Re: Xref completion

[Dmitry Gutov]

On 07.12.2020 11:27, Daniel Martín wrote:
> Dmitry Gutov <dgutov@yandex.ru> writes:
> > On the one hand, it feels kinda faster, on the other, it lacks the
> > ability to "look around" when you really need it. In an ideal world, I
> > guess the UI would be somewhere in the middle.
>
> One of the reasons I see people integrate Ivy/Helm with Xref is to have
> fuzzy filtering of the results, but I don't see why we couldn't have
> that in the *xref* buffer.

I think xref buffers have other ways of reaching the same goal. E.g., if 
we're talking about the results of project-find-regexp or 
xref-find-apropos, those commands themselves allow you to enter search 
queries where you can choose the appropriate amount of "fuzziness".

That said...

> First I thought if we could implement this by extending an existing
> Emacs command like flush-lines or occur to "teach" it about the
> specificities of the *xref* buffer, but that doesn't seem very clean.

...adding a command like xref-flush-groups shouldn't hurt. You can file 
a feature request with 'M-x report-emacs-bug' and perhaps even attach a 
patch?

> So perhaps we could add a new command that asks for a regexp in the
> minibuffer and filters the results in the *xref* buffer to only contain
> those items from a group that matches that regular expression.  With q
> you will go back to show the complete list of xref items and groups.

Hmm, if mean dynamically? That sounds a bit more complicated but hey, 
there can be some way to implement this without too much effort.

> Is
> there any core Emacs package that performs a similar filtering?  We
> could learn from its workflow, then.

swiper, perhaps?

Not a core package, but it is in GNU ELPA.

> Why matching the group exclusively? In my opinion, matching the group
> only is better because the typical use case I have in mind is a big
> codebase with thousands of xref results that are spread around hundreds
> of files.  You usually want to filter by the string that varies the
> most, which in most cases is the group (eg. if I only want to see
> results from unit tests, then I'd filter the *xref* buffer by
> "*Tests.cpp"; If I only want to see results from header files, I'd
> filter by "*.h").

Sounds reasonable. If you wanted to filter by summary contents anyway, 
you can just use swiper.