view contrib/mq.el @ 27142:060f83d219b9

extensions: refuse to load extensions if minimum hg version not met

As the author of several 3rd party extensions, I frequently see bug
reports from users attempting to run my extension with an old version
of Mercurial that I no longer support in my extension. Oftentimes, the
extension will import just fine. But as soon as we run extsetup(),
reposetup(), or get into the guts of a wrapped function, we encounter
an exception and abort. Today, Mercurial will print a message about
extensions that don't have a "testedwith" declaring explicit
compatibility with the current version.

The existing mechanism is a good start. But it isn't as robust as I
would like. Specifically, Mercurial assumes compatibility by default.
This means extension authors must perform compatibility checking in
their extsetup() or we wait and see if we encounter an abort at
runtime. And, compatibility checking can involve a lot of code and
lots of error checking. It's a lot of effort for extension authors.

Oftentimes, extension authors know which versions of Mercurial there
extension works on and more importantly where it is broken.

This patch introduces a magic "minimumhgversion" attribute in
extensions. When found, the extension loading mechanism will compare
the declared version against the current Mercurial version. If the
extension explicitly states we require a newer Mercurial version, a
warning is printed and the extension isn't loaded beyond importing
the Python module. This causes a graceful failure while alerting
the user of the compatibility issue.

I would be receptive to the idea of making the failure more fatal.
However, care would need to be taken to not criple every hg command.
e.g. the user may use `hg config` to fix the hgrc and if we aborted
trying to run that, the user would effectively be locked out of `hg`!

A potential future improvement to this functionality would be to catch
ImportError for the extension/module and parse the source code for
"minimumhgversion = 'XXX'" and do similar checking. This way we could
give more information about why the extension failed to load.

;;; mq.el --- Emacs support for Mercurial Queues

;; Copyright (C) 2006 Bryan O'Sullivan

;; Author: Bryan O'Sullivan <[e-mail]>

;; mq.el is free software; you can redistribute it and/or modify it
;; under the terms of the GNU General Public License version 2 or any
;; later version.

;; mq.el is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with mq.el, GNU Emacs, or XEmacs; see the file COPYING (`C-h
;; C-l').  If not, see <http://www.gnu.org/licenses/>.

(eval-when-compile (require 'cl))
(require 'mercurial)


(defcustom mq-mode-hook nil
  "Hook run when a buffer enters mq-mode."
  :type 'sexp
  :group 'mercurial)

(defcustom mq-global-prefix "\C-cq"
  "The global prefix for Mercurial Queues keymap bindings."
  :type 'sexp
  :group 'mercurial)

(defcustom mq-edit-mode-hook nil
  "Hook run after a buffer is populated to edit a patch description."
  :type 'sexp
  :group 'mercurial)

(defcustom mq-edit-finish-hook nil
  "Hook run before a patch description is finished up with."
  :type 'sexp
  :group 'mercurial)

(defcustom mq-signoff-address nil
  "Address with which to sign off on a patch."
  :type 'string
  :group 'mercurial)


;;; Internal variables.

(defvar mq-mode nil
  "Is this file managed by MQ?")
(make-variable-buffer-local 'mq-mode)
(put 'mq-mode 'permanent-local t)

(defvar mq-patch-history nil)

(defvar mq-top-patch '(nil))

(defvar mq-prev-buffer nil)
(make-variable-buffer-local 'mq-prev-buffer)
(put 'mq-prev-buffer 'permanent-local t)

(defvar mq-top nil)
(make-variable-buffer-local 'mq-top)
(put 'mq-top 'permanent-local t)

;;; Global keymap.

