diff options
Diffstat (limited to 'gtwiwtg.lisp')
| -rw-r--r-- | gtwiwtg.lisp | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/gtwiwtg.lisp b/gtwiwtg.lisp index 42e7731..1deadce 100644 --- a/gtwiwtg.lisp +++ b/gtwiwtg.lisp @@ -149,6 +149,7 @@ (a-generator-class resumable-generator! () + already-resumed-p (wrapped (error "Resumable generators must wrap another generator"))) (defmethod next ((gen resumable-generator!)) @@ -388,10 +389,34 @@ The last generated value of the returned generator will be NIL. (defun can-be-resumed-p (gen) (and (typep gen 'resumable-generator!) + (not (slot-value gen 'already-resumed-p)) (stopped-p gen))) (defun resume! (resumable) + "Resumes a resumable generator. Creates a new generator from +RESUMABLE. + +A particular resumable generator instance can only be resumed +once. Here is how you would resume a generator several times: + +> (defvar *foobar* (make-resumable! (range))) +*FOOBAR* + +> (take 10 *foobar*) +(0 1 2 3 4 5 6 7 8 9) + +> (defvar *new-foobar* (resume! *foobar*)) + +> (defvar *wont-work* (resume! *foobar*)) ;; THROWS AN ERROR + +> (take 10 *new-foobar*) +(10 11 12 13 14 15 16 17 18 19) + +;; but *new-foobar* can be resumed +> (setf *new-foobar* (resume! *new-foobar*)) +" (assert (can-be-resumed-p resumable)) + (setf (slot-value resumable 'already-resumed-p) t) (make-instance 'resumable-generator! :wrapped (slot-value resumable 'wrapped))) (defun map! (map-fn gen &rest gens) |