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34 lines
1.1 KiB
Racket
34 lines
1.1 KiB
Racket
#lang racket/base
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(require parser-tools/lex (prefix-in : parser-tools/lex-sre) ragg/support)
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(provide tokenize)
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;; tokenizer prepares source for parser by
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;; 1) identifying tokens, the smallest unit of information
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;; 2) throwing away anything irrelevant (whitespace, comments)
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;; tokenizer cooperates with the lexer, which is a fancy regular-expression processor
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(define (tokenize ip)
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(define get-token
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(lexer
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[(char-set "><-.,+[]") lexeme]
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;; todo: try adding support for line comments
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#;[(:: "#" (:* (complement "\n")) "\n") (token 'comment #:skip? #t)]
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[whitespace (token 'white #:skip? #t)]
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;; treat other characters as comments
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[(char-range #\nul #\~) (token 'ascii #:skip? #t)]
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[(eof) eof]))
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(define (next-token) (get-token ip))
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next-token)
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(module+ test
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(require rackunit)
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(define (test-tokenize str)
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(define ip (open-input-string str))
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(define token-producer (tokenize ip))
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(for/list ([token (in-producer token-producer eof)])
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token))
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(check-equal? (test-tokenize "+") (list "+")))
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