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61 lines
1.9 KiB
Racket
61 lines
1.9 KiB
Racket
#lang racket/base
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(require racket/class
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racket/match
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"base.rkt"
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"int.rkt"
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racket/contract
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racket/list)
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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 x:enum%
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(class x:base%
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(super-new)
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(init-field [(@type type)] [(@values values)])
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(unless (x:int? @type)
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(raise-argument-error 'x:enum "xenomorphic integer type" @type))
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(unless (list? @values)
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(raise-argument-error 'x:enum "list of values" @values))
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(define/augment (x:decode port parent)
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(define index (send @type x:decode port parent))
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(if (< index (length @values))
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(or (list-ref @values index) index)
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index))
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(define/augment (x:encode val port [parent #f])
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(match (index-of @values val)
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[(? values idx) (send @type x:encode idx port parent)]
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[_ (raise-argument-error 'x:enum-encode "valid option" val)]))
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(define/augment (x:size [val #f] [parent #f])
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(send @type x:size val parent))))
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(define (x:enum? x) (is-a? x x:enum%))
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(define/contract (x:enum [type-arg #f]
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[values-arg #f]
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#:type [type-kwarg uint8]
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#:values [values-kwarg null]
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#:pre-encode [pre-proc #f]
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#:post-decode [post-proc #f]
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#:base-class [base-class x:enum%])
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(()
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((or/c x:int? #false)
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(listof any/c)
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#:type (or/c x:int? #false)
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#:values (listof any/c)
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#:pre-encode (or/c (any/c . -> . any/c) #false)
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#:post-decode (or/c (any/c . -> . any/c) #false)
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#:base-class (λ (c) (subclass? c x:enum%)))
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. ->* .
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x:enum?)
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(define type (or type-arg type-kwarg))
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(define values (or values-arg values-kwarg))
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(new (generate-subclass base-class pre-proc post-proc) [type type] [values values])) |