+(if (fboundp 'union)
+ (defalias 'gnus-union 'union)
+ (defun gnus-union (l1 l2)
+ "Set union of lists L1 and L2."
+ (cond ((null l1) l2)
+ ((null l2) l1)
+ ((equal l1 l2) l1)
+ (t
+ (or (>= (length l1) (length l2))
+ (setq l1 (prog1 l2 (setq l2 l1))))
+ (while l2
+ (or (member (car l2) l1)
+ (push (car l2) l1))
+ (pop l2))
+ l1))))
+
+(defun gnus-add-text-properties-when
+ (property value start end properties &optional object)
+ "Like `gnus-add-text-properties', only applied on where PROPERTY is VALUE."
+ (let (point)
+ (while (and start
+ (< start end) ;; XEmacs will loop for every when start=end.
+ (setq point (text-property-not-all start end property value)))
+ (gnus-add-text-properties start point properties object)
+ (setq start (text-property-any point end property value)))
+ (if start
+ (gnus-add-text-properties start end properties object))))
+
+(defun gnus-remove-text-properties-when
+ (property value start end properties &optional object)
+ "Like `remove-text-properties', only applied on where PROPERTY is VALUE."
+ (let (point)
+ (while (and start
+ (< start end)
+ (setq point (text-property-not-all start end property value)))
+ (remove-text-properties start point properties object)
+ (setq start (text-property-any point end property value)))
+ (if start
+ (remove-text-properties start end properties object))
+ t))
+
+(defun gnus-string-equal (x y)
+ "Like `string-equal', except it compares case-insensitively."
+ (and (= (length x) (length y))
+ (or (string-equal x y)
+ (string-equal (downcase x) (downcase y)))))