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https://github.com/golang/go
synced 2024-11-25 08:57:58 -07:00
time: add ParseDuration.
R=rsc, r, r CC=golang-dev https://golang.org/cl/5489111
This commit is contained in:
David Symonds
parent
e6a322b0b9
commit
f298d0ce29
@ -283,25 +283,16 @@ var atoiError = errors.New("time: invalid number")
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// Duplicates functionality in strconv, but avoids dependency.
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func atoi(s string) (x int, err error) {
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i := 0
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if len(s) > 0 && s[0] == '-' {
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i++
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neg := false
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if s != "" && s[0] == '-' {
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neg = true
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s = s[1:]
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}
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if i >= len(s) {
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x, rem, err := leadingInt(s)
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if err != nil || rem != "" {
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return 0, atoiError
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}
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for ; i < len(s); i++ {
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c := s[i]
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if c < '0' || c > '9' {
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return 0, atoiError
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}
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if x >= (1<<31-10)/10 {
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// will overflow
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return 0, atoiError
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}
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x = x*10 + int(c) - '0'
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}
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if s[0] == '-' {
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if neg {
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x = -x
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}
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return x, nil
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@ -893,3 +884,126 @@ func parseNanoseconds(value string, nbytes int) (ns int, rangeErrString string,
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}
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return
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}
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var errLeadingInt = errors.New("time: bad [0-9]*") // never printed
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// leadingInt consumes the leading [0-9]* from s.
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func leadingInt(s string) (x int, rem string, err error) {
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i := 0
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for ; i < len(s); i++ {
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c := s[i]
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if c < '0' || c > '9' {
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break
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}
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if x >= (1<<31-10)/10 {
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// overflow
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return 0, "", errLeadingInt
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}
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x = x*10 + int(c) - '0'
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}
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return x, s[i:], nil
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}
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var unitMap = map[string]float64{
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"ns": float64(Nanosecond),
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"us": float64(Microsecond),
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"µs": float64(Microsecond), // U+00B5 = micro symbol
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"μs": float64(Microsecond), // U+03BC = Greek letter mu
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"ms": float64(Millisecond),
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"s": float64(Second),
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"m": float64(Minute),
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"h": float64(Hour),
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}
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// ParseDuration parses a duration string.
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// A duration string is a possibly signed sequence of
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// decimal numbers, each with optional fraction and a unit suffix,
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// such as "300ms", "-1.5h" or "2h45m".
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// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
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func ParseDuration(s string) (Duration, error) {
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// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
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orig := s
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f := float64(0)
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neg := false
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// Consume [-+]?
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if s != "" {
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c := s[0]
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if c == '-' || c == '+' {
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neg = c == '-'
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s = s[1:]
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}
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}
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// Special case: if all that is left is "0", this is zero.
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if s == "0" {
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return 0, nil
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}
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if s == "" {
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return 0, errors.New("time: invalid duration " + orig)
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}
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for s != "" {
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g := float64(0) // this element of the sequence
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var x int
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var err error
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// The next character must be [0-9.]
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if !(s[0] == '.' || ('0' <= s[0] && s[0] <= '9')) {
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return 0, errors.New("time: invalid duration " + orig)
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}
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// Consume [0-9]*
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pl := len(s)
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x, s, err = leadingInt(s)
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if err != nil {
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return 0, errors.New("time: invalid duration " + orig)
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}
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g = float64(x)
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pre := pl != len(s) // whether we consumed anything before a period
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// Consume (\.[0-9]*)?
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post := false
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if s != "" && s[0] == '.' {
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s = s[1:]
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pl := len(s)
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x, s, err = leadingInt(s)
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if err != nil {
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return 0, errors.New("time: invalid duration " + orig)
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}
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scale := 1
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for n := pl - len(s); n > 0; n-- {
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scale *= 10
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}
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g += float64(x) / float64(scale)
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post = pl != len(s)
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}
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if !pre && !post {
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// no digits (e.g. ".s" or "-.s")
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return 0, errors.New("time: invalid duration " + orig)
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}
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// Consume unit.
