bug#41766: Make it possible to change regexp to identify and highlight grep matches via customization

[Simon Lang]

Hi,

I changed grep-regexp-match to grep-match-regexp.

Pls note that ripgrep knows about ignore files etc. hence the more fair 
comparison would probably be git grep (e.g. vc-git-grep). But ripgrep is still 
considerably faster and does not only work for git repositories.

Thanks!

________________________________________
From: DG <raaahh@gmail.com> on behalf of Dmitry Gutov <dgutov@yandex.ru>
Sent: 09 June 2020 01:44
To: Simon Lang; 41766@debbugs.gnu.org
Subject: Re: bug#41766: Make it possible to change regexp to identify and 
highlight grep matches via customization

On 08.06.2020 23:25, Simon Lang wrote:
> For example:
>
> change  grep command to
>
> "rg -n -H -S --no-heading --color always -e"

I wonder if we can use a similar customization more generally. For
instance, in my testing Grep searches the full Emacs checkout in ~230ms,
whereas RipGrep does that in ~40ms. The difference is perceptible.

The obvious idea is to use grep-template, but we're passing -s and -E to
it. rg would interpret these options differently.

Here's a perftest patch if someone was personally curious about the
difference:

diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 5b5fb4bc47..2c6ed4da7d 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -1262,7 +1262,7 @@ xref-matches-in-files
         (dir (file-name-directory (car files)))
         (remote-id (file-remote-p dir))
         ;; 'git ls-files' can output broken symlinks.
-       (command (format "xargs -0 grep %s -snHE -e %s"
+       (command (format "xargs -0 rg %s -nH -e %s"
                          (if (and case-fold-search
                                   (isearch-no-upper-case-p regexp t))
                              "-i"
@@ -1275,6 +1275,7 @@ xref-matches-in-files
                         #'tramp-file-local-name
                         #'file-local-name)
                     files)))
+    (setq tt (time-to-seconds))
      (with-current-buffer output
        (erase-buffer)
        (with-temp-buffer
@@ -1289,6 +1290,7 @@ xref-matches-in-files
                                              shell-command-switch
                                              command)))
        (goto-char (point-min))
+      (message "%s" (- (time-to-seconds) tt))
        (when (and (/= (point-min) (point-max))
                   (not (looking-at grep-re))
                   ;; TODO: Show these matches as well somehow?

0001-Make-regexp-used-to-highlight-grep-matches-customiza.patch
Description: 0001-Make-regexp-used-to-highlight-grep-matches-customiza.patch