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125 lines
4.9 KiB
Racket
125 lines
4.9 KiB
Racket
#lang debug racket/base
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(require racket/dict
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racket/class
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racket/sequence
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racket/list
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"helper.rkt"
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"number.rkt"
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sugar/unstable/dict)
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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/Struct.coffee
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|#
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(define (xstruct-setup port parent len)
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(define mheq (make-hasheq))
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(dict-set*! mheq
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'parent parent
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'_startOffset (pos port)
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'_currentOffset 0
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'_length len)
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mheq)
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(define (xstruct-parse-fields port sdr fields-arg)
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(define fields (if (xstruct? fields-arg) (get-field fields fields-arg) fields-arg))
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(unless (assocs? fields)
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(raise-argument-error 'xstruct-parse-fields "assocs" fields))
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(for/fold ([sdr sdr])
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([(key type) (in-dict fields)])
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(define val (if (procedure? type)
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(type sdr)
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(send type x:decode port sdr)))
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(unless (void? val)
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(dict-set! sdr key val))
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(dict-set! sdr '_currentOffset (- (pos port) (dict-ref sdr '_startOffset)))
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sdr))
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(define private-keys '(parent _startOffset _currentOffset _length))
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(define (dict->mutable-hash x)
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(define h (make-hasheq))
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(for ([(k v) (in-dict x)]
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#:unless (memq k private-keys))
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(hash-set! h k v))
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h)
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(define x:struct%
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(class x:enobase%
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(super-new)
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(init-field [(@fields fields)])
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(when @fields (unless (dict? @fields)
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(raise-argument-error '+xstruct "dict" @fields)))
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(define/augride (x:decode port parent [len 0])
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;; xstruct-setup and xstruct-parse-fields are separate to cooperate with VersionedStruct
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(define decoded-hash
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(xstruct-parse-fields port (xstruct-setup port parent len) @fields))
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(unless (dict? decoded-hash)
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(raise-result-error 'xstruct-decode "dict" decoded-hash))
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decoded-hash)
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(define/override (decode port parent)
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(dict->mutable-hash (x:decode port parent)))
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(define/augride (x:encode val port [parent-arg #f])
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;; check keys first, since `size` also relies on keys being valid
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(unless (dict? val)
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(raise-result-error 'xstruct-encode "dict" val))
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(unless (andmap (λ (key) (memq key (dict-keys val))) (dict-keys @fields))
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(raise-argument-error 'xstruct-encode
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(format "dict that contains superset of xstruct keys: ~a"
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(dict-keys @fields)) (dict-keys val)))
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(define parent (mhash 'pointers empty
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'startOffset (pos port)
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'parent parent-arg
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'val val
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'pointerSize 0))
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(dict-set! parent 'pointerOffset (+ (pos port) (x:size val parent #f)))
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(for ([(key type) (in-dict @fields)])
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(send type x:encode (dict-ref val key) port parent))
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(for ([ptr (in-list (dict-ref parent 'pointers))])
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(send (dict-ref ptr 'type) x:encode (dict-ref ptr 'val) port (dict-ref ptr 'parent))))
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(define/augride (x:size [val #f] [parent-arg #f] [include-pointers #t])
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(define parent (mhasheq 'parent parent-arg
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'val val
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'pointerSize 0))
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(define fields-size (for/sum ([(key type) (in-dict @fields)]
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#:when (xenomorphic-type? type))
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(send type x:size (and val (dict-ref val key)) parent)))
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(define pointers-size (if include-pointers (dict-ref parent 'pointerSize) 0))
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(+ fields-size pointers-size))))
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(define (xstruct? x) (is-a? x x:struct%))
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(define (x:struct #:pre-encode [pre-proc #f]
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#:post-decode [post-proc #f] . dicts)
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(define args (flatten dicts))
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(unless (even? (length args))
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(raise-argument-error '+xstruct "equal number of keys and values" dicts))
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(define fields (for/list ([kv (in-slice 2 args)])
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(unless (symbol? (car kv))
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(raise-argument-error '+xstruct "symbol" (car kv)))
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(apply cons kv)))
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(new (generate-subclass x:struct% pre-proc post-proc) [fields fields]))
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(module+ test
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(require rackunit "number.rkt" "generic.rkt")
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(define (random-pick xs) (list-ref xs (random (length xs))))
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(check-exn exn:fail:contract? (λ () (x:struct 42)))
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(for ([i (in-range 20)])
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;; make random structs and make sure we can round trip
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(define field-types
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(for/list ([i (in-range 40)])
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(random-pick (list uint8 uint16be uint16le uint32be uint32le double))))
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(define size-num-types
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(for/sum ([num-type (in-list field-types)])
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(size num-type)))
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(define xs (x:struct (for/list ([num-type (in-list field-types)])
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(cons (gensym) num-type))))
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(define bs (apply bytes (for/list ([i (in-range size-num-types)])
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(random 256))))
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(check-equal? (encode xs (decode xs bs) #f) bs))) |