(defvar mq-global-map
  (let ((map (make-sparse-keymap)))
    (define-key map "." 'mq-push)
    (define-key map ">" 'mq-push-all)
    (define-key map "," 'mq-pop)
    (define-key map "<" 'mq-pop-all)
    (define-key map "=" 'mq-diff)
    (define-key map "r" 'mq-refresh)
    (define-key map "e" 'mq-refresh-edit)
    (define-key map "i" 'mq-new)
    (define-key map "n" 'mq-next)
    (define-key map "o" 'mq-signoff)
    (define-key map "p" 'mq-previous)
    (define-key map "s" 'mq-edit-series)
    (define-key map "t" 'mq-top)
    map))

(global-set-key mq-global-prefix mq-global-map)

(add-minor-mode 'mq-mode 'mq-mode)


;;; Refresh edit mode keymap.

(defvar mq-edit-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map "\C-c\C-c" 'mq-edit-finish)
    (define-key map "\C-c\C-k" 'mq-edit-kill)
    (define-key map "\C-c\C-s" 'mq-signoff)
    map))


;;; Helper functions.

(defun mq-read-patch-name (&optional source prompt force)
  "Read a patch name to use with a command.
May return nil, meaning \"use the default\"."
  (let ((patches (split-string
		  (hg-chomp (hg-run0 (or source "qseries"))) "\n")))
    (when force
      (completing-read (format "Patch%s: " (or prompt ""))
		       (mapcar (lambda (x) (cons x x)) patches)
		       nil
		       nil
		       nil
		       'mq-patch-history))))

(defun mq-refresh-buffers (root)
  (save-excursion
    (dolist (buf (hg-buffers-visiting-repo root))
      (when (not (verify-visited-file-modtime buf))
	(set-buffer buf)
	(let ((ctx (hg-buffer-context)))
	  (message "Refreshing %s..." (buffer-name))
	  (revert-buffer t t t)
	  (hg-restore-context ctx)
	  (message "Refreshing %s...done" (buffer-name))))))
  (hg-update-mode-lines root)
  (mq-update-mode-lines root))

(defun mq-last-line ()
  (goto-char (point-max))
  (beginning-of-line)
  (when (looking-at "^$")
    (forward-line -1))
  (let ((bol (point)))
    (end-of-line)
    (let ((line (buffer-substring bol (point))))
      (when (> (length line) 0)
	line))))

(defun mq-push (&optional patch)
  "Push patches until PATCH is reached.
If PATCH is nil, push at most one patch."
  (interactive (list (mq-read-patch-name "qunapplied" " to push"
					 current-prefix-arg)))
  (let ((root (hg-root))
	(prev-buf (current-buffer))
	last-line ok)
    (unless root
      (error "Cannot push outside a repository!"))
    (hg-sync-buffers root)
    (let ((buf-name (format "MQ: Push %s" (or patch "next patch"))))
      (kill-buffer (get-buffer-create buf-name))
      (split-window-vertically)
      (other-window 1)
      (switch-to-buffer (get-buffer-create buf-name))
      (cd root)
      (message "Pushing...")
      (setq ok (= 0 (apply 'call-process (hg-binary) nil t t "qpush"
			   (if patch (list patch))))
	    last-line (mq-last-line))
      (let ((lines (count-lines (point-min) (point-max))))
	(if (or (<= lines 1)
		(and (equal lines 2) (string-match "Now at:" last-line)))
	    (progn
	      (kill-buffer (current-buffer))
	      (delete-window))
	  (hg-view-mode prev-buf))))
    (mq-refresh-buffers root)
    (sit-for 0)
    (when last-line
      (if ok
	  (message "Pushing... %s" last-line)
	(error "Pushing... %s" last-line)))))

(defun mq-push-all ()
  "Push patches until all are applied."
  (interactive)
  (mq-push "-a"))

(defun mq-pop (&optional patch)
  "Pop patches until PATCH is reached.
If PATCH is nil, pop at most one patch."
  (interactive (list (mq-read-patch-name "qapplied" " to pop to"
					 current-prefix-arg)))
  (let ((root (hg-root))
	last-line ok)
    (unless root
      (error "Cannot pop outside a repository!"))
    (hg-sync-buffers root)
    (set-buffer (generate-new-buffer "qpop"))
    (cd root)
    (message "Popping...")
    (setq ok (= 0 (apply 'call-process (hg-binary) nil t t "qpop"
			 (if patch (list patch))))
	  last-line (mq-last-line))
    (kill-buffer (current-buffer))
    (mq-refresh-buffers root)
    (sit-for 0)
    (when last-line
      (if ok
	  (message "Popping... %s" last-line)
	(error "Popping... %s" last-line)))))

