mirror of
https://github.com/autc04/Retro68.git
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1560 lines
45 KiB
Go
1560 lines
45 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package time provides functionality for measuring and displaying time.
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//
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// The calendrical calculations always assume a Gregorian calendar, with
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// no leap seconds.
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//
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// Monotonic Clocks
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//
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// Operating systems provide both a “wall clock,” which is subject to
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// changes for clock synchronization, and a “monotonic clock,” which is
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// not. The general rule is that the wall clock is for telling time and
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// the monotonic clock is for measuring time. Rather than split the API,
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// in this package the Time returned by time.Now contains both a wall
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// clock reading and a monotonic clock reading; later time-telling
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// operations use the wall clock reading, but later time-measuring
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// operations, specifically comparisons and subtractions, use the
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// monotonic clock reading.
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//
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// For example, this code always computes a positive elapsed time of
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// approximately 20 milliseconds, even if the wall clock is changed during
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// the operation being timed:
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//
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// start := time.Now()
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// ... operation that takes 20 milliseconds ...
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// t := time.Now()
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// elapsed := t.Sub(start)
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//
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// Other idioms, such as time.Since(start), time.Until(deadline), and
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// time.Now().Before(deadline), are similarly robust against wall clock
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// resets.
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//
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// The rest of this section gives the precise details of how operations
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// use monotonic clocks, but understanding those details is not required
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// to use this package.
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//
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// The Time returned by time.Now contains a monotonic clock reading.
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// If Time t has a monotonic clock reading, t.Add adds the same duration to
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// both the wall clock and monotonic clock readings to compute the result.
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// Because t.AddDate(y, m, d), t.Round(d), and t.Truncate(d) are wall time
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// computations, they always strip any monotonic clock reading from their results.
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// Because t.In, t.Local, and t.UTC are used for their effect on the interpretation
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// of the wall time, they also strip any monotonic clock reading from their results.
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// The canonical way to strip a monotonic clock reading is to use t = t.Round(0).
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//
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// If Times t and u both contain monotonic clock readings, the operations
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// t.After(u), t.Before(u), t.Equal(u), and t.Sub(u) are carried out
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// using the monotonic clock readings alone, ignoring the wall clock
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// readings. If either t or u contains no monotonic clock reading, these
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// operations fall back to using the wall clock readings.
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//
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// On some systems the monotonic clock will stop if the computer goes to sleep.
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// On such a system, t.Sub(u) may not accurately reflect the actual
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// time that passed between t and u.
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//
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// Because the monotonic clock reading has no meaning outside
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// the current process, the serialized forms generated by t.GobEncode,
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// t.MarshalBinary, t.MarshalJSON, and t.MarshalText omit the monotonic
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// clock reading, and t.Format provides no format for it. Similarly, the
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// constructors time.Date, time.Parse, time.ParseInLocation, and time.Unix,
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// as well as the unmarshalers t.GobDecode, t.UnmarshalBinary.
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// t.UnmarshalJSON, and t.UnmarshalText always create times with
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// no monotonic clock reading.
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//
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// Note that the Go == operator compares not just the time instant but
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// also the Location and the monotonic clock reading. See the
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// documentation for the Time type for a discussion of equality
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// testing for Time values.
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//
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// For debugging, the result of t.String does include the monotonic
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// clock reading if present. If t != u because of different monotonic clock readings,
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// that difference will be visible when printing t.String() and u.String().
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//
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package time
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import (
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"errors"
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_ "unsafe" // for go:linkname
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)
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// A Time represents an instant in time with nanosecond precision.
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//
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// Programs using times should typically store and pass them as values,
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// not pointers. That is, time variables and struct fields should be of
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// type time.Time, not *time.Time.
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//
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// A Time value can be used by multiple goroutines simultaneously except
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// that the methods GobDecode, UnmarshalBinary, UnmarshalJSON and
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// UnmarshalText are not concurrency-safe.
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//
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// Time instants can be compared using the Before, After, and Equal methods.
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// The Sub method subtracts two instants, producing a Duration.
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// The Add method adds a Time and a Duration, producing a Time.
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//
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// The zero value of type Time is January 1, year 1, 00:00:00.000000000 UTC.
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// As this time is unlikely to come up in practice, the IsZero method gives
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// a simple way of detecting a time that has not been initialized explicitly.
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//
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// Each Time has associated with it a Location, consulted when computing the
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// presentation form of the time, such as in the Format, Hour, and Year methods.
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// The methods Local, UTC, and In return a Time with a specific location.
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// Changing the location in this way changes only the presentation; it does not
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// change the instant in time being denoted and therefore does not affect the
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// computations described in earlier paragraphs.
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//
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// Representations of a Time value saved by the GobEncode, MarshalBinary,
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// MarshalJSON, and MarshalText methods store the Time.Location's offset, but not
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// the location name. They therefore lose information about Daylight Saving Time.
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//
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// In addition to the required “wall clock” reading, a Time may contain an optional
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// reading of the current process's monotonic clock, to provide additional precision
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// for comparison or subtraction.
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// See the “Monotonic Clocks” section in the package documentation for details.
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//
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// Note that the Go == operator compares not just the time instant but also the
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// Location and the monotonic clock reading. Therefore, Time values should not
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// be used as map or database keys without first guaranteeing that the
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// identical Location has been set for all values, which can be achieved
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// through use of the UTC or Local method, and that the monotonic clock reading
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// has been stripped by setting t = t.Round(0). In general, prefer t.Equal(u)
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// to t == u, since t.Equal uses the most accurate comparison available and
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// correctly handles the case when only one of its arguments has a monotonic
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// clock reading.
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//
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type Time struct {
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// wall and ext encode the wall time seconds, wall time nanoseconds,
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// and optional monotonic clock reading in nanoseconds.
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//
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// From high to low bit position, wall encodes a 1-bit flag (hasMonotonic),
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// a 33-bit seconds field, and a 30-bit wall time nanoseconds field.
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// The nanoseconds field is in the range [0, 999999999].
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// If the hasMonotonic bit is 0, then the 33-bit field must be zero
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// and the full signed 64-bit wall seconds since Jan 1 year 1 is stored in ext.
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// If the hasMonotonic bit is 1, then the 33-bit field holds a 33-bit
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// unsigned wall seconds since Jan 1 year 1885, and ext holds a
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// signed 64-bit monotonic clock reading, nanoseconds since process start.
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wall uint64
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ext int64
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// loc specifies the Location that should be used to
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// determine the minute, hour, month, day, and year
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// that correspond to this Time.
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// The nil location means UTC.
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// All UTC times are represented with loc==nil, never loc==&utcLoc.
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loc *Location
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}
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const (
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hasMonotonic = 1 << 63
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maxWall = wallToInternal + (1<<33 - 1) // year 2157
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minWall = wallToInternal // year 1885
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nsecMask = 1<<30 - 1
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nsecShift = 30
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)
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// These helpers for manipulating the wall and monotonic clock readings
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// take pointer receivers, even when they don't modify the time,
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// to make them cheaper to call.
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// nsec returns the time's nanoseconds.
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func (t *Time) nsec() int32 {
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return int32(t.wall & nsecMask)
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}
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// sec returns the time's seconds since Jan 1 year 1.
