32 lines
1020 B
Scheme
32 lines
1020 B
Scheme
;;; Command-line argument access
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; Some globals.
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(define %command-line '()) ; Includes program.
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(define command-line-arguments #f) ; Doesn't include program.
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(define (set-command-line-args! args)
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(set! %command-line args)
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(set! command-line-arguments (append (cdr args) '())))
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(define (arg* arglist n . maybe-default-thunk)
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(let ((oops (lambda () (error "argument out of bounds" arglist n))))
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(if (< n 1) (oops)
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(let lp ((al arglist) (n n))
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(if (pair? al)
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(if (= n 1) (car al)
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(lp (cdr al) (- n 1)))
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(if (and (pair? maybe-default-thunk)
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(null? (cdr maybe-default-thunk)))
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((car maybe-default-thunk))
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(oops)))))))
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(define (arg arglist n . maybe-default)
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(if maybe-default (arg* arglist n (lambda () (car maybe-default)))
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(arg* arglist n)))
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(define (argv n . maybe-default)
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(apply arg %command-line (+ n 1) maybe-default))
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(define (command-line) (append %command-line '()))
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