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39 lines
1.2 KiB
Racket
39 lines
1.2 KiB
Racket
#lang racket/base
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(require racket/class "helper.rkt" "util.rkt" "number.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/Buffer.coffee
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|#
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(define xbuffer%
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(class xenobase%
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(super-new)
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(init-field len)
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(define/augment (xxdecode port parent)
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(define decoded-len (resolve-length len #:parent parent))
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(read-bytes decoded-len))
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(define/augment (xxencode buf port [parent #f])
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(unless (bytes? buf)
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(raise-argument-error 'xbuffer-encode "bytes" buf))
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(when (xint? len)
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(send len xxencode (bytes-length buf) port))
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(write-bytes buf port))
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(define/augment (xxsize [val #f] [parent #f])
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(when val (unless (bytes? val)
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(raise-argument-error 'xbuffer-size "bytes" val)))
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(if (bytes? val)
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(bytes-length val)
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(resolve-length len val #:parent parent)))))
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(define (+xbuffer [len-arg #f]
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#:length [len-kwarg #f]
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#:subclass [class xbuffer%])
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(define len (or len-arg len-kwarg #xffff))
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(unless (length-resolvable? len)
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(raise-argument-error '+xbuffer "resolvable length" len))
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(new class [len len])) |