diff options
Diffstat (limited to 'lisp/emacs-lisp/seq.el')
| -rw-r--r-- | lisp/emacs-lisp/seq.el | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el index 6ddd8de6e8d..b6f0f66e5b1 100644 --- a/lisp/emacs-lisp/seq.el +++ b/lisp/emacs-lisp/seq.el @@ -458,11 +458,21 @@ TESTFN is used to compare elements, or `equal' if TESTFN is nil." (cl-defmethod seq-uniq ((sequence list) &optional testfn) (let ((result nil)) (if (not testfn) - ;; Fast path. - (while sequence - (unless (member (car sequence) result) - (push (car sequence) result)) - (pop sequence)) + ;; Fast path. If the list is long, use a hash table to speed + ;; things up even more. + (let ((l (length sequence))) + (if (> l 100) + (let ((hash (make-hash-table :test #'equal :size l))) + (while sequence + (unless (gethash (car sequence) hash) + (setf (gethash (car sequence) hash) t) + (push (car sequence) result)) + (setq sequence (cdr sequence)))) + ;; Short list. + (while sequence + (unless (member (car sequence) result) + (push (car sequence) result)) + (pop sequence)))) ;; Slower path. (while sequence (unless (seq-find (lambda (elem) |