Get rid of bogus use of unicode package, go back to only require go 1.20

duration.go

@@ -13,14 +13,21 @@ import (
 	"strings"
 	"time"
 	_ "time/tzdata" // load fallback timezone data for use in docker images.
-	"unicode"
 )
 
 const (
 	Day  = 24 * time.Hour
 	Week = 7 * Day
 )
 
+func isPartOfNumber(c byte) bool {
+	return ('0' <= c && c <= '9') || c == '.' || c == '-'
+}
+
+func isSpaceOrTab(c byte) bool {
+	return c == ' ' || c == '\t'
+}
+
 // Parse parses a duration string with "d" for days (24 hours)
 // and "w" for weeks (7 days) in addition to what stdlib [time.ParseDuration] supports.
 func Parse(s string) (time.Duration, error) {
@@ -36,12 +43,12 @@ func Parse(s string) (time.Duration, error) {
 	hasDecimal := false
 	for s != "" {
 		// consume spaces and tabs between parts
-		for len(s) > 0 && (s[0] == ' ' || s[0] == '\t') {
+		for len(s) > 0 && isSpaceOrTab(s[0]) {
 			s = s[1:]
 		}
 		// find number part
 		i := 0
-		for i < len(s) && (('0' <= s[i] && s[i] <= '9') || s[i] == '.' || s[i] == '-') {
+		for i < len(s) && isPartOfNumber(s[i]) {
 			if s[i] == '.' {
 				hasDecimal = true
 			}
@@ -55,7 +62,7 @@ func Parse(s string) (time.Duration, error) {
 
 		// find unit
 		j := 0
-		for j < len(s) && unicode.IsLetter(rune(s[j])) {
+		for j < len(s) && !isPartOfNumber(s[j]) && !isSpaceOrTab(s[j]) {
 			j++
 		}
 		if j == 0 {
@@ -91,7 +98,9 @@ func Parse(s string) (time.Duration, error) {
 		default:
 			return 0, errors.New("unknown unit " + unit + " in duration " + orig)
 		}
-		smallestUnit = min(smallestUnit, mult)
+		if mult < smallestUnit {
+			smallestUnit = mult
+		}
 		if v < 0 {
 			return 0, errors.New("unexpected negative sign in middle of duration " + orig)
 		}

go.mod

@@ -1,3 +1,3 @@
 module fortio.org/duration
 
-go 1.21
+go 1.20