X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Frandom.lisp;h=f91ca4671535a10dbfd11c021ee75c5ff061ecf0;hb=dd25ec9992371a9aa37e2dfdec64d9a149c54e79;hp=1a1392ce33960c32c73f39c6bedce6f56eaf4eb7;hpb=94f3524a314aa2fe0d1e30edbe48ff878de4cdf5;p=fiveam.git

diff --git a/src/random.lisp b/src/random.lisp
index 1a1392c..f91ca46 100644
--- a/src/random.lisp
+++ b/src/random.lisp
@@ -14,6 +14,16 @@
 ;;;; failure we stop running and report what values of the variables
 ;;;; caused the code to fail.
 
+;;;; The generation of the random data is done using "generator
+;;;; functions" (see below for details). A generator function is a
+;;;; function which creates, based on user supplied parameters, a
+;;;; function which returns random data. In order to facilitate
+;;;; generating good random data the FOR-ALL macro also supports guard
+;;;; conditions and creating one random input based on the values of
+;;;; another (see the FOR-ALL macro for details).
+
+;;;; *** Public Interface to the Random Tester
+
 (defparameter *num-trials* 100
   "Number of times we attempt to run the body of the FOR-ALL test.")
 
@@ -27,13 +37,51 @@ where the test code is never run due to the guards never
 returning true. This second run limit prevents that.")
 
 (defmacro for-all (bindings &body body)
-  `(perform-random-testing
-    (list ,@(mapcar #'second bindings))
-    (lambda ,(mapcar #'first bindings)
-      (if (and ,@(delete-if #'null (mapcar #'third bindings)))
-          (progn ,@body)
-          (throw 'run-once
-            (list :guard-conditions-failed))))))
+  "Bind BINDINGS to random variables and test BODY *num-trials* times.
+
+BINDINGS is a list of binding forms, each element is a list
+of (BINDING VALUE &optional GUARD). Value, which is evaluated
+once when the for-all is evaluated, must return a generator which
+be called each time BODY is evaluated. BINDING is either a symbol
+or a list which will be passed to destructuring-bind. GUARD is a
+form which, if present, stops BODY from executing when IT returns
+NIL. The GUARDS are evaluated after all the random data has been
+generated and they can refer to the current value of any
+binding. NB: Generator forms, unlike guard forms, can not contain
+references to the boud variables.
+
+Examples:
+
+  (for-all ((a (gen-integer)))
+    (is (integerp a)))
+
+  (for-all ((a (gen-integer) (plusp a)))
+    (is (integerp a))
+    (is (plusp a)))
+
+  (for-all ((less (gen-integer))
+            (more (gen-integer) (< less more)))
+    (is (<= less more)))
+
+  (for-all (((a b) (gen-two-integers)))
+    (is (integerp a))
+    (is (integerp b)))"
+  (with-unique-names (test-lambda-args)
+    `(perform-random-testing
+      (list ,@(mapcar #'second bindings))
+      (lambda (,test-lambda-args)
+        (destructuring-bind ,(mapcar #'first bindings)
+            ,test-lambda-args
+          (if (and ,@(delete-if #'null (mapcar #'third bindings)))
+              (progn ,@body)
+              (throw 'run-once
+                (list :guard-conditions-failed))))))))
+
+;;;; *** Implementation 
+
+;;;; We could just make FOR-ALL a monster macro, but having FOR-ALL be
+;;;; a preproccessor for the perform-random-testing function is
+;;;; actually much easier.
 
 (defun perform-random-testing (generators body)
   (loop
@@ -72,7 +120,7 @@ returning true. This second run limit prevents that.")
   (catch 'run-once
     (bind-run-state ((result-list '()))
       (let ((values (mapcar #'funcall generators)))
-        (apply body values)
+        (funcall body values)
         (cond
           ((null result-list)
            (throw 'run-once (list :no-tests)))
@@ -112,58 +160,91 @@ returning true. This second run limit prevents that.")
 
 ;;;; We provide a set of built-in generators.
 
