time

Documentation

Overview

Package time defines time-related types.

In CUE time values are represented as a string of the format time.RFC3339Nano.

Index

• Constants
• func Duration(s string) (bool, error)
• func Format(value, layout string) (bool, error)
• func FormatDuration(d int64) string
• func FormatString(layout, value string) (string, error)
• func Parse(layout, value string) (string, error)
• func ParseDuration(s string) (int64, error)
• func Time(s string) (bool, error)
• func Unix(sec int64, nsec int64) string
• type Parts
  • func Split(t string) (*Parts, error)

Constants

const (
	Nanosecond  = 1
	Microsecond = 1000
	Millisecond = 1000000
	Second      = 1000000000
	Minute      = 60000000000
	Hour        = 3600000000000
)

Common durations. There is no definition for units of Day or larger to avoid confusion across daylight savings time zone transitions.

To count the number of units in a Duration, divide:

second := time.Second
fmt.Print(int64(second/time.Millisecond)) // prints 1000

To convert an integer number of units to a Duration, multiply:

seconds := 10
fmt.Print(time.Duration(seconds)*time.Second) // prints 10s

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"
	RFC3339Date = "2006-01-02"
	Kitchen     = "3:04PM"
	Kitchen24   = "15:04"
)

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".

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. The RFC3339Nano format removes trailing zeros from the seconds field and thus may not sort correctly once formatted.

const (
	January   = 1
	February  = 2
	March     = 3
	April     = 4
	May       = 5
	June      = 6
	July      = 7
	August    = 8
	September = 9
	October   = 10
	November  = 11
	December  = 12
)

const (
	Sunday    = 0
	Monday    = 1
	Tuesday   = 2
	Wednesday = 3
	Thursday  = 4
	Friday    = 5
	Saturday  = 6
)

Functions

func Duration

func Duration(s string) (bool, error)

Duration validates a duration string.

Note: this format also accepts strings of the form '1h3m', '2ms', etc. To limit this to seconds only, as often used in JSON, add the !~"hmuµn" constraint.

func Format

func Format(value, layout string) (bool, error)

Format defines a type string that must adhere to a certain layout.

See Parse for a description on layout strings.

func FormatDuration

func FormatDuration(d int64) string

FormatDuration converts nanoseconds to a string representing the duration in the form "72h3m0.5s".

Leading zero units are omitted. As a special case, durations less than one second use a smaller unit (milli-, micro-, or nanoseconds) to ensure that the leading digit is non-zero. The zero duration formats as 0s.

func FormatString

func FormatString(layout, value string) (string, error)

FormatString returns a textual representation of the time value. The formatted value is formatted according to the layout defined by the argument. See Parse for more information on the layout string.

func Parse

func Parse(layout, value string) (string, error)

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.

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.

Parse currently does not support zone abbreviations like MST. All are interpreted as UTC.

func ParseDuration

func ParseDuration(s string) (int64, error)

ParseDuration reports the nanoseconds represented by 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 Time

func Time(s string) (bool, error)

Time validates a RFC3339 date-time.

Caveat: this implementation uses the Go implementation, which does not accept leap seconds.

func Unix

func Unix(sec int64, nsec int64) string

Unix returns the Time, in UTC, corresponding to the given Unix time, sec seconds and nsec nanoseconds since January 1, 1970 UTC. It is valid to pass nsec outside the range [0, 999999999]. Not all sec values have a corresponding time value. One such value is 1<<63-1 (the largest int64 value).

Types

type Parts

type Parts struct {
	Year   int `json:"year"`
	Month  int `json:"month"`
	Day    int `json:"day"`
	Hour   int `json:"hour"`
	Minute int `json:"minute"`

	// Second is equal to div(Nanosecond, 1_000_000_000)
	Second     int `json:"second"`
	Nanosecond int `json:"nanosecond"`
}

Parts holds individual parts of a parsed time stamp.

func Split

func Split(t string) (*Parts, error)

Split parses a time string into its individual parts.