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gcc/libgo/go/time/format.go
Ian Lance Taylor f75af8c146 libgo: update to go1.15rc1 
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/245157
2020-08-01 11:21:40 -07:00

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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package time
import "errors"
// These are predefined layouts for use in Time.Format and time.Parse.
// The reference time used in the layouts is the specific time:
// Mon Jan 2 15:04:05 MST 2006
// which is Unix time 1136239445. Since MST is GMT-0700,
// the reference time can be thought of as
// 01/02 03:04:05PM '06 -0700
// To define your own format, write down what the reference time would look
// like formatted your way; see the values of constants like ANSIC,
// StampMicro or Kitchen for examples. The model is to demonstrate what the
// reference time looks like so that the Format and Parse methods can apply
// the same transformation to a general time value.
//
// Some valid layouts are invalid time values for time.Parse, due to formats
// such as _ for space padding and Z for zone information.
//
// Within the format string, an underscore _ represents a space that may be
// replaced by a digit if the following number (a day) has two digits; for
// compatibility with fixed-width Unix time formats.
//
// A decimal point followed by one or more zeros represents a fractional
// second, printed to the given number of decimal places. A decimal point
// followed by one or more nines represents a fractional second, printed to
// the given number of decimal places, with trailing zeros removed.
// When parsing (only), the input may contain a fractional second
// field immediately after the seconds field, even if the layout does not
// signify its presence. In that case a decimal point followed by a maximal
// series of digits is parsed as a fractional second.
//
// Numeric time zone offsets format as follows:
// -0700 ±hhmm
// -07:00 ±hh:mm
// -07 ±hh
// Replacing the sign in the format with a Z triggers
// the ISO 8601 behavior of printing Z instead of an
// offset for the UTC zone. Thus:
// Z0700 Z or ±hhmm
// Z07:00 Z or ±hh:mm
// Z07 Z or ±hh
//
// The recognized day of week formats are "Mon" and "Monday".
// The recognized month formats are "Jan" and "January".
//
// The formats 2, _2, and 02 are unpadded, space-padded, and zero-padded
// day of month. The formats __2 and 002 are space-padded and zero-padded
// three-character day of year; there is no unpadded day of year format.
//
// Text in the format string that is not recognized as part of the reference
// time is echoed verbatim during Format and expected to appear verbatim
// in the input to Parse.
//
// The executable example for Time.Format demonstrates the working
// of the layout string in detail and is a good reference.
//
// Note that the RFC822, RFC850, and RFC1123 formats should be applied
// only to local times. Applying them to UTC times will use "UTC" as the
// time zone abbreviation, while strictly speaking those RFCs require the
// use of "GMT" in that case.
// In general RFC1123Z should be used instead of RFC1123 for servers
// that insist on that format, and RFC3339 should be preferred for new protocols.
// RFC3339, RFC822, RFC822Z, RFC1123, and RFC1123Z are useful for formatting;
// when used with time.Parse they do not accept all the time formats
// permitted by the RFCs and they do accept time formats not formally defined.
// The RFC3339Nano format removes trailing zeros from the seconds field
// and thus may not sort correctly once formatted.
const (
ANSIC = "Mon Jan _2 15:04:05 2006"
UnixDate = "Mon Jan _2 15:04:05 MST 2006"
RubyDate = "Mon Jan 02 15:04:05 -0700 2006"
RFC822 = "02 Jan 06 15:04 MST"
RFC822Z = "02 Jan 06 15:04 -0700" // RFC822 with numeric zone
RFC850 = "Monday, 02-Jan-06 15:04:05 MST"
RFC1123 = "Mon, 02 Jan 2006 15:04:05 MST"
RFC1123Z = "Mon, 02 Jan 2006 15:04:05 -0700" // RFC1123 with numeric zone
RFC3339 = "2006-01-02T15:04:05Z07:00"
RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00"
Kitchen = "3:04PM"
// Handy time stamps.
Stamp = "Jan _2 15:04:05"
StampMilli = "Jan _2 15:04:05.000"
StampMicro = "Jan _2 15:04:05.000000"
StampNano = "Jan _2 15:04:05.000000000"
)
const (
_ = iota
stdLongMonth = iota + stdNeedDate // "January"
stdMonth // "Jan"
stdNumMonth // "1"
stdZeroMonth // "01"
stdLongWeekDay // "Monday"
stdWeekDay // "Mon"
stdDay // "2"
stdUnderDay // "_2"
stdZeroDay // "02"
stdUnderYearDay // "__2"
stdZeroYearDay // "002"
stdHour = iota + stdNeedClock // "15"
stdHour12 // "3"
stdZeroHour12 // "03"
stdMinute // "4"
stdZeroMinute // "04"
stdSecond // "5"
stdZeroSecond // "05"
stdLongYear = iota + stdNeedDate // "2006"
stdYear // "06"
stdPM = iota + stdNeedClock // "PM"
stdpm // "pm"
stdTZ = iota // "MST"
stdISO8601TZ // "Z0700" // prints Z for UTC
stdISO8601SecondsTZ // "Z070000"
stdISO8601ShortTZ // "Z07"
stdISO8601ColonTZ // "Z07:00" // prints Z for UTC
stdISO8601ColonSecondsTZ // "Z07:00:00"
stdNumTZ // "-0700" // always numeric
stdNumSecondsTz // "-070000"
stdNumShortTZ // "-07" // always numeric
stdNumColonTZ // "-07:00" // always numeric
stdNumColonSecondsTZ // "-07:00:00"
stdFracSecond0 // ".0", ".00", ... , trailing zeros included
stdFracSecond9 // ".9", ".99", ..., trailing zeros omitted
stdNeedDate = 1 << 8 // need month, day, year
stdNeedClock = 2 << 8 // need hour, minute, second
stdArgShift = 16 // extra argument in high bits, above low stdArgShift
stdMask = 1<<stdArgShift - 1 // mask out argument
)
// std0x records the std values for "01", "02", ..., "06".
var std0x = [...]int{stdZeroMonth, stdZeroDay, stdZeroHour12, stdZeroMinute, stdZeroSecond, stdYear}
// startsWithLowerCase reports whether the string has a lower-case letter at the beginning.
