21 lines
629 B
Scheme
21 lines
629 B
Scheme
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; Copyright (c) 1993, 1994 Richard Kelsey and Jonathan Rees. See file COPYING.
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; Continuations implemented as vectors.
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(define *continuation-marker* (list '*continuation-marker*))
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(define (make-continuation len init)
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(let ((c (make-vector (+ len 1) init)))
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(vector-set! c 0 *continuation-marker*)
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c))
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(define (continuation? obj)
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(and (vector? obj)
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(> (vector-length obj) 0)
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(eq? (vector-ref obj 0) *continuation-marker*)))
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(define (continuation-length c) (- (vector-length c) 1))
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(define (continuation-ref c i) (vector-ref c (+ i 1)))
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(define (continuation-set! c i x) (vector-set! c (+ i 1) x))
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