25 lines
614 B
Scheme
25 lines
614 B
Scheme
;;; weak table with weak values
|
|
|
|
(define-record-type weak-table
|
|
(really-make-weak-table table)
|
|
weak-table?
|
|
(table weak-table-table))
|
|
|
|
(define (make-value-weak-table)
|
|
(really-make-weak-table (make-integer-table)))
|
|
|
|
(define (add-to-weak-table! table address object)
|
|
(table-set! (weak-table-table table)
|
|
address
|
|
(make-weak-pointer object)))
|
|
|
|
(define (remove-from-weak-table! table address)
|
|
(table-set! (weak-table-table table)
|
|
address #f))
|
|
|
|
(define (lookup-in-weak-table table address)
|
|
(cond
|
|
((table-ref (weak-table-table table) address)
|
|
=> weak-pointer-ref)
|
|
(else #f)))
|