// Its purpose is to prevent matching strings like "Month" when looking for "Mon".
func startsWithLowerCase(str string) bool {
if len(str) == 0 {
return false
}
c := str[0]
return 'a' <= c && c <= 'z'
}
// nextStdChunk finds the first occurrence of a std string in
// layout and returns the text before, the std string, and the text after.
func nextStdChunk(layout string) (prefix string, std int, suffix string) {
for i := 0; i < len(layout); i++ {
switch c := int(layout[i]); c {
case 'J': // January, Jan
if len(layout) >= i+3 && layout[i:i+3] == "Jan" {
if len(layout) >= i+7 && layout[i:i+7] == "January" {
return layout[0:i], stdLongMonth, layout[i+7:]
}
if !startsWithLowerCase(layout[i+3:]) {
return layout[0:i], stdMonth, layout[i+3:]
}
}
case 'M': // Monday, Mon, MST
if len(layout) >= i+3 {
if layout[i:i+3] == "Mon" {
if len(layout) >= i+6 && layout[i:i+6] == "Monday" {
return layout[0:i], stdLongWeekDay, layout[i+6:]
}
if !startsWithLowerCase(layout[i+3:]) {
return layout[0:i], stdWeekDay, layout[i+3:]
}
}
if layout[i:i+3] == "MST" {
return layout[0:i], stdTZ, layout[i+3:]
}
}
case '0': // 01, 02, 03, 04, 05, 06, 002
if len(layout) >= i+2 && '1' <= layout[i+1] && layout[i+1] <= '6' {
return layout[0:i], std0x[layout[i+1]-'1'], layout[i+2:]
}
if len(layout) >= i+3 && layout[i+1] == '0' && layout[i+2] == '2' {
return layout[0:i], stdZeroYearDay, layout[i+3:]
}
case '1': // 15, 1
if len(layout) >= i+2 && layout[i+1] == '5' {
return layout[0:i], stdHour, layout[i+2:]
}
return layout[0:i], stdNumMonth, layout[i+1:]
case '2': // 2006, 2
if len(layout) >= i+4 && layout[i:i+4] == "2006" {
return layout[0:i], stdLongYear, layout[i+4:]
}
return layout[0:i], stdDay, layout[i+1:]
case '_': // _2, _2006, __2
if len(layout) >= i+2 && layout[i+1] == '2' {
//_2006 is really a literal _, followed by stdLongYear
if len(layout) >= i+5 && layout[i+1:i+5] == "2006" {
return layout[0 : i+1], stdLongYear, layout[i+5:]
}
return layout[0:i], stdUnderDay, layout[i+2:]
}
if len(layout) >= i+3 && layout[i+1] == '_' && layout[i+2] == '2' {
return layout[0:i], stdUnderYearDay, layout[i+3:]
}
case '3':
return layout[0:i], stdHour12, layout[i+1:]
case '4':
return layout[0:i], stdMinute, layout[i+1:]
case '5':
return layout[0:i], stdSecond, layout[i+1:]
case 'P': // PM
if len(layout) >= i+2 && layout[i+1] == 'M' {
return layout[0:i], stdPM, layout[i+2:]
}
case 'p': // pm
if len(layout) >= i+2 && layout[i+1] == 'm' {
return layout[0:i], stdpm, layout[i+2:]
}
case '-': // -070000, -07:00:00, -0700, -07:00, -07
if len(layout) >= i+7 && layout[i:i+7] == "-070000" {
return layout[0:i], stdNumSecondsTz, layout[i+7:]
}
if len(layout) >= i+9 && layout[i:i+9] == "-07:00:00" {
return layout[0:i], stdNumColonSecondsTZ, layout[i+9:]
}
if len(layout) >= i+5 && layout[i:i+5] == "-0700" {
return layout[0:i], stdNumTZ, layout[i+5:]
}
if len(layout) >= i+6 && layout[i:i+6] == "-07:00" {
return layout[0:i], stdNumColonTZ, layout[i+6:]
}
if len(layout) >= i+3 && layout[i:i+3] == "-07" {
return layout[0:i], stdNumShortTZ, layout[i+3:]
}
case 'Z': // Z070000, Z07:00:00, Z0700, Z07:00,
if len(layout) >= i+7 && layout[i:i+7] == "Z070000" {
return layout[0:i], stdISO8601SecondsTZ, layout[i+7:]
}
if len(layout) >= i+9 && layout[i:i+9] == "Z07:00:00" {
return layout[0:i], stdISO8601ColonSecondsTZ, layout[i+9:]
}
if len(layout) >= i+5 && layout[i:i+5] == "Z0700" {
return layout[0:i], stdISO8601TZ, layout[i+5:]
}
if len(layout) >= i+6 && layout[i:i+6] == "Z07:00" {
return layout[0:i], stdISO8601ColonTZ, layout[i+6:]
}
if len(layout) >= i+3 && layout[i:i+3] == "Z07" {
return layout[0:i], stdISO8601ShortTZ, layout[i+3:]
}
case '.': // .000 or .999 - repeated digits for fractional seconds.
