More work on porting the diff kitten

tools/utils/misc.go

@@ -4,6 +4,7 @@ package utils
 
 import (
 	"fmt"
+	"regexp"
 	"sort"
 
 	"golang.org/x/exp/constraints"
@@ -143,3 +144,15 @@ func Memset[T any](dest []T, pattern ...T) []T {
 	}
 	return dest
 }
+
+var ControlCodesPat = (&Once[*regexp.Regexp]{Run: func() *regexp.Regexp {
+	return regexp.MustCompile("[\x00-\x09\x0b-\x1f\x7f\x80-\x9f]")
+}}).Get
+
+func SanitizeControlCodes(raw string, replace_with ...string) string {
+	r := ""
+	if len(replace_with) > 0 {
+		r = replace_with[0]
+	}
+	return ControlCodesPat().ReplaceAllLiteralString(raw, r)
+}