[PATCH v2 6/7] shell32/autocomplete: Use the optional IACList interface and IACList::Expand, if available

[Huw Davies]

On Mon, Oct 15, 2018 at 02:24:01PM +0300, Gabriel Ivăncescu wrote:
> On Mon, Oct 15, 2018 at 1:15 PM Huw Davies <huw at codeweavers.com> wrote:
> >
> > This is going to need some work; trying to follow this code is just too hard.
> >
> > Huw.
> 
> The expand method gets called with the path ending in a slash, but
> only if it's needed (the tests show this). For example, if the text is
> a\b\c\d and the previous text was a\b\c\e, there's no expansion as
> both would expand to a\b\c\ and Windows doesn't do it redundantly
> (this is needed for things like paste or replacing selections to work
> correctly, we can't just keep track of last character input, again,
> the tests show this with selection deletions and caret movements and
> others).
> 
> Now what the code does is 3 "stages". First it skips all the shared
> prefix (case insensitively). So basically the beginning of both
> txtbackup and the new txt are skipped if identical (and stops where
> they mismatch). At this point we know all characters before i (the
> mismatch pos) are identical so no need to check them.
> 
> Then, starting from the mismatch position, it looks for a delimiter in
> the new text. If it finds one, obviously, it will look for the last
> delim and expand the whole text up to that last delim (since they
> differ).
> 
> If it doesn't find one, it checks if txtbackup (the old text) has a
> delim after they mismatch, because if they don't, it means they only
> differ by non-delim characters, so no expansion is needed. (e.g.
> a\b\c\foo and a\b\c\bar don't need any expansion)
> 
> But if there is a delim in txtbackup (e.g. a\b\c\foo and
> a\b\c\bar\baz), we need to find the last delim in the shared prefix,
> so it scans backwards for the first delim (in this case, to expand
> a\b\c\ since otherwise a\b\c\bar\ was expanded before).
>
> I know I could comment it better, but I don't want to be too verbose
> so some advice would be appreciated.

Well we've dicussed gotos already.  Admittedly this one isn't
inside a nested switch, but still.

You might also find strpbrkW() helpful.

Huw.