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11 lines
442 B
Racket
11 lines
442 B
Racket
#lang restructure/racket
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(provide (all-defined-out))
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(require "number.rkt")
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(define (resolveLength length stream parent)
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(cond
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[(number? length) length]
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[(procedure? length) (length parent)]
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[(and parent (symbol? length) (hash-ref parent length))] ; treat as key into RStruct parent
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[(and stream (is-a? length Number) (send length decode stream))]
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[else (raise-argument-error 'resolveLength "fixed-size item" length)])) |