = append(dst, quote)
quoted = true
}
dst = append(dst, b)
return nil
}
parser.format = func(spec, flag byte) error {
if quoted {
dst = append(dst, quote)
quoted = false
}
if pattern := uts35Pattern(spec, flag); pattern != "" {
dst = append(dst, pattern...)
return nil
}
return formatError{}
}
if err := parser.parse(fmt); err != nil {
return "", err
}
if quoted {
dst = append(dst, quote)
}
return string(dst), nil
}
func buffer(format string) (buf []byte) {
const bufSize = 64
max := len(format) + 10
if max < bufSize {
var b [bufSize]byte
buf = b[:0]
} else {
buf = make([]byte, 0, max)
}
return
}
func year(y int) time.Time {
return time.Date(y, time.January, 1, 0, 0, 0, 0, time.UTC)
}
func appendWeekNumber(dst []byte, t time.Time, flag byte, sunday bool) []byte {
offset := int(t.Weekday())
if sunday {
offset = 6 - offset
} else if offset != 0 {
offset = 7 - offset
}
return appendInt2(dst, (t.YearDay()+offset)/7, flag)
}
func append12Hour(dst []byte, t time.Time, flag byte) []byte {
h := t.Hour()
if h == 0 {
h = 12
} else if h > 12 {
h -= 12
}
return appendInt2(dst, h, flag)
}
func appendInt1(dst []byte, i int) []byte {
return append(dst, byte('0'+i))
}
func appendInt2(dst []byte, i int, flag byte) []byte {
if flag == 0 || i >= 10 {
return append(dst, smallsString[i*2:i*2+2]...)
}
if flag == ' ' {
dst = append(dst, flag)
}
return appendInt1(dst, i)
}
const smallsString = "" +
"00010203040506070809" +
"10111213141516171819" +
"20212223242526272829" +
"30313233343536373839" +
"40414243444546474849" +
"50515253545556575859" +
"60616263646566676869" +
"70717273747576777879" +
"80818283848586878889" +
"90919293949596979899"