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