if i+1 < len(layout) && (layout[i+1] == '0' || layout[i+1] == '9') {
ch := layout[i+1]
j := i + 1
for j < len(layout) && layout[j] == ch {
j++
}
// String of digits must end here - only fractional second is all digits.
if !isDigit(layout, j) {
std := stdFracSecond0
if layout[i+1] == '9' {
std = stdFracSecond9
}
std |= (j - (i + 1)) << stdArgShift
return layout[0:i], std, layout[j:]
}
}
}
}
return layout, 0, ""
}
var longDayNames = []string{
"Sunday",
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday",
}
var shortDayNames = []string{
"Sun",
"Mon",
"Tue",
"Wed",
"Thu",
"Fri",
"Sat",
}
var shortMonthNames = []string{
"Jan",
"Feb",
"Mar",
"Apr",
"May",
"Jun",
"Jul",
"Aug",
"Sep",
"Oct",
"Nov",
"Dec",
}
var longMonthNames = []string{
"January",
"February",
"March",
"April",
"May",
"June",
"July",
"August",
"September",
"October",
"November",
"December",
}
// match reports whether s1 and s2 match ignoring case.
// It is assumed s1 and s2 are the same length.
func match(s1, s2 string) bool {
for i := 0; i < len(s1); i++ {
c1 := s1[i]
c2 := s2[i]
if c1 != c2 {
// Switch to lower-case; 'a'-'A' is known to be a single bit.
c1 |= 'a' - 'A'
c2 |= 'a' - 'A'
if c1 != c2 || c1 < 'a' || c1 > 'z' {
return false
}
}
}
return true
}
func lookup(tab []string, val string) (int, string, error) {
for i, v := range tab {
if len(val) >= len(v) && match(val[0:len(v)], v) {
return i, val[len(v):], nil
}
}
return -1, val, errBad
}
// appendInt appends the decimal form of x to b and returns the result.
// If the decimal form (excluding sign) is shorter than width, the result is padded with leading 0's.
// Duplicates functionality in strconv, but avoids dependency.
func appendInt(b []byte, x int, width int) []byte {
u := uint(x)
if x < 0 {
b = append(b, '-')
u = uint(-x)
}
// Assemble decimal in reverse order.
var buf [20]byte
i := len(buf)
for u >= 10 {
i--
q := u / 10
buf[i] = byte('0' + u - q*10)
u = q
}
i--
buf[i] = byte('0' + u)
// Add 0-padding.
for w := len(buf) - i; w < width; w++ {
b = append(b, '0')
}
return append(b, buf[i:]...)
}
// Never printed, just needs to be non-nil for return by atoi.
var atoiError = errors.New("time: invalid number")
// Duplicates functionality in strconv, but avoids dependency.
func atoi(s string) (x int, err error) {
neg := false
if s != "" && (s[0] == '-' || s[0] == '+') {
neg = s[0] == '-'
s = s[1:]
}
q, rem, err := leadingInt(s)
x = int(q)
if err != nil || rem != "" {
return 0, atoiError
}
if neg {
x = -x
}
return x, nil
}
// formatNano appends a fractional second, as nanoseconds, to b
// and returns the result.
func formatNano(b []byte, nanosec uint, n int, trim bool) []byte {
u := nanosec
var buf [9]byte
for start := len(buf); start > 0; {
start--
buf[start] = byte(u%10 + '0')
u /= 10
}
if n > 9 {
n = 9
}
if trim {
for n > 0 && buf[n-1] == '0' {
n--
}
if n == 0 {
return b
}
}
b = append(b, '.')
return append(b, buf[:n]...)
}
// String returns the time formatted using the format string
// "2006-01-02 15:04:05.999999999 -0700 MST"
//
// If the time has a monotonic clock reading, the returned string
// includes a final field "m=±<value>", where value is the monotonic
// clock reading formatted as a decimal number of seconds.
//
// The returned string is meant for debugging; for a stable serialized
// representation, use t.MarshalText, t.MarshalBinary, or t.Format
// with an explicit format string.
func (t Time) String() string {
s := t.Format("2006-01-02 15:04:05.999999999 -0700 MST")
// Format monotonic clock reading as m=±ddd.nnnnnnnnn.
if t.wall&hasMonotonic != 0 {
m2 := uint64(t.ext)
sign := byte('+')
if t.ext < 0 {
sign = '-'
m2 = -m2
}
m1, m2 := m2/1e9, m2%1e9
m0, m1 := m1/1e9, m1%1e9
var buf []byte
buf = append(buf, " m="...)
buf = append(buf, sign)
wid := 0
if m0 != 0 {
buf = appendInt(buf, int(m0), 0)
wid = 9
}
buf = appendInt(buf, int(m1), wid)
buf = append(buf, '.')
buf = appendInt(buf, int(m2), 9)
s += string(buf)
}
return s
}
// Format returns a textual representation of the time value formatted
// according to layout, which defines the format by showing how the reference
// time, defined to be
// Mon Jan 2 15:04:05 -0700 MST 2006
// would be displayed if it were the value; it serves as an example of the
// desired output. The same display rules will then be applied to the time
// value.
//
// A fractional second is represented by adding a period and zeros
// to the end of the seconds section of layout string, as in "15:04:05.000"
// to format a time stamp with millisecond precision.
