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typesetting/pitfall/restructure/string.rkt

40 lines
1.3 KiB
Racket

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