[PATCH v3] emacs: Report a lack of matches when calling `notmuch-show'.

[Mark Walters]

Just to confirm that this LGTM +1.

Best wishes

Mark

On Thu, 11 Feb 2016, David Edmondson <dme at dme.org> wrote:
> If the basic query passed to `notmuch-show' generates no results, ring
> the bell and inform the user that no messages matched the query rather
> than displaying an empty buffer and showing an obscure error.
>
> Similarly when refreshing a `notmuch-show' buffer and no messages match.
> ---
>  emacs/notmuch-show.el | 144 +++++++++++++++++++++++++++++---------------------
>  emacs/notmuch.el      |   6 ++-
>  2 files changed, 89 insertions(+), 61 deletions(-)
>
> diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
> index 3345878..4629c64 100644
> --- a/emacs/notmuch-show.el
> +++ b/emacs/notmuch-show.el
> @@ -153,27 +153,21 @@ indentation."
>  
>  (defvar notmuch-show-thread-id nil)
>  (make-variable-buffer-local 'notmuch-show-thread-id)
> -(put 'notmuch-show-thread-id 'permanent-local t)
>  
>  (defvar notmuch-show-parent-buffer nil)
>  (make-variable-buffer-local 'notmuch-show-parent-buffer)
> -(put 'notmuch-show-parent-buffer 'permanent-local t)
>  
>  (defvar notmuch-show-query-context nil)
>  (make-variable-buffer-local 'notmuch-show-query-context)
> -(put 'notmuch-show-query-context 'permanent-local t)
>  
>  (defvar notmuch-show-process-crypto nil)
>  (make-variable-buffer-local 'notmuch-show-process-crypto)
> -(put 'notmuch-show-process-crypto 'permanent-local t)
>  
>  (defvar notmuch-show-elide-non-matching-messages nil)
>  (make-variable-buffer-local 'notmuch-show-elide-non-matching-messages)
> -(put 'notmuch-show-elide-non-matching-messages 'permanent-local t)
>  
>  (defvar notmuch-show-indent-content t)
>  (make-variable-buffer-local 'notmuch-show-indent-content)
> -(put 'notmuch-show-indent-content 'permanent-local t)
>  
>  (defvar notmuch-show-attachment-debug nil
>    "If t log stdout and stderr from attachment handlers
> @@ -1197,71 +1191,101 @@ non-nil.
>  The optional BUFFER-NAME provides the name of the buffer in
>  which the message thread is shown. If it is nil (which occurs
>  when the command is called interactively) the argument to the
> -function is used."
> +function is used.
> +
> +Returns the buffer containing the messages, or NIL if no messages
> +matched."
>    (interactive "sNotmuch show: \nP")
>    (let ((buffer-name (generate-new-buffer-name
>  		      (or buffer-name
>  			  (concat "*notmuch-" thread-id "*")))))
>      (switch-to-buffer (get-buffer-create buffer-name))
> -    ;; Set the default value for `notmuch-show-process-crypto' in this
> -    ;; buffer.
> -    (setq notmuch-show-process-crypto notmuch-crypto-process-mime)
> -    ;; Set the default value for
> -    ;; `notmuch-show-elide-non-matching-messages' in this buffer. If
> -    ;; elide-toggle is set, invert the default.
> -    (setq notmuch-show-elide-non-matching-messages notmuch-show-only-matching-messages)
> -    (if elide-toggle
> -	(setq notmuch-show-elide-non-matching-messages (not notmuch-show-elide-non-matching-messages)))
> +    ;; No need to track undo information for this buffer.
> +    (setq buffer-undo-list t)
> +
> +    (notmuch-show-mode)
>  
> +    ;; Set various buffer local variables to their appropriate initial
> +    ;; state. Do this after enabling `notmuch-show-mode' so that they
> +    ;; aren't wiped out.
>      (setq notmuch-show-thread-id thread-id
>  	  notmuch-show-parent-buffer parent-buffer
> -	  notmuch-show-query-context query-context)
> -    (notmuch-show-build-buffer)
> -    (notmuch-show-goto-first-wanted-message)
> -    (current-buffer)))
> +	  notmuch-show-query-context query-context
>  
> -(defun notmuch-show-build-buffer ()
> -  (let ((inhibit-read-only t))
> +	  notmuch-show-process-crypto notmuch-crypto-process-mime
> +	  ;; If `elide-toggle', invert the default value.
> +	  notmuch-show-elide-non-matching-messages
> +	  (if elide-toggle
> +	      (not notmuch-show-only-matching-messages)
> +	    notmuch-show-only-matching-messages))
>  
> -    (notmuch-show-mode)
>      (add-hook 'post-command-hook #'notmuch-show-command-hook nil t)
> -
> -    ;; Don't track undo information for this buffer
> -    (set 'buffer-undo-list t)
> +    (jit-lock-register #'notmuch-show-buttonise-links)
>  
>      (notmuch-tag-clear-cache)
> -    (erase-buffer)
> -    (goto-char (point-min))
> -    (save-excursion
> -      (let* ((basic-args (list notmuch-show-thread-id))
> -	     (args (if notmuch-show-query-context
> -		       (append (list "\'") basic-args
> -			       (list "and (" notmuch-show-query-context ")\'"))
> -		     (append (list "\'") basic-args (list "\'"))))
> -	     (cli-args (cons "--exclude=false"
> -			     (when notmuch-show-elide-non-matching-messages
