scsh-0.6/scheme/big/thread-fluids.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 top cell)
thread-fluid?
(top thread-fluid-top-level-value)
(cell thread-fluid-cell set-thread-fluid-cell!))
(define *no-fluid-value* (list 'no-fluid-value))
(define (thread-fluid thread-fluid)
(let ((val (thread-cell-ref (thread-fluid-cell thread-fluid))))
(if (eq? val *no-fluid-value*)
(thread-fluid-top-level-value thread-fluid)
val)))
(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 top (make-thread-cell *no-fluid-value*)))
;; (define-record-type thread-fluid :thread-fluid
;; (really-make-thread-fluid fluid)
;; thread-fluid?
;; (fluid thread-fluid-fluid))
;;
;; (define (make-thread-fluid top)
;; (really-make-thread-fluid (make-fluid (make-thread-cell top))))
;;
;; (define (thread-fluid t-fluid)
;; (thread-cell-ref (fluid (thread-fluid-fluid t-fluid))))
;;
;; (define (set-thread-fluid! thread-fluid val)
;; (thread-cell-set! (fluid (thread-fluid-fluid thread-fluid)) val))
;;
;; (define (let-thread-fluid t-fluid val thunk)
;; (let-fluid (thread-fluid-fluid t-fluid)
;; (make-thread-cell val)
;; thunk))
;;
;; ;; avoid creating too many dynamic environments
;; (define (let-thread-fluids . args)
;; (let loop ((args args) (rev-new-args '()))
;; (if (not (null? (cdr args)))
;; (loop (cddr args)
;; (cons (make-thread-cell (cadr args))
;; (cons (thread-fluid-fluid (car args))
;; rev-new-args)))
;; ;; we're done
;; (apply let-fluids (reverse (cons (car args) rev-new-args))))))