go - what's the difference between decodeRuneInternal and decodeRuneInStringInternal -

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in golang's std package, "func decoderuneinternal" , "func decoderuneinstringinternal" same except args, is:

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

why not 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 same decoderuneinternal.

why?

the 2 functions avoid memory allocation in conversion []byte(s) in case string function wraps []byte function or memory allocation in conversion string(p) in case []byte function wraps string function.


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