[PATCH 1/2] emacs: Use text properties rather than overlays in `notmuch-show-mode'.

[Austin Clements]

LGTM other than one very minor nit, though I pretty reliably make
fence post errors when dealing with text properties, so perhaps
somebody else should check that.

Quoth David Edmondson on Jan 24 at 11:36 am:
> Except for where invisibility is involved, replace the use of overlays
> in `notmuch-show-mode' with text properties, which are more efficient
> and can be merged together more effectively.
> ---
>  emacs/notmuch-show.el |   66 +++++++++++++++++++++++++++++++-----------------
>  emacs/notmuch-wash.el |    8 ++++-
>  2 files changed, 48 insertions(+), 26 deletions(-)
> 
> diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
> index e6a5b31..d6a0ac0 100644
> --- a/emacs/notmuch-show.el
> +++ b/emacs/notmuch-show.el
> @@ -258,10 +258,10 @@ operation on the contents of the current buffer."
>  	       (t
>  		'message-header-other))))
>  
> -    (overlay-put (make-overlay (point) (re-search-forward ":"))
> -		 'face 'message-header-name)
> -    (overlay-put (make-overlay (point) (re-search-forward ".*$"))
> -		 'face face)))
> +    (put-text-property (point) (re-search-forward ":")
> +		       'face 'message-header-name)
> +    (put-text-property (point) (re-search-forward ".*$")
> +		       'face face)))

Does this need rear-nonsticky or are the headers already formed enough
by this point that it isn't necessary?

>  
>  (defun notmuch-show-colour-headers ()
>    "Apply some colouring to the current headers."
> @@ -278,12 +278,11 @@ operation on the contents of the current buffer."
>    "Update the displayed tags of the current message."
>    (save-excursion
>      (goto-char (notmuch-show-message-top))
> -    (if (re-search-forward "(\\([^()]*\\))$" (line-end-position) t)
> -	(let ((inhibit-read-only t))
> -	  (replace-match (concat "("
> -				 (propertize (mapconcat 'identity tags " ")
> -					     'face 'notmuch-tag-face)
> -				 ")"))))))
> +    (when (re-search-forward "(\\([^()]*\\))$" (line-end-position) t)
> +      (let ((inhibit-read-only t))
> +	(replace-match (propertize (mapconcat 'identity tags " ")
> +				   'face '(notmuch-tag-face notmuch-message-summary-face))
> +		       nil nil nil 1)))))
>  
>  (defun notmuch-show-clean-address (address)
>    "Try to clean a single email ADDRESS for display.  Return
> @@ -310,15 +309,26 @@ unchanged ADDRESS if parsing fails."
>    "Insert a notmuch style headerline based on HEADERS for a
>  message at DEPTH in the current thread."
>    (let ((start (point)))
> -    (insert (notmuch-show-spaces-n (* notmuch-show-indent-messages-width depth))
> -	    (notmuch-show-clean-address (plist-get headers :From))
> -	    " ("
> -	    date
> -	    ") ("
> -	    (propertize (mapconcat 'identity tags " ")
> -			'face 'notmuch-tag-face)
> -	    ")\n")
> -    (overlay-put (make-overlay start (point)) 'face 'notmuch-message-summary-face)))
> +    (insert
> +     (propertize (concat (notmuch-show-clean-address (plist-get headers :From))
> +			 " ("
> +			 date
> +			 ") (")
> +		 'face 'notmuch-message-summary-face)
> +     (propertize (mapconcat 'identity tags " ")
> +		 'face '(notmuch-tag-face notmuch-message-summary-face))

I feel like I should know this, but what's the effect of giving a list
as the face property?  I assume it merges them in the same way it
merges, say, overlay and text property faces, but the documentation
only says that you can give a list, not what it means.

