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68 lines
2.0 KiB
Racket
68 lines
2.0 KiB
Racket
#lang racket/base
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(require racket/generic
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racket/dict
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racket/port)
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(provide (all-defined-out))
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(define (->input-port arg)
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(cond
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[(bytes? arg) (open-input-bytes arg)]
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[(input-port? arg) arg]
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[else (raise-argument-error '->input-port "byte string or input port" arg)]))
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(define private-keys '(parent _startOffset _currentOffset _length))
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(define (dump-mutable x)
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(define h (make-hasheq))
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(for ([(k v) (in-dict (dump x))])
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(hash-set! h k v))
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h)
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(define (dump x)
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(cond
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[(input-port? x) (port->bytes x)]
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[(output-port? x) (get-output-bytes x)]
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[(dict? x) (for/hasheq ([(k v) (in-dict x)]
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#:unless (memq k private-keys))
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(values k v))]
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[(list? x) (map dump x)]
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[else x]))
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(define (pos p [new-pos #f])
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(when new-pos
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(file-position p new-pos))
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(file-position p))
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(struct xbase ([pre-encode #:auto] [post-decode #:auto]) #:transparent #:mutable
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#:auto-value values)
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(define (pre-encode xb val)
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((xbase-pre-encode xb) val))
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(define (set-pre-encode! xb func)
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(set-xbase-pre-encode! xb func))
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(define (post-decode xb val)
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((xbase-post-decode xb) val))
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(define (set-post-decode! xb func)
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(set-xbase-post-decode! xb func))
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(define-syntax-rule (define/post-decode (ID X VAL . ARGS) . BODY)
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(define (ID X VAL . ARGS) (post-decode X (let () . BODY))))
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(define-syntax-rule (define/pre-encode (ID X VAL . ARGS) . BODY)
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(define (ID X val-in . ARGS) (let ([VAL (pre-encode X val-in)]) . BODY)))
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(define-syntax-rule (define/finalize-size ID+ARGS . BODY) (define ID+ARGS (finalize-size (let () . BODY))))
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(define-generics xenomorphic
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(encode xenomorphic val [port] #:parent [parent])
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(xdecode xenomorphic [port] #:parent [parent])
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(decode xenomorphic [port])
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(size xenomorphic [item] #:parent [parent]))
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(define (finalize-size size)
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(cond
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[(void? size) 0]
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[(and (integer? size) (not (negative? size))) size]
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[else (raise-argument-error 'size "nonnegative integer" size)])) |