(defun mq-pop-all ()
  "Push patches until none are applied."
  (interactive)
  (mq-pop "-a"))

(defun mq-refresh-internal (root &rest args)
  (hg-sync-buffers root)
  (let ((patch (mq-patch-info "qtop")))
    (message "Refreshing %s..." patch)
    (let ((ret (apply 'hg-run "qrefresh" args)))
      (if (equal (car ret) 0)
	  (message "Refreshing %s... done." patch)
	(error "Refreshing %s... %s" patch (hg-chomp (cdr ret)))))))

(defun mq-refresh (&optional git)
  "Refresh the topmost applied patch.
With a prefix argument, generate a git-compatible patch."
  (interactive "P")
  (let ((root (hg-root)))
    (unless root
      (error "Cannot refresh outside of a repository!"))
    (apply 'mq-refresh-internal root (if git '("--git")))))

(defun mq-patch-info (cmd &optional msg)
  (let* ((ret (hg-run cmd))
	 (info (hg-chomp (cdr ret))))
    (if (equal (car ret) 0)
	(if msg
	    (message "%s patch: %s" msg info)
	  info)
      (error "%s" info))))

(defun mq-top ()
  "Print the name of the topmost applied patch."
  (interactive)
  (mq-patch-info "qtop" "Top"))

(defun mq-next ()
  "Print the name of the next patch to be pushed."
  (interactive)
  (mq-patch-info "qnext" "Next"))

(defun mq-previous ()
  "Print the name of the first patch below the topmost applied patch.
This would become the active patch if popped to."
  (interactive)
  (mq-patch-info "qprev" "Previous"))

(defun mq-edit-finish ()
  "Finish editing the description of this patch, and refresh the patch."
  (interactive)
  (unless (equal (mq-patch-info "qtop") mq-top)
    (error "Topmost patch has changed!"))
  (hg-sync-buffers hg-root)
  (run-hooks 'mq-edit-finish-hook)
  (mq-refresh-internal hg-root "-m" (buffer-substring (point-min) (point-max)))
  (let ((buf mq-prev-buffer))
    (kill-buffer nil)
    (switch-to-buffer buf)))

(defun mq-edit-kill ()
  "Kill the edit currently being prepared."
  (interactive)
  (when (or (not (buffer-modified-p)) (y-or-n-p "Really kill this edit? "))
    (let ((buf mq-prev-buffer))
      (kill-buffer nil)
      (switch-to-buffer buf))))

(defun mq-get-top (root)
  (let ((entry (assoc root mq-top-patch)))
    (if entry
        (cdr entry))))

(defun mq-set-top (root patch)
  (let ((entry (assoc root mq-top-patch)))
    (if entry
        (if patch
            (setcdr entry patch)
          (setq mq-top-patch (delq entry mq-top-patch)))
      (setq mq-top-patch (cons (cons root patch) mq-top-patch)))))

(defun mq-update-mode-lines (root)
  (let ((cwd default-directory))
    (cd root)
    (condition-case nil
        (mq-set-top root (mq-patch-info "qtop"))
      (error (mq-set-top root nil)))
    (cd cwd))
  (let ((patch (mq-get-top root)))
    (save-excursion
      (dolist (buf (hg-buffers-visiting-repo root))
        (set-buffer buf)
        (if mq-mode
            (setq mq-mode (or (and patch (concat " MQ:" patch)) " MQ")))))))
	
(defun mq-mode (&optional arg)
  "Minor mode for Mercurial repositories with an MQ patch queue"
  (interactive "i")
  (cond ((hg-root)
         (setq mq-mode (if (null arg) (not mq-mode)
                         arg))
         (mq-update-mode-lines (hg-root))))
  (run-hooks 'mq-mode-hook))

(defun mq-edit-mode ()
  "Mode for editing the description of a patch.

