refactor(timezone): Optimize time zone parsing logic to support variable parameters

Author: kuafuRace

creator.go

@@ -13,7 +13,7 @@ func CreateFromStdTime(stdTime StdTime, timezone ...string) *Carbon {
 		loc *Location
 		err error
 	)
-	if loc, err = parseTimezone(timezone[0]); err != nil {
+	if loc, err = parseTimezone(timezone...); err != nil {
 		return &Carbon{Error: err}
 	}
 	return NewCarbon(stdTime.In(loc))
@@ -22,16 +22,10 @@ func CreateFromStdTime(stdTime StdTime, timezone ...string) *Carbon {
 // CreateFromTimestamp creates a Carbon instance from a given timestamp with second precision.
 func CreateFromTimestamp(timestamp int64, timezone ...string) *Carbon {
 	var (
-		tz  string
 		loc *Location
 		err error
 	)
-	if len(timezone) > 0 {
-		tz = timezone[0]
-	} else {
-		tz = DefaultTimezone
-	}
-	if loc, err = parseTimezone(tz); err != nil {
+	if loc, err = parseTimezone(timezone...); err != nil {
 		return &Carbon{Error: err}
 	}
 	return NewCarbon(time.Unix(timestamp, MinNanosecond).In(loc))
@@ -40,16 +34,10 @@ func CreateFromTimestamp(timestamp int64, timezone ...string) *Carbon {
 // CreateFromTimestampMilli creates a Carbon instance from a given timestamp with millisecond precision.
 func CreateFromTimestampMilli(timestampMilli int64, timezone ...string) *Carbon {
 	var (
-		tz  string
 		loc *Location
 		err error
 	)
-	if len(timezone) > 0 {
-		tz = timezone[0]
-	} else {
-		tz = DefaultTimezone
-	}
-	if loc, err = parseTimezone(tz); err != nil {
+	if loc, err = parseTimezone(timezone...); err != nil {
 		return &Carbon{Error: err}
 	}
 	return NewCarbon(time.Unix(timestampMilli/1e3, (timestampMilli%1e3)*1e6).In(loc))
@@ -58,16 +46,10 @@ func CreateFromTimestampMilli(timestampMilli int64, timezone ...string) *Carbon
 // CreateFromTimestampMicro creates a Carbon instance from a given timestamp with microsecond precision.
 func CreateFromTimestampMicro(timestampMicro int64, timezone ...string) *Carbon {
 	var (
-		tz  string
 		loc *Location
 		err error
 	)
-	if len(timezone) > 0 {
-		tz = timezone[0]
-	} else {
-		tz = DefaultTimezone
-	}
-	if loc, err = parseTimezone(tz); err != nil {
+	if loc, err = parseTimezone(timezone...); err != nil {
 		return &Carbon{Error: err}
 	}
 	return NewCarbon(time.Unix(timestampMicro/1e6, (timestampMicro%1e6)*1e3).In(loc))
@@ -76,16 +58,10 @@ func CreateFromTimestampMicro(timestampMicro int64, timezone ...string) *Carbon
 // CreateFromTimestampNano creates a Carbon instance from a given timestamp with nanosecond precision.
 func CreateFromTimestampNano(timestampNano int64, timezone ...string) *Carbon {
 	var (
-		tz  string
 		loc *Location
 		err error
 	)
-	if len(timezone) > 0 {
-		tz = timezone[0]
-	} else {
-		tz = DefaultTimezone
-	}
-	if loc, err = parseTimezone(tz); err != nil {
+	if loc, err = parseTimezone(timezone...); err != nil {
 		return &Carbon{Error: err}
 	}
 	return NewCarbon(time.Unix(timestampNano/1e9, timestampNano%1e9).In(loc))
@@ -158,16 +134,10 @@ func CreateFromTimeNano(hour, minute, second, nanosecond int, timezone ...string
 // creates a new Carbon instance from a given date, time and nanosecond.
 func create(year, month, day, hour, minute, second, nanosecond int, timezone ...string) *Carbon {
 	var (
-		tz  string
 		loc *Location
 		err error
 	)
-	if len(timezone) > 0 {
-		tz = timezone[0]
-	} else {
-		tz = DefaultTimezone
-	}
-	if loc, err = parseTimezone(tz); err != nil {
+	if loc, err = parseTimezone(timezone...); err != nil {
 		return &Carbon{Error: err}
 	}
 	return NewCarbon(time.Date(year, time.Month(month), day, hour, minute, second, nanosecond, loc))

helper.go

@@ -131,24 +131,30 @@ func format2layout(format string) string {
 // timezoneCache caches parsed timezone locations to avoid repeated parsing
 var timezoneCache sync.Map
 
-// parses a timezone string as a time.Location instance.
-func parseTimezone(timezone string) (loc *Location, err error) {
-	if timezone == "" {
+// parses timezone strings as a time.Location instance.
+func parseTimezone(timezone ...string) (loc *Location, err error) {
+	var tz string
+	if len(timezone) > 0 {
+		tz = timezone[0]
+	} else {
+		tz = DefaultTimezone
+	}
+	if tz == "" {
 		return nil, ErrEmptyTimezone()
 	}
 
 	// Check cache first
-	if cached, exists := timezoneCache.Load(timezone); exists {
+	if cached, exists := timezoneCache.Load(tz); exists {
 		return cached.(*Location), nil
 	}
 
-	if loc, err = time.LoadLocation(timezone); err != nil {
-		err = fmt.Errorf("%w: %w", ErrInvalidTimezone(timezone), err)
+	if loc, err = time.LoadLocation(tz); err != nil {
+		err = fmt.Errorf("%w: %w", ErrInvalidTimezone(tz), err)
 		return
 	}
 
 	// Cache the successful result
-	timezoneCache.Store(timezone, loc)
+	timezoneCache.Store(tz, loc)
 	return
 }