src/pkg/time/time.go - go - Git at Google

 // Copyright 2009 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.

 // The time package provides functionality for measuring and
 // displaying time.
 package time

 import (
 	"os"
 )

 // Seconds reports the number of seconds since the Unix epoch,
 // January 1, 1970 00:00:00 UTC.
 func Seconds() int64 {
 	sec, _, err := os.Time()
 	if err != nil {
 		panic("time: os.Time: ", err.String())
 	}
 	return sec
 }

 // Nanoseconds reports the number of nanoseconds since the Unix epoch,
 // January 1, 1970 00:00:00 UTC.
 func Nanoseconds() int64 {
 	sec, nsec, err := os.Time()
 	if err != nil {
 		panic("time: os.Time: ", err.String())
 	}
 	return sec*1e9 + nsec
 }

 // Days of the week.
 const (
 	Sunday = iota
 	Monday
 	Tuesday
 	Wednesday
 	Thursday
 	Friday
 	Saturday
 )

 // Time is the struct representing a parsed time value.
 type Time struct {
 	Year                 int64 // 2008 is 2008
 	Month, Day           int   // Sep-17 is 9, 17
 	Hour, Minute, Second int   // 10:43:12 is 10, 43, 12
 	Weekday              int   // Sunday, Monday, ...
 	ZoneOffset           int   // seconds east of UTC
 	Zone                 string
 }

 var nonleapyear = []int{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
 var leapyear = []int{31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}

 func months(year int64) []int {
 	if year%4 == 0 && (year%100 != 0 || year%400 == 0) {
 		return leapyear
 	}
 	return nonleapyear
 }

 const (
 	secondsPerDay   = 24 * 60 * 60
 	daysPer400Years = 365*400 + 97
 	daysPer100Years = 365*100 + 24
 	daysPer4Years   = 365*4 + 1
 	days1970To2001  = 31*365 + 8
 )

 // SecondsToUTC converts sec, in number of seconds since the Unix epoch,
 // into a parsed Time value in the UTC time zone.
 func SecondsToUTC(sec int64) *Time {
 	t := new(Time)

 	// Split into time and day.
 	day := sec / secondsPerDay
 	sec -= day * secondsPerDay
 	if sec < 0 {
 		day--
 		sec += secondsPerDay
 	}

 	// Time
 	t.Hour = int(sec / 3600)
 	t.Minute = int((sec / 60) % 60)
 	t.Second = int(sec % 60)

 	// Day 0 = January 1, 1970 was a Thursday
 	t.Weekday = int((day + Thursday) % 7)
 	if t.Weekday < 0 {
 		t.Weekday += 7
 	}

 	// Change day from 0 = 1970 to 0 = 2001,
 	// to make leap year calculations easier
 	// (2001 begins 4-, 100-, and 400-year cycles ending in a leap year.)
 	day -= days1970To2001

 	year := int64(2001)
 	if day < 0 {
 		// Go back enough 400 year cycles to make day positive.
 		n := -day/daysPer400Years + 1
 		year -= 400 * n
 		day += daysPer400Years * n
 	}

 	// Cut off 400 year cycles.
 	n := day / daysPer400Years
 	year += 400 * n
 	day -= daysPer400Years * n

 	// Cut off 100-year cycles
 	n = day / daysPer100Years
 	if n > 3 { // happens on last day of 400th year
 		n = 3
 	}
 	year += 100 * n
 	day -= daysPer100Years * n

 	// Cut off 4-year cycles
 	n = day / daysPer4Years
 	if n > 24 { // happens on last day of 100th year
 		n = 24
 	}
 	year += 4 * n
 	day -= daysPer4Years * n

 	// Cut off non-leap years.
 	n = day / 365
 	if n > 3 { // happens on last day of 4th year
 		n = 3
 	}
 	year += n
 	day -= 365 * n

 	t.Year = year

 	// If someone ever needs yearday,
 	// tyearday = day (+1?)

 	months := months(year)
 	var m int
 	yday := int(day)
 	for m = 0; m < 12 && yday >= months[m]; m++ {
 		yday -= months[m]
 	}
 	t.Month = m + 1
 	t.Day = yday + 1
 	t.Zone = "UTC"

 	return t
 }

 // UTC returns the current time as a parsed Time value in the UTC time zone.
 func UTC() *Time { return SecondsToUTC(Seconds()) }

