|
|
#lang restructure/racket
|
|
|
(require "number.rkt" "utils.rkt" "stream.rkt")
|
|
|
(provide (all-defined-out))
|
|
|
|
|
|
#|
|
|
|
approximates
|
|
|
https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
|
|
|
|#
|
|
|
|
|
|
(define-subclass Streamcoder (Array type [_length #f] [lengthType 'count])
|
|
|
|
|
|
(define/augride (decode stream [parent #f])
|
|
|
(let ([len (cond
|
|
|
;; explicit length
|
|
|
[_length (resolveLength _length stream parent)]
|
|
|
[else ;; implicit length: length of stream divided by size of item
|
|
|
(define num (send stream length))
|
|
|
(define denom (send type size))
|
|
|
(unless (andmap (λ (x) (and x (number? x))) (list num denom))
|
|
|
(raise-argument-error 'Array:decode "valid length and size" (list num denom)))
|
|
|
(floor (/ (send stream length) (send type size)))])])
|
|
|
|
|
|
(caseq lengthType
|
|
|
[(count) (for/list ([i (in-range len)])
|
|
|
(send type decode stream this))])))
|
|
|
|
|
|
(define/override (size [array #f])
|
|
|
(when (and array (not (list? array)))
|
|
|
(raise-argument-error 'Array:size "list" array))
|
|
|
(cond
|
|
|
[(not array) (* (send type size) (resolveLength _length (+DecodeStream) #f))]
|
|
|
[(Number? _length) (send _length size)]
|
|
|
[else (* (send type size) (length array))]))
|
|
|
|
|
|
(define/augride (encode stream array [parent #f])
|
|
|
(unless (list? array) (raise-argument-error 'Array:encode "list" array))
|
|
|
(for ([item (in-list array)])
|
|
|
(send type encode stream item))))
|
|
|
|
|
|
|
|
|
(test-module
|
|
|
(define stream (+DecodeStream #"ABCDEFG"))
|
|
|
|
|
|
(define A (+Array uint16be 3))
|
|
|
(check-equal? (send A decode stream) '(16706 17220 17734))
|
|
|
(define os (+EncodeStream))
|
|
|
(send A encode os '(16706 17220 17734))
|
|
|
(check-equal? (send os dump) #"ABCDEF")
|
|
|
|
|
|
(check-equal? (send (+Array uint16be) size '(1 2 3)) 6)
|
|
|
(check-equal? (send (+Array doublebe) size '(1 2 3 4 5)) 40))
|
|
|
|
|
|
#|
|
|
|
approximates
|
|
|
https://github.com/mbutterick/restructure/blob/master/src/LazyArray.coffee
|
|
|
|#
|
|
|
|
|
|
(define-subclass object% (InnerLazyArray type [_length #f] [stream #f] [parent #f])
|
|
|
(field [base (· stream pos)]
|
|
|
[items (mhash)]) ; implement with hash (random add) rather than array
|
|
|
|
|
|
(define/public-final (get index)
|
|
|
(when (or (< index 0) (<= _length index))
|
|
|
(raise-argument-error 'InnerLazyArray:get (format "array index between 0 and ~a" _length) index))
|
|
|
(hash-ref! items index (λ ()
|
|
|
(define stashed-pos (· stream pos))
|
|
|
(send stream pos (+ base (* index (send type size))))
|
|
|
(define new-val (send type decode stream parent))
|
|
|
(send stream pos stashed-pos)
|
|
|
new-val)))
|
|
|
|
|
|
(define/public-final (toArray)
|
|
|
(for/list ([i (in-range _length)])
|
|
|
(get i))))
|
|
|
|
|
|
(define-subclass Array (LazyArray)
|
|
|
(inherit-field _length type)
|
|
|
(define/override (decode stream [parent #f])
|
|
|
(define len (resolveLength _length stream parent))
|
|
|
(define res (+InnerLazyArray type len stream parent))
|
|
|
(send stream pos (+ (· stream pos) (* len (send type size)))) ; skip the bytes that LazyArray would occupy
|
|
|
res)
|
|
|
|
|
|
(define/override (size [val #f])
|
|
|
(super size (if (InnerLazyArray? val)
|
|
|
(send val toArray)
|
|
|
val)))
|
|
|
|
|
|
(define/override (encode stream val)
|
|
|
(super encode stream (if (InnerLazyArray? val)
|
|
|
(send val toArray)
|
|
|
val))))
|
|
|
|
|
|
(test-module
|
|
|
(define bstr #"ABCD1234")
|
|
|
(define ds (+DecodeStream bstr))
|
|
|
(define la (+LazyArray uint8 4))
|
|
|
(define ila (send la decode ds))
|
|
|
(check-equal? (send ds pos) 4)
|
|
|
(check-equal? (send ila get 1) 66)
|
|
|
(check-equal? (send ila get 3) 68)
|
|
|
(check-equal? (send ds pos) 4)
|
|
|
(check-equal? (send ila toArray) '(65 66 67 68))
|
|
|
|
|
|
(define la2 (+LazyArray int16be (λ (t) 4)))
|
|
|
(define es (+EncodeStream))
|
|
|
(send la2 encode es '(1 2 3 4))
|
|
|
(check-equal? (send es dump) #"\0\1\0\2\0\3\0\4")
|
|
|
(check-equal? (send (send la2 decode (+DecodeStream #"\0\1\0\2\0\3\0\4")) toArray) '(1 2 3 4))
|
|
|
|
|
|
)
|
|
|
|
|
|
|