emacs: notmuch-show-header-line: allow format strings and functions

If a string value is assigned to notmuch-show-header-line, it's used
as a format string to be passed passed to format-spec with `%s`
substituted by the message's subject.  If a function is given, it's
called with the subject as argument, and its return value used as
header line.

As before, t means displaying the subject and nil not using any header
line.

Signed-off-by: jao <jao@gnu.org>
Amended-by: db, docstring spelling fix
This commit is contained in:
jao 2022-06-01 10:53:36 +01:00 committed by David Bremner
parent eab665c573
commit 66369ddf1c

View file

@ -85,8 +85,30 @@ visible for any given message."
:group 'notmuch-show)
(defcustom notmuch-show-header-line t
"Show a header line with the current message's subject."
:type 'boolean
"Show a header line in notmuch show buffers.
If t (the default), the header line will contain the current
message's subject.
If a string, this value is interpreted as a format string to be
passed to `format-spec` with `%s` as the substitution variable
for the message's subject. E.g., to display the subject trimmed
to a maximum of 80 columns, you could use \"%>-80s\" as format.
If you assign to this variable a function, it will be called with
the subject as argument, and the return value will be used as the
header line format. Since the function is called with the
message buffer as the current buffer, it is also possible to
access any other properties of the message, using for instance
notmuch-show functions such as
`notmuch-show-get-message-properties'.
Finally, if this variable is set to nil, no header is
displayed."
:type '(choice (const :tag "No header" ni)
(const :tag "Subject" t)
(string :tag "Format")
(function :tag "Function"))
:group 'notmuch-show)
(defcustom notmuch-show-relative-dates t
@ -1313,6 +1335,18 @@ fallback if the prior matches no messages."
(push (list thread "and (" context ")") queries))
queries))
(defun notmuch-show--header-line-format ()
"Compute the header line format of a notmuch-show buffer."
(when notmuch-show-header-line
(let* ((s (notmuch-sanitize
(notmuch-show-strip-re (notmuch-show-get-subject))))
(subject (replace-regexp-in-string "%" "%%" s)))
(cond ((stringp notmuch-show-header-line)
(format-spec notmuch-show-header-line `((?s . ,subject))))
((functionp notmuch-show-header-line)
(funcall notmuch-show-header-line subject))
(notmuch-show-header-line subject)))))
(defun notmuch-show--build-buffer (&optional state)
"Display messages matching the current buffer context.
@ -1343,13 +1377,7 @@ If no messages match the query return NIL."
;; 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.
(when notmuch-show-header-line
(setq header-line-format
(replace-regexp-in-string "%" "%%"
(notmuch-sanitize
(notmuch-show-strip-re
(notmuch-show-get-subject))))))
(setq header-line-format (notmuch-show--header-line-format))
(run-hooks 'notmuch-show-hook)
(if state
(notmuch-show-apply-state state)