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81 lines
2.5 KiB
Racket
81 lines
2.5 KiB
Racket
#lang br
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(provide #%top-interaction #%app #%datum
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(rename-out [basic-module-begin #%module-begin])
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(rename-out [basic-top #%top])
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(all-defined-out))
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(require (for-syntax racket/syntax))
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(define #'(basic-module-begin PARSE-TREE ...)
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#'(#%module-begin
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(println (quote PARSE-TREE ...))
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PARSE-TREE ...))
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; #%app and #%datum have to be present to make #%top work
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(define #'(basic-top . id)
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#'(begin
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(displayln (format "got unbound identifier: ~a" 'id))
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(procedure-rename (λ xs (cons 'id xs)) (format-datum "undefined:~a" 'id))))
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(define #'(basic-program CR-LINE ...)
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#'(begin CR-LINE ...))
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(define (basic-run . lines)
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(define program-lines (list->vector lines))
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(void (for/fold ([line-idx 0])
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([i (in-naturals)]
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#:break (= line-idx (vector-length program-lines)))
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(match-define (cons line-number proc)
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(vector-ref program-lines line-idx))
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(define maybe-jump-number (and proc (proc)))
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(if (number? maybe-jump-number)
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(let ([jump-number maybe-jump-number])
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(for/or ([idx (in-range (vector-length program-lines))])
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(and (= (car (vector-ref program-lines idx)) jump-number)
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idx)))
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(add1 line-idx)))))
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(define-cases #'cr-line ; erases "cr"s
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[#'(_ "cr" LINE) #'LINE]
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[#'(_ "cr") #'(begin)])
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(define #'(line NUMBER STATEMENT ...)
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#'(begin STATEMENT ...))
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(define-cases #'statement
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[#'(statement ID "=" EXPR) (if (identifier-binding #'ID)
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#'(set! ID EXPR)
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#'(define ID EXPR))]
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[#'(statement PROC ARG ...) #'(PROC ARG ...)])
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(define-cases #'value
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[#'(value "(" EXPR ")") #'EXPR]
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[#'(value ID "(" ARG ... ")") #'(ID ARG ...)]
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[#'(value DATUM) #'DATUM])
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(define #'(expr EXPR) #'EXPR)
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(define-cases sum
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[(_ term op sum) (op term sum)]
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[(_ term) term])
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(provide - +)
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(define-cases product
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[(_ factor op product) (op factor product)]
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[(_ factor) factor])
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(provide * /)
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(define print-list list)
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(define (PRINT args)
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(match args
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[(list) (displayln "")]
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[(list items ... ";" pl) (begin (for-each display items) (PRINT pl))]
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[(list items ... ";") (for-each display items)]
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[(list items ...) (for-each displayln items)]))
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(define (TAB num) (make-string num #\space))
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(define (INT num) (inexact->exact (round num)))
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(define (SIN num) (sin num))
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(define (comment . args) void)
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