Added parse error on empty program.

diff --git a/parser.scm b/parser.scm
index c112cf9..b075e5a 100644 (file)
--- a/parser.scm
+++ b/parser.scm
@@ -75,8 +75,8 @@
         (accept-token redcode-irx #t)
         (let loop ((instrs '())
                    (offset 0)
         (accept-token redcode-irx #t)
         (let loop ((instrs '())
                    (offset 0)

-                   (name '())
-                   (author '()))      
+                   (name #f)
+                   (author "Unspecified"))

           (let ((this-line (line)))
             (if this-line
                 (case (car this-line)
           (let ((this-line (line)))
             (if this-line
                 (case (car this-line)


@@ -85,7 +85,10 @@
                   ((comment) (loop instrs offset name author))
                   ((org) (loop instrs (cdr this-line) name author))
                   ((instr) (loop (cons (cdr this-line) instrs) offset name author)))
                   ((comment) (loop instrs offset name author))
                   ((org) (loop instrs (cdr this-line) name author))
                   ((instr) (loop (cons (cdr this-line) instrs) offset name author)))

-                (make-prog name author (reverse instrs) offset)))))
+                (begin
+                  (if (and name (not (null? instrs)))
+                      (make-prog name author (reverse instrs) offset)
+                      (error "Failed to parse name and/or instructions")))))))

 
       (define (line)
         (or (name-line)
 
       (define (line)
         (or (name-line)