;;; ----------------------------------------------------------------------
;;; One idea to speed up my search (and thereby be able to extend the
;;; number of plies) is to precycle nodes.  Precycling will allocate
;;; a bunch of nodes and reuse them instead of always creating "new"
;;; nodes.  This will save time spent allocating and garbage collection.
;;; Paul McNamee, 5/95

(let ((*available-nodes* nil)
      (*used-nodes* nil))

(defun Get-Node (&key (first-players-turn? t)
		      (old-board (node-board *initial-node*)))
  (unless *available-nodes*
    (loop repeat 1000
	  do (push (make-node :board (make-board)) *available-nodes*) ))
  (let ((node (pop *available-nodes*)))
    (setf (node-first-players-turn? node) first-players-turn?)
    ;; Destructively sets (node-board node)
    (copy-board-into-board old-board (node-board node))
    node  ; return node
))

(defun Restore-Used-Nodes ()
  (setf *available-nodes* (nconc *available-nodes* *used-nodes*))
  (setf *used-nodes* nil)
)

)  ;End of closure

(defmacro With-Node-Precycling (&body forms)
  "Free up all the precycled nodes.  Then excecute forms (which will
   use up some nodes). Example:

   (let (move)
     (With-Node-Precycling
       (setq move (alpha-beta-search *current-state* ...)) )
     ; print board... 
   )"
  `(progn (restore-used-nodes)
    (progn ,@forms))
)