//
// Predefined layouts ANSIC, UnixDate, RFC3339 and others describe standard
// and convenient representations of the reference time. For more information
// about the formats and the definition of the reference time, see the
// documentation for ANSIC and the other constants defined by this package.
func (t Time) Format(layout string) string {
const bufSize = 64
var b []byte
max := len(layout) + 10
if max < bufSize {
var buf [bufSize]byte
b = buf[:0]
} else {
b = make([]byte, 0, max)
}
b = t.AppendFormat(b, layout)
return string(b)
}
// AppendFormat is like Format but appends the textual
// representation to b and returns the extended buffer.
func (t Time) AppendFormat(b []byte, layout string) []byte {
var (
name, offset, abs = t.locabs()
year int = -1
month Month
day int
yday int
hour int = -1
min int
sec int
)
// Each iteration generates one std value.
for layout != "" {
prefix, std, suffix := nextStdChunk(layout)
if prefix != "" {
b = append(b, prefix...)
}
if std == 0 {
break
}
layout = suffix
// Compute year, month, day if needed.
if year < 0 && std&stdNeedDate != 0 {
year, month, day, yday = absDate(abs, true)
yday++
}
// Compute hour, minute, second if needed.
if hour < 0 && std&stdNeedClock != 0 {
hour, min, sec = absClock(abs)
}
switch std & stdMask {
case stdYear:
y := year
if y < 0 {
y = -y
}
b = appendInt(b, y%100, 2)
case stdLongYear:
b = appendInt(b, year, 4)
case stdMonth:
b = append(b, month.String()[:3]...)
case stdLongMonth:
m := month.String()
b = append(b, m...)
case stdNumMonth:
b = appendInt(b, int(month), 0)
case stdZeroMonth:
b = appendInt(b, int(month), 2)
case stdWeekDay:
b = append(b, absWeekday(abs).String()[:3]...)
case stdLongWeekDay:
s := absWeekday(abs).String()
b = append(b, s...)
case stdDay:
b = appendInt(b, day, 0)
case stdUnderDay:
if day < 10 {
b = append(b, ' ')
}
b = appendInt(b, day, 0)
case stdZeroDay:
b = appendInt(b, day, 2)
case stdUnderYearDay:
if yday < 100 {
b = append(b, ' ')
if yday < 10 {
b = append(b, ' ')
}
}
b = appendInt(b, yday, 0)
case stdZeroYearDay:
b = appendInt(b, yday, 3)
case stdHour:
b = appendInt(b, hour, 2)
case stdHour12:
// Noon is 12PM, midnight is 12AM.
hr := hour % 12
if hr == 0 {
hr = 12
}
b = appendInt(b, hr, 0)
case stdZeroHour12:
// Noon is 12PM, midnight is 12AM.
hr := hour % 12
if hr == 0 {
hr = 12
}
b = appendInt(b, hr, 2)
case stdMinute:
b = appendInt(b, min, 0)
case stdZeroMinute:
b = appendInt(b, min, 2)
case stdSecond:
b = appendInt(b, sec, 0)
case stdZeroSecond:
b = appendInt(b, sec, 2)
case stdPM:
if hour >= 12 {
b = append(b, "PM"...)
} else {
b = append(b, "AM"...)
}
case stdpm:
if hour >= 12 {
b = append(b, "pm"...)
} else {
b = append(b, "am"...)
}
case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumColonTZ, stdNumSecondsTz, stdNumShortTZ, stdNumColonSecondsTZ:
// Ugly special case. We cheat and take the "Z" variants
// to mean "the time zone as formatted for ISO 8601".
if offset == 0 && (std == stdISO8601TZ || std == stdISO8601ColonTZ || std == stdISO8601SecondsTZ || std == stdISO8601ShortTZ || std == stdISO8601ColonSecondsTZ) {
b = append(b, 'Z')
break
}
zone := offset / 60 // convert to minutes
absoffset := offset
if zone < 0 {
b = append(b, '-')
zone = -zone
absoffset = -absoffset
} else {
b = append(b, '+')
}
b = appendInt(b, zone/60, 2)
if std == stdISO8601ColonTZ || std == stdNumColonTZ || std == stdISO8601ColonSecondsTZ || std == stdNumColonSecondsTZ {
b = append(b, ':')
}
if std != stdNumShortTZ && std != stdISO8601ShortTZ {
b = appendInt(b, zone%60, 2)
}
// append seconds if appropriate
if std == stdISO8601SecondsTZ || std == stdNumSecondsTz || std == stdNumColonSecondsTZ || std == stdISO8601ColonSecondsTZ {
if std == stdNumColonSecondsTZ || std == stdISO8601ColonSecondsTZ {
b = append(b, ':')
}
b = appendInt(b, absoffset%60, 2)
}
case stdTZ:
if name != "" {
b = append(b, name...)
break
}
// No time zone known for this time, but we must print one.