Key bindings
------------
\\[mq-edit-finish]	use this description
\\[mq-edit-kill]	abandon this description"
  (interactive)
  (use-local-map mq-edit-mode-map)
  (set-syntax-table text-mode-syntax-table)
  (setq local-abbrev-table text-mode-abbrev-table
	major-mode 'mq-edit-mode
	mode-name "MQ-Edit")
  (set-buffer-modified-p nil)
  (setq buffer-undo-list nil)
  (run-hooks 'text-mode-hook 'mq-edit-mode-hook))

(defun mq-refresh-edit ()
  "Refresh the topmost applied patch, editing the patch description."
  (interactive)
  (while mq-prev-buffer
    (set-buffer mq-prev-buffer))
  (let ((root (hg-root))
	(prev-buffer (current-buffer))
	(patch (mq-patch-info "qtop")))
    (hg-sync-buffers root)
    (let ((buf-name (format "*MQ: Edit description of %s*" patch)))
      (switch-to-buffer (get-buffer-create buf-name))
      (when (= (point-min) (point-max))
	(set (make-local-variable 'hg-root) root)
	(set (make-local-variable 'mq-top) patch)
	(setq mq-prev-buffer prev-buffer)
	(insert (hg-run0 "qheader"))
	(goto-char (point-min)))
      (mq-edit-mode)
      (cd root)))
  (message "Type `C-c C-c' to finish editing and refresh the patch."))

(defun mq-new (name)
  "Create a new empty patch named NAME.
The patch is applied on top of the current topmost patch.
With a prefix argument, forcibly create the patch even if the working
directory is modified."
  (interactive (list (mq-read-patch-name "qseries" " to create" t)))
  (message "Creating patch...")
  (let ((ret (if current-prefix-arg
		 (hg-run "qnew" "-f" name)
	       (hg-run "qnew" name))))
    (if (equal (car ret) 0)
	(progn
	  (hg-update-mode-lines (buffer-file-name))
	  (message "Creating patch... done."))
      (error "Creating patch... %s" (hg-chomp (cdr ret))))))

(defun mq-edit-series ()
  "Edit the MQ series file directly."
  (interactive)
  (let ((root (hg-root)))
    (unless root
      (error "Not in an MQ repository!"))
    (find-file (concat root ".hg/patches/series"))))

(defun mq-diff (&optional git)
  "Display a diff of the topmost applied patch.
With a prefix argument, display a git-compatible diff."
  (interactive "P")
  (hg-view-output ((format "MQ: Diff of %s" (mq-patch-info "qtop")))
    (if git
	(call-process (hg-binary) nil t nil "qdiff" "--git")
    (call-process (hg-binary) nil t nil "qdiff"))
    (diff-mode)
    (font-lock-fontify-buffer)))

(defun mq-signoff ()
  "Sign off on the current patch, in the style used by the Linux kernel.
If the variable mq-signoff-address is non-nil, it will be used, otherwise
the value of the ui.username item from your hgrc will be used."
  (interactive)
  (let ((was-editing (eq major-mode 'mq-edit-mode))
	signed)
    (unless was-editing
      (mq-refresh-edit))
    (save-excursion
      (let* ((user (or mq-signoff-address
		       (hg-run0 "debugconfig" "ui.username")))
	     (signoff (concat "Signed-off-by: " user)))
	(if (search-forward signoff nil t)
	    (message "You have already signed off on this patch.")
	  (goto-char (point-max))
	  (let ((case-fold-search t))
	    (if (re-search-backward "^Signed-off-by: " nil t)
		(forward-line 1)
	      (insert "\n")))
	  (insert signoff)
	  (message "%s" signoff)
	  (setq signed t))))
    (unless was-editing
      (if signed
	  (mq-edit-finish)
	(mq-edit-kill)))))


(provide 'mq)


;;; Local Variables:
;;; prompt-to-byte-compile: nil
;;; end: