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-rw-r--r--gtwiwtg.lisp21
1 files changed, 17 insertions, 4 deletions
diff --git a/gtwiwtg.lisp b/gtwiwtg.lisp
index 896a733..46f8752 100644
--- a/gtwiwtg.lisp
+++ b/gtwiwtg.lisp
@@ -2,7 +2,10 @@
(in-package :gtwiwtg)
(defclass generator! ()
- ((state
+ ((dirty-p
+ :accessor dirty-p
+ :initform nil)
+ (state
:accessor gen-state
:initarg :state
:initform (error "no state"))
@@ -20,7 +23,8 @@
(defmethod next ((gen generator!))
(assert (has-next-p gen))
- (with-slots (state next-fn) gen
+ (with-slots (state next-fn dirty-p) gen
+ (setf dirty-p t)
(multiple-value-bind (val new-state) (funcall next-fn state)
(setf state new-state)
val)))
@@ -80,6 +84,13 @@ the values passed as ARGS looped forever."
(defun all-different (things)
(= (length things) (length (remove-duplicates things))))
+
+(defun all-clean (gens)
+ (every (complement #'dirty-p) gens))
+
+(defun all-good (gens)
+ (and (all-clean gens) (all-different gens)))
+
;;; MODIFIERS and COMBINATORS
(defmethod yield-to! (gen1 gen2)
@@ -123,7 +134,7 @@ generators.
THIS FUNCTION MODIFIES AND RETURNS ITS FIRST GENERATOR ARGUMENT.
Also, all of the generators must be different from one another. If any
compare EQL then an error is signaled."
- (assert (all-different (list* gen gens)))
+ (assert (all-good (list* gen gens)))
(let ((orig-fns (mapcar #'next-fn (cons gen gens)))
(orig-preds (mapcar #'next-p-fn (cons gen gens))))
(setf (gen-state gen) (mapcar #'gen-state (cons gen gens))
@@ -151,6 +162,7 @@ compare EQL then an error is signaled."
when applied to PRED.
THIS FUNCTION MODIFIES AND RETURNS ITS GENERATOR ARGUMENT."
+ (assert (not (dirty-p gen)))
(let* ((orig-fn (next-fn gen))
(orig-p-fn (next-p-fn gen))
(last-good nil)
@@ -186,6 +198,7 @@ equivalent to (FUNCALL #'CONCAT! (MAP! FN GEN))
That is it generates each element of (FN X) for each X in GEN.
BIND! MODIFIES AND RETURNS ITS GENERATOR ARGUMENT."
+ (assert (not (dirty-p gen)))
(let ((orig-fn (next-fn gen))
(orig-p (next-p-fn gen))
(orig-state (gen-state gen)))
@@ -213,7 +226,7 @@ Each of the arguments to CONCAT! must be different. If any compare
EQL, an error will be signalled.
CONCAT! MODIFIES AND RETURNS ITS FIRST ARGUMENT."
- (assert (all-different (list* gen gens)))
+ (assert (all-good (list* gen gens)))
(bind! #'identity (seq (list* gen gens))))
(defun zip! (gen &rest gens)