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func (t *Time) sec() int64 {
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if t.wall&hasMonotonic != 0 {
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return wallToInternal + int64(t.wall<<1>>(nsecShift+1))
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}
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return t.ext
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}
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// unixSec returns the time's seconds since Jan 1 1970 (Unix time).
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func (t *Time) unixSec() int64 { return t.sec() + internalToUnix }
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// addSec adds d seconds to the time.
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func (t *Time) addSec(d int64) {
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if t.wall&hasMonotonic != 0 {
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sec := int64(t.wall << 1 >> (nsecShift + 1))
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dsec := sec + d
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if 0 <= dsec && dsec <= 1<<33-1 {
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t.wall = t.wall&nsecMask | uint64(dsec)<<nsecShift | hasMonotonic
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return
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}
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// Wall second now out of range for packed field.
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// Move to ext.
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t.stripMono()
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}
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// TODO: Check for overflow.
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t.ext += d
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}
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// setLoc sets the location associated with the time.
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func (t *Time) setLoc(loc *Location) {
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if loc == &utcLoc {
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loc = nil
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}
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t.stripMono()
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t.loc = loc
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}
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// stripMono strips the monotonic clock reading in t.
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func (t *Time) stripMono() {
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if t.wall&hasMonotonic != 0 {
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t.ext = t.sec()
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t.wall &= nsecMask
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}
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}
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// setMono sets the monotonic clock reading in t.
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// If t cannot hold a monotonic clock reading,
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// because its wall time is too large,
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// setMono is a no-op.
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func (t *Time) setMono(m int64) {
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if t.wall&hasMonotonic == 0 {
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sec := t.ext
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if sec < minWall || maxWall < sec {
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return
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}
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t.wall |= hasMonotonic | uint64(sec-minWall)<<nsecShift
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}
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t.ext = m
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}
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// mono returns t's monotonic clock reading.
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// It returns 0 for a missing reading.
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// This function is used only for testing,
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// so it's OK that technically 0 is a valid
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// monotonic clock reading as well.
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func (t *Time) mono() int64 {
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if t.wall&hasMonotonic == 0 {
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return 0
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}
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return t.ext
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}
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// After reports whether the time instant t is after u.
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func (t Time) After(u Time) bool {
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if t.wall&u.wall&hasMonotonic != 0 {
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return t.ext > u.ext
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}
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ts := t.sec()
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us := u.sec()
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return ts > us || ts == us && t.nsec() > u.nsec()
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}
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// Before reports whether the time instant t is before u.
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func (t Time) Before(u Time) bool {
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if t.wall&u.wall&hasMonotonic != 0 {
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return t.ext < u.ext
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}
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return t.sec() < u.sec() || t.sec() == u.sec() && t.nsec() < u.nsec()
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}
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// Equal reports whether t and u represent the same time instant.
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// Two times can be equal even if they are in different locations.
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// For example, 6:00 +0200 CEST and 4:00 UTC are Equal.
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// See the documentation on the Time type for the pitfalls of using == with
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// Time values; most code should use Equal instead.
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func (t Time) Equal(u Time) bool {
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if t.wall&u.wall&hasMonotonic != 0 {
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return t.ext == u.ext
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}
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return t.sec() == u.sec() && t.nsec() == u.nsec()
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}
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// A Month specifies a month of the year (January = 1, ...).
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type Month int
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const (
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January Month = 1 + iota
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February
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March
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April
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May
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June
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July
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August
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September
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October
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November
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December
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)
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var months = [...]string{
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"January",
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"February",
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"March",
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"April",
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"May",
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"June",
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"July",
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"August",
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"September",
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"October",
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"November",
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"December",
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}
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// String returns the English name of the month ("January", "February", ...).
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func (m Month) String() string {
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if January <= m && m <= December {
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return months[m-1]
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}
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buf := make([]byte, 20)
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n := fmtInt(buf, uint64(m))
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return "%!Month(" + string(buf[n:]) + ")"
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}
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// A Weekday specifies a day of the week (Sunday = 0, ...).
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type Weekday int
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const (
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Sunday Weekday = iota
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Monday
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Tuesday
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Wednesday
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Thursday
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Friday
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Saturday
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)
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var days = [...]string{
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"Sunday",
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"Monday",
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"Tuesday",
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"Wednesday",
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"Thursday",
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"Friday",
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"Saturday",
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}
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// String returns the English name of the day ("Sunday", "Monday", ...).
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func (d Weekday) String() string {
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if Sunday <= d && d <= Saturday {
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return days[d]
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}
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buf := make([]byte, 20)
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n := fmtInt(buf, uint64(d))
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return "%!Weekday(" + string(buf[n:]) + ")"
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}
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// Computations on time.
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//
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// The zero value for a Time is defined to be
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// January 1, year 1, 00:00:00.000000000 UTC
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// which (1) looks like a zero, or as close as you can get in a date
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// (1-1-1 00:00:00 UTC), (2) is unlikely enough to arise in practice to
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// be a suitable "not set" sentinel, unlike Jan 1 1970, and (3) has a
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// non-negative year even in time zones west of UTC, unlike 1-1-0
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// 00:00:00 UTC, which would be 12-31-(-1) 19:00:00 in New York.
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//
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// The zero Time value does not force a specific epoch for the time
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// representation. For example, to use the Unix epoch internally, we
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// could define that to distinguish a zero value from Jan 1 1970, that
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// time would be represented by sec=-1, nsec=1e9. However, it does
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// suggest a representation, namely using 1-1-1 00:00:00 UTC as the
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// epoch, and that's what we do.
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//
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// The Add and Sub computations are oblivious to the choice of epoch.
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//
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// The presentation computations - year, month, minute, and so on - all
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// rely heavily on division and modulus by positive constants. For
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// calendrical calculations we want these divisions to round down, even
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// for negative values, so that the remainder is always positive, but
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// Go's division (like most hardware division instructions) rounds to
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// zero. We can still do those computations and then adjust the result
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// for a negative numerator, but it's annoying to write the adjustment
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// over and over. Instead, we can change to a different epoch so long
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// ago that all the times we care about will be positive, and then round
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// to zero and round down coincide. These presentation routines already
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// have to add the zone offset, so adding the translation to the
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// alternate epoch is cheap. For example, having a non-negative time t
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// means that we can write
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//
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// sec = t % 60
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//
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// instead of
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//
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// sec = t % 60
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// if sec < 0 {
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// sec += 60
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// }
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//
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// everywhere.
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//
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// The calendar runs on an exact 400 year cycle: a 400-year calendar
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// printed for 1970-2369 will apply as well to 2370-2769. Even the days
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// of the week match up. It simplifies the computations to choose the
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// cycle boundaries so that the exceptional years are always delayed as
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// long as possible. That means choosing a year equal to 1 mod 400, so
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// that the first leap year is the 4th year, the first missed leap year
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// is the 100th year, and the missed missed leap year is the 400th year.
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// So we'd prefer instead to print a calendar for 2001-2400 and reuse it
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// for 2401-2800.
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//
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// Finally, it's convenient if the delta between the Unix epoch and
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// long-ago epoch is representable by an int64 constant.
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//
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// These three considerations—choose an epoch as early as possible, that
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// uses a year equal to 1 mod 400, and that is no more than 2⁶³ seconds
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// earlier than 1970—bring us to the year -292277022399. We refer to
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// this year as the absolute zero year, and to times measured as a uint64
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// seconds since this year as absolute times.
