Re: [PATCH 3/6] emacs: make "+" and "-" tagging operations more robust

[Austin Clements <amdragon@MIT.EDU>]

I'm looking forward to having this.  I think it'll streamline tagging
operations.

Quoth Dmitry Kurochkin on Jan 28 at  8:41 am:
> Before the change, "+" and "-" tagging operations in notmuch-search
> and notmuch-show views accepted only a single tag.  The patch makes
> them use the recently added `notmuch-select-tags-with-completion'
> function, which allows to enter multiple tags with "+" and "-"
> prefixes.  So after the change, "+" and "-" bindings allow to both add
> and remove multiple tags.  The only difference between "+" and "-" is
> the minibuffer initial input ("+" and "-" respectively).

This patch was a little difficult to review because it was largish and
the diff happened to contain a bunch of forward references.  If it's
convenient (don't bother if it's not), could you divide up the next
version a little?  Something simple like sending the show changes as a
separate patch would probably make it a lot easier.

> ---
>  emacs/notmuch-show.el |   65 +++++++------------
>  emacs/notmuch.el      |  165 +++++++++++++++++++++++++------------------------
>  2 files changed, 107 insertions(+), 123 deletions(-)
> 
> diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
> index 84ac624..03eadfb 100644
> --- a/emacs/notmuch-show.el
> +++ b/emacs/notmuch-show.el
> @@ -38,8 +38,9 @@
>  
>  (declare-function notmuch-call-notmuch-process "notmuch" (&rest args))
>  (declare-function notmuch-fontify-headers "notmuch" nil)
> -(declare-function notmuch-select-tag-with-completion "notmuch" (prompt &rest search-terms))
> +(declare-function notmuch-select-tags-with-completion "notmuch" (&optional initial-input &rest search-terms))
>  (declare-function notmuch-search-show-thread "notmuch" nil)
> +(declare-function notmuch-update-tags "notmuch" (current-tags changed-tags))
>  
>  (defcustom notmuch-message-headers '("Subject" "To" "Cc" "Date")
>    "Headers that should be shown in a message, in this order.
> @@ -1267,7 +1268,7 @@ Some useful entries are:
>  
>  (defun notmuch-show-mark-read ()
>    "Mark the current message as read."
> -  (notmuch-show-remove-tag "unread"))
> +  (notmuch-show-tag-message "-unread"))
>  
>  ;; Functions for getting attributes of several messages in the current
>  ;; thread.
> @@ -1470,51 +1471,33 @@ than only the current message."
>  	    (message (format "Command '%s' exited abnormally with code %d"
>  			     shell-command exit-code))))))))
>  
> -(defun notmuch-show-add-tags-worker (current-tags add-tags)
> -  "Add to `current-tags' with any tags from `add-tags' not
> -currently present and return the result."
> -  (let ((result-tags (copy-sequence current-tags)))
> -    (mapc (lambda (add-tag)
> -	    (unless (member add-tag current-tags)
> -	      (setq result-tags (push add-tag result-tags))))
> -	    add-tags)
> -    (sort result-tags 'string<)))
> -
> -(defun notmuch-show-del-tags-worker (current-tags del-tags)
> -  "Remove any tags in `del-tags' from `current-tags' and return
> -the result."
> -  (let ((result-tags (copy-sequence current-tags)))
> -    (mapc (lambda (del-tag)
> -	    (setq result-tags (delete del-tag result-tags)))
> -	  del-tags)
> -    result-tags))
> -
> -(defun notmuch-show-add-tag (&rest toadd)
> -  "Add a tag to the current message."
> -  (interactive
> -   (list (notmuch-select-tag-with-completion "Tag to add: ")))
> +(defun notmuch-show-tag-message (&rest changed-tags)
> +  "Change tags for the current message.
>  
> +`Changed-tags' is a list of tag operations for \"notmuch tag\",
> +i.e. a list of tags to change with '+' and '-' prefixes."

