Optimize code validator to not use regexp

internal/util/util.go

@@ -5,28 +5,62 @@ import (
 	"errors"
 	"os"
 	"path/filepath"
-	"regexp"
+	"strings"
 
 	"fyne.io/fyne/v2"
 )
 
 //lint:ignore ST1005 The error is not printed to a terminal as usual but displayed to the user in the ui.
 var errInvalidCode = errors.New("Invalid code. Must begin with a number followed by groups of letters, separated with \"-\".")
-var codeRegexp = regexp.MustCompile(`^\d+(-(\w|\d)+)+$`)
 
 // CodeValidator provides a validator for wormhole codes.
 func CodeValidator(input string) error {
 	if input == "" {
 		return nil // We don't want empty entry to report an error.
 	}
 
-	if !codeRegexp.MatchString(input) {
+	next := strings.IndexByte(input, '-')
+	if next == -1 {
 		return errInvalidCode
 	}
 
+	mailbox := strings.IndexFunc(input[:next], runeIsNotNumerical)
+	if mailbox != -1 {
+		return errInvalidCode
+	}
+
+	input = input[next+1:]
+	if input == "" {
+		return errInvalidCode
+	}
+
+	for input != "" {
+		next = strings.IndexByte(input, '-')
+		if next == -1 {
+			next += len(input)
+		} else if next == len(input)-1 || next == 0 {
+			return errInvalidCode
+		}
+
+		invalidChars := strings.IndexFunc(input[:next], runeIsNotAlphaNumerical)
+		if invalidChars != -1 {
+			return errInvalidCode
+		}
+
+		input = input[next+1:]
+	}
+
 	return nil
 }
 
+func runeIsNotAlphaNumerical(r rune) bool {
+	return (r < '0' || r > '9') && (r < 'a' || r > 'z') && (r < 'A' || r > 'Z')
+}
+
+func runeIsNotNumerical(r rune) bool {
+	return r < '0' || r > '9'
+}
+
 // UserDownloadsFolder returns the downloads folder corresponding to the current user.
 func UserDownloadsFolder() string {
 	dir, err := os.UserHomeDir()

internal/util/util_test.go

@@ -7,6 +7,18 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+var globalValidationError error
+
+func BenchmarkCodeValidator(b *testing.B) {
+	local := error(nil)
+
+	for i := 0; i < b.N; i++ {
+		local = CodeValidator("125-upset-universe-mistake")
+	}
+
+	globalValidationError = local
+}
+
 func TestCodeValidator(t *testing.T) {
 	validate := CodeValidator
 
@@ -17,6 +29,21 @@ func TestCodeValidator(t *testing.T) {
 	valid = validate("invalid-code")
 	assert.Error(t, valid)
 
+	valid = validate("IOI-")
+	assert.Error(t, valid)
+
+	valid = validate("126-")
+	assert.Error(t, valid)
+
+	valid = validate("126--almost--valid")
+	assert.Error(t, valid)
+
+	valid = validate("126-almost--valid")
+	assert.Error(t, valid)
+
+	valid = validate("126-almost-valid--")
+	assert.Error(t, valid)
+
 	valid = validate("15")
 	assert.Error(t, valid)