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85 lines
2.7 KiB
Racket
85 lines
2.7 KiB
Racket
8 years ago
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#lang br/quicklang
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(require (for-syntax racket/list sugar/debug))
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(provide (matching-identifiers-out #rx"^b-" (all-defined-out)))
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(struct line-error (msg))
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(define (handle-line-error num le)
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(error (format "error in line ~a: ~a" num (line-error-msg le))))
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(define return-ks empty)
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(define (b-gosub num-expr)
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(let/cc return-k
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(push! return-ks return-k)
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(b-goto num-expr)))
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(define (b-return)
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(unless (pair? return-ks)
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(raise (line-error "return without gosub")))
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(define top-return-k (pop! return-ks))
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(top-return-k))
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(define-macro (b-line NUM STATEMENT ...)
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(with-pattern ([LINE-NUM (prefix-id "line-" #'NUM
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#:source #'NUM)])
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(syntax/loc caller-stx
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(define (LINE-NUM)
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(with-handlers ([line-error? (λ (le) (handle-line-error NUM le))])
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(void) STATEMENT ...)))))
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(define-for-syntax (find-unique-var-names stx)
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(remove-duplicates
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(for/list ([var-stx (in-list (syntax-flatten stx))]
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#:when (syntax-property var-stx 'b-id))
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var-stx)
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#:key syntax->datum))
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(define-macro (b-module-begin (b-program LINE ...))
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(with-pattern
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([((b-line NUM STMT ...) ...) #'(LINE ...)]
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[(LINE-FUNC ...) (prefix-id "line-" #'(NUM ...))]
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[(VAR-NAME ...) (find-unique-var-names #'(LINE ...))])
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#'(#%module-begin
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(define VAR-NAME 0) ...
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LINE ...
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(define line-table
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(apply hasheqv (append (list NUM LINE-FUNC) ...)))
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(void (run line-table)))))
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(provide (rename-out [b-module-begin #%module-begin]))
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(define-macro (b-let ID VAL)
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#'(set! ID VAL))
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(struct end-program-signal ())
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(struct change-line-signal (val))
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(define (b-end) (raise (end-program-signal)))
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(define (b-goto num-expr) (raise (change-line-signal num-expr)))
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(define (run line-table)
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(define line-vec
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(list->vector (sort (hash-keys line-table) <)))
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(with-handlers ([end-program-signal? (λ (exn-val) (void))])
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(for/fold ([line-idx 0])
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([i (in-naturals)]
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#:break (>= line-idx (vector-length line-vec)))
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(define line-num (vector-ref line-vec line-idx))
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(define line-func (hash-ref line-table line-num))
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(with-handlers
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([change-line-signal?
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(λ (cls)
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(define clsv (change-line-signal-val cls))
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(or
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(and (exact-positive-integer? clsv)
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(vector-member clsv line-vec))
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(error (format "error in line ~a: line ~a not found"
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line-num clsv))))])
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(line-func)
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(add1 line-idx)))))
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(define (b-rem val) (void))
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(define (b-print [val ""]) (displayln val))
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(define (b-sum . nums) (apply + nums))
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(define (b-num-expr expr)
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(if (integer? expr) (inexact->exact expr) expr))
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