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Diffstat (limited to 'lisp/emacs-lisp/seq.el')
| -rw-r--r-- | lisp/emacs-lisp/seq.el | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el index 1b8d86563a1..b6f0f66e5b1 100644 --- a/lisp/emacs-lisp/seq.el +++ b/lisp/emacs-lisp/seq.el @@ -455,6 +455,33 @@ TESTFN is used to compare elements, or `equal' if TESTFN is nil." (setq result (cons elt result)))) (nreverse result))) +(cl-defmethod seq-uniq ((sequence list) &optional testfn) + (let ((result nil)) + (if (not testfn) + ;; 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) + (funcall testfn elem (car sequence))) + result) + (push (car sequence) result)) + (pop sequence))) + (nreverse result))) + (cl-defgeneric seq-mapcat (function sequence &optional type) "Concatenate the result of applying FUNCTION to each element of SEQUENCE. The result is a sequence of type TYPE, or a list if TYPE is nil." |