couple of cheap heap utilities (#40)

* couple of cheap heap utilities

* export new symbols

Author: ecpeterson

src/cheap-heap.lisp

@@ -55,3 +55,16 @@
      (q-peek (cdaddr heap)))
     (t
      nil)))
+
+(defun cheap-heap-empty? (heap)
+  (equalp heap (make-cheap-heap)))
+
+(defun cheap-heap->list (heap)
+  (labels ((aux (heap &optional (list nil))
+             (let ((next (cheap-heap-dequeue heap)))
+               (cond
+                 ((null next)
+                  (reverse list))
+                 (t
+                  (aux heap (list* next list)))))))
+    (aux heap)))

src/package.lisp

@@ -39,6 +39,8 @@
    #:cheap-heap-enqueue                 ; FUNCTION
    #:cheap-heap-dequeue                 ; FUNCTION
    #:cheap-heap-peep                    ; FUNCTION
+   #:cheap-heap-empty?                  ; FUNCTION (PREDICATE)
+   #:cheap-heap->list                   ; FUNCTION
    )
 
   ;; logger.lisp