> +     (propertize ")\n"
> +		 'face 'notmuch-message-summary-face))
> +
> +    ;; Ensure that any insertions at the start of this line (usually
> +    ;; just spaces for indentation purposes) inherit the face of the
> +    ;; rest of the line...
> +    (put-text-property start (1+ start)
> +		       'front-sticky '(face))
> +    ;; ...and that insertions at the end of this region do _not_
> +    ;; inherit the face of the rest of this line.
> +    (put-text-property (1- (point)) (point)
> +		       'rear-nonsticky '(face))))
>  
>  (defun notmuch-show-insert-header (header header-value)
>    "Insert a single header."
> @@ -753,8 +763,15 @@ current buffer, if possible."
>  (defun notmuch-show-insert-bodypart (msg part depth)
>    "Insert the body part PART at depth DEPTH in the current thread."
>    (let ((content-type (downcase (plist-get part :content-type)))
> -	(nth (plist-get part :id)))
> -    (notmuch-show-insert-bodypart-internal msg part content-type nth depth content-type))
> +	(nth (plist-get part :id))
> +	(start (point)))
> +    (notmuch-show-insert-bodypart-internal msg part content-type nth depth content-type)
> +
> +    ;; Ensure that face properties applied to text in the buffer by
> +    ;; the part handler don't leak into the following text.
> +    (put-text-property start (point-max)
> +		       'rear-nonsticky '(face)))
> +
>    ;; Some of the body part handlers leave point somewhere up in the
>    ;; part, so we make sure that we're down at the end.
>    (goto-char (point-max))
> @@ -845,11 +862,12 @@ current buffer, if possible."
>      (setq body-end (point-marker))
>      (setq content-end (point-marker))
>  
> -    ;; Indent according to the depth in the thread.
> -    (indent-rigidly content-start content-end (* notmuch-show-indent-messages-width depth))
> -
>      (setq message-end (point-max-marker))
>  
> +    ;; Indent according to the depth in the thread.
> +    (indent-rigidly message-start message-end
> +    		    (* notmuch-show-indent-messages-width depth))
> +

Why swap the order of the setq and the indent-rigidly?

>      ;; Save the extents of this message over the whole text of the
>      ;; message.
>      (put-text-property message-start message-end :notmuch-message-extent (cons message-start message-end))
> diff --git a/emacs/notmuch-wash.el b/emacs/notmuch-wash.el
> index 5c1e830..84428a4 100644
> --- a/emacs/notmuch-wash.el
> +++ b/emacs/notmuch-wash.el
> @@ -183,7 +183,9 @@ insert before the button, probably for indentation."
>      (let* ((cite-start (match-beginning 0))
>  	   (cite-end (match-end 0))
>  	   (cite-lines (count-lines cite-start cite-end)))
> -      (overlay-put (make-overlay cite-start cite-end) 'face 'message-cited-text)
> +      (put-text-property cite-start cite-end 'face 'message-cited-text)
> +      ;; Ensure that the next line doesn't inherit our face.
> +      (put-text-property (1- cite-end) cite-end 'rear-nonsticky '(face))
>        (when (> cite-lines (+ notmuch-wash-citation-lines-prefix
>  			     notmuch-wash-citation-lines-suffix
>  			     1))
> @@ -205,7 +207,9 @@ insert before the button, probably for indentation."
>  		  (sig-end-marker (make-marker)))
>  	      (set-marker sig-start-marker sig-start)
>  	      (set-marker sig-end-marker (point-max))
> -	      (overlay-put (make-overlay sig-start-marker sig-end-marker) 'face 'message-cited-text)
> +	      (put-text-property sig-start-marker sig-end-marker 'face 'message-cited-text)
> +	      ;; Ensure that the next line doesn't inherit our face.
> +	      (put-text-property (1- sig-end-marker) sig-end-marker 'rear-nonsticky '(face))
>  	      (notmuch-wash-region-to-button
>  	       msg sig-start-marker sig-end-marker
>  	       "signature" "\n"))))))