Ticks in a docstring indicate functions (and will be hyperlinked as
such by describe-function).  Typically, argument names are indicated
by writing them in all caps.

Also, it probably makes more sense to reference `notmuch-tag' than
"notmuch tag", since this is Lisp land (and, since that will be
helpfully hyperlinked, you probably don't need to explain changed-tags
here).

>    (let* ((current-tags (notmuch-show-get-tags))
> -	 (new-tags (notmuch-show-add-tags-worker current-tags toadd)))
> -
> +	 (new-tags (notmuch-update-tags current-tags changed-tags)))
>      (unless (equal current-tags new-tags)
> -      (apply 'notmuch-tag (notmuch-show-get-message-id)
> -	     (mapcar (lambda (s) (concat "+" s)) toadd))
> +      (apply 'notmuch-tag (notmuch-show-get-message-id) changed-tags)
>        (notmuch-show-set-tags new-tags))))
>  
> -(defun notmuch-show-remove-tag (&rest toremove)
> -  "Remove a tag from the current message."
> -  (interactive
> -   (list (notmuch-select-tag-with-completion
> -	  "Tag to remove: " (notmuch-show-get-message-id))))
> +(defun notmuch-show-tag (&optional initial-input)
> +  "Change tags for the current message, read input from the minibuffer."
> +  (interactive)
> +  (let ((changed-tags (notmuch-select-tags-with-completion
> +		       initial-input (notmuch-show-get-message-id))))
> +    (apply 'notmuch-show-tag-message changed-tags)))
>  
> -  (let* ((current-tags (notmuch-show-get-tags))
> -	 (new-tags (notmuch-show-del-tags-worker current-tags toremove)))
> +(defun notmuch-show-add-tag ()
> +  "Same as `notmuch-show-tag' but sets initial input to '+'."
> +  (interactive)
> +  (notmuch-show-tag "+"))
>  
> -    (unless (equal current-tags new-tags)
> -      (apply 'notmuch-tag (notmuch-show-get-message-id)
> -	     (mapcar (lambda (s) (concat "-" s)) toremove))
> -      (notmuch-show-set-tags new-tags))))
> +(defun notmuch-show-remove-tag ()
> +  "Same as `notmuch-show-tag' but sets initial input to '-'."
> +  (interactive)
> +  (notmuch-show-tag "-"))

Should notmuch-show-{add,remove}-tag be considered public functions?
Previously, they were amenable to creating bindings for adding or
removing individual tags, and I believe people have done this.  If
we're okay with breaking backward-compatibility, there should at least
be a NEWS item explaining how to convert such custom bindings to use
notmuch-show-tag-message.

