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

[npostavs@users.sourceforge.net]

Philipp Stephani <p.stephani2@gmail.com> writes:

>>> - Coupling of unrelated entities is always an antipattern.
>>> - For N iterables and M looping constructs, you need to implement
>>> N*M integrations.
>
> Yes, I don't care about Common Lisp. The iter-by clause is less of a
> problem than 'buffers' etc. because it's not a one-off that couples a
> looping construct with some random semantics.

It's sort of related to Drew's concerns in that Emacs deals with the N*M
problem by setting M=1, hence why only cl-loop gets the pressure to add
more enhancments.

There are some practical problem with iter-defun though: it has several
bugs on which there doesn't seem to be any movement[1][2][3], it's
reported to be slow[4], and cl-loop's iter-by keyword is not documented
at all (that could be easily fixed, at least).  I wonder if streams[5]
is a better direction.  It already has stream-regexp, though it returns
match-data rather than a matched string.

(package-install 'stream)
(require 'stream)
(require 'seq)

(seq-do (lambda (m)
          (set-match-data m)
          (print (match-string 0)))
        (stream-regexp (current-buffer) (rx digit)))

(cl-loop with matches = (stream-regexp (current-buffer) (rx digit))
         for m = (stream-pop matches) while m
         do (set-match-data m) (print (match-string 0)))

[1]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=26073
[2]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25965
[3]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=26068
[4]: http://lists.gnu.org/archive/html/emacs-devel/2017-03/msg00264.html
[5]: https://elpa.gnu.org/packages/stream.html