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38 lines
1.3 KiB
Racket
38 lines
1.3 KiB
Racket
8 years ago
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#lang restructure/racket
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(require "number.rkt" "utils.rkt" "streamcoder.rkt")
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(provide RString)
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#|
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approximates
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https://github.com/mbutterick/restructure/blob/master/src/String.coffee
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|#
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(define-subclass RStreamcoder (RString [length #f] [encoding 'ascii])
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(field [_codec (caseq encoding
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[(latin-1) (cons string->bytes/latin-1 bytes->string/latin-1)]
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[(ascii utf-8 utf8)(cons string->bytes/utf-8 bytes->string/utf-8)])])
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(define/augment (decode stream [parent #f])
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(define count (if length
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(resolveLength length stream parent)
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(send stream length)))
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(define bytes (send stream read count))
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((cdr _codec) bytes))
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(define/augment (encode stream val [parent #f])
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(define bytes ((car _codec) val))
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(when (is-a? length Number) ;; length-prefixed string
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(send length encode stream (bytes-length bytes)))
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(send stream write bytes)))
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(test-module
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(require "decodestream.rkt" "encodestream.rkt")
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(define stream (make-object RDecodeStream #"\2BCDEF"))
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(define S (make-object RString uint8 'utf8))
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(check-equal? (send S decode stream) "BC")
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(define os (make-object REncodeStream))
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(send S encode os "Mike")
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(check-equal? (send os dump) #"\4Mike"))
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