 // SecondsToLocalTime converts sec, in number of seconds since the Unix epoch,
 // into a parsed Time value in the local time zone.
 func SecondsToLocalTime(sec int64) *Time {
 	z, offset := lookupTimezone(sec)
 	t := SecondsToUTC(sec + int64(offset))
 	t.Zone = z
 	t.ZoneOffset = offset
 	return t
 }

 // LocalTime returns the current time as a parsed Time value in the local time zone.
 func LocalTime() *Time { return SecondsToLocalTime(Seconds()) }

 // Seconds returns the number of seconds since January 1, 1970 represented by the
 // parsed Time value.
 func (t *Time) Seconds() int64 {
 	// First, accumulate days since January 1, 2001.
 	// Using 2001 instead of 1970 makes the leap-year
 	// handling easier (see SecondsToUTC), because
 	// it is at the beginning of the 4-, 100-, and 400-year cycles.
 	day := int64(0)

 	// Rewrite year to be >= 2001.
 	year := t.Year
 	if year < 2001 {
 		n := (2001-year)/400 + 1
 		year += 400 * n
 		day -= daysPer400Years * n
 	}

 	// Add in days from 400-year cycles.
 	n := (year - 2001) / 400
 	year -= 400 * n
 	day += daysPer400Years * n

 	// Add in 100-year cycles.
 	n = (year - 2001) / 100
 	year -= 100 * n
 	day += daysPer100Years * n

 	// Add in 4-year cycles.
 	n = (year - 2001) / 4
 	year -= 4 * n
 	day += daysPer4Years * n

 	// Add in non-leap years.
 	n = year - 2001
 	day += 365 * n

 	// Add in days this year.
 	months := months(t.Year)
 	for m := 0; m < t.Month-1; m++ {
 		day += int64(months[m])
 	}
 	day += int64(t.Day - 1)

 	// Convert days to seconds since January 1, 2001.
 	sec := day * secondsPerDay

 	// Add in time elapsed today.
 	sec += int64(t.Hour) * 3600
 	sec += int64(t.Minute) * 60
 	sec += int64(t.Second)

 	// Convert from seconds since 2001 to seconds since 1970.
 	sec += days1970To2001 * secondsPerDay

 	// Account for local time zone.
 	sec -= int64(t.ZoneOffset)
 	return sec
 }

 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",
 }

 func copy(dst []byte, s string) {
 	for i := 0; i < len(s); i++ {
 		dst[i] = s[i]
 	}
 }

 func decimal(dst []byte, n int) {
 	if n < 0 {
 		n = 0
 	}
 	for i := len(dst) - 1; i >= 0; i-- {
 		dst[i] = byte(n%10 + '0')
 		n /= 10
 	}
 }

 func addString(buf []byte, bp int, s string) int {
 	n := len(s)
 	copy(buf[bp:bp+n], s)
 	return bp + n
 }

 // Just enough of strftime to implement the date formats below.
 // Not exported.
 func format(t *Time, fmt string) string {
 	buf := make([]byte, 128)
 	bp := 0

