153 lines
3.5 KiB
Go
153 lines
3.5 KiB
Go
package strftime
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import (
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"fmt"
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"sync"
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"github.com/lestrrat-go/strftime/internal/errors"
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)
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// because there is no such thing was a sync.RWLocker
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type rwLocker interface {
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RLock()
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RUnlock()
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sync.Locker
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}
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// SpecificationSet is a container for patterns that Strftime uses.
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// If you want a custom strftime, you can copy the default
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// SpecificationSet and tweak it
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type SpecificationSet interface {
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Lookup(byte) (Appender, error)
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Delete(byte) error
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Set(byte, Appender) error
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}
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type specificationSet struct {
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mutable bool
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lock rwLocker
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store map[byte]Appender
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}
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// The default specification set does not need any locking as it is never
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// accessed from the outside, and is never mutated.
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var defaultSpecificationSet SpecificationSet
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func init() {
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defaultSpecificationSet = newImmutableSpecificationSet()
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}
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func newImmutableSpecificationSet() SpecificationSet {
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// Create a mutable one so that populateDefaultSpecifications work through
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// its magic, then copy the associated map
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// (NOTE: this is done this way because there used to be
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// two struct types for specification set, united under an interface.
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// it can now be removed, but we would need to change the entire
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// populateDefaultSpecifications method, and I'm currently too lazy
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// PRs welcome)
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tmp := NewSpecificationSet()
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ss := &specificationSet{
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mutable: false,
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lock: nil, // never used, so intentionally not initialized
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store: tmp.(*specificationSet).store,
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}
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return ss
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}
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// NewSpecificationSet creates a specification set with the default specifications.
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func NewSpecificationSet() SpecificationSet {
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ds := &specificationSet{
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mutable: true,
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lock: &sync.RWMutex{},
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store: make(map[byte]Appender),
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}
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populateDefaultSpecifications(ds)
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return ds
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}
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var defaultSpecifications = map[byte]Appender{
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'A': fullWeekDayName,
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'a': abbrvWeekDayName,
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'B': fullMonthName,
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'b': abbrvMonthName,
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'C': centuryDecimal,
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'c': timeAndDate,
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'D': mdy,
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'd': dayOfMonthZeroPad,
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'e': dayOfMonthSpacePad,
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'F': ymd,
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'H': twentyFourHourClockZeroPad,
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'h': abbrvMonthName,
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'I': twelveHourClockZeroPad,
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'j': dayOfYear,
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'k': twentyFourHourClockSpacePad,
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'l': twelveHourClockSpacePad,
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'M': minutesZeroPad,
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'm': monthNumberZeroPad,
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'n': newline,
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'p': ampm,
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'R': hm,
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'r': imsp,
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'S': secondsNumberZeroPad,
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'T': hms,
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't': tab,
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'U': weekNumberSundayOrigin,
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'u': weekdayMondayOrigin,
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'V': weekNumberMondayOriginOneOrigin,
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'v': eby,
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'W': weekNumberMondayOrigin,
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'w': weekdaySundayOrigin,
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'X': natReprTime,
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'x': natReprDate,
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'Y': year,
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'y': yearNoCentury,
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'Z': timezone,
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'z': timezoneOffset,
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'%': percent,
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}
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func populateDefaultSpecifications(ds SpecificationSet) {
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for c, handler := range defaultSpecifications {
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if err := ds.Set(c, handler); err != nil {
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panic(fmt.Sprintf("failed to set default specification for %c: %s", c, err))
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}
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}
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}
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func (ds *specificationSet) Lookup(b byte) (Appender, error) {
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if ds.mutable {
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ds.lock.RLock()
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defer ds.lock.RLock()
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}
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v, ok := ds.store[b]
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if !ok {
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return nil, errors.Errorf(`lookup failed: '%%%c' was not found in specification set`, b)
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}
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return v, nil
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}
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func (ds *specificationSet) Delete(b byte) error {
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if !ds.mutable {
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return errors.New(`delete failed: this specification set is marked immutable`)
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}
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ds.lock.Lock()
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defer ds.lock.Unlock()
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delete(ds.store, b)
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return nil
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}
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func (ds *specificationSet) Set(b byte, a Appender) error {
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if !ds.mutable {
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return errors.New(`set failed: this specification set is marked immutable`)
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}
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ds.lock.Lock()
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defer ds.lock.Unlock()
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ds.store[b] = a
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return nil
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}
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