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//
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// Times measured as an int64 seconds since the year 1—the representation
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// used for Time's sec field—are called internal times.
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//
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// Times measured as an int64 seconds since the year 1970 are called Unix
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// times.
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//
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// It is tempting to just use the year 1 as the absolute epoch, defining
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// that the routines are only valid for years >= 1. However, the
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// routines would then be invalid when displaying the epoch in time zones
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// west of UTC, since it is year 0. It doesn't seem tenable to say that
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// printing the zero time correctly isn't supported in half the time
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// zones. By comparison, it's reasonable to mishandle some times in
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// the year -292277022399.
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//
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// All this is opaque to clients of the API and can be changed if a
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// better implementation presents itself.
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const (
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// The unsigned zero year for internal calculations.
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// Must be 1 mod 400, and times before it will not compute correctly,
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// but otherwise can be changed at will.
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absoluteZeroYear = -292277022399
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// The year of the zero Time.
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// Assumed by the unixToInternal computation below.
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internalYear = 1
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// Offsets to convert between internal and absolute or Unix times.
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absoluteToInternal int64 = (absoluteZeroYear - internalYear) * 365.2425 * secondsPerDay
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internalToAbsolute = -absoluteToInternal
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unixToInternal int64 = (1969*365 + 1969/4 - 1969/100 + 1969/400) * secondsPerDay
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internalToUnix int64 = -unixToInternal
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wallToInternal int64 = (1884*365 + 1884/4 - 1884/100 + 1884/400) * secondsPerDay
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internalToWall int64 = -wallToInternal
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)
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// IsZero reports whether t represents the zero time instant,
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// January 1, year 1, 00:00:00 UTC.
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func (t Time) IsZero() bool {
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return t.sec() == 0 && t.nsec() == 0
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}
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|
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// abs returns the time t as an absolute time, adjusted by the zone offset.
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// It is called when computing a presentation property like Month or Hour.
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func (t Time) abs() uint64 {
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l := t.loc
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// Avoid function calls when possible.
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if l == nil || l == &localLoc {
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l = l.get()
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}
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sec := t.unixSec()
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if l != &utcLoc {
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if l.cacheZone != nil && l.cacheStart <= sec && sec < l.cacheEnd {
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sec += int64(l.cacheZone.offset)
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} else {
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_, offset, _, _ := l.lookup(sec)
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sec += int64(offset)
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}
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}
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return uint64(sec + (unixToInternal + internalToAbsolute))
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}
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|
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// locabs is a combination of the Zone and abs methods,
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// extracting both return values from a single zone lookup.
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func (t Time) locabs() (name string, offset int, abs uint64) {
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l := t.loc
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if l == nil || l == &localLoc {
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l = l.get()
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}
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// Avoid function call if we hit the local time cache.
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sec := t.unixSec()
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if l != &utcLoc {
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if l.cacheZone != nil && l.cacheStart <= sec && sec < l.cacheEnd {
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name = l.cacheZone.name
|
|
offset = l.cacheZone.offset
|
|
} else {
|
|
name, offset, _, _ = l.lookup(sec)
|
|
}
|
|
sec += int64(offset)
|
|
} else {
|
|
name = "UTC"
|
|
}
|
|
abs = uint64(sec + (unixToInternal + internalToAbsolute))
|
|
return
|
|
}
|
|
|
|
// Date returns the year, month, and day in which t occurs.
|
|
func (t Time) Date() (year int, month Month, day int) {
|
|
year, month, day, _ = t.date(true)
|
|
return
|
|
}
|
|
|
|
// Year returns the year in which t occurs.
|
|
func (t Time) Year() int {
|
|
year, _, _, _ := t.date(false)
|
|
return year
|
|
}
|
|
|
|
// Month returns the month of the year specified by t.
|
|
func (t Time) Month() Month {
|
|
_, month, _, _ := t.date(true)
|
|
return month
|
|
}
|
|
|
|
// Day returns the day of the month specified by t.
|
|
func (t Time) Day() int {
|
|
_, _, day, _ := t.date(true)
|
|
return day
|
|
}
|
|
|
|
// Weekday returns the day of the week specified by t.
|
|
func (t Time) Weekday() Weekday {
|
|
return absWeekday(t.abs())
|
|
}
|
|
|
|
// absWeekday is like Weekday but operates on an absolute time.
|
|
func absWeekday(abs uint64) Weekday {
|
|
// January 1 of the absolute year, like January 1 of 2001, was a Monday.
|
|
sec := (abs + uint64(Monday)*secondsPerDay) % secondsPerWeek
|
|
return Weekday(int(sec) / secondsPerDay)
|
|
}
|
|
|
|
// ISOWeek returns the ISO 8601 year and week number in which t occurs.
|
|
// Week ranges from 1 to 53. Jan 01 to Jan 03 of year n might belong to
|
|
// week 52 or 53 of year n-1, and Dec 29 to Dec 31 might belong to week 1
|
|
// of year n+1.
|
|
func (t Time) ISOWeek() (year, week int) {
|
|
year, month, day, yday := t.date(true)
|
|
wday := int(t.Weekday()+6) % 7 // weekday but Monday = 0.
|
|
const (
|
|
Mon int = iota
|
|
Tue
|
|
Wed
|
|
Thu
|
|
Fri
|
|
Sat
|
|
Sun
|
|
)
|
|
|
|
// Calculate week as number of Mondays in year up to
|
|
// and including today, plus 1 because the first week is week 0.
|
|
// Putting the + 1 inside the numerator as a + 7 keeps the
|
|
// numerator from being negative, which would cause it to
|
|
// round incorrectly.
|
|
week = (yday - wday + 7) / 7
|
|
|
|
// The week number is now correct under the assumption
|
|
// that the first Monday of the year is in week 1.
|
|
// If Jan 1 is a Tuesday, Wednesday, or Thursday, the first Monday
|
|
// is actually in week 2.
|
|
jan1wday := (wday - yday + 7*53) % 7
|
|
if Tue <= jan1wday && jan1wday <= Thu {
|
|
week++
|
|
}
|
|
|
|
// If the week number is still 0, we're in early January but in
|
|
// the last week of last year.
|
|
if week == 0 {
|
|
year--
|
|
week = 52
|
|
// A year has 53 weeks when Jan 1 or Dec 31 is a Thursday,
|
|
// meaning Jan 1 of the next year is a Friday
|
|
// or it was a leap year and Jan 1 of the next year is a Saturday.
|
|
if jan1wday == Fri || (jan1wday == Sat && isLeap(year)) {
|
|
week++
|
|
}
|
|
}
|
|
|
|
// December 29 to 31 are in week 1 of next year if
|
|
// they are after the last Thursday of the year and
|
|
// December 31 is a Monday, Tuesday, or Wednesday.
|
|
if month == December && day >= 29 && wday < Thu {
|
|
if dec31wday := (wday + 31 - day) % 7; Mon <= dec31wday && dec31wday <= Wed {
|
|
year++
|
|
week = 1
|
|
}
|
|
}
|
|
|
|
return
|
|
}
|
|
|
|
// Clock returns the hour, minute, and second within the day specified by t.
|
|
func (t Time) Clock() (hour, min, sec int) {
|
|
return absClock(t.abs())
|
|
}
|
|
|
|
// absClock is like clock but operates on an absolute time.
