Re: [PATCH 1/3] completion: put matching ctags symbol names directly into COMPREPLY

[Jeff King <peff@peff.net>]

On Thu, Mar 23, 2017 at 04:38:37PM +0100, SZEDER Gábor wrote:

> The one-liner awk script in __git_match_ctag() listing ctags symbol
> names for 'git grep <TAB>' is already smart enough to list only symbol
> names matching the current word to be completed.
> 
> Extend this helper function to accept prefix and suffix parameters to
> be prepended and appended, respectively, to each listed symbol name in
> the awk script, so its output won't require any additional processing
> or filtering in the completion script before being handed over to
> Bash.  Use the faster __gitcomp_direct() helper instead of
> __gitcomp_nl() to fill the fully processed matching symbol names into
> Bash's COMPREPLY array.

Seems like an easy win (well, neglecting the other 14 patches that let
to having gitcomp_direct).

I never really noticed it as particularly slow in git.git, but faster is
always better if it comes cheaply.

> Notes:
>     It's still just a simple linear search through the tags file, so there
>     are no miracles: it's still hopelessly, unusably slow e.g. in the
>     Linux repository.

I just tried "git grep foo<Tab>" in the kernel and it was pretty fast.
But then I tried "git grep <Tab>". Ouch. So it seems like it's not the
awk matching that's slow, but everything that comes after (and is
dependent on how much output it produces).

-Peff