> -			       (list "--entire-thread=false")))))
> -
> -	(notmuch-show-insert-forest (notmuch-query-get-threads (append cli-args args)))
> -	;; If the query context reduced the results to nothing, run
> -	;; the basic query.
> -	(when (and (eq (buffer-size) 0)
> -		   notmuch-show-query-context)
> -	  (notmuch-show-insert-forest
> -	   (notmuch-query-get-threads (append cli-args basic-args)))))
> -
> -      (jit-lock-register #'notmuch-show-buttonise-links)
> -
> -      (notmuch-show-mapc (lambda () (notmuch-show-set-prop :orig-tags (notmuch-show-get-tags))))
> +
> +    (let ((inhibit-read-only t))
> +      (if (notmuch-show--build-buffer)
> +	  ;; Messages were inserted into the buffer.
> +	  (current-buffer)
> +
> +	;; No messages were inserted - presumably none matched the
> +	;; query.
> +	(kill-buffer (current-buffer))
> +	(ding)
> +	(message "No messages matched the query!")
> +	nil))))
> +
> +(defun notmuch-show--build-buffer (&optional state)
> +  "Display messages matching the current buffer context.
> +
> +Apply the previously saved STATE if supplied, otherwise show the
> +first relevant message.
> +
> +If no messages match the query return NIL."
> +  (let* ((basic-args (list notmuch-show-thread-id))
> +	 (args (if notmuch-show-query-context
> +		   (append (list "\'") basic-args
> +			   (list "and (" notmuch-show-query-context ")\'"))
> +		 (append (list "\'") basic-args (list "\'"))))
> +	 (cli-args (cons "--exclude=false"
> +			 (when notmuch-show-elide-non-matching-messages
> +			   (list "--entire-thread=false"))))
> +
> +	 (forest (or (notmuch-query-get-threads (append cli-args args))
> +		     ;; If a query context reduced the number of
> +		     ;; results to zero, try again without it.
> +		     (and notmuch-show-query-context
> +			  (notmuch-query-get-threads (append cli-args basic-args)))))
> +
> +	 ;; Must be reset every time we are going to start inserting
> +	 ;; messages into the buffer.
> +	 (notmuch-show-previous-subject ""))
> +
> +    (when forest
> +      (notmuch-show-insert-forest forest)
> +
> +      ;; Store the original tags for each message so that we can
> +      ;; display changes.
> +      (notmuch-show-mapc
> +       (lambda () (notmuch-show-set-prop :orig-tags (notmuch-show-get-tags))))
>  
>        ;; Set the header line to the subject of the first message.
>        (setq header-line-format
>  	    (replace-regexp-in-string "%" "%%"
> -			    (notmuch-sanitize
> -			     (notmuch-show-strip-re
> -			      (notmuch-show-get-subject)))))
> +				      (notmuch-sanitize
> +				       (notmuch-show-strip-re
> +					(notmuch-show-get-subject)))))
>  
> -      (run-hooks 'notmuch-show-hook))))
> +      (run-hooks 'notmuch-show-hook)
> +
> +      (if state
> +	  (notmuch-show-apply-state state)
> +	;; With no state to apply, just go to the first message.
> +	(notmuch-show-goto-first-wanted-message)))
> +
> +    ;; Report back to the caller whether any messages matched.
> +    forest))
>  
>  (defun notmuch-show-capture-state ()
>    "Capture the state of the current buffer.
> @@ -1320,17 +1344,17 @@ reset based on the original query."
>    (let ((inhibit-read-only t)
>  	(state (unless reset-state
>  		 (notmuch-show-capture-state))))
> -    ;; erase-buffer does not seem to remove overlays, which can lead
> +    ;; `erase-buffer' does not seem to remove overlays, which can lead
>      ;; to weird effects such as remaining images, so remove them
>      ;; manually.
>      (remove-overlays)
>      (erase-buffer)
> -    (notmuch-show-build-buffer)
> -    (if state
> -	(notmuch-show-apply-state state)
> -      ;; We're resetting state, so navigate to the first open message
> -      ;; and mark it read, just like opening a new show buffer.
> -      (notmuch-show-goto-first-wanted-message))))
> +
> +    (unless (notmuch-show--build-buffer state)
> +      ;; No messages were inserted.
> +      (kill-buffer (current-buffer))
> +      (ding)
> +      (message "Refreshing the buffer resulted in no messages!"))))
>  
>  (defvar notmuch-show-stash-map
>    (let ((map (make-sparse-keymap)))
> diff --git a/emacs/notmuch.el b/emacs/notmuch.el
> index 463b926..3100b97 100644
> --- a/emacs/notmuch.el
> +++ b/emacs/notmuch.el
> @@ -458,7 +458,11 @@ no messages in the region then return nil."
>    (notmuch-search-properties-in-region :subject beg end))
>  
>  (defun notmuch-search-show-thread (&optional elide-toggle)
> -  "Display the currently selected thread."
> +  "Display the currently selected thread.
> +
> +With a prefix argument, invert the default value of
> +`notmuch-show-only-matching-messages' when displaying the
> +thread."
>    (interactive "P")
>    (let ((thread-id (notmuch-search-find-thread-id))
>  	(subject (notmuch-search-find-subject)))
> -- 
> 2.1.4
>
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