|
|
func absClock(abs uint64) (hour, min, sec int) {
|
|
sec = int(abs % secondsPerDay)
|
|
hour = sec / secondsPerHour
|
|
sec -= hour * secondsPerHour
|
|
min = sec / secondsPerMinute
|
|
sec -= min * secondsPerMinute
|
|
return
|
|
}
|
|
|
|
// Hour returns the hour within the day specified by t, in the range [0, 23].
|
|
func (t Time) Hour() int {
|
|
return int(t.abs()%secondsPerDay) / secondsPerHour
|
|
}
|
|
|
|
// Minute returns the minute offset within the hour specified by t, in the range [0, 59].
|
|
func (t Time) Minute() int {
|
|
return int(t.abs()%secondsPerHour) / secondsPerMinute
|
|
}
|
|
|
|
// Second returns the second offset within the minute specified by t, in the range [0, 59].
|
|
func (t Time) Second() int {
|
|
return int(t.abs() % secondsPerMinute)
|
|
}
|
|
|
|
// Nanosecond returns the nanosecond offset within the second specified by t,
|
|
// in the range [0, 999999999].
|
|
func (t Time) Nanosecond() int {
|
|
return int(t.nsec())
|
|
}
|
|
|
|
// YearDay returns the day of the year specified by t, in the range [1,365] for non-leap years,
|
|
// and [1,366] in leap years.
|
|
func (t Time) YearDay() int {
|
|
_, _, _, yday := t.date(false)
|
|
return yday + 1
|
|
}
|
|
|
|
// A Duration represents the elapsed time between two instants
|
|
// as an int64 nanosecond count. The representation limits the
|
|
// largest representable duration to approximately 290 years.
|
|
type Duration int64
|
|
|
|
const (
|
|
minDuration Duration = -1 << 63
|
|
maxDuration Duration = 1<<63 - 1
|
|
)
|
|
|
|
// 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 (
|
|
Nanosecond Duration = 1
|
|
Microsecond = 1000 * Nanosecond
|
|
Millisecond = 1000 * Microsecond
|
|
Second = 1000 * Millisecond
|
|
Minute = 60 * Second
|
|
Hour = 60 * Minute
|
|
)
|
|
|
|
// String returns a string representing the duration in the form "72h3m0.5s".
|
|
// Leading zero units are omitted. As a special case, durations less than one
|
|
// second format use a smaller unit (milli-, micro-, or nanoseconds) to ensure
|
|
// that the leading digit is non-zero. The zero duration formats as 0s.
|
|
func (d Duration) String() string {
|
|
// Largest time is 2540400h10m10.000000000s
|
|
var buf [32]byte
|
|
w := len(buf)
|
|
|
|
u := uint64(d)
|
|
neg := d < 0
|
|
if neg {
|
|
u = -u
|
|
}
|
|
|
|
if u < uint64(Second) {
|
|
// Special case: if duration is smaller than a second,
|
|
// use smaller units, like 1.2ms
|
|
var prec int
|
|
w--
|
|
buf[w] = 's'
|
|
w--
|
|
switch {
|
|
case u == 0:
|
|
return "0s"
|
|
case u < uint64(Microsecond):
|
|
// print nanoseconds
|
|
prec = 0
|
|
buf[w] = 'n'
|
|
case u < uint64(Millisecond):
|
|
// print microseconds
|
|
prec = 3
|
|
// U+00B5 'µ' micro sign == 0xC2 0xB5
|
|
w-- // Need room for two bytes.
|
|
copy(buf[w:], "µ")
|
|
default:
|
|
// print milliseconds
|
|
prec = 6
|
|
buf[w] = 'm'
|
|
}
|
|
w, u = fmtFrac(buf[:w], u, prec)
|
|
w = fmtInt(buf[:w], u)
|
|
} else {
|
|
w--
|
|
buf[w] = 's'
|
|
|
|
w, u = fmtFrac(buf[:w], u, 9)
|
|
|
|
// u is now integer seconds
|
|
w = fmtInt(buf[:w], u%60)
|
|
u /= 60
|
|
|
|
// u is now integer minutes
|
|
if u > 0 {
|
|
w--
|
|
buf[w] = 'm'
|
|
w = fmtInt(buf[:w], u%60)
|
|
u /= 60
|
|
|
|
// u is now integer hours
|
|
// Stop at hours because days can be different lengths.
|
|
if u > 0 {
|
|
w--
|
|
buf[w] = 'h'
|
|
w = fmtInt(buf[:w], u)
|
|
}
|
|
}
|
|
}
|
|
|
|
if neg {
|
|
w--
|
|
buf[w] = '-'
|
|
}
|
|
|
|
return string(buf[w:])
|
|
}
|
|
|
|
// fmtFrac formats the fraction of v/10**prec (e.g., ".12345") into the
|
|
// tail of buf, omitting trailing zeros. It omits the decimal
|
|
// point too when the fraction is 0. It returns the index where the
|
|
// output bytes begin and the value v/10**prec.
|
|
func fmtFrac(buf []byte, v uint64, prec int) (nw int, nv uint64) {
|
|
// Omit trailing zeros up to and including decimal point.
|
|
w := len(buf)
|
|
print := false
|
|
for i := 0; i < prec; i++ {
|
|
digit := v % 10
|
|
print = print || digit != 0
|
|
if print {
|
|
w--
|
|
buf[w] = byte(digit) + '0'
|
|
}
|
|
v /= 10
|
|
}
|
|
if print {
|
|
w--
|
|
buf[w] = '.'
|
|
}
|
|
return w, v
|
|
}
|
|
|
|
// fmtInt formats v into the tail of buf.
|
|
// It returns the index where the output begins.
|
|
func fmtInt(buf []byte, v uint64) int {
|
|
w := len(buf)
|
|
if v == 0 {
|
|
w--
|
|
buf[w] = '0'
|
|
} else {
|
|
for v > 0 {
|
|
w--
|
|
buf[w] = byte(v%10) + '0'
|
|
v /= 10
|
|
}
|
|
}
|
|
return w
|
|
}
|
|
|
|
// Nanoseconds returns the duration as an integer nanosecond count.
|
|
func (d Duration) Nanoseconds() int64 { return int64(d) }
|
|
|
|
// These methods return float64 because the dominant
|
|
// use case is for printing a floating point number like 1.5s, and
|
|
// a truncation to integer would make them not useful in those cases.
|
|
// Splitting the integer and fraction ourselves guarantees that
|
|
// converting the returned float64 to an integer rounds the same
|
|
// way that a pure integer conversion would have, even in cases
|
|
// where, say, float64(d.Nanoseconds())/1e9 would have rounded
|
|
// differently.
|
|
|
|
// Seconds returns the duration as a floating point number of seconds.
|
|
func (d Duration) Seconds() float64 {
|
|
sec := d / Second
|
|
nsec := d % Second
|
|
return float64(sec) + float64(nsec)/1e9
|
|
}
|
|
|
|
// Minutes returns the duration as a floating point number of minutes.
|
|
func (d Duration) Minutes() float64 {
|
|
min := d / Minute
|
|
nsec := d % Minute
|
|
return float64(min) + float64(nsec)/(60*1e9)
|
|
}
|
|
|
|
// Hours returns the duration as a floating point number of hours.
