On Wed, Sep 18, 2019 at 2:42 AM Francis <francissteph...@gmail.com> wrote:
>
> I am looking at the correct way to convert from a byte slice to a string and
> back with no allocations. All very unsafe.
>
> I think these two cases are fairly symmetrical. So to simplify the discussion
> below I will only talk about converting from a string to []byte.
>
> func StringToBytes(s string) (b []byte)
No reason to use SliceHeader, and avoiding SliceHeader avoids the
problems you discuss.
func StringToBytes(s string) []byte {
const max = 0x7fff0000
if len(s) > max {
panic("string too long")
}
return
(*[max]byte)(unsafe.Pointer((*reflect.StringHeader)(unsafe.Pointer(&s)).Data))[:len(s):len(s)]
}
Of course, as you say, you must not mutate the returned []byte.
Ian
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