- "Format TAG by looking into `notmuch-tag-formats'."
- (let ((formats (assoc tag notmuch-tag-formats)))
- (cond
- ((null formats) ;; - Tag not in `notmuch-tag-formats',
- tag) ;; the format is the tag itself.
- ((null (cdr formats)) ;; - Tag was deliberately hidden,
- nil) ;; no format must be returned
- (t ;; - Tag was found and has formats,
- (let ((tag tag)) ;; we must apply all the formats.
- (dolist (format (cdr formats) tag)
- (setq tag (eval format))))))))
-
-(defun notmuch-tag-format-tags (tags)
+ "Format TAG by according to `notmuch-tag-formats'.
+
+Callers must ensure that the tag format cache has been recently cleared
+via `notmuch-tag-clear-cache' before using this function. For example,
+it would be appropriate to clear the cache just prior to filling a
+buffer that uses formatted tags."
+
+ (let ((formatted (gethash tag notmuch-tag--format-cache 'missing)))
+ (when (eq formatted 'missing)
+ (let* ((formats
+ (save-match-data
+ ;; Don't use assoc-default since there's no way to
+ ;; distinguish a missing key from a present key with a
+ ;; null cdr:.
+ (assoc* tag notmuch-tag-formats
+ :test (lambda (tag key)
+ (and (eq (string-match key tag) 0)
+ (= (match-end 0) (length tag))))))))
+ (setq formatted
+ (cond
+ ((null formats) ;; - Tag not in `notmuch-tag-formats',
+ tag) ;; the format is the tag itself.
+ ((null (cdr formats)) ;; - Tag was deliberately hidden,
+ nil) ;; no format must be returned
+ (t ;; - Tag was found and has formats,
+ (let ((tag tag)) ;; we must apply all the formats.
+ (dolist (format (cdr formats) tag)
+ (setq tag (eval format)))))))
+ (puthash tag formatted notmuch-tag--format-cache)))
+ formatted))
+
+(defun notmuch-tag-format-tags (tags &optional face)