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38 lines
1.5 KiB
Racket
38 lines
1.5 KiB
Racket
5 years ago
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#lang racket/base
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(require racket/class "base.rkt" "number.rkt" "string.rkt")
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(provide (all-defined-out))
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(define x:symbol%
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(class x:string%
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(super-new)
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(define/override (pre-encode val)
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(unless (or (string? val) (symbol? val))
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(raise-argument-error 'x:symbol-encode "symbol or string" val))
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(if (symbol? val) (symbol->string val) val))
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(define/override (post-decode val) (string->symbol val))))
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(define (x:symbol [len-arg #f] [enc-arg #f]
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#:length [len-kwarg #f]
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#:encoding [enc-kwarg #f]
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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:symbol%])
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(define len (or len-arg len-kwarg))
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(define encoding (or enc-arg enc-kwarg 'utf8))
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(new (generate-subclass base-class pre-proc post-proc) [len len] [encoding encoding]))
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(module+ test
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(require rackunit "base.rkt")
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(define S-fixed (x:string 4 'utf8))
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(check-equal? (encode S-fixed "Mike" #f) #"Mike")
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(check-exn exn:fail? (λ () (encode S-fixed "Mikes" #f))) ; too long for fixed string
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(define S (x:string uint8 'utf8))
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(check-equal? (decode S #"\2BCDEF") "BC")
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(check-equal? (encode S "Mike" #f) #"\4Mike")
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(check-equal? (size (x:string) "foobar") 7) ; null terminated when no len
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(check-equal? (decode (x:symbol 4) #"Mike") 'Mike)
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(check-equal? (encode (x:symbol 4) 'Mike #f) #"Mike")
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(check-equal? (encode (x:symbol 4) "Mike" #f) #"Mike")
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(check-exn exn:fail:contract? (λ () (encode (x:symbol 4) 42 #f))))
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