>  
>  (defun notmuch-show-toggle-headers ()
>    "Toggle the visibility of the current message headers."
> @@ -1559,7 +1542,7 @@ argument, hide all of the messages."
>  (defun notmuch-show-archive-thread-internal (show-next)
>    ;; Remove the tag from the current set of messages.
>    (goto-char (point-min))
> -  (loop do (notmuch-show-remove-tag "inbox")
> +  (loop do (notmuch-show-tag-message "-inbox")
>  	until (not (notmuch-show-goto-message-next)))
>    ;; Move to the next item in the search results, if any.
>    (let ((parent-buffer notmuch-show-parent-buffer))
> diff --git a/emacs/notmuch.el b/emacs/notmuch.el
> index ff46617..24b0ea3 100644
> --- a/emacs/notmuch.el
> +++ b/emacs/notmuch.el
> @@ -76,38 +76,56 @@ For example:
>  (defvar notmuch-query-history nil
>    "Variable to store minibuffer history for notmuch queries")
>  
> -(defun notmuch-tag-completions (&optional prefixes search-terms)
> -  (let ((tag-list
> -	 (split-string
> -	  (with-output-to-string
> -	    (with-current-buffer standard-output
> -	      (apply 'call-process notmuch-command nil t
> -		     nil "search-tags" search-terms)))
> -	  "\n+" t)))
> -    (if (null prefixes)
> -	tag-list
> -      (apply #'append
> -	     (mapcar (lambda (tag)
> -		       (mapcar (lambda (prefix)
> -				 (concat prefix tag)) prefixes))
> -		     tag-list)))))
> +(defun notmuch-tag-completions (&optional search-terms)
> +  (split-string
> +   (with-output-to-string
> +     (with-current-buffer standard-output
> +       (apply 'call-process notmuch-command nil t
> +	      nil "search-tags" search-terms)))
> +   "\n+" t))
>  
>  (defun notmuch-select-tag-with-completion (prompt &rest search-terms)
> -  (let ((tag-list (notmuch-tag-completions nil search-terms)))
> +  (let ((tag-list (notmuch-tag-completions search-terms)))
>      (completing-read prompt tag-list)))
>  
> -(defun notmuch-select-tags-with-completion (prompt &optional prefixes &rest search-terms)
> -  (let ((tag-list (notmuch-tag-completions prefixes search-terms))
> -	(crm-separator " ")
> -	;; By default, space is bound to "complete word" function.
> -	;; Re-bind it to insert a space instead.  Note that <tab>
> -	;; still does the completion.
> -	(crm-local-completion-map
> -	 (let ((map (make-sparse-keymap)))
> -	   (set-keymap-parent map crm-local-completion-map)
> -	   (define-key map " " 'self-insert-command)
> -	   map)))
> -    (delete "" (completing-read-multiple prompt tag-list))))
> +(defun notmuch-select-tags-with-completion (&optional initial-input &rest search-terms)

I don't know if notmuch-select-tags-with-completion is the right name
for this now that it hard-codes the +/- prefixes (which seems like the
right thing to do, BTW).  Maybe notmuch-read-tags-add-remove?

> +  (let* ((add-tag-list (mapcar (apply-partially 'concat "+")
> +			       (notmuch-tag-completions)))
> +	 (remove-tag-list (mapcar (apply-partially 'concat "-")
> +				  (notmuch-tag-completions search-terms)))

This will make two calls to notmuch search, but often one will
suffice.  It's probably worth optimizing the case were search-terms is
nil.

> +	 (tag-list (append add-tag-list remove-tag-list))
> +	 (crm-separator " ")
> +	 ;; By default, space is bound to "complete word" function.
> +	 ;; Re-bind it to insert a space instead.  Note that <tab>
> +	 ;; still does the completion.
> +	 (crm-local-completion-map
> +	  (let ((map (make-sparse-keymap)))
> +	    (set-keymap-parent map crm-local-completion-map)
> +	    (define-key map " " 'self-insert-command)
> +	    map)))
> +    (delete "" (completing-read-multiple
> +		"Operations (+add -drop): notmuch tag " tag-list nil

I don't think the "notmuch tag" part is necessary.  From the
perspective of a person who only uses the Emacs UI, this will be
meaningless.  Maybe "Tag changes (+add -drop): " or even just "Tags
(+add -drop): " since the "+add -drop" part implies what you're doing.

> +		nil initial-input))))
> +
> +(defun notmuch-update-tags (current-tags changed-tags)

Maybe just "tags" instead of "current-tags"?  Nothing says they have
to be current.  It's just a list of tags.

Also, changed-tags makes it sound like a list of tags, which is isn't.
Maybe tag-changes?

> +  "Update `current-tags' with `changed-tags' and return the result.
> +
> +`Changed-tags' is a list of tag operations given to \"notmuch
> +tag\", i.e. a list of changed tags with '+' and '-' prefixes."

Same comment about ticks and "notmuch tag".

I found this docstring a bit confusing.  I wasn't sure exactly what it
meant to "update current-tags with changed-tags" (though replacing
changed-tags with tag-changes would probably help).  Plus, this
function does not, in fact, update current-tags.  Maybe,

  "Return a copy of TAGS with additions and removals from TAG-CHANGES.

TAG-CHANGES must be a list of tags names, each prefixed with either a
\"+\" to indicate the tag should be added to TAGS if not present or a
\"-\" to indicate that the tag should be removed from TAGS if
present."

> +  (let ((result-tags (copy-sequence current-tags)))
> +    (mapc (lambda (changed-tag)

Consider dolist instead of mapc, though this is a matter of taste.  It
leads to less indentation (and does have precedent in the notmuch
code, though mapc is more common).

Too bad Elisp doesn't have fold.

> +	    (unless (string= changed-tag "")
> +	      (let ((op (substring changed-tag 0 1))
> +		    (tag (substring changed-tag 1)))
> +		(cond ((string= op "+")
> +		       (unless (member tag result-tags)
> +			 (push tag result-tags)))
> +		      ((string= op "-")
> +		       (setq result-tags (delete tag result-tags)))
> +		      (t
> +		       (error "Changed tag must be of the form `+this_tag' or `-that_tag'"))))))

I would suggest case instead of cond, but, again, that's a matter of
taste.

> +       changed-tags)
> +    (sort result-tags 'string<)))
>  
>  (defun notmuch-foreach-mime-part (function mm-handle)
>    (cond ((stringp (car mm-handle))
> @@ -447,6 +465,10 @@ Complete list of currently available key bindings:
>    "Return a list of threads for the current region"
>    (notmuch-search-properties-in-region 'notmuch-search-thread-id beg end))
>  
> +(defun notmuch-search-find-thread-id-region-search (beg end)
> +  "Return a search string for threads for the current region"
> +  (mapconcat 'identity (notmuch-search-find-thread-id-region beg end) " or "))
> +
>  (defun notmuch-search-find-authors ()
>    "Return the authors for the current thread"
>    (get-text-property (point) 'notmuch-search-authors))
> @@ -590,74 +612,55 @@ the messages that were tagged"
>  	(forward-line 1))
>        output)))
>  
> -(defun notmuch-search-add-tag-thread (tag)
> -  (notmuch-search-add-tag-region tag (point) (point)))
> +(defun notmuch-search-tag-thread (&rest tags)
> +  "Change tags for the currently selected thread.
>  
> -(defun notmuch-search-add-tag-region (tag beg end)
> -  (let ((search-id-string (mapconcat 'identity (notmuch-search-find-thread-id-region beg end) " or ")))
> -    (notmuch-tag search-id-string (concat "+" tag))
> -    (save-excursion
> -      (let ((last-line (line-number-at-pos end))
> -	    (max-line (- (line-number-at-pos (point-max)) 2)))
> -	(goto-char beg)
> -	(while (<= (line-number-at-pos) (min last-line max-line))
> -	  (notmuch-search-set-tags (delete-dups (sort (cons tag (notmuch-search-get-tags)) 'string<)))
> -	  (forward-line))))))
> +See `notmuch-search-tag-region' for details."
> +  (apply 'notmuch-search-tag-region (point) (point) tags))
>  
> -(defun notmuch-search-remove-tag-thread (tag)
> -  (notmuch-search-remove-tag-region tag (point) (point)))
> +(defun notmuch-search-tag-region (beg end &rest tags)
> +  "Change tags for threads in the given region.
>  
> -(defun notmuch-search-remove-tag-region (tag beg end)
> -  (let ((search-id-string (mapconcat 'identity (notmuch-search-find-thread-id-region beg end) " or ")))
> -    (notmuch-tag search-id-string (concat "-" tag))
> +`Tags' is a list of tag operations for \"notmuch tag\", i.e. a
> +list of tags to change with '+' and '-' prefixes.  The tags are
> +added or removed for all threads in the region from `beg' to
> +`end'."

Same comment about ticks and "notmuch tag".