-(defmacro defgenerator (name arguments &body body)
-  `(defun ,name ,arguments
-     (lambda () ,@body)))
-
-(defgenerator gen-integer (&key (max (1+ most-positive-fixnum))
-                                (min (1- most-negative-fixnum)))
-  (+ min (random (1+ (- max min)))))
-
-(defgenerator gen-float (&key bound (type 'short-float))
-  (let* ((most-negative (ecase type
-                          (short-float most-negative-short-float)
-                          (single-float most-negative-single-float)
-                          (double-float most-negative-double-float)
-                          (long-float most-negative-long-float)))
-         (most-positive (ecase type
-                          (short-float most-positive-short-float)
-                          (single-float most-positive-single-float)
-                          (double-float most-positive-double-float)
-                          (long-float most-positive-long-float)))
-         (bound (or bound (max most-positive (- most-negative)))))
-    (coerce 
-     (ecase (random 2)
-      (0 ;; generate a positive number
-       (random (min most-positive bound)))
-      (1 ;; generate a negative number
-       (- (random (min (- most-negative) bound)))))
-     type)))
-
-(defgenerator gen-character (&key (code (gen-integer :min 0 :max (1- char-code-limit)))
-                                  (alphanumericp nil))
-  (if alphanumericp
-      (code-char (funcall code))
-      (loop
-         for char = (code-char (funcall code))
-         until (alphanumericp char)
-         finally (return char))))
-
-(defgenerator gen-string (&key (length (gen-integer :min 0 :max 80))
-                               (elements (gen-character))
-                               (element-type 'character))
-  (loop
-     with length = (funcall length)
-     with string = (make-string length :element-type element-type)
-     for index below length
-     do (setf (aref string index) (funcall elements))
-     finally (return string)))
-
-(defgenerator gen-list (&key (length (gen-integer :min 0 :max 10))
-                             (elements (gen-integer :min -10 :max 10)))
-  (loop
-     repeat (funcall length)
-     collect (funcall elements)))
+(defun gen-integer (&key (max (1+ most-positive-fixnum))
+                         (min (1- most-negative-fixnum)))
+  "Returns a generator which produces random integers greater
+than or equal to MIN and less than or equal to MIN."
+  (lambda ()
+    (+ min (random (1+ (- max min))))))
+
+(defun gen-float (&key bound (type 'short-float))
+  "Returns a generator which producs floats of type TYPE. BOUND,
+if specified, constrains the ruselts to be in the range (-BOUND,
+BOUND)."
+  (lambda ()
+    (let* ((most-negative (ecase type
+                            (short-float most-negative-short-float)
+                            (single-float most-negative-single-float)
+                            (double-float most-negative-double-float)
+                            (long-float most-negative-long-float)))
+           (most-positive (ecase type
+                            (short-float most-positive-short-float)
+                            (single-float most-positive-single-float)
+                            (double-float most-positive-double-float)
+                            (long-float most-positive-long-float)))
+           (bound (or bound (max most-positive (- most-negative)))))
+      (coerce 
+       (ecase (random 2)
+         (0 ;; generate a positive number
+          (random (min most-positive bound)))
+         (1 ;; generate a negative number
+          (- (random (min (- most-negative) bound)))))
+       type))))
+
+(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.
+
+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)))))
+
+(defun gen-string (&key (length (gen-integer :min 0 :max 80))
+                        (elements (gen-character))
+                        (element-type 'character))
+  "Returns a generator which producs random strings. LENGTH must
+be a generator which producs integers, ELEMENTS must be a
+generator which produces characters of type ELEMENT-TYPE."
+  (lambda ()
+    (loop
+       with length = (funcall length)
+       with string = (make-string length :element-type element-type)
+       for index below length
+       do (setf (aref string index) (funcall elements))
+       finally (return string))))
+
+(defun gen-list (&key (length (gen-integer :min 0 :max 10))
+                      (elements (gen-integer :min -10 :max 10)))
+  "Returns a generator which producs random lists. LENGTH must be
+an integer generator and ELEMENTS must be a generator which
+producs objects."
+  (lambda ()
+    (loop
+       repeat (funcall length)
+       collect (funcall elements))))
+
+(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)))))
+  (lambda ()
+    (let ((buffer (make-array (funcall length) :element-type element-type)))
+      (map-into buffer elements))))
+
+(defun gen-one-element (&rest elements)
+  (lambda ()
+    (nth (random (length elements)) elements)))
 
 ;;;; The trivial always-produce-the-same-thing generator is done using
 ;;;; cl:constantly.