You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
89 lines
2.8 KiB
Racket
89 lines
2.8 KiB
Racket
#lang restructure/racket
|
|
(provide (all-defined-out))
|
|
|
|
#|
|
|
approximates
|
|
https://github.com/mbutterick/restructure/blob/master/src/Pointer.coffee
|
|
|#
|
|
|
|
(define-subclass object% (Pointer offsetType type [options (mhash)])
|
|
(when (eq? type 'void) (set! type #f))
|
|
(hash-ref! options 'type 'local)
|
|
(hash-ref! options 'allowNull #t)
|
|
(hash-ref! options 'nullValue 0)
|
|
(hash-ref! options 'lazy #f)
|
|
(define relativeToGetter (ref options 'relativeTo)) ; change this to a simple lambda
|
|
|
|
(define/public (decode stream [ctx #f])
|
|
(define offset (send offsetType decode stream ctx))
|
|
|
|
(cond
|
|
;; handle NULL pointers
|
|
[(and (eq? offset (ref options 'nullValue)) (ref options 'allowNull)) #f]
|
|
[else
|
|
(define relative (caseq (ref options 'type)
|
|
[(local) (ref ctx '_startOffset)]
|
|
[(immediate) (- (· stream pos) (send offsetType size))]
|
|
[(parent) (ref* ctx 'parent '_startOffset)]
|
|
[else (let loop ([ctx ctx])
|
|
(cond
|
|
[(· ctx parent) => loop]
|
|
[(ref ctx '_startOffset)]
|
|
[else 0]))]))
|
|
|
|
(when (ref options 'relativeTo)
|
|
; relativeToGetter only defined if 'relativeTo key exists, so this is safe
|
|
(increment! relative (relativeToGetter ctx)))
|
|
|
|
(define ptr (+ offset relative))
|
|
|
|
(cond
|
|
[type (define val #f)
|
|
(define (decodeValue)
|
|
(cond
|
|
[val]
|
|
[else (define pos (· stream pos))
|
|
(send stream pos ptr)
|
|
(define val (send type decode stream ctx))
|
|
(send stream pos pos)
|
|
val]))
|
|
|
|
;; skip lazy pointer chores
|
|
|
|
(decodeValue)]
|
|
[else ptr])]))
|
|
|
|
|
|
(define/public (size [val #f] [ctx #f])
|
|
(define parent ctx)
|
|
(caseq (ref options 'type)
|
|
[(local immediate) (void)]
|
|
[(parent) (set! ctx (ref ctx 'parent))]
|
|
[else ; global
|
|
(set! ctx (let loop ([ctx ctx])
|
|
(cond
|
|
[(ref ctx 'parent) => loop]
|
|
[else ctx])))])
|
|
|
|
(define type_ type)
|
|
(unless type_
|
|
; todo: uncomment when VoidPointer class is ready
|
|
#;(unless (VoidPointer? val)
|
|
(raise-argument-error 'Pointer:size "VoidPointer" val))
|
|
|
|
(set! type (ref val 'type))
|
|
(set! val (ref val 'value)))
|
|
|
|
(when (and val ctx)
|
|
(ref-set! ctx 'pointerSize (+ (ref ctx 'pointerSize) (send type size val parent))))
|
|
|
|
(send offsetType size))
|
|
|
|
|
|
#;(define/public (encode stream val)
|
|
(error 'Pointer-encode-not-done))
|
|
|
|
|
|
|
|
|
|
) |