[feature request] Make "*Embark Occur*" supporting wgrep for some special command

[jixiuf]

Xref provides helpful commands for code navigation and discovery, such as xref-find-definitions and project-find-regexp ,and project-find-regexp support ripgrep now( on emacs master) .

When a xref query hits multiple candidates Emacs shows a Xref
buffer with the various candidates and their location.

On emacs master, it support using completing-read showing the multiple candidates now with xref--show-defs-minibuffer

https://lists.gnu.org/archive/html/emacs-devel/2020-11/msg00707.html

(with-eval-after-load 'xref
  (setq xref-search-program 'ripgrep)     ;default `grep`,  for project-find-regexp
  (when (functionp 'xref--show-defs-minibuffer)
    (setq xref-show-definitions-function 'xref--show-defs-minibuffer) ; using completing-read
    (setq xref-show-xrefs-function 'xref--show-defs-minibuffer)))

this is a screenshot of project-find-regexp in minibuffer

And I can export the result to "Embark Occur" with embark-occur

So I think it is great for "Embark Occur" support wgrep like ivy-occur/grep,
I think minad/consult#46 can benefit from it too, once consult-rg/ag is implemented.

[oantolin]

I wouldn't want to reinvent wgrep here. So I think the best option is to not use embark-occur, but rather make it so embark-export works with these functions you mentioned, and produces an actual grep buffer you can use with the standard wgrep.

[jixiuf]

it’s ok for me

[manuel-uberti]

I second @jixiuf enthusiasm on this. :)

[jixiuf]

(require 'wgrep)

;;;###autoload
(defun embark-occur-wgrep-setup ()
  (set (make-local-variable 'wgrep-header/footer-parser)
       'embark-occur-wgrep-prepare-header/footer)
  (set (make-local-variable 'wgrep-results-parser)
       'embark-occur-wgrep-parse-command-results)
  (wgrep-setup-internal))

(defun embark-occur-wgrep-prepare-header/footer ()
  (let ((beg (point-min))
        (end (point-min))
        (overlays (overlays-at (point-min))))
    ;; Set read-only grep result header
    (dolist (o overlays)
      (when (eq (overlay-get o 'face) 'tabulated-list-fake-header)
        (setq end (overlay-end o))))
    (put-text-property beg end 'read-only t)
    (put-text-property beg end 'wgrep-header t)
    ;; embark-occur-mode have NO footer.
    (put-text-property (1- (point-max)) (point-max) 'read-only t)
    (put-text-property (1- (point-max)) (point-max) 'wgrep-footer t)))


(defun embark-occur-wgrep-parse-command-results ()
  (while (not (eobp))
    (when (looking-at wgrep-line-file-regexp)
      (let* ((start (match-beginning 0))
             (end (match-end 0))
             (line (string-to-number (match-string 3)))
             (fn (match-string 1))
             (fnamelen (length fn))
             (dir (locate-dominating-file default-directory fn)))
        (unless (file-name-absolute-p fn)
          (setq fn (expand-file-name fn dir)))
        (let* ((fprop (wgrep-construct-filename-property fn)))
          (put-text-property start end 'wgrep-line-filename fn)
          (put-text-property start end 'wgrep-line-number line)
          (put-text-property start (+ start fnamelen) fprop fn))))
    (forward-line 1)))


;;;###autoload
(add-hook 'embark-occur-mode-hook 'embark-occur-wgrep-setup)

With this code, "Embark Occur" should support wgrep for project-find-regexp xref-find-definitions .

Edit: still has bug, and need wgrep change something in https://github.com/mhayashi1120/Emacs-wgrep/blob/master/wgrep.el#L416 wgrep-set-readonly-area.
"Embark Occur" do not has a wgrep-header, and it make wgrep-set-readonly-area does not work

[manuel-uberti]

Thanks, but I am not able to save the changes with it. I can edit the Embark Occur buffer, replace something in it with query-replace and see the changes in the buffer, but I cannot "commit" the changes nor save the modified files. Am I missing something?

[oantolin]

I'm sorry I took so long, this turned out to be trivial to do!

I added an exporter for grep mode results, and I associated it to category grep because that's the category consult uses for consult-grep, consult-git-grep and consult-ripgrep. If you want to use the exporter for project-find-regexp, the easiest way is to install Marginalia, add (project-find-regexp . grep) to marginalia-command-categories, and activate marginalia-mode (same for any other commands you might

Once you've done that, running embark-export (which you can get as action E in embark-act) from one of these grepping commands, will produce a normal grep buffer. Then you can use wgrep on it as usual.

[oantolin]

Oh, I spoke too soon. The grep mode buffers produced by export seem to work fine as grep buffers (pressing RET on a link works, and next/previous-error works too), but wgrep doesn't seem to work on them, it makes the text read-only, which is the opposite of what you want.

[oantolin]

OK, I inserted a fake header into the exported buffer, and now wgrep works.

If wgrep accepts your pull request, @jixiuf, then we could remove this fake header.

[oantolin]

Please test, and reopen or file another issue if there is any problem.

[oantolin]

@jixiuf, I noticed that Emacs 28 will report xref-location as the category when prompting you in the minibuffer for a grep result. So you can add (xref-location . embark-export-grep) to embark-exporters-alist instead of configuring Marginalia as I described above. If you can confirm that adding xref-location works, I'll add it to the defaults in Embark. (My Emacs doesn't have these xref features yet).

[oantolin]

Quick update: Embark now uses the grep exporter for the xref-location category (instead of grep), so it should work with project-find-regexp out of the box now, as well as with the consult-*grep family of commands.