// Use the -0700 format.
zone := offset / 60 // convert to minutes
if zone < 0 {
b = append(b, '-')
zone = -zone
} else {
b = append(b, '+')
}
b = appendInt(b, zone/60, 2)
b = appendInt(b, zone%60, 2)
case stdFracSecond0, stdFracSecond9:
b = formatNano(b, uint(t.Nanosecond()), std>>stdArgShift, std&stdMask == stdFracSecond9)
}
}
return b
}
var errBad = errors.New("bad value for field") // placeholder not passed to user
// ParseError describes a problem parsing a time string.
type ParseError struct {
Layout string
Value string
LayoutElem string
ValueElem string
Message string
}
func quote(s string) string {
return "\"" + s + "\""
}
// Error returns the string representation of a ParseError.
func (e *ParseError) Error() string {
if e.Message == "" {
return "parsing time " +
quote(e.Value) + " as " +
quote(e.Layout) + ": cannot parse " +
quote(e.ValueElem) + " as " +
quote(e.LayoutElem)
}
return "parsing time " +
quote(e.Value) + e.Message
}
// isDigit reports whether s[i] is in range and is a decimal digit.
func isDigit(s string, i int) bool {
if len(s) <= i {
return false
}
c := s[i]
return '0' <= c && c <= '9'
}
// getnum parses s[0:1] or s[0:2] (fixed forces s[0:2])
// as a decimal integer and returns the integer and the
// remainder of the string.
func getnum(s string, fixed bool) (int, string, error) {
if !isDigit(s, 0) {
return 0, s, errBad
}
if !isDigit(s, 1) {
if fixed {
return 0, s, errBad
}
return int(s[0] - '0'), s[1:], nil
}
return int(s[0]-'0')*10 + int(s[1]-'0'), s[2:], nil
}
// getnum3 parses s[0:1], s[0:2], or s[0:3] (fixed forces s[0:3])
// as a decimal integer and returns the integer and the remainder
// of the string.
func getnum3(s string, fixed bool) (int, string, error) {
var n, i int
for i = 0; i < 3 && isDigit(s, i); i++ {
n = n*10 + int(s[i]-'0')
}
if i == 0 || fixed && i != 3 {
return 0, s, errBad
}
return n, s[i:], nil
}
func cutspace(s string) string {
for len(s) > 0 && s[0] == ' ' {
s = s[1:]
}
return s
}
// skip removes the given prefix from value,
// treating runs of space characters as equivalent.
func skip(value, prefix string) (string, error) {
for len(prefix) > 0 {
if prefix[0] == ' ' {
if len(value) > 0 && value[0] != ' ' {
return value, errBad
}
prefix = cutspace(prefix)
value = cutspace(value)
continue
}
if len(value) == 0 || value[0] != prefix[0] {
return value, errBad
}
prefix = prefix[1:]
value = value[1:]
}
return value, nil
}
// Parse parses a formatted string and returns the time value it represents.
// The layout defines the format by showing how the reference time,
// defined to be
// Mon Jan 2 15:04:05 -0700 MST 2006
// would be interpreted if it were the value; it serves as an example of
// the input format. The same interpretation will then be made to the
// input string.
//
// Predefined layouts ANSIC, UnixDate, RFC3339 and others describe standard
// and convenient representations of the reference time. For more information
// about the formats and the definition of the reference time, see the
// documentation for ANSIC and the other constants defined by this package.
// Also, the executable example for Time.Format demonstrates the working
// of the layout string in detail and is a good reference.
//
// Elements omitted from the value are assumed to be zero or, when
// zero is impossible, one, so parsing "3:04pm" returns the time
// corresponding to Jan 1, year 0, 15:04:00 UTC (note that because the year is
// 0, this time is before the zero Time).
// Years must be in the range 0000..9999. The day of the week is checked
// for syntax but it is otherwise ignored.
//
// For layouts specifying the two-digit year 06, a value NN >= 69 will be treated
// as 19NN and a value NN < 69 will be treated as 20NN.
//
// In the absence of a time zone indicator, Parse returns a time in UTC.
//
// When parsing a time with a zone offset like -0700, if the offset corresponds
// to a time zone used by the current location (Local), then Parse uses that
// location and zone in the returned time. Otherwise it records the time as
// being in a fabricated location with time fixed at the given zone offset.
//
// When parsing a time with a zone abbreviation like MST, if the zone abbreviation
// has a defined offset in the current location, then that offset is used.
// The zone abbreviation "UTC" is recognized as UTC regardless of location.
// If the zone abbreviation is unknown, Parse records the time as being
// in a fabricated location with the given zone abbreviation and a zero offset.
// This choice means that such a time can be parsed and reformatted with the
// same layout losslessly, but the exact instant used in the representation will
// differ by the actual zone offset. To avoid such problems, prefer time layouts
// that use a numeric zone offset, or use ParseInLocation.
func Parse(layout, value string) (Time, error) {
return parse(layout, value, UTC, Local)
}
// ParseInLocation is like Parse but differs in two important ways.
// First, in the absence of time zone information, Parse interprets a time as UTC;
// ParseInLocation interprets the time as in the given location.
// Second, when given a zone offset or abbreviation, Parse tries to match it
// against the Local location; ParseInLocation uses the given location.
func ParseInLocation(layout, value string, loc *Location) (Time, error) {
return parse(layout, value, loc, loc)
}
func parse(layout, value string, defaultLocation, local *Location) (Time, error) {
alayout, avalue := layout, value
rangeErrString := "" // set if a value is out of range
amSet := false // do we need to subtract 12 from the hour for midnight?
pmSet := false // do we need to add 12 to the hour?
