X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Frandom.lisp;h=615e9ea8e4abae9b25189c6328b82dc798488c2d;hb=1b24abf09e9fbb2a23c25a9583e5547514482f1b;hp=ba0abf8d7833381ce3d65e0e1f697760361cff76;hpb=25b02b6e536197f46c8951fed21a452340328bb9;p=fiveam.git

diff --git a/src/random.lisp b/src/random.lisp
index ba0abf8..615e9ea 100644
--- a/src/random.lisp
+++ b/src/random.lisp
@@ -77,7 +77,7 @@ Examples:
               (throw 'run-once
                 (list :guard-conditions-failed))))))))
 
-;;;; *** Implementation 
+;;;; *** Implementation
 
 ;;;; We could just make FOR-ALL a monster macro, but having FOR-ALL be
 ;;;; a preproccessor for the perform-random-testing function is
@@ -183,7 +183,7 @@ BOUND)."
                             (double-float most-positive-double-float)
                             (long-float most-positive-long-float)))
            (bound (or bound (max most-positive (- most-negative)))))
-      (coerce 
+      (coerce
        (ecase (random 2)
          (0 ;; generate a positive number
           (random (min most-positive bound)))
@@ -191,7 +191,8 @@ BOUND)."
           (- (random (min (- most-negative) bound)))))
        type))))
 
-(defun gen-character (&key (code (gen-integer :min 0 :max (1- char-code-limit)))
+(defun gen-character (&key (code-limit char-code-limit)
+                           (code (gen-integer :min 0 :max (1- code-limit)))
                            (alphanumericp nil))
   "Returns a generator of characters.
 
@@ -199,16 +200,16 @@ CODE must be a generator of random integers. ALPHANUMERICP, if
 non-NIL, limits the returned chars to those which pass
 alphanumericp."
   (lambda ()
-    (if alphanumericp            
-        (loop
-           for count upfrom 0
-           for char = (code-char (funcall code))
-           until (alphanumericp char)
-           when (= 1000 count)
-             do (error "After 1000 iterations ~S has still not generated an alphanumeric character :(."
-                       code)
-           finally (return char))
-        (code-char (funcall code)))))
+    (loop
+       for count upfrom 0
+       for char = (code-char (funcall code))
+       until (and char
+                  (or (not alphanumericp)
+                      (alphanumericp char)))
+       when (= 1000 count)
+       do (error "After 1000 iterations ~S has still not generated ~:[a valid~;an alphanumeric~] character :(."
+                 code alphanumericp)
+       finally (return char))))
 
 (defun gen-string (&key (length (gen-integer :min 0 :max 80))
                         (elements (gen-character))
@@ -234,6 +235,21 @@ producs objects."
        repeat (funcall length)
        collect (funcall elements))))
 
+(defun gen-tree (&key (size 20)
+                      (elements (gen-integer :min -10 :max 10)))
+  "Returns a generator which producs random trees. SIZE control
+the approximate size of the tree, but don't try anything above
+ 30, you have been warned. ELEMENTS must be a generator which
+will produce the elements."
+  (labels ((rec (&optional (current-depth 0))
+             (let ((key (random (+ 3 (- size current-depth)))))
+               (cond ((> key 2)
+                      (list (rec (+ current-depth 1))
+                            (rec (+ current-depth 1))))
+                     (t (funcall elements))))))
+    (lambda ()
+      (rec))))
+
 (defun gen-buffer (&key (length (gen-integer :min 0 :max 50))
                         (element-type '(unsigned-byte 8))
                         (elements (gen-integer :min 0 :max (1- (expt 2 8)))))