defineRuneInternal和encodeRuneInStringInternal有什么区别

Question

In golang's std package, "func decodeRuneInternal" and "func decodeRuneInStringInternal" are the same except the args, that is:

func decodeRuneInternal(p []byte) (r rune, size int, short bool)
func decodeRuneInStringInternal(s string) (r rune, size int, short bool)

Why not just define decodeRuneInStringInternal as:

func decodeRuneInStringInternal(s string) (r rune, size int, short bool) {
    return decodeRuneInternal([]byte(s)) (r rune, size int, short bool)
}

in utf8.go, decodeRuneInStringInternal's implementations is the same with decodeRuneInternal.

WHY?

Answer 1

The two functions avoid the memory allocation in the conversion []byte(s) in the case where the string function wraps the []byte function or the memory allocation in the conversion string(p) in the case where the []byte function wraps the string function.