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51 lines
1.4 KiB
Racket
51 lines
1.4 KiB
Racket
#lang racket/base
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(require brag/examples/0n1
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brag/support
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rackunit)
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(define (lex ip)
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(port-count-lines! ip)
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(lambda ()
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(define next-char (read-char ip))
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(cond [(eof-object? next-char)
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(token eof)]
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[(char=? next-char #\0)
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(token "0" "0")]
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[(char=? next-char #\1)
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(token "1" "1")])))
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(check-equal? (syntax->datum (parse #f (lex (open-input-string "1"))))
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'(rule "1"))
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(check-equal? (syntax->datum (parse #f (lex (open-input-string "01"))))
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'(rule "0" "1"))
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(check-equal? (syntax->datum (parse #f (lex (open-input-string "001"))))
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'(rule "0" "0" "1"))
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(check-exn exn:fail:parsing?
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(lambda ()
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(parse #f (lex (open-input-string "0")))))
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(check-exn exn:fail:parsing?
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(lambda ()
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(parse #f (lex (open-input-string "10")))))
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(check-exn exn:fail:parsing?
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(lambda ()
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(parse #f (lex (open-input-string "010")))))
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;; This should fail predictably because we're passing in tokens
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;; that the parser doesn't know.
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(check-exn exn:fail:parsing?
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(lambda () (parse '("zero" "one" "zero"))))
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(check-exn (regexp (regexp-quote
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"Encountered unexpected token of type \"zero\" (value \"zero\") while parsing"))
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(lambda () (parse '("zero" "one" "zero"))))
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