bug#26338: 26.0.50; Collect all matches for REGEXP in current buffer

[Tino Calancha <tino.calancha@gmail.com>]

Juri Linkov <juri@linkov.net> writes:

>> we have `count-matches' in replace.el, which returns the
>> number of matches of a regexp.  Why not to have an standard
>> function `collect-matches' as well?
>>
>> I know `xref-collect-matches' but it uses grep program: some users might
>> not have grep installed, or they may prefer to use Emacs regexps.
>>
>> I've being using for a while something similar than the patch below.
>> Probably it doesn't need to be a command, just a normal function.
>>
>> What do you think?
>
> But there is already the occur-collect feature implemented in occur-1
> and occur-read-primary-args.  Why would we need a separate command?
Indeed i don't think we need a new command for this.  I am thinking more
in an standard function.
Following:
(occur "defun\\s +\\(\\S +\\)" "\\1")

doesn't return the collected things.  It writes the matches in *Occur*
buffer.  Then, if you want a list with the matches you must loop
again inside *Occur* which is sub-optimal.
For me, it has sense to have a `occur-collect' which just returns the
list of matches.
Then, we might use such function in the implementation of occur-1
which could bring a cleaner implementation.
We might get also the LIMIT argument for occur which might come
in handy for multi-occur with lot of input buffers (just an idea).