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41 lines
1.3 KiB
Racket
41 lines
1.3 KiB
Racket
8 years ago
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#lang restructure/racket
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(require "streamcoder.rkt")
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(provide RBitfield)
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#|
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approximates
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https://github.com/mbutterick/restructure/blob/master/src/Bitfield.coffee
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|#
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(define-subclass RStreamcoder (RBitfield type [flags empty])
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(define/augment (decode stream [parent #f])
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(for*/fold ([res (mhash)])
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([val (in-value (send type decode stream))]
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[(flag i) (in-indexed flags)])
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(hash-set! res flag (bitwise-bit-set? val i))
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res))
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(define/public (size) (send type size))
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(define/augment (encode stream flag-hash)
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(send type encode stream (for/sum ([(flag i) (in-indexed flags)]
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#:when (hash-ref flag-hash flag))
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(expt 2 i)))))
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(test-module
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(require "number.rkt" "decodestream.rkt" "encodestream.rkt")
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(define bfer (make-object RBitfield uint16be '(bold italic underline outline shadow condensed extended)))
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(define bf (send bfer decode #"\0\25"))
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(check-true (hash-ref bf 'bold))
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(check-true (hash-ref bf 'underline))
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(check-true (hash-ref bf 'shadow))
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(check-false (hash-ref bf 'italic))
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(check-false (hash-ref bf 'outline))
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(check-false (hash-ref bf 'condensed))
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(check-false (hash-ref bf 'extended))
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(define os (make-object REncodeStream))
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(send bfer encode os bf)
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(check-equal? (send os dump) #"\0\25"))
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