Avoid unnecessary []byte -> string -> []byte conversion

psiphon/common/transforms/transforms.go

@@ -155,7 +155,7 @@ func (spec Spec) ApplyString(seed *prng.Seed, input string) (string, error) {
 		if err != nil {
 			return "", errors.Trace(err)
 		}
-		value = re.ReplaceAllString(value, replacement)
+		value = re.ReplaceAllString(value, string(replacement))
 	}
 	return value, nil
 }
@@ -173,15 +173,15 @@ func (spec Spec) Apply(seed *prng.Seed, input []byte) ([]byte, error) {
 		if err != nil {
 			return nil, errors.Trace(err)
 		}
-		value = re.ReplaceAll(value, []byte(replacement))
+		value = re.ReplaceAll(value, replacement)
 	}
 	return value, nil
 }
 
 // makeRegexAndRepl generates the regex and replacement for a given seed and
 // transform. The same seed can be supplied to produce the same output, for
 // replay.
-func makeRegexAndRepl(seed *prng.Seed, transform [2]string) (*regexp.Regexp, string, error) {
+func makeRegexAndRepl(seed *prng.Seed, transform [2]string) (*regexp.Regexp, []byte, error) {
 
 	// TODO: the compiled regexp and regen could be cached, but the seed is an
 	// issue with caching the regen.
@@ -192,18 +192,18 @@ func makeRegexAndRepl(seed *prng.Seed, transform [2]string) (*regexp.Regexp, str
 	}
 	rg, err := regen.NewGenerator(transform[1], args)
 	if err != nil {
-		return nil, "", errors.Trace(err)
+		return nil, nil, errors.Trace(err)
 	}
 
 	replacement, err := rg.Generate()
 	if err != nil {
-		return nil, "", errors.Trace(err)
+		return nil, nil, errors.Trace(err)
 	}
 
 	re, err := regexp.Compile(transform[0])
 	if err != nil {
-		return nil, "", errors.Trace(err)
+		return nil, nil, errors.Trace(err)
 	}
 
-	return re, string(replacement), nil
+	return re, replacement, nil
 }