+;; Dynamic variables.
+(defvar part-number)
+(defvar total-parts)
+(defvar type)
+(defvar condition)
+(defvar length)
+(defun gnus-treat-predicate (val)
+ (cond
+ (condition
+ (eq condition val))
+ ((null val)
+ nil)
+ ((eq val t)
+ t)
+ ((eq val 'head)
+ nil)
+ ((eq val 'last)
+ (eq part-number total-parts))
+ ((numberp val)
+ (< length val))
+ ((listp val)
+ (let ((pred (pop val)))
+ (cond
+ ((eq pred 'or)
+ (apply 'gnus-or (mapcar 'gnus-treat-predicate val)))
+ ((eq pred 'and)
+ (apply 'gnus-and (mapcar 'gnus-tread-predicate val)))
+ ((eq pred 'not)
+ (not (gnus-treat-predicate val)))
+ ((eq pred 'typep)
+ (equal (cadr val) type))
+ (t
+ (error "%S is not a valid predicate" pred)))))
+ (t
+ (error "%S is not a valid value" val))))
+