On 3/16/20 2:39 PM, [email protected] wrote:
Hi,
in my quest to play parsing, I'm failing when I try to cope with
comments.
Here's an excerpt from my current file
(define my-grammar
(lalr-spec
(start my-file)
(grammar
;; boring grammar details elided
)))
(define mach (make-lalr-machine aq-grammar))
(define mtab (lalr-match-table mach))
(define gen-lexer (make-lexer-generator mtab
#:comm-reader (make-comm-reader '(("#" . "\n")))))
(define raw-parse (make-lalr-parser mach))
(define (parse) (raw-parse (gen-lexer)))
;; (gen-lexer)
(parse)
Comments are shell-like, from "#" to end of line. Grammar
works fine so-far, but when (parse) sees a hash-comment
(even just a one-line input
# this is a comment
it panics:
Backtrace:
In ice-9/boot-9.scm:
1736:10 6 (with-exception-handler _ _ #:unwind? _ # _)
In unknown file:
5 (apply-smob/0 #<thunk 557754319740>)
In ice-9/boot-9.scm:
718:2 4 (call-with-prompt ("prompt") #<procedure 5577543308e0 …> …)
In ice-9/eval.scm:
619:8 3 (_ #(#(#<directory (guile-user) 5577543c1f00>)))
In ice-9/boot-9.scm:
2806:4 2 (save-module-excursion #<procedure 5577543b31b0 at ice-…>)
4351:12 1 (_)
In nyacc/parse.scm:
78:4 0 (_ _ #:debug _)
nyacc/parse.scm:78:4: Throw to key `nyacc-error' with args `("~A:~A: parse failed at state ~A, on input ~S" "(unknown)" 1 0 " a comment")'.
I feel I'm doing something stupid. What can I do to understand
what's going on?
Thanks & cheers
-- tomás
make-comm-reader will not eat newlines at end of comment by default.
If you want the comment # ... \n to include the newline try adding
#:eat-newline #t.
Matt