 	for i := 0; i < len(fmt); i++ {
 		if fmt[i] == '%' {
 			i++
 			switch fmt[i] {
 			case 'A': // %A full weekday name
 				bp = addString(buf, bp, longDayNames[t.Weekday])
 			case 'a': // %a abbreviated weekday name
 				bp = addString(buf, bp, shortDayNames[t.Weekday])
 			case 'b': // %b abbreviated month name
 				bp = addString(buf, bp, shortMonthNames[t.Month])
 			case 'd': // %d day of month (01-31)
 				decimal(buf[bp:bp+2], t.Day)
 				bp += 2
 			case 'e': // %e day of month ( 1-31)
 				if t.Day >= 10 {
 					decimal(buf[bp:bp+2], t.Day)
 				} else {
 					buf[bp] = ' '
 					buf[bp+1] = byte(t.Day + '0')
 				}
 				bp += 2
 			case 'H': // %H hour 00-23
 				decimal(buf[bp:bp+2], t.Hour)
 				bp += 2
 			case 'M': // %M minute 00-59
 				decimal(buf[bp:bp+2], t.Minute)
 				bp += 2
 			case 'm': // %m month 01-12
 				decimal(buf[bp:bp+2], t.Month)
 				bp += 2
 			case 'S': // %S second 00-59
 				decimal(buf[bp:bp+2], t.Second)
 				bp += 2
 			case 'Y': // %Y year 2008
 				decimal(buf[bp:bp+4], int(t.Year))
 				bp += 4
 			case 'y': // %y year 08
 				decimal(buf[bp:bp+2], int(t.Year%100))
 				bp += 2
 			case 'z': // %z tz in the form -0500
 				if t.ZoneOffset == 0 {
 					bp = addString(buf, bp, "Z")
 				} else if t.ZoneOffset < 0 {
 					bp = addString(buf, bp, "-")
 					decimal(buf[bp:bp+2], -t.ZoneOffset/3600)
 					decimal(buf[bp+2:bp+4], (-t.ZoneOffset%3600)/60)
 					bp += 4
 				} else {
 					bp = addString(buf, bp, "+")
 					decimal(buf[bp:bp+2], t.ZoneOffset/3600)
 					decimal(buf[bp+2:bp+4], (t.ZoneOffset%3600)/60)
 					bp += 4
 				}
 			case 'Z':
 				bp = addString(buf, bp, t.Zone)
 			default:
 				buf[bp] = '%'
 				buf[bp+1] = fmt[i]
 				bp += 2
 			}
 		} else {
 			buf[bp] = fmt[i]
 			bp++
 		}
 	}
 	return string(buf[0:bp])
 }

 // Asctime formats the parsed time value in the style of
 // ANSI C asctime: Sun Nov  6 08:49:37 1994
 func (t *Time) Asctime() string { return format(t, "%a %b %e %H:%M:%S %Y") }

 // RFC850 formats the parsed time value in the style of
 // RFC 850: Sunday, 06-Nov-94 08:49:37 UTC
 func (t *Time) RFC850() string { return format(t, "%A, %d-%b-%y %H:%M:%S %Z") }

 // RFC1123 formats the parsed time value in the style of
 // RFC 1123: Sun, 06 Nov 1994 08:49:37 UTC
 func (t *Time) RFC1123() string { return format(t, "%a, %d %b %Y %H:%M:%S %Z") }

 // ISO8601 formats the parsed time value in the style of
 // ISO 8601: 1994-11-06T08:49:37Z
 func (t *Time) ISO8601() string { return format(t, "%Y-%m-%dT%H:%M:%S%z") }

 // String formats the parsed time value in the style of
 // date(1): Sun Nov  6 08:49:37 UTC 1994
 func (t *Time) String() string { return format(t, "%a %b %e %H:%M:%S %Z %Y") }
	// Copyright 2009 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.

	// The time package provides functionality for measuring and
	// displaying time.
	package time

	import (
	"os"
	)

	// Seconds reports the number of seconds since the Unix epoch,
	// January 1, 1970 00:00:00 UTC.
	func Seconds() int64 {
	sec, _, err := os.Time()
	if err != nil {
	panic("time: os.Time: ", err.String())
	}
	return sec
	}

	// Nanoseconds reports the number of nanoseconds since the Unix epoch,
	// January 1, 1970 00:00:00 UTC.
	func Nanoseconds() int64 {
	sec, nsec, err := os.Time()
	if err != nil {
	panic("time: os.Time: ", err.String())
	}
	return sec*1e9 + nsec
	}

	// Days of the week.
	const (
	Sunday = iota
	Monday
	Tuesday
	Wednesday
	Thursday
	Friday
	Saturday
	)

	// Time is the struct representing a parsed time value.
	type Time struct {
	Year int64 // 2008 is 2008
	Month, Day int // Sep-17 is 9, 17
	Hour, Minute, Second int // 10:43:12 is 10, 43, 12
	Weekday int // Sunday, Monday, ...
	ZoneOffset int // seconds east of UTC
	Zone string
	}

	var nonleapyear = []int{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
	var leapyear = []int{31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}

	func months(year int64) []int {
	if year%4 == 0 && (year%100 != 0 \|\| year%400 == 0) {
	return leapyear
	}
	return nonleapyear
	}

	const (
	secondsPerDay = 24 * 60 * 60
	daysPer400Years = 365*400 + 97
	daysPer100Years = 365*100 + 24
	daysPer4Years = 365*4 + 1
	days1970To2001 = 31*365 + 8
	)

	// SecondsToUTC converts sec, in number of seconds since the Unix epoch,
	// into a parsed Time value in the UTC time zone.
	func SecondsToUTC(sec int64) *Time {
	t := new(Time)

