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58 lines
1.5 KiB
Racket
58 lines
1.5 KiB
Racket
#lang br
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(provide #%module-begin #%top-interaction
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bf-program op loop)
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(module reader syntax/module-reader
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#:language 'br-bf
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#:read bf-read
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#:read-syntax bf-read-syntax
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;; need this because we keep state,
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;; therefore expansion is "all or nothing"
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#:whole-body-readers? #t
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(require "tokenizer.rkt" "parser.rkt")
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(define (bf-read in)
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(syntax->datum (bf-read-syntax #f in)))
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(define (bf-read-syntax src ip)
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(define result (list (parse src (tokenize ip))))
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;; prints out corresponding s-exp source
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(for-each println (map syntax->datum result))
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result))
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(define #'(bf-program arg ...)
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#'(begin arg ...))
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(define #'(op arg)
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(case (syntax->datum #'arg)
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[(">") #'(move-pointer 1)]
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[("<") #'(move-pointer -1)]
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[("+") #'(set-pointer-byte! (add1 (pointer-byte)))]
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[("-") #'(set-pointer-byte! (sub1 (pointer-byte)))]
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[(".") #'(write-byte (pointer-byte))]
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[(",") #'(set-pointer-byte! (read-byte (current-input-port)))]
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[else #'arg]))
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(define #'(loop lb arg ... rb)
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#'(let loop ()
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(unless (zero? (pointer-byte))
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arg ...
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(loop))))
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(define bf-vector (make-vector 10 0))
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(define bf-pointer 0)
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(define (pointer-byte) (vector-ref bf-vector bf-pointer))
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(define (set-pointer-byte! val) (vector-set! bf-vector bf-pointer val))
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(define (move-pointer how-far)
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(set! bf-pointer (+ bf-pointer how-far)))
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(define (dump)
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(displayln "")
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(displayln bf-pointer)
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(displayln bf-vector))
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