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#lang restructure/racket
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(require "number.rkt" "utils.rkt" "stream.rkt")
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(provide (all-defined-out))
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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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(struct $codec (encoder decoder) #:transparent)
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(define-subclass Streamcoder (String [strlen #f] [encoding 'ascii])
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(field [codec (caseq encoding
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[(latin-1 ascii) ($codec string->bytes/latin-1 bytes->string/latin-1)]
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[(utf-8 utf8) ($codec string->bytes/utf-8 bytes->string/utf-8)])])
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(define/augment (decode stream [parent #f])
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(define count (if strlen
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(resolveLength strlen stream parent)
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(send stream length)))
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(define bytes (send stream read count))
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(($codec-decoder codec) bytes))
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(define/augment (encode stream val [parent #f])
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(define bytes (($codec-encoder codec) (format "~a" val)))
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(when (Number? strlen) ;; length-prefixed string
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(send strlen encode stream (bytes-length bytes)))
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(send stream write bytes))
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(define/override (size [str-in #f])
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(define str (or str-in (make-string strlen #\x)))
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(define es (+EncodeStream))
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(encode es str)
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(bytes-length (send es dump))))
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(test-module
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(require "stream.rkt")
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(define stream (+DecodeStream #"\2BCDEF"))
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(define S (+String uint8 'utf8))
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(check-equal? (send S decode stream) "BC")
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(define os (+EncodeStream))
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(send S encode os "Mike")
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(check-equal? (send os dump) #"\4Mike")
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(check-equal? (send (+String) size "foobar") 6))
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