Use sync.OnceValue only on go1.21+

Signed-off-by: Kimmo Lehto <[email protected]>

lazy.go

@@ -0,0 +1,14 @@
+//go:build go1.21
+
+package validator
+
+import (
+	"regexp"
+	"sync"
+)
+
+func lazyRegexCompile(str string) func() *regexp.Regexp {
+	return sync.OnceValue(func() *regexp.Regexp {
+		return regexp.MustCompile(str)
+	})
+}

lazy_compat.go

@@ -0,0 +1,19 @@
+//go:build !go1.21
+
+package validator
+
+import (
+	"regexp"
+	"sync"
+)
+
+func lazyRegexCompile(str string) func() *regexp.Regexp {
+	var regex *regexp.Regexp
+	var once sync.Once
+	return func() *regexp.Regexp {
+		once.Do(func() {
+			regex = regexp.MustCompile(str)
+		})
+		return regex
+	}
+}

regexes.go

@@ -1,10 +1,5 @@
 package validator
 
-import (
-	"regexp"
-	"sync"
-)
-
 const (
 	alphaRegexString                 = "^[a-zA-Z]+$"
 	alphaNumericRegexString          = "^[a-zA-Z0-9]+$"
@@ -79,12 +74,6 @@ const (
 	spicedbTypeRegexString           = "^([a-z][a-z0-9_]{1,61}[a-z0-9]/)?[a-z][a-z0-9_]{1,62}[a-z0-9]$"
 )
 
-func lazyRegexCompile(str string) func() *regexp.Regexp {
-	return sync.OnceValue(func() *regexp.Regexp {
-		return regexp.MustCompile(str)
-	})
-}
-
 var (
 	alphaRegex                 = lazyRegexCompile(alphaRegexString)
 	alphaNumericRegex          = lazyRegexCompile(alphaNumericRegexString)