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beautiful-racket/beautiful-racket-ragg/br/ragg/test/test-0n1n.rkt

50 lines
1.4 KiB
Racket

9 years ago
#lang racket/base
(require br/ragg/examples/0n1n
br/ragg/support
rackunit)
(define (lex ip)
(port-count-lines! ip)
(lambda ()
(define next-char (read-char ip))
(cond [(eof-object? next-char)
(token eof)]
[(char=? next-char #\0)
(token "0" "0")]
[(char=? next-char #\1)
(token "1" "1")])))
;; The only rule in the grammar is:
;;
;; rule-0n1n: ["0" rule-0n1n "1"]
;;
;; It makes use of the "maybe" pattern. The result type of the
;; grammar rule is:
;;
;; rule-0n1n: (U #f
;; (list "0" rule-0n1n "1"))
(check-equal? (syntax->datum (parse #f (lex (open-input-string "0011"))))
'(rule-0n1n "0" (rule-0n1n "0" (rule-0n1n) "1") "1"))
(check-equal? (syntax->datum (parse #f (lex (open-input-string "01"))))
'(rule-0n1n "0" (rule-0n1n) "1"))
(check-equal? (syntax->datum (parse #f (lex (open-input-string ""))))
'(rule-0n1n))
(check-equal? (syntax->datum (parse #f (lex (open-input-string "000111"))))
'(rule-0n1n "0" (rule-0n1n "0" (rule-0n1n "0" (rule-0n1n) "1") "1") "1"))
(check-exn exn:fail:parsing?
(lambda () (parse #f (lex (open-input-string "0001111")))))
(check-exn exn:fail:parsing?
(lambda () (parse #f (lex (open-input-string "0001110")))))
(check-exn exn:fail:parsing?
(lambda () (parse #f (lex (open-input-string "10001110")))))