	// Split into time and day.
	day := sec / secondsPerDay
	sec -= day * secondsPerDay
	if sec < 0 {
	day--
	sec += secondsPerDay
	}

	// Time
	t.Hour = int(sec / 3600)
	t.Minute = int((sec / 60) % 60)
	t.Second = int(sec % 60)

	// Day 0 = January 1, 1970 was a Thursday
	t.Weekday = int((day + Thursday) % 7)
	if t.Weekday < 0 {
	t.Weekday += 7
	}

	// Change day from 0 = 1970 to 0 = 2001,
	// to make leap year calculations easier
	// (2001 begins 4-, 100-, and 400-year cycles ending in a leap year.)
	day -= days1970To2001

	year := int64(2001)
	if day < 0 {
	// Go back enough 400 year cycles to make day positive.
	n := -day/daysPer400Years + 1
	year -= 400 * n
	day += daysPer400Years * n
	}

	// Cut off 400 year cycles.
	n := day / daysPer400Years
	year += 400 * n
	day -= daysPer400Years * n

	// Cut off 100-year cycles
	n = day / daysPer100Years
	if n > 3 { // happens on last day of 400th year
	n = 3
	}
	year += 100 * n
	day -= daysPer100Years * n

	// Cut off 4-year cycles
	n = day / daysPer4Years
	if n > 24 { // happens on last day of 100th year
	n = 24
	}
	year += 4 * n
	day -= daysPer4Years * n

	// Cut off non-leap years.
	n = day / 365
	if n > 3 { // happens on last day of 4th year
	n = 3
	}
	year += n
	day -= 365 * n

	t.Year = year

	// If someone ever needs yearday,
	// tyearday = day (+1?)

	months := months(year)
	var m int
	yday := int(day)
	for m = 0; m < 12 && yday >= months[m]; m++ {
	yday -= months[m]
	}
	t.Month = m + 1
	t.Day = yday + 1
	t.Zone = "UTC"

	return t
	}

	// UTC returns the current time as a parsed Time value in the UTC time zone.
	func UTC() *Time { return SecondsToUTC(Seconds()) }

	// SecondsToLocalTime converts sec, in number of seconds since the Unix epoch,
	// into a parsed Time value in the local time zone.
	func SecondsToLocalTime(sec int64) *Time {
	z, offset := lookupTimezone(sec)
	t := SecondsToUTC(sec + int64(offset))
	t.Zone = z
	t.ZoneOffset = offset
	return t
	}

	// LocalTime returns the current time as a parsed Time value in the local time zone.
	func LocalTime() *Time { return SecondsToLocalTime(Seconds()) }

	// Seconds returns the number of seconds since January 1, 1970 represented by the
	// parsed Time value.
	func (t *Time) Seconds() int64 {
	// First, accumulate days since January 1, 2001.
	// Using 2001 instead of 1970 makes the leap-year
	// handling easier (see SecondsToUTC), because
	// it is at the beginning of the 4-, 100-, and 400-year cycles.
	day := int64(0)

	// Rewrite year to be >= 2001.
	year := t.Year
	if year < 2001 {
	n := (2001-year)/400 + 1
	year += 400 * n
	day -= daysPer400Years * n
	}

	// Add in days from 400-year cycles.
	n := (year - 2001) / 400
	year -= 400 * n
	day += daysPer400Years * n

	// Add in 100-year cycles.
	n = (year - 2001) / 100
	year -= 100 * n
	day += daysPer100Years * n

	// Add in 4-year cycles.
	n = (year - 2001) / 4
	year -= 4 * n
	day += daysPer4Years * n

	// Add in non-leap years.
	n = year - 2001
	day += 365 * n

	// Add in days this year.
	months := months(t.Year)
	for m := 0; m < t.Month-1; m++ {
	day += int64(months[m])
	}
	day += int64(t.Day - 1)

	// Convert days to seconds since January 1, 2001.
	sec := day * secondsPerDay

	// Add in time elapsed today.
	sec += int64(t.Hour) * 3600
	sec += int64(t.Minute) * 60
	sec += int64(t.Second)

	// Convert from seconds since 2001 to seconds since 1970.
	sec += days1970To2001 * secondsPerDay