|
|
func (d Duration) Hours() float64 {
|
|
hour := d / Hour
|
|
nsec := d % Hour
|
|
return float64(hour) + float64(nsec)/(60*60*1e9)
|
|
}
|
|
|
|
// Truncate returns the result of rounding d toward zero to a multiple of m.
|
|
// If m <= 0, Truncate returns d unchanged.
|
|
func (d Duration) Truncate(m Duration) Duration {
|
|
if m <= 0 {
|
|
return d
|
|
}
|
|
return d - d%m
|
|
}
|
|
|
|
// lessThanHalf reports whether x+x < y but avoids overflow,
|
|
// assuming x and y are both positive (Duration is signed).
|
|
func lessThanHalf(x, y Duration) bool {
|
|
return uint64(x)+uint64(x) < uint64(y)
|
|
}
|
|
|
|
// Round returns the result of rounding d to the nearest multiple of m.
|
|
// The rounding behavior for halfway values is to round away from zero.
|
|
// If the result exceeds the maximum (or minimum)
|
|
// value that can be stored in a Duration,
|
|
// Round returns the maximum (or minimum) duration.
|
|
// If m <= 0, Round returns d unchanged.
|
|
func (d Duration) Round(m Duration) Duration {
|
|
if m <= 0 {
|
|
return d
|
|
}
|
|
r := d % m
|
|
if d < 0 {
|
|
r = -r
|
|
if lessThanHalf(r, m) {
|
|
return d + r
|
|
}
|
|
if d1 := d - m + r; d1 < d {
|
|
return d1
|
|
}
|
|
return minDuration // overflow
|
|
}
|
|
if lessThanHalf(r, m) {
|
|
return d - r
|
|
}
|
|
if d1 := d + m - r; d1 > d {
|
|
return d1
|
|
}
|
|
return maxDuration // overflow
|
|
}
|
|
|
|
// Add returns the time t+d.
|
|
func (t Time) Add(d Duration) Time {
|
|
dsec := int64(d / 1e9)
|
|
nsec := t.nsec() + int32(d%1e9)
|
|
if nsec >= 1e9 {
|
|
dsec++
|
|
nsec -= 1e9
|
|
} else if nsec < 0 {
|
|
dsec--
|
|
nsec += 1e9
|
|
}
|
|
t.wall = t.wall&^nsecMask | uint64(nsec) // update nsec
|
|
t.addSec(dsec)
|
|
if t.wall&hasMonotonic != 0 {
|
|
te := t.ext + int64(d)
|
|
if d < 0 && te > t.ext || d > 0 && te < t.ext {
|
|
// Monotonic clock reading now out of range; degrade to wall-only.
|
|
t.stripMono()
|
|
} else {
|
|
t.ext = te
|
|
}
|
|
}
|
|
return t
|
|
}
|
|
|
|
// Sub returns the duration t-u. If the result exceeds the maximum (or minimum)
|
|
// value that can be stored in a Duration, the maximum (or minimum) duration
|
|
// will be returned.
|
|
// To compute t-d for a duration d, use t.Add(-d).
|
|
func (t Time) Sub(u Time) Duration {
|
|
if t.wall&u.wall&hasMonotonic != 0 {
|
|
te := t.ext
|
|
ue := u.ext
|
|
d := Duration(te - ue)
|
|
if d < 0 && te > ue {
|
|
return maxDuration // t - u is positive out of range
|
|
}
|
|
if d > 0 && te < ue {
|
|
return minDuration // t - u is negative out of range
|
|
}
|
|
return d
|
|
}
|
|
d := Duration(t.sec()-u.sec())*Second + Duration(t.nsec()-u.nsec())
|
|
// Check for overflow or underflow.
|
|
switch {
|
|
case u.Add(d).Equal(t):
|
|
return d // d is correct
|
|
case t.Before(u):
|
|
return minDuration // t - u is negative out of range
|
|
default:
|
|
return maxDuration // t - u is positive out of range
|
|
}
|
|
}
|
|
|
|
// Since returns the time elapsed since t.
|
|
// It is shorthand for time.Now().Sub(t).
|
|
func Since(t Time) Duration {
|
|
var now Time
|
|
if t.wall&hasMonotonic != 0 {
|
|
// Common case optimization: if t has monotomic time, then Sub will use only it.
|
|
now = Time{hasMonotonic, runtimeNano() - startNano, nil}
|
|
} else {
|
|
now = Now()
|
|
}
|
|
return now.Sub(t)
|
|
}
|
|
|
|
// Until returns the duration until t.
|
|
// It is shorthand for t.Sub(time.Now()).
|
|
func Until(t Time) Duration {
|
|
var now Time
|
|
if t.wall&hasMonotonic != 0 {
|
|
// Common case optimization: if t has monotomic time, then Sub will use only it.
|
|
now = Time{hasMonotonic, runtimeNano() - startNano, nil}
|
|
} else {
|
|
now = Now()
|
|
}
|
|
return t.Sub(now)
|
|
}
|
|
|
|
// AddDate returns the time corresponding to adding the
|
|
// given number of years, months, and days to t.
|
|
// For example, AddDate(-1, 2, 3) applied to January 1, 2011
|
|
// returns March 4, 2010.
|
|
//
|
|
// AddDate normalizes its result in the same way that Date does,
|
|
// so, for example, adding one month to October 31 yields
|
|
// December 1, the normalized form for November 31.
|
|
func (t Time) AddDate(years int, months int, days int) Time {
|
|
year, month, day := t.Date()
|
|
hour, min, sec := t.Clock()
|
|
return Date(year+years, month+Month(months), day+days, hour, min, sec, int(t.nsec()), t.Location())
|
|
}
|
|
|
|
const (
|
|
secondsPerMinute = 60
|
|
secondsPerHour = 60 * secondsPerMinute
|
|
secondsPerDay = 24 * secondsPerHour
|
|
secondsPerWeek = 7 * secondsPerDay
|
|
daysPer400Years = 365*400 + 97
|
|
daysPer100Years = 365*100 + 24
|
|
daysPer4Years = 365*4 + 1
|
|
)
|
|
|
|
// date computes the year, day of year, and when full=true,
|
|
// the month and day in which t occurs.
|
|
func (t Time) date(full bool) (year int, month Month, day int, yday int) {
|
|
return absDate(t.abs(), full)
|
|
}
|
|
|
|
// absDate is like date but operates on an absolute time.
|
|
func absDate(abs uint64, full bool) (year int, month Month, day int, yday int) {
|
|
// Split into time and day.
|
|
d := abs / secondsPerDay
|
|
|
|
// Account for 400 year cycles.
|
|
n := d / daysPer400Years
|
|
y := 400 * n
|
|
d -= daysPer400Years * n
|
|
|
|
// Cut off 100-year cycles.
|
|
// The last cycle has one extra leap year, so on the last day
|
|
// of that year, day / daysPer100Years will be 4 instead of 3.
|
|
// Cut it back down to 3 by subtracting n>>2.
|
|
n = d / daysPer100Years
|
|
n -= n >> 2
|
|
y += 100 * n
|
|
d -= daysPer100Years * n
|
|
|
|
// Cut off 4-year cycles.
|
|
// The last cycle has a missing leap year, which does not
|
|
// affect the computation.
