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43 lines
1.5 KiB
Racket
43 lines
1.5 KiB
Racket
#lang restructure/racket
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(require "number.rkt" "utils.rkt" "streamcoder.rkt")
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(provide RArray)
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#|
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approximates
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https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
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|#
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(define-subclass RStreamcoder (RArray type [length #f] [lengthType 'count])
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(define/augment (decode stream [parent #f])
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(let ([length (cond
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[length
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(resolveLength length stream parent)]
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[else
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(define num (send stream length))
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(define denom (send type size))
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(unless (andmap (λ (x) (and x (number? x))) (list num denom))
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(raise-argument-error 'RArray:decode "valid length and size" (list num denom)))
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;; implied length: length of stream divided by size of item
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(floor (/ (send stream length) (send type size)))])])
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(caseq lengthType
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[(count) (for/list ([i (in-range length)])
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(send type decode stream this))])))
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(define/public (size) (unfinished))
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(define/augment (encode stream array [parent #f])
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(for ([item (in-list array)])
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(send type encode stream item))))
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(test-module
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(require "decodestream.rkt" "encodestream.rkt")
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(define stream (make-object RDecodeStream #"ABCDEFG"))
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(define A (make-object RArray uint16be 3))
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(check-equal? (send A decode stream) '(16706 17220 17734))
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(define os (make-object REncodeStream))
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(send A encode os '(16706 17220 17734))
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(check-equal? (send os dump) #"ABCDEF")) |