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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the go.dev/LICENSE file.
package xtime
import (
"errors"
"strconv"
"time"
)
// function borrowed from https://cs.opensource.google/go/go/+/refs/tags/go1.22.5:src/time/format.go;l=1589
// supports days and weeks such as '1d1ms', '1w1ms'
func parseDuration(s string) (time.Duration, error) {
// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
orig := s
var d int64
neg := false
// Consume [-+]?
if s != "" {
c := s[0]
if c == '-' || c == '+' {
neg = c == '-'
s = s[1:]
}
}
// Special case: if all that is left is "0", this is zero.
if s == "0" {
return 0, nil
}
if s == "" {
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
for s != "" {
var (
v, f int64 // integers before, after decimal point
scale float64 = 1 // value = v + f/scale
)
var err error
// The next character must be [0-9.]
if !(s[0] == '.' || '0' <= s[0] && s[0] <= '9') {
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
// Consume [0-9]*
pl := len(s)
v, s, err = leadingInt(s)
if err != nil {
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
pre := pl != len(s) // whether we consumed anything before a period
// Consume (\.[0-9]*)?
post := false
if s != "" && s[0] == '.' {
s = s[1:]
pl := len(s)
f, scale, s = leadingFraction(s)
post = pl != len(s)
}
if !pre && !post {
// no digits (e.g. ".s" or "-.s")
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
// Consume unit.
i := 0
for ; i < len(s); i++ {
c := s[i]
if c == '.' || '0' <= c && c <= '9' {
break
}
}
if i == 0 {
return 0, errors.New("missing unit in duration " + strconv.Quote(orig))
}
u := s[:i]
s = s[i:]
unit, ok := unitMap[u]
if !ok {
return 0, errors.New("unknown unit " + strconv.Quote(u) + " in duration " + strconv.Quote(orig))
}
if v > (1<<63-1)/unit {
// overflow
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
v *= unit
if f > 0 {
// float64 is needed to be nanosecond accurate for fractions of hours.
// v >= 0 && (f*unit/scale) <= 3.6e+12 (ns/h, h is the largest unit)
v += int64(float64(f) * (float64(unit) / scale))
if v < 0 {
// overflow
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
}
d += v
if d < 0 {
// overflow
return 0, errors.New("invalid duration " + strconv.Quote(orig))
}
}
if neg {
d = -d
}
return time.Duration(d), nil
}
var errLeadingInt = errors.New("bad [0-9]*") // never printed
// leadingInt consumes the leading [0-9]* from s.
func leadingInt(s string) (x int64, rem string, err error) {
i := 0
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if x > (1<<63-1)/10 {
// overflow
return 0, "", errLeadingInt
}
x = x*10 + int64(c) - '0'
if x < 0 {
// overflow
return 0, "", errLeadingInt
}
}
return x, s[i:], nil
}
// leadingFraction consumes the leading [0-9]* from s.
// It is used only for fractions, so does not return an error on overflow,
// it just stops accumulating precision.
func leadingFraction(s string) (x int64, scale float64, rem string) {
i := 0
scale = 1
overflow := false
for ; i < len(s); i++ {
c := s[i]
if c < '0' || c > '9' {
break
}
if overflow {
continue
}
if x > (1<<63-1)/10 {
// It's possible for overflow to give a positive number, so take care.
overflow = true
continue
}
y := x*10 + int64(c) - '0'
if y < 0 {
overflow = true
continue
}
x = y
scale *= 10
}
return x, scale, s[i:]
}
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