	// Account for local time zone.
	sec -= int64(t.ZoneOffset)
	return sec
	}

	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",
	}

	func copy(dst []byte, s string) {
	for i := 0; i < len(s); i++ {
	dst[i] = s[i]
	}
	}

	func decimal(dst []byte, n int) {
	if n < 0 {
	n = 0
	}
	for i := len(dst) - 1; i >= 0; i-- {
	dst[i] = byte(n%10 + '0')
	n /= 10
	}
	}

	func addString(buf []byte, bp int, s string) int {
	n := len(s)
	copy(buf[bp:bp+n], s)
	return bp + n
	}

	// Just enough of strftime to implement the date formats below.
	// Not exported.
	func format(t *Time, fmt string) string {
	buf := make([]byte, 128)
	bp := 0

	for i := 0; i < len(fmt); i++ {
	if fmt[i] == '%' {
	i++
	switch fmt[i] {
	case 'A': // %A full weekday name
	bp = addString(buf, bp, longDayNames[t.Weekday])
	case 'a': // %a abbreviated weekday name
	bp = addString(buf, bp, shortDayNames[t.Weekday])
	case 'b': // %b abbreviated month name
	bp = addString(buf, bp, shortMonthNames[t.Month])
	case 'd': // %d day of month (01-31)
	decimal(buf[bp:bp+2], t.Day)
	bp += 2
	case 'e': // %e day of month ( 1-31)
	if t.Day >= 10 {
	decimal(buf[bp:bp+2], t.Day)
	} else {
	buf[bp] = ' '
	buf[bp+1] = byte(t.Day + '0')
	}
	bp += 2
	case 'H': // %H hour 00-23
	decimal(buf[bp:bp+2], t.Hour)
	bp += 2
	case 'M': // %M minute 00-59
	decimal(buf[bp:bp+2], t.Minute)
	bp += 2
	case 'm': // %m month 01-12
	decimal(buf[bp:bp+2], t.Month)
	bp += 2
	case 'S': // %S second 00-59
	decimal(buf[bp:bp+2], t.Second)
	bp += 2
	case 'Y': // %Y year 2008
	decimal(buf[bp:bp+4], int(t.Year))
	bp += 4
	case 'y': // %y year 08
	decimal(buf[bp:bp+2], int(t.Year%100))
	bp += 2
	case 'z': // %z tz in the form -0500
	if t.ZoneOffset == 0 {
	bp = addString(buf, bp, "Z")
	} else if t.ZoneOffset < 0 {
	bp = addString(buf, bp, "-")
	decimal(buf[bp:bp+2], -t.ZoneOffset/3600)
	decimal(buf[bp+2:bp+4], (-t.ZoneOffset%3600)/60)
	bp += 4
	} else {
	bp = addString(buf, bp, "+")
	decimal(buf[bp:bp+2], t.ZoneOffset/3600)
	decimal(buf[bp+2:bp+4], (t.ZoneOffset%3600)/60)
	bp += 4
	}
	case 'Z':
	bp = addString(buf, bp, t.Zone)
	default:
	buf[bp] = '%'
	buf[bp+1] = fmt[i]
	bp += 2
	}
	} else {
	buf[bp] = fmt[i]
	bp++
	}
	}
	return string(buf[0:bp])
	}

	// Asctime formats the parsed time value in the style of
	// ANSI C asctime: Sun Nov 6 08:49:37 1994
	func (t *Time) Asctime() string { return format(t, "%a %b %e %H:%M:%S %Y") }

	// RFC850 formats the parsed time value in the style of
	// RFC 850: Sunday, 06-Nov-94 08:49:37 UTC
	func (t *Time) RFC850() string { return format(t, "%A, %d-%b-%y %H:%M:%S %Z") }

	// RFC1123 formats the parsed time value in the style of
	// RFC 1123: Sun, 06 Nov 1994 08:49:37 UTC
	func (t *Time) RFC1123() string { return format(t, "%a, %d %b %Y %H:%M:%S %Z") }

	// ISO8601 formats the parsed time value in the style of
	// ISO 8601: 1994-11-06T08:49:37Z
	func (t *Time) ISO8601() string { return format(t, "%Y-%m-%dT%H:%M:%S%z") }

	// String formats the parsed time value in the style of
	// date(1): Sun Nov 6 08:49:37 UTC 1994
	func (t *Time) String() string { return format(t, "%a %b %e %H:%M:%S %Z %Y") }