|
|
n = d / daysPer4Years
|
|
y += 4 * n
|
|
d -= daysPer4Years * n
|
|
|
|
// Cut off years within a 4-year cycle.
|
|
// The last year is a leap year, so on the last day of that year,
|
|
// day / 365 will be 4 instead of 3. Cut it back down to 3
|
|
// by subtracting n>>2.
|
|
n = d / 365
|
|
n -= n >> 2
|
|
y += n
|
|
d -= 365 * n
|
|
|
|
year = int(int64(y) + absoluteZeroYear)
|
|
yday = int(d)
|
|
|
|
if !full {
|
|
return
|
|
}
|
|
|
|
day = yday
|
|
if isLeap(year) {
|
|
// Leap year
|
|
switch {
|
|
case day > 31+29-1:
|
|
// After leap day; pretend it wasn't there.
|
|
day--
|
|
case day == 31+29-1:
|
|
// Leap day.
|
|
month = February
|
|
day = 29
|
|
return
|
|
}
|
|
}
|
|
|
|
// Estimate month on assumption that every month has 31 days.
|
|
// The estimate may be too low by at most one month, so adjust.
|
|
month = Month(day / 31)
|
|
end := int(daysBefore[month+1])
|
|
var begin int
|
|
if day >= end {
|
|
month++
|
|
begin = end
|
|
} else {
|
|
begin = int(daysBefore[month])
|
|
}
|
|
|
|
month++ // because January is 1
|
|
day = day - begin + 1
|
|
return
|
|
}
|
|
|
|
// daysBefore[m] counts the number of days in a non-leap year
|
|
// before month m begins. There is an entry for m=12, counting
|
|
// the number of days before January of next year (365).
|
|
var daysBefore = [...]int32{
|
|
0,
|
|
31,
|
|
31 + 28,
|
|
31 + 28 + 31,
|
|
31 + 28 + 31 + 30,
|
|
31 + 28 + 31 + 30 + 31,
|
|
31 + 28 + 31 + 30 + 31 + 30,
|
|
31 + 28 + 31 + 30 + 31 + 30 + 31,
|
|
31 + 28 + 31 + 30 + 31 + 30 + 31 + 31,
|
|
31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30,
|
|
31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31,
|
|
31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30,
|
|
31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + 31,
|
|
}
|
|
|
|
func daysIn(m Month, year int) int {
|
|
if m == February && isLeap(year) {
|
|
return 29
|
|
}
|
|
return int(daysBefore[m] - daysBefore[m-1])
|
|
}
|
|
|
|
// Provided by package runtime.
|
|
func now() (sec int64, nsec int32, mono int64)
|
|
|
|
// runtimeNano returns the current value of the runtime clock in nanoseconds.
|
|
//go:linkname runtimeNano runtime.nanotime
|
|
func runtimeNano() int64
|
|
|
|
// Monotonic times are reported as offsets from startNano.
|
|
// We initialize startNano to runtimeNano() - 1 so that on systems where
|
|
// monotonic time resolution is fairly low (e.g. Windows 2008
|
|
// which appears to have a default resolution of 15ms),
|
|
// we avoid ever reporting a monotonic time of 0.
|
|
// (Callers may want to use 0 as "time not set".)
|
|
var startNano int64 = runtimeNano() - 1
|
|
|
|
// Now returns the current local time.
|
|
func Now() Time {
|
|
sec, nsec, mono := now()
|
|
mono -= startNano
|
|
sec += unixToInternal - minWall
|
|
if uint64(sec)>>33 != 0 {
|
|
return Time{uint64(nsec), sec + minWall, Local}
|
|
}
|
|
return Time{hasMonotonic | uint64(sec)<<nsecShift | uint64(nsec), mono, Local}
|
|
}
|
|
|
|
func unixTime(sec int64, nsec int32) Time {
|
|
return Time{uint64(nsec), sec + unixToInternal, Local}
|
|
}
|
|
|
|
// UTC returns t with the location set to UTC.
|
|
func (t Time) UTC() Time {
|
|
t.setLoc(&utcLoc)
|
|
return t
|
|
}
|
|
|
|
// Local returns t with the location set to local time.
|
|
func (t Time) Local() Time {
|
|
t.setLoc(Local)
|
|
return t
|
|
}
|
|
|
|
// In returns a copy of t representing the same time instant, but
|
|
// with the copy's location information set to loc for display
|
|
// purposes.
|
|
//
|
|
// In panics if loc is nil.
|
|
func (t Time) In(loc *Location) Time {
|
|
if loc == nil {
|
|
panic("time: missing Location in call to Time.In")
|
|
}
|
|
t.setLoc(loc)
|
|
return t
|
|
}
|
|
|
|
// Location returns the time zone information associated with t.
|
|
func (t Time) Location() *Location {
|
|
l := t.loc
|
|
if l == nil {
|
|
l = UTC
|
|
}
|
|
return l
|
|
}
|
|
|
|
// Zone computes the time zone in effect at time t, returning the abbreviated
|
|
// name of the zone (such as "CET") and its offset in seconds east of UTC.
|
|
func (t Time) Zone() (name string, offset int) {
|
|
name, offset, _, _ = t.loc.lookup(t.unixSec())
|
|
return
|
|
}
|
|
|
|
// Unix returns t as a Unix time, the number of seconds elapsed
|
|
// since January 1, 1970 UTC. The result does not depend on the
|
|
// location associated with t.
|
|
func (t Time) Unix() int64 {
|
|
return t.unixSec()
|
|
}
|
|
|
|
// UnixNano returns t as a Unix time, the number of nanoseconds elapsed
|
|
// since January 1, 1970 UTC. The result is undefined if the Unix time
|
|
// in nanoseconds cannot be represented by an int64 (a date before the year
|
|
// 1678 or after 2262). Note that this means the result of calling UnixNano
|
|
// on the zero Time is undefined. The result does not depend on the
|
|
// location associated with t.
|
|
func (t Time) UnixNano() int64 {
|
|
return (t.unixSec())*1e9 + int64(t.nsec())
|
|
}
|
|
|
|
const timeBinaryVersion byte = 1
|
|
|
|
// MarshalBinary implements the encoding.BinaryMarshaler interface.
|
|
func (t Time) MarshalBinary() ([]byte, error) {
|
|
var offsetMin int16 // minutes east of UTC. -1 is UTC.
