> mg979 wrote:
>
> > Test 1 finds an index inside a string long 100.000 characters, for 100.000
> > times.
> > Test 2 and 3 iterate the same string once.
>
> So test1 took 7.059 seconds and test3 took 0.005 seconds.
>
> That is expected considering that `string[index]` is O(n) in Vim9
> (making test3 O(n^2)).
> Being O(n) was a design tradeoff as strings are stored in utf-8, which
> is variable size per characters. An alternative would be to use
> utf-32, which would make it O(1), but it would consume more memory in
> general (4 times more memory for ASCII strings).
And it would introduce a new value type, and require all functions that
currently work on a string (which is very many) also to work with the new
type. And the standard C functions working on strings can't be used,
I'm not sure how good wide string support is, many compilers only use 16
bits for wchar_t.
Using a list to store the characters also works. It remembers the last
used item, looking up by an index close to a previously used index
is fast. Creating the list has overhead though.
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