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24 lines
607 B
Racket
24 lines
607 B
Racket
7 years ago
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#lang restructure/racket
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(require "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/Enum.coffee
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|#
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(define-subclass Streamcoder (Enum type [options empty])
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(define/augment (decode stream . _)
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(define index (send type decode stream))
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(or (list-ref options index) index))
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(define/override (size . _) (send type size))
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(define/augment (encode stream val [ctx #f])
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(define index (index-of options val))
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(unless index
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(raise-argument-error 'Enum:encode "valid option" val))
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(send type encode stream index)))
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