// Time being constructed.
var (
year int
month int = -1
day int = -1
yday int = -1
hour int
min int
sec int
nsec int
z *Location
zoneOffset int = -1
zoneName string
)
// Each iteration processes one std value.
for {
var err error
prefix, std, suffix := nextStdChunk(layout)
stdstr := layout[len(prefix) : len(layout)-len(suffix)]
value, err = skip(value, prefix)
if err != nil {
return Time{}, &ParseError{alayout, avalue, prefix, value, ""}
}
if std == 0 {
if len(value) != 0 {
return Time{}, &ParseError{alayout, avalue, "", value, ": extra text: " + quote(value)}
}
break
}
layout = suffix
var p string
switch std & stdMask {
case stdYear:
if len(value) < 2 {
err = errBad
break
}
hold := value
p, value = value[0:2], value[2:]
year, err = atoi(p)
if err != nil {
value = hold
} else if year >= 69 { // Unix time starts Dec 31 1969 in some time zones
year += 1900
} else {
year += 2000
}
case stdLongYear:
if len(value) < 4 || !isDigit(value, 0) {
err = errBad
break
}
p, value = value[0:4], value[4:]
year, err = atoi(p)
case stdMonth:
month, value, err = lookup(shortMonthNames, value)
month++
case stdLongMonth:
month, value, err = lookup(longMonthNames, value)
month++
case stdNumMonth, stdZeroMonth:
month, value, err = getnum(value, std == stdZeroMonth)
if err == nil && (month <= 0 || 12 < month) {
rangeErrString = "month"
}
case stdWeekDay:
// Ignore weekday except for error checking.
_, value, err = lookup(shortDayNames, value)
case stdLongWeekDay:
_, value, err = lookup(longDayNames, value)
case stdDay, stdUnderDay, stdZeroDay:
if std == stdUnderDay && len(value) > 0 && value[0] == ' ' {
value = value[1:]
}
day, value, err = getnum(value, std == stdZeroDay)
// Note that we allow any one- or two-digit day here.
// The month, day, year combination is validated after we've completed parsing.
case stdUnderYearDay, stdZeroYearDay:
for i := 0; i < 2; i++ {
if std == stdUnderYearDay && len(value) > 0 && value[0] == ' ' {
value = value[1:]
}
}
yday, value, err = getnum3(value, std == stdZeroYearDay)
// Note that we allow any one-, two-, or three-digit year-day here.
// The year-day, year combination is validated after we've completed parsing.
case stdHour:
hour, value, err = getnum(value, false)
if hour < 0 || 24 <= hour {
rangeErrString = "hour"
}
case stdHour12, stdZeroHour12:
hour, value, err = getnum(value, std == stdZeroHour12)
if hour < 0 || 12 < hour {
rangeErrString = "hour"
}
case stdMinute, stdZeroMinute:
min, value, err = getnum(value, std == stdZeroMinute)
if min < 0 || 60 <= min {
rangeErrString = "minute"
}
case stdSecond, stdZeroSecond:
sec, value, err = getnum(value, std == stdZeroSecond)
if sec < 0 || 60 <= sec {
rangeErrString = "second"
break
}
// Special case: do we have a fractional second but no
// fractional second in the format?
if len(value) >= 2 && value[0] == '.' && isDigit(value, 1) {
_, std, _ = nextStdChunk(layout)
std &= stdMask
if std == stdFracSecond0 || std == stdFracSecond9 {
// Fractional second in the layout; proceed normally
break
}
// No fractional second in the layout but we have one in the input.
n := 2
for ; n < len(value) && isDigit(value, n); n++ {
}
nsec, rangeErrString, err = parseNanoseconds(value, n)
value = value[n:]
}
case stdPM:
if len(value) < 2 {
err = errBad
break
}
p, value = value[0:2], value[2:]
switch p {
case "PM":
pmSet = true
case "AM":
amSet = true
default:
err = errBad
}
case stdpm:
if len(value) < 2 {
err = errBad
break
}
p, value = value[0:2], value[2:]
switch p {
case "pm":
pmSet = true
case "am":
amSet = true
default:
err = errBad
}
case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumShortTZ, stdNumColonTZ, stdNumSecondsTz, stdNumColonSecondsTZ:
if (std == stdISO8601TZ || std == stdISO8601ShortTZ || std == stdISO8601ColonTZ) && len(value) >= 1 && value[0] == 'Z' {
value = value[1:]
z = UTC
break
}
var sign, hour, min, seconds string
if std == stdISO8601ColonTZ || std == stdNumColonTZ {
if len(value) < 6 {
err = errBad
break
}
if value[3] != ':' {
err = errBad
break
}
sign, hour, min, seconds, value = value[0:1], value[1:3], value[4:6], "00", value[6:]
} else if std == stdNumShortTZ || std == stdISO8601ShortTZ {
if len(value) < 3 {
err = errBad
break
}
sign, hour, min, seconds, value = value[0:1], value[1:3], "00", "00", value[3:]
} else if std == stdISO8601ColonSecondsTZ || std == stdNumColonSecondsTZ {
if len(value) < 9 {
err = errBad
break
}
if value[3] != ':' || value[6] != ':' {
err = errBad
break
}
sign, hour, min, seconds, value = value[0:1], value[1:3], value[4:6], value[7:9], value[9:]
} else if std == stdISO8601SecondsTZ || std == stdNumSecondsTz {
if len(value) < 7 {
err = errBad
break
}
sign, hour, min, seconds, value = value[0:1], value[1:3], value[3:5], value[5:7], value[7:]
} else {
if len(value) < 5 {
err = errBad
break
}
sign, hour, min, seconds, value = value[0:1], value[1:3], value[3:5], "00", value[5:]
}
var hr, mm, ss int
hr, err = atoi(hour)
if err == nil {
mm, err = atoi(min)
}
if err == nil {
ss, err = atoi(seconds)
}
zoneOffset = (hr*60+mm)*60 + ss // offset is in seconds
switch sign[0] {
case '+':
case '-':
zoneOffset = -zoneOffset
default:
err = errBad
}
case stdTZ:
// Does it look like a time zone?
