macro table gen. , syntax-rule works with *grammar*

1 files changed, 11 insertions, 5 deletions

diff --git a/utilities.lisp b/utilities.lisp
index 414f0f2..c231f72 100644
--- a/utilities.lisp
+++ b/utilities.lisp
@@ -19,7 +19,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 |#
 
 (defun extract-keys (alist)
-  "Extract the keys of associative lists."
+  "Extract the keys of an associative list."
   (let ((return-value nil))
 	(progn
 	  (dolist (i alist)
@@ -27,8 +27,11 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 			  (cons (car i) return-value)))
 	  (reverse return-value))))
 
+(defun last-char (s)
+  (char s (- (length s) 1)))
+
 (defun hexd? (string)
-  "Is a string a hexd number?"
+  "Is string a hexadecimal number?"
   (let ((stack ()))
 	(dotimes (i (length string))
 	  (push
@@ -45,9 +48,10 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 	(eval stack)))
 
 (defun hex2dec (string)
-  "Convert an arbitrarily sized hexd number (as string) to a positive decimal."
+  "Convert an arbitrarily sized hexadecimal number (as string) to a positive decimal."
   (if (hexd? string)
-	 (flet ((hex (c) ;Return character as hexadecimal
+	  ;; Return a character as a hexadecimal digit.
+	 (flet ((hex (c)
 			  (cond
 				((and (char-not-lessp c #\0)
 					  (char-not-greaterp c #\9))
@@ -58,6 +62,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 				 (+ (- (char-code (char-downcase c))
 					   (char-code #\a)) 10)))))
 	   (let ((return-value 0))
+		 ;; Loop through string and convert.
 		 (do ((i 0 (incf i))
 			  (j (- (length string) 1) (decf j)))
 			 ((minusp j) ())
@@ -66,4 +71,5 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 					(* (expt 16 j)
 					   (hex (char string i))))))
 		 return-value))
-	nil))
+	 ;; Return nil if string was not a hexadecimal number.
+	 nil))