;;; gnus-range.el --- range and sequence functions for Gnus
-;; Copyright (C) 1996-2012 Free Software Foundation, Inc.
+;; Copyright (C) 1996-2013 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: news
(defun gnus-set-difference (list1 list2)
"Return a list of elements of LIST1 that do not appear in LIST2."
- (let ((list1 (copy-sequence list1)))
- (while list2
- (setq list1 (delq (car list2) list1))
- (setq list2 (cdr list2)))
- list1))
+ (let ((hash2 (make-hash-table :test 'eq))
+ (result nil))
+ (dolist (elt list2) (puthash elt t hash2))
+ (dolist (elt list1)
+ (unless (gethash elt hash2)
+ (setq result (cons elt result))))
+ (nreverse result)))
(defun gnus-range-nconcat (&rest ranges)
"Return a range comprising all the RANGES, which are pre-sorted.