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

19 lines
623 B
Racket

#lang br
(require parser-tools/lex
(prefix-in : parser-tools/lex-sre)
brag/support)
(provide (all-defined-out))
(define basic-lexer
(lexer-src-pos
[(eof) eof]
[whitespace (token lexeme #:skip? #t)]
[(from/to "rem" "\n") (token 'REM (string-downcase lexeme))]
[(:or "print" "goto" "end") (token (string-downcase lexeme)
(string-downcase lexeme))]
[(:+ numeric) (token 'NUMBER (string->number lexeme))]
[(from/to "\"" "\"") (token 'STRING (trim-ends "\"" lexeme "\""))]))
(define (tokenize ip)
(port-count-lines! ip)
(λ () (basic-lexer ip)))