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beautiful-racket/beautiful-racket-ragg/br/ragg/examples/simple-line-drawing/lexer.rkt

28 lines
568 B
Racket

#lang racket/base
(provide tokenize)
;; A simple lexer for simple-line-drawing.
(require br/ragg/support
parser-tools/lex)
(define (tokenize ip)
(port-count-lines! ip)
(define my-lexer
(lexer-src-pos
[(repetition 1 +inf.0 numeric)
(token 'INTEGER (string->number lexeme))]
[upper-case
(token 'STRING lexeme)]
["b"
(token 'STRING " ")]
[";"
(token ";" lexeme)]
[whitespace
(token 'WHITESPACE lexeme #:skip? #t)]
[(eof)
(void)]))
(define (next-token) (my-lexer ip))
next-token)