added error checking

svn: r16448
This commit is contained in:
Robby Findler 2009-10-29 15:43:50 +00:00
parent 35b809d0d7
commit 2f47a882c9

View File

@ -320,6 +320,9 @@
(define (make-parser start-number)
(lambda (get-token)
(unless (and (procedure? get-token)
(procedure-arity-includes? get-token 0))
(error 'get-token "expected a nullary procedure, got ~e" get-token))
(let parsing-loop ((stack (make-empty-stack start-number))
(ip (get-token)))
(let-values (((tok val start-pos end-pos)