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-rw-r--r--lisp/gnus/gnus-range.el12
1 files changed, 7 insertions, 5 deletions
diff --git a/lisp/gnus/gnus-range.el b/lisp/gnus/gnus-range.el
index 68729da0910..091276ee4f8 100644
--- a/lisp/gnus/gnus-range.el
+++ b/lisp/gnus/gnus-range.el
@@ -52,11 +52,13 @@ If RANGE is a single range, return (RANGE). Otherwise, return RANGE."
(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.