> +  (let ((search-string (notmuch-search-find-thread-id-region-search beg end)))
> +    (apply 'notmuch-tag search-string tags)
>      (save-excursion
>        (let ((last-line (line-number-at-pos end))
>  	    (max-line (- (line-number-at-pos (point-max)) 2)))
>  	(goto-char beg)
>  	(while (<= (line-number-at-pos) (min last-line max-line))
> -	  (notmuch-search-set-tags (delete tag (notmuch-search-get-tags)))
> +	  (notmuch-search-set-tags
> +	   (notmuch-update-tags (notmuch-search-get-tags) tags))
>  	  (forward-line))))))
>  
> -(defun notmuch-search-add-tag (tag)
> -  "Add a tag to the currently selected thread or region.
> -
> -The tag is added to all messages in the currently selected thread
> -or threads in the current region."
> -  (interactive
> -   (list (notmuch-select-tag-with-completion "Tag to add: ")))
> -  (save-excursion
> -    (if (region-active-p)
> -	(let* ((beg (region-beginning))
> -	       (end (region-end)))
> -	  (notmuch-search-add-tag-region tag beg end))
> -      (notmuch-search-add-tag-thread tag))))
> -
> -(defun notmuch-search-remove-tag (tag)
> -  "Remove a tag from the currently selected thread or region.
> +(defun notmuch-search-tag (&optional initial-input)
> +  "Change tags for the currently selected thread or region."
> +  (interactive)
> +  (let* ((beg (if (region-active-p) (region-beginning) (point)))
> +	 (end (if (region-active-p) (region-end) (point)))

While you're in here, these should probably be `use-region-p'.

> +	 (search-string (notmuch-search-find-thread-id-region-search beg end))
> +	 (tags (notmuch-select-tags-with-completion initial-input search-string)))
> +    (apply 'notmuch-search-tag-region beg end tags)))
> +
> +(defun notmuch-search-add-tag ()
> +  "Same as `notmuch-search-tag' but sets initial input to '+'."
> +  (interactive)
> +  (notmuch-search-tag "+"))
>  
> -The tag is removed from all messages in the currently selected
> -thread or threads in the current region."
> -  (interactive
> -   (list (notmuch-select-tag-with-completion
> -	  "Tag to remove: "
> -	  (if (region-active-p)
> -	      (mapconcat 'identity
> -			 (notmuch-search-find-thread-id-region (region-beginning) (region-end))
> -			 " ")
> -	    (notmuch-search-find-thread-id)))))
> -  (save-excursion
> -    (if (region-active-p)
> -	(let* ((beg (region-beginning))
> -	       (end (region-end)))
> -	  (notmuch-search-remove-tag-region tag beg end))
> -      (notmuch-search-remove-tag-thread tag))))
> +(defun notmuch-search-remove-tag ()
> +  "Same as `notmuch-search-tag' but sets initial input to '-'."
> +  (interactive)
> +  (notmuch-search-tag "-"))
>  
>  (defun notmuch-search-archive-thread ()
>    "Archive the currently selected thread (remove its \"inbox\" tag).
>  
>  This function advances the next thread when finished."
>    (interactive)
> -  (notmuch-search-remove-tag-thread "inbox")
> +  (notmuch-search-tag-thread "-inbox")
>    (notmuch-search-next-thread))
>  
>  (defvar notmuch-search-process-filter-data nil
> @@ -893,9 +896,7 @@ will prompt for tags to be added or removed. Tags prefixed with
>  Each character of the tag name may consist of alphanumeric
>  characters as well as `_.+-'.
>  "
> -  (interactive (notmuch-select-tags-with-completion
> -		"Operations (+add -drop): notmuch tag "
> -		'("+" "-")))
> +  (interactive (notmuch-select-tags-with-completion))
>    (apply 'notmuch-tag notmuch-search-query-string actions))
>  
>  (defun notmuch-search-buffer-title (query)