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beautiful-racket/beautiful-racket-demo/basic-demo/lexer.rkt

25 lines
675 B
Racket

#lang br
(require brag/support racket/contract)
(define basic-lexer
(lexer-srcloc
[(eof) (return-without-srcloc eof)]
[whitespace (token lexeme #:skip? #t)]
[(from/to "rem" "\n") (token 'REM lexeme)]
[(:or "print" "goto" "end" "+" ":") lexeme]
[(:+ numeric) (token 'INTEGER (string->number lexeme))]
[(:or (:seq (:+ numeric) ".")
(:seq (:* numeric) "." (:+ numeric)))
(token 'DECIMAL (string->number lexeme))]
[(from/to "\"" "\"")
(token 'STRING (trim-ends "\"" lexeme "\""))]))
(provide basic-lexer)
(define (apply-lexer lexer str)
(for/list ([t (in-port lexer (open-input-string str))])
t))
(apply-lexer basic-lexer "10 rem")