122 lines
2.7 KiB
Go
122 lines
2.7 KiB
Go
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// Package duration provides a partial implementation of ISO8601 durations. (no months)
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package duration
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import (
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"bytes"
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"errors"
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"fmt"
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"regexp"
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"strconv"
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"text/template"
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"time"
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)
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var (
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// ErrBadFormat is returned when parsing fails
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ErrBadFormat = errors.New("bad format string")
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// ErrNoMonth is raised when a month is in the format string
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ErrNoMonth = errors.New("no months allowed")
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tmpl = template.Must(template.New("duration").Parse(`P{{if .Years}}{{.Years}}Y{{end}}{{if .Weeks}}{{.Weeks}}W{{end}}{{if .Days}}{{.Days}}D{{end}}{{if .HasTimePart}}T{{end }}{{if .Hours}}{{.Hours}}H{{end}}{{if .Minutes}}{{.Minutes}}M{{end}}{{if .Seconds}}{{.Seconds}}S{{end}}`))
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full = regexp.MustCompile(`P((?P<year>\d+)Y)?((?P<month>\d+)M)?((?P<day>\d+)D)?(T((?P<hour>\d+)H)?((?P<minute>\d+)M)?((?P<second>\d+)S)?)?`)
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week = regexp.MustCompile(`P((?P<week>\d+)W)`)
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)
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type Duration struct {
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Years int
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Weeks int
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Days int
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Hours int
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Minutes int
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Seconds int
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}
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func FromString(dur string) (*Duration, error) {
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var (
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match []string
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re *regexp.Regexp
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)
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if week.MatchString(dur) {
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match = week.FindStringSubmatch(dur)
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re = week
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} else if full.MatchString(dur) {
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match = full.FindStringSubmatch(dur)
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re = full
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} else {
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return nil, ErrBadFormat
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}
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d := &Duration{}
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for i, name := range re.SubexpNames() {
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part := match[i]
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if i == 0 || name == "" || part == "" {
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continue
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}
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val, err := strconv.Atoi(part)
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if err != nil {
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return nil, err
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}
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switch name {
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case "year":
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d.Years = val
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case "month":
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return nil, ErrNoMonth
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case "week":
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d.Weeks = val
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case "day":
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d.Days = val
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case "hour":
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d.Hours = val
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case "minute":
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d.Minutes = val
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case "second":
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d.Seconds = val
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default:
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return nil, errors.New(fmt.Sprintf("unknown field %s", name))
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}
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}
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return d, nil
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}
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// String prints out the value passed in. It's not strictly according to the
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// ISO spec, but it's pretty close. In particular, to completely conform it
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// would need to round up to the next largest unit. 61 seconds to 1 minute 1
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// second, for example. It would also need to disallow weeks mingling with
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// other units.
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func (d *Duration) String() string {
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var s bytes.Buffer
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err := tmpl.Execute(&s, d)
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if err != nil {
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panic(err)
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}
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return s.String()
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}
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func (d *Duration) HasTimePart() bool {
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return d.Hours != 0 || d.Minutes != 0 || d.Seconds != 0
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}
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func (d *Duration) ToDuration() time.Duration {
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day := time.Hour * 24
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year := day * 365
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tot := time.Duration(0)
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tot += year * time.Duration(d.Years)
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tot += day * 7 * time.Duration(d.Weeks)
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tot += day * time.Duration(d.Days)
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tot += time.Hour * time.Duration(d.Hours)
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tot += time.Minute * time.Duration(d.Minutes)
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tot += time.Second * time.Duration(d.Seconds)
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return tot
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}
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