|
|
|
|
if t.Location() == UTC {
|
|
offsetMin = -1
|
|
} else {
|
|
_, offset := t.Zone()
|
|
if offset%60 != 0 {
|
|
return nil, errors.New("Time.MarshalBinary: zone offset has fractional minute")
|
|
}
|
|
offset /= 60
|
|
if offset < -32768 || offset == -1 || offset > 32767 {
|
|
return nil, errors.New("Time.MarshalBinary: unexpected zone offset")
|
|
}
|
|
offsetMin = int16(offset)
|
|
}
|
|
|
|
sec := t.sec()
|
|
nsec := t.nsec()
|
|
enc := []byte{
|
|
timeBinaryVersion, // byte 0 : version
|
|
byte(sec >> 56), // bytes 1-8: seconds
|
|
byte(sec >> 48),
|
|
byte(sec >> 40),
|
|
byte(sec >> 32),
|
|
byte(sec >> 24),
|
|
byte(sec >> 16),
|
|
byte(sec >> 8),
|
|
byte(sec),
|
|
byte(nsec >> 24), // bytes 9-12: nanoseconds
|
|
byte(nsec >> 16),
|
|
byte(nsec >> 8),
|
|
byte(nsec),
|
|
byte(offsetMin >> 8), // bytes 13-14: zone offset in minutes
|
|
byte(offsetMin),
|
|
}
|
|
|
|
return enc, nil
|
|
}
|
|
|
|
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
|
|
func (t *Time) UnmarshalBinary(data []byte) error {
|
|
buf := data
|
|
if len(buf) == 0 {
|
|
return errors.New("Time.UnmarshalBinary: no data")
|
|
}
|
|
|
|
if buf[0] != timeBinaryVersion {
|
|
return errors.New("Time.UnmarshalBinary: unsupported version")
|
|
}
|
|
|
|
if len(buf) != /*version*/ 1+ /*sec*/ 8+ /*nsec*/ 4+ /*zone offset*/ 2 {
|
|
return errors.New("Time.UnmarshalBinary: invalid length")
|
|
}
|
|
|
|
buf = buf[1:]
|
|
sec := int64(buf[7]) | int64(buf[6])<<8 | int64(buf[5])<<16 | int64(buf[4])<<24 |
|
|
int64(buf[3])<<32 | int64(buf[2])<<40 | int64(buf[1])<<48 | int64(buf[0])<<56
|
|
|
|
buf = buf[8:]
|
|
nsec := int32(buf[3]) | int32(buf[2])<<8 | int32(buf[1])<<16 | int32(buf[0])<<24
|
|
|
|
buf = buf[4:]
|
|
offset := int(int16(buf[1])|int16(buf[0])<<8) * 60
|
|
|
|
*t = Time{}
|
|
t.wall = uint64(nsec)
|
|
t.ext = sec
|
|
|
|
if offset == -1*60 {
|
|
t.setLoc(&utcLoc)
|
|
} else if _, localoff, _, _ := Local.lookup(t.unixSec()); offset == localoff {
|
|
t.setLoc(Local)
|
|
} else {
|
|
t.setLoc(FixedZone("", offset))
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// TODO(rsc): Remove GobEncoder, GobDecoder, MarshalJSON, UnmarshalJSON in Go 2.
|
|
// The same semantics will be provided by the generic MarshalBinary, MarshalText,
|
|
// UnmarshalBinary, UnmarshalText.
|
|
|
|
// GobEncode implements the gob.GobEncoder interface.
|
|
func (t Time) GobEncode() ([]byte, error) {
|
|
return t.MarshalBinary()
|
|
}
|
|
|
|
// GobDecode implements the gob.GobDecoder interface.
|
|
func (t *Time) GobDecode(data []byte) error {
|
|
return t.UnmarshalBinary(data)
|
|
}
|
|
|
|
// MarshalJSON implements the json.Marshaler interface.
|
|
// The time is a quoted string in RFC 3339 format, with sub-second precision added if present.
|
|
func (t Time) MarshalJSON() ([]byte, error) {
|
|
if y := t.Year(); y < 0 || y >= 10000 {
|
|
// RFC 3339 is clear that years are 4 digits exactly.
|
|
// See golang.org/issue/4556#c15 for more discussion.
|
|
return nil, errors.New("Time.MarshalJSON: year outside of range [0,9999]")
|
|
}
|
|
|
|
b := make([]byte, 0, len(RFC3339Nano)+2)
|
|
b = append(b, '"')
|
|
b = t.AppendFormat(b, RFC3339Nano)
|
|
b = append(b, '"')
|
|
return b, nil
|
|
}
|
|
|
|
// UnmarshalJSON implements the json.Unmarshaler interface.
|
|
// The time is expected to be a quoted string in RFC 3339 format.
|
|
func (t *Time) UnmarshalJSON(data []byte) error {
|
|
// Ignore null, like in the main JSON package.
|
|
if string(data) == "null" {
|
|
return nil
|
|
}
|
|
// Fractional seconds are handled implicitly by Parse.
|
|
var err error
|
|
*t, err = Parse(`"`+RFC3339+`"`, string(data))
|
|
return err
|
|
}
|
|
|
|
// MarshalText implements the encoding.TextMarshaler interface.
|
|
// The time is formatted in RFC 3339 format, with sub-second precision added if present.
|
|
func (t Time) MarshalText() ([]byte, error) {
|
|
if y := t.Year(); y < 0 || y >= 10000 {
|
|
return nil, errors.New("Time.MarshalText: year outside of range [0,9999]")
|
|
}
|
|
|
|
b := make([]byte, 0, len(RFC3339Nano))
|
|
return t.AppendFormat(b, RFC3339Nano), nil
|
|
}
|
|
|
|
// UnmarshalText implements the encoding.TextUnmarshaler interface.
|
|
// The time is expected to be in RFC 3339 format.
|
|
func (t *Time) UnmarshalText(data []byte) error {
|
|
// Fractional seconds are handled implicitly by Parse.
|
|
var err error
|
|
*t, err = Parse(RFC3339, string(data))
|
|
return err
|
|
}
|
|
|
|
// Unix returns the local Time 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).
|
|
func Unix(sec int64, nsec int64) Time {
|
|
if nsec < 0 || nsec >= 1e9 {
|
|
n := nsec / 1e9
|
|
sec += n
|
|
nsec -= n * 1e9
|
|
if nsec < 0 {
|
|
nsec += 1e9
|
|
sec--
|
|
}
|
|
}
|
|
return unixTime(sec, int32(nsec))
|
|
}
|
|
|
|
func isLeap(year int) bool {
|
|
return year%4 == 0 && (year%100 != 0 || year%400 == 0)
|
|
}
|
|
|
|
// norm returns nhi, nlo such that
|
|
// hi * base + lo == nhi * base + nlo
|
|
// 0 <= nlo < base
|
|
func norm(hi, lo, base int) (nhi, nlo int) {
|
|
if lo < 0 {
|
|
n := (-lo-1)/base + 1
|
|
hi -= n
|
|
lo += n * base
|
|
}
|
|
if lo >= base {
|
|
n := lo / base
|
|
hi += n
|
|
lo -= n * base
|
|
}
|
|
return hi, lo
|
|
}
|
|
|
|
// Date returns the Time corresponding to
|
|
// yyyy-mm-dd hh:mm:ss + nsec nanoseconds
|
|
// in the appropriate zone for that time in the given location.
|
|
//
|
|
// The month, day, hour, min, sec, and nsec values may be outside
|
|
// their usual ranges and will be normalized during the conversion.
|
|
// For example, October 32 converts to November 1.
|
|
//
|
|
// A daylight savings time transition skips or repeats times.
|
|
// For example, in the United States, March 13, 2011 2:15am never occurred,
|
|
// while November 6, 2011 1:15am occurred twice. In such cases, the
|
|
// choice of time zone, and therefore the time, is not well-defined.
|
|
// Date returns a time that is correct in one of the two zones involved
|
|
// in the transition, but it does not guarantee which.
|
|
//
|
|
// Date panics if loc is nil.
|
|
func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time {
|
|
if loc == nil {
|
|
panic("time: missing Location in call to Date")
|
|
}
|
|
|
|
// Normalize month, overflowing into year.