if len(value) >= 3 && value[0:3] == "UTC" {
z = UTC
value = value[3:]
break
}
n, ok := parseTimeZone(value)
if !ok {
err = errBad
break
}
zoneName, value = value[:n], value[n:]
case stdFracSecond0:
// stdFracSecond0 requires the exact number of digits as specified in
// the layout.
ndigit := 1 + (std >> stdArgShift)
if len(value) < ndigit {
err = errBad
break
}
nsec, rangeErrString, err = parseNanoseconds(value, ndigit)
value = value[ndigit:]
case stdFracSecond9:
if len(value) < 2 || value[0] != '.' || value[1] < '0' || '9' < value[1] {
// Fractional second omitted.
break
}
// Take any number of digits, even more than asked for,
// because it is what the stdSecond case would do.
i := 0
for i < 9 && i+1 < len(value) && '0' <= value[i+1] && value[i+1] <= '9' {
i++
}
nsec, rangeErrString, err = parseNanoseconds(value, 1+i)
value = value[1+i:]
}
if rangeErrString != "" {
return Time{}, &ParseError{alayout, avalue, stdstr, value, ": " + rangeErrString + " out of range"}
}
if err != nil {
return Time{}, &ParseError{alayout, avalue, stdstr, value, ""}
}
}
if pmSet && hour < 12 {
hour += 12
} else if amSet && hour == 12 {
hour = 0
}
// Convert yday to day, month.
if yday >= 0 {
var d int
var m int
if isLeap(year) {
if yday == 31+29 {
m = int(February)
d = 29
} else if yday > 31+29 {
yday--
}
}
if yday < 1 || yday > 365 {
return Time{}, &ParseError{alayout, avalue, "", value, ": day-of-year out of range"}
}
if m == 0 {
m = (yday-1)/31 + 1
if int(daysBefore[m]) < yday {
m++
}
d = yday - int(daysBefore[m-1])
}
// If month, day already seen, yday's m, d must match.
// Otherwise, set them from m, d.
if month >= 0 && month != m {
return Time{}, &ParseError{alayout, avalue, "", value, ": day-of-year does not match month"}
}
month = m
if day >= 0 && day != d {
return Time{}, &ParseError{alayout, avalue, "", value, ": day-of-year does not match day"}
}
day = d
} else {
if month < 0 {
month = int(January)
}
if day < 0 {
day = 1
}
}
// Validate the day of the month.
if day < 1 || day > daysIn(Month(month), year) {
return Time{}, &ParseError{alayout, avalue, "", value, ": day out of range"}
}
if z != nil {
return Date(year, Month(month), day, hour, min, sec, nsec, z), nil
}
if zoneOffset != -1 {
t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
t.addSec(-int64(zoneOffset))
// Look for local zone with the given offset.
// If that zone was in effect at the given time, use it.
name, offset, _, _ := local.lookup(t.unixSec())
if offset == zoneOffset && (zoneName == "" || name == zoneName) {
t.setLoc(local)
return t, nil
}
// Otherwise create fake zone to record offset.
t.setLoc(FixedZone(zoneName, zoneOffset))
return t, nil
}
if zoneName != "" {
t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
// Look for local zone with the given offset.
// If that zone was in effect at the given time, use it.
offset, ok := local.lookupName(zoneName, t.unixSec())
if ok {
t.addSec(-int64(offset))
t.setLoc(local)
return t, nil
}
// Otherwise, create fake zone with unknown offset.
if len(zoneName) > 3 && zoneName[:3] == "GMT" {
offset, _ = atoi(zoneName[3:]) // Guaranteed OK by parseGMT.
offset *= 3600
}
t.setLoc(FixedZone(zoneName, offset))
return t, nil
}
// Otherwise, fall back to default.
return Date(year, Month(month), day, hour, min, sec, nsec, defaultLocation), nil
}
// parseTimeZone parses a time zone string and returns its length. Time zones
// are human-generated and unpredictable. We can't do precise error checking.
// On the other hand, for a correct parse there must be a time zone at the
// beginning of the string, so it's almost always true that there's one
// there. We look at the beginning of the string for a run of upper-case letters.
// If there are more than 5, it's an error.
// If there are 4 or 5 and the last is a T, it's a time zone.
// If there are 3, it's a time zone.
// Otherwise, other than special cases, it's not a time zone.
// GMT is special because it can have an hour offset.
func parseTimeZone(value string) (length int, ok bool) {
if len(value) < 3 {
return 0, false
}
// Special case 1: ChST and MeST are the only zones with a lower-case letter.
if len(value) >= 4 && (value[:4] == "ChST" || value[:4] == "MeST") {
return 4, true
}
// Special case 2: GMT may have an hour offset; treat it specially.
if value[:3] == "GMT" {
length = parseGMT(value)
return length, true
}
// Special Case 3: Some time zones are not named, but have +/-00 format
if value[0] == '+' || value[0] == '-' {
length = parseSignedOffset(value)
ok := length > 0 // parseSignedOffset returns 0 in case of bad input
return length, ok
}
// How many upper-case letters are there? Need at least three, at most five.
var nUpper int
for nUpper = 0; nUpper < 6; nUpper++ {
if nUpper >= len(value) {
break
}
if c := value[nUpper]; c < 'A' || 'Z' < c {
break
}
}
switch nUpper {
case 0, 1, 2, 6:
return 0, false
case 5: // Must end in T to match.
if value[4] == 'T' {
return 5, true
}
case 4:
// Must end in T, except one special case.
if value[3] == 'T' || value[:4] == "WITA" {
return 4, true
}
case 3:
return 3, true
}
return 0, false
}
// parseGMT parses a GMT time zone. The input string is known to start "GMT".