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i := 0
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for ; i < len(s); i++ {
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c := s[i]
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if c == '.' || ('0' <= c && c <= '9') {
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break
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}
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}
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if i == 0 {
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return 0, errors.New("time: missing unit in duration " + orig)
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}
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u := s[:i]
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s = s[i:]
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unit, ok := unitMap[u]
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if !ok {
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return 0, errors.New("time: unknown unit " + u + " in duration " + orig)
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}
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f += g * unit
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}
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if neg {
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f = -f
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}
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return Duration(f), nil
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}
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@ -8,6 +8,7 @@ import (
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"bytes"
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"encoding/gob"
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"encoding/json"
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"math/rand"
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"strconv"
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"strings"
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"testing"
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@ -816,6 +817,82 @@ func TestNotJSONEncodableTime(t *testing.T) {
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}
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}
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var parseDurationTests = []struct {
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in string
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ok bool
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want Duration
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}{
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// simple
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{"0", true, 0},
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{"5s", true, 5 * Second},
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{"30s", true, 30 * Second},
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{"1478s", true, 1478 * Second},
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// sign
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{"-5s", true, -5 * Second},
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{"+5s", true, 5 * Second},
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{"-0", true, 0},
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{"+0", true, 0},
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// decimal
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{"5.0s", true, 5 * Second},
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{"5.6s", true, 5*Second + 600*Millisecond},
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{"5.s", true, 5 * Second},
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{".5s", true, 500 * Millisecond},
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{"1.0s", true, 1 * Second},
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{"1.00s", true, 1 * Second},
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{"1.004s", true, 1*Second + 4*Millisecond},
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{"1.0040s", true, 1*Second + 4*Millisecond},
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{"100.00100s", true, 100*Second + 1*Millisecond},
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// different units
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{"10ns", true, 10 * Nanosecond},
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{"11us", true, 11 * Microsecond},
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{"12µs", true, 12 * Microsecond}, // U+00B5
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{"12μs", true, 12 * Microsecond}, // U+03BC
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{"13ms", true, 13 * Millisecond},
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{"14s", true, 14 * Second},
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{"15m", true, 15 * Minute},
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{"16h", true, 16 * Hour},
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// composite durations
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{"3h30m", true, 3*Hour + 30*Minute},
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{"10.5s4m", true, 4*Minute + 10*Second + 500*Millisecond},
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{"-2m3.4s", true, -(2*Minute + 3*Second + 400*Millisecond)},
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{"1h2m3s4ms5us6ns", true, 1*Hour + 2*Minute + 3*Second + 4*Millisecond + 5*Microsecond + 6*Nanosecond},
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{"39h9m14.425s", true, 39*Hour + 9*Minute + 14*Second + 425*Millisecond},
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// errors
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{"", false, 0},
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{"3", false, 0},
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{"-", false, 0},
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{"s", false, 0},
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{".", false, 0},
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{"-.", false, 0},
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{".s", false, 0},
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{"+.s", false, 0},
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}
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func TestParseDuration(t *testing.T) {
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for _, tc := range parseDurationTests {
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d, err := ParseDuration(tc.in)
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if tc.ok && (err != nil || d != tc.want) {
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t.Errorf("ParseDuration(%q) = %v, %v, want %v, nil", tc.in, d, err, tc.want)
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} else if !tc.ok && err == nil {
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t.Errorf("ParseDuration(%q) = _, nil, want _, non-nil", tc.in)
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}
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}
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}
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func TestParseDurationRoundTrip(t *testing.T) {
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for i := 0; i < 100; i++ {
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// Resolutions finer than milliseconds will result in
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// imprecise round-trips.
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d0 := Duration(rand.Int31()) * Millisecond
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s := d0.String()
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d1, err := ParseDuration(s)
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if err != nil || d0 != d1 {
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t.Errorf("round-trip failed: %d => %q => %d, %v", d0, s, d1, err)
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}
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}
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}
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func BenchmarkNow(b *testing.B) {
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for i := 0; i < b.N; i++ {
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Now()
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