|
|
m := int(month) - 1
|
|
year, m = norm(year, m, 12)
|
|
month = Month(m) + 1
|
|
|
|
// Normalize nsec, sec, min, hour, overflowing into day.
|
|
sec, nsec = norm(sec, nsec, 1e9)
|
|
min, sec = norm(min, sec, 60)
|
|
hour, min = norm(hour, min, 60)
|
|
day, hour = norm(day, hour, 24)
|
|
|
|
y := uint64(int64(year) - absoluteZeroYear)
|
|
|
|
// Compute days since the absolute epoch.
|
|
|
|
// Add in days from 400-year cycles.
|
|
n := y / 400
|
|
y -= 400 * n
|
|
d := daysPer400Years * n
|
|
|
|
// Add in 100-year cycles.
|
|
n = y / 100
|
|
y -= 100 * n
|
|
d += daysPer100Years * n
|
|
|
|
// Add in 4-year cycles.
|
|
n = y / 4
|
|
y -= 4 * n
|
|
d += daysPer4Years * n
|
|
|
|
// Add in non-leap years.
|
|
n = y
|
|
d += 365 * n
|
|
|
|
// Add in days before this month.
|
|
d += uint64(daysBefore[month-1])
|
|
if isLeap(year) && month >= March {
|
|
d++ // February 29
|
|
}
|
|
|
|
// Add in days before today.
|
|
d += uint64(day - 1)
|
|
|
|
// Add in time elapsed today.
|
|
abs := d * secondsPerDay
|
|
abs += uint64(hour*secondsPerHour + min*secondsPerMinute + sec)
|
|
|
|
unix := int64(abs) + (absoluteToInternal + internalToUnix)
|
|
|
|
// Look for zone offset for t, so we can adjust to UTC.
|
|
// The lookup function expects UTC, so we pass t in the
|
|
// hope that it will not be too close to a zone transition,
|
|
// and then adjust if it is.
|
|
_, offset, start, end := loc.lookup(unix)
|
|
if offset != 0 {
|
|
switch utc := unix - int64(offset); {
|
|
case utc < start:
|
|
_, offset, _, _ = loc.lookup(start - 1)
|
|
case utc >= end:
|
|
_, offset, _, _ = loc.lookup(end)
|
|
}
|
|
unix -= int64(offset)
|
|
}
|
|
|
|
t := unixTime(unix, int32(nsec))
|
|
t.setLoc(loc)
|
|
return t
|
|
}
|
|
|
|
// Truncate returns the result of rounding t down to a multiple of d (since the zero time).
|
|
// If d <= 0, Truncate returns t stripped of any monotonic clock reading but otherwise unchanged.
|
|
//
|
|
// Truncate operates on the time as an absolute duration since the
|
|
// zero time; it does not operate on the presentation form of the
|
|
// time. Thus, Truncate(Hour) may return a time with a non-zero
|
|
// minute, depending on the time's Location.
|
|
func (t Time) Truncate(d Duration) Time {
|
|
t.stripMono()
|
|
if d <= 0 {
|
|
return t
|
|
}
|
|
_, r := div(t, d)
|
|
return t.Add(-r)
|
|
}
|
|
|
|
// Round returns the result of rounding t to the nearest multiple of d (since the zero time).
|
|
// The rounding behavior for halfway values is to round up.
|
|
// If d <= 0, Round returns t stripped of any monotonic clock reading but otherwise unchanged.
|
|
//
|
|
// Round operates on the time as an absolute duration since the
|
|
// zero time; it does not operate on the presentation form of the
|
|
// time. Thus, Round(Hour) may return a time with a non-zero
|
|
// minute, depending on the time's Location.
|
|
func (t Time) Round(d Duration) Time {
|
|
t.stripMono()
|
|
if d <= 0 {
|
|
return t
|
|
}
|
|
_, r := div(t, d)
|
|
if lessThanHalf(r, d) {
|
|
return t.Add(-r)
|
|
}
|
|
return t.Add(d - r)
|
|
}
|
|
|
|
// div divides t by d and returns the quotient parity and remainder.
|
|
// We don't use the quotient parity anymore (round half up instead of round to even)
|
|
// but it's still here in case we change our minds.
|
|
func div(t Time, d Duration) (qmod2 int, r Duration) {
|
|
neg := false
|
|
nsec := t.nsec()
|
|
sec := t.sec()
|
|
if sec < 0 {
|
|
// Operate on absolute value.
|
|
neg = true
|
|
sec = -sec
|
|
nsec = -nsec
|
|
if nsec < 0 {
|
|
nsec += 1e9
|
|
sec-- // sec >= 1 before the -- so safe
|
|
}
|
|
}
|
|
|
|
switch {
|
|
// Special case: 2d divides 1 second.
|
|
case d < Second && Second%(d+d) == 0:
|
|
qmod2 = int(nsec/int32(d)) & 1
|
|
r = Duration(nsec % int32(d))
|
|
|
|
// Special case: d is a multiple of 1 second.
|
|
case d%Second == 0:
|
|
d1 := int64(d / Second)
|
|
qmod2 = int(sec/d1) & 1
|
|
r = Duration(sec%d1)*Second + Duration(nsec)
|
|
|
|
// General case.
|
|
// This could be faster if more cleverness were applied,
|
|
// but it's really only here to avoid special case restrictions in the API.
|
|
// No one will care about these cases.
|
|
default:
|
|
// Compute nanoseconds as 128-bit number.
|
|
sec := uint64(sec)
|
|
tmp := (sec >> 32) * 1e9
|
|
u1 := tmp >> 32
|
|
u0 := tmp << 32
|
|
tmp = (sec & 0xFFFFFFFF) * 1e9
|
|
u0x, u0 := u0, u0+tmp
|
|
if u0 < u0x {
|
|
u1++
|
|
}
|
|
u0x, u0 = u0, u0+uint64(nsec)
|
|
if u0 < u0x {
|
|
u1++
|
|
}
|
|
|
|
// Compute remainder by subtracting r<<k for decreasing k.
|
|
// Quotient parity is whether we subtract on last round.
|
|
d1 := uint64(d)
|
|
for d1>>63 != 1 {
|
|
d1 <<= 1
|
|
}
|
|
d0 := uint64(0)
|
|
for {
|
|
qmod2 = 0
|
|
if u1 > d1 || u1 == d1 && u0 >= d0 {
|
|
// subtract
|
|
qmod2 = 1
|
|
u0x, u0 = u0, u0-d0
|
|
if u0 > u0x {
|
|
u1--
|
|
}
|
|
u1 -= d1
|
|
}
|
|
if d1 == 0 && d0 == uint64(d) {
|
|
break
|
|
}
|
|
d0 >>= 1
|
|
d0 |= (d1 & 1) << 63
|
|
d1 >>= 1
|
|
}
|
|
r = Duration(u0)
|
|
}
|
|
|
|
if neg && r != 0 {
|
|
// If input was negative and not an exact multiple of d, we computed q, r such that
|
|
// q*d + r = -t
|
|
// But the right answers are given by -(q-1), d-r:
|
|
// q*d + r = -t
|
|
// -q*d - r = t
|
|
// -(q-1)*d + (d - r) = t
|
|
qmod2 ^= 1
|
|
r = d - r
|
|
}
|
|
return
|
|
}
|