scsh-0.6/scheme/big/thread-fluid.scm

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; Copyright (c) 1993-2001 by Richard Kelsey and Jonathan Rees. See file COPYING.
(define-record-type thread-fluid :thread-fluid
(really-make-thread-fluid cell)
thread-fluid?
(cell thread-fluid-cell set-thread-fluid-cell!))
(define *no-fluid-value* (list 'no-fluid-value))
(define (thread-fluid thread-fluid)
(thread-cell-ref (thread-fluid-cell thread-fluid)))
(define (set-thread-fluid! thread-fluid val)
(thread-cell-set! (thread-fluid-cell thread-fluid) val))
(define (let-thread-fluid t-fluid val thunk)
(let ((old-val (thread-fluid t-fluid)))
(dynamic-wind
(lambda () (set-thread-fluid! t-fluid val))
thunk
(lambda () (set-thread-fluid! t-fluid old-val)))))
(define (let-thread-fluids . args)
(call-with-values
(lambda ()
(let loop ((args args) (rev-old-vals '()))
(if (null? (cdr args))
(values (car args) (reverse rev-old-vals))
(loop (cddr args)
(cons (thread-fluid (car args))
rev-old-vals)))))
(lambda (thunk old-vals)
(dynamic-wind
(lambda ()
(let loop ((args args))
(if (not (null? (cdr args)))
(begin
(set-thread-fluid! (car args) (cadr args))
(loop (cddr args))))))
thunk
(lambda ()
(let loop ((args args) (old-vals old-vals))
(if (not (null? (cdr args)))
(begin
(set-thread-fluid! (car args) (car old-vals))
(loop (cddr args) (cdr old-vals))))))))))
(define (make-thread-fluid top)
(really-make-thread-fluid (make-thread-cell top)))
(define *preserved-fluids* (make-population))
(define (make-preserved-thread-fluid top)
(let* ((t-fluid (make-thread-fluid top)))
(add-to-population! t-fluid *preserved-fluids*)
t-fluid))
(define (preserve-thread-fluids thunk)
(let ((args (list thunk)))
(walk-population
(lambda (t-fluid)
(set! args
(cons t-fluid
(cons (thread-fluid t-fluid)
args))))
*preserved-fluids*)
(lambda ()
(apply let-thread-fluids args))))
(define (fork-thread thunk)
(spawn (preserve-thread-fluids thunk)))