// The function checks whether that is followed by a sign and a number in the
// range -23 through +23 excluding zero.
func parseGMT(value string) int {
value = value[3:]
if len(value) == 0 {
return 3
}
return 3 + parseSignedOffset(value)
}
// parseSignedOffset parses a signed timezone offset (e.g. "+03" or "-04").
// The function checks for a signed number in the range -23 through +23 excluding zero.
// Returns length of the found offset string or 0 otherwise
func parseSignedOffset(value string) int {
sign := value[0]
if sign != '-' && sign != '+' {
return 0
}
x, rem, err := leadingInt(value[1:])
// fail if nothing consumed by leadingInt
if err != nil || value[1:] == rem {
return 0
}
if sign == '-' {
x = -x
}
if x < -23 || 23 < x {
return 0
}
return len(value) - len(rem)
}
func parseNanoseconds(value string, nbytes int) (ns int, rangeErrString string, err error) {
if value[0] != '.' {
err = errBad
return
}
if ns, err = atoi(value[1:nbytes]); err != nil {
return
}
if ns < 0 || 1e9 <= ns {
rangeErrString = "fractional second"
return
}
// We need nanoseconds, which means scaling by the number
// of missing digits in the format, maximum length 10. If it's
// longer than 10, we won't scale.
scaleDigits := 10 - nbytes
for i := 0; i < scaleDigits; i++ {
ns *= 10
}
return
}
var errLeadingInt = errors.New("time: bad [0-9]*") // never printed
// leadingInt consumes the leading [0-9]* from s.
func leadingInt(s string) (x int64, rem string, err error) {
i := 0
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if x > (1<<63-1)/10 {
// overflow
return 0, "", errLeadingInt
}
x = x*10 + int64(c) - '0'
if x < 0 {
// overflow
return 0, "", errLeadingInt
}
}
return x, s[i:], nil
}
// leadingFraction consumes the leading [0-9]* from s.
// It is used only for fractions, so does not return an error on overflow,
// it just stops accumulating precision.
func leadingFraction(s string) (x int64, scale float64, rem string) {
i := 0
scale = 1
overflow := false
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if overflow {
continue
}
if x > (1<<63-1)/10 {
// It's possible for overflow to give a positive number, so take care.
overflow = true
continue
}
y := x*10 + int64(c) - '0'
if y < 0 {
overflow = true
continue
}
x = y
scale *= 10
}
return x, scale, s[i:]
}
var unitMap = map[string]int64{
"ns": int64(Nanosecond),
"us": int64(Microsecond),
"µs": int64(Microsecond), // U+00B5 = micro symbol
"μs": int64(Microsecond), // U+03BC = Greek letter mu
"ms": int64(Millisecond),
"s": int64(Second),
"m": int64(Minute),
"h": int64(Hour),
}
// ParseDuration parses a duration string.
// A duration string is a possibly signed sequence of
// decimal numbers, each with optional fraction and a unit suffix,
// such as "300ms", "-1.5h" or "2h45m".
// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
func ParseDuration(s string) (Duration, error) {
// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
orig := s
var d int64
neg := false
// Consume [-+]?
if s != "" {
c := s[0]
if c == '-' || c == '+' {
neg = c == '-'
s = s[1:]
}
}
// Special case: if all that is left is "0", this is zero.
if s == "0" {
return 0, nil
}
if s == "" {
return 0, errors.New("time: invalid duration " + quote(orig))
}
for s != "" {
var (
v, f int64 // integers before, after decimal point
scale float64 = 1 // value = v + f/scale
)
var err error
// The next character must be [0-9.]
if !(s[0] == '.' || '0' <= s[0] && s[0] <= '9') {
return 0, errors.New("time: invalid duration " + quote(orig))
}
// Consume [0-9]*
pl := len(s)
v, s, err = leadingInt(s)
if err != nil {
return 0, errors.New("time: invalid duration " + quote(orig))
}
pre := pl != len(s) // whether we consumed anything before a period
// Consume (\.[0-9]*)?
post := false
if s != "" && s[0] == '.' {
s = s[1:]
pl := len(s)
f, scale, s = leadingFraction(s)
post = pl != len(s)
}
if !pre && !post {
// no digits (e.g. ".s" or "-.s")
return 0, errors.New("time: invalid duration " + quote(orig))
}
// Consume unit.
i := 0
for ; i < len(s); i++ {
c := s[i]
if c == '.' || '0' <= c && c <= '9' {
break
}
}
if i == 0 {
return 0, errors.New("time: missing unit in duration " + quote(orig))
}
u := s[:i]
s = s[i:]
unit, ok := unitMap[u]
if !ok {
return 0, errors.New("time: unknown unit " + quote(u) + " in duration " + quote(orig))
}
if v > (1<<63-1)/unit {
// overflow
return 0, errors.New("time: invalid duration " + quote(orig))
}
v *= unit
if f > 0 {
// float64 is needed to be nanosecond accurate for fractions of hours.
// v >= 0 && (f*unit/scale) <= 3.6e+12 (ns/h, h is the largest unit)
v += int64(float64(f) * (float64(unit) / scale))
if v < 0 {
// overflow
return 0, errors.New("time: invalid duration " + quote(orig))
}
}
d += v
if d < 0 {
// overflow
return 0, errors.New("time: invalid duration " + quote(orig))
}
}
if neg {
d = -d
}
return Duration(d), nil
}
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