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.
26 lines
1.1 KiB
Racket
26 lines
1.1 KiB
Racket
#lang restructure/racket
|
|
(require racket/dict "struct.rkt")
|
|
(provide (all-defined-out))
|
|
|
|
#|
|
|
approximates
|
|
https://github.com/mbutterick/restructure/blob/master/src/VersionedStruct.coffee
|
|
|#
|
|
|
|
(define-subclass RStruct (RVersionedStruct type [versions (dictify)])
|
|
(define/override (decode stream [parent #f] [length 0] #:version [maybe-version #f])
|
|
(define res (send this _setup stream parent length))
|
|
(define version (cond
|
|
[maybe-version] ; for testing purposes: pass an explicit version
|
|
[(procedure? type) (type parent)]
|
|
[(is-a? type RBase) (send type decode stream)]
|
|
[else (raise-argument-error 'decode "way of finding version" type)]))
|
|
(hash-set! res 'version version)
|
|
(define fields (dict-ref versions version (λ () (raise-argument-error 'RVersionedStruct:decode "valid version key" version))))
|
|
(send this make-key-index! fields)
|
|
(cond
|
|
[(is-a? fields RVersionedStruct) (send fields decode stream parent)]
|
|
[else
|
|
(send this _parseFields stream res fields)
|
|
(send this process res stream)
|
|
res]))) |