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108 lines
4.9 KiB
Racket
108 lines
4.9 KiB
Racket
#lang debug racket/base
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(require "helper.rkt" "struct.rkt"
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racket/dict
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racket/class
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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/VersionedStruct.coffee
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|#
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(define xversioned-struct%
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(class xstruct%
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(super-new)
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(init-field [(@type type)] [(@versions versions)])
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(unless (for/or ([proc (list integer? procedure? xenomorphic-type? symbol?)])
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(proc @type))
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(raise-argument-error '+xversioned-struct "integer, procedure, symbol, or xenomorphic" @type))
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(unless (and (dict? @versions) (andmap (λ (v) (or (dict? v) (xstruct? v))) (dict-values @versions)))
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(raise-argument-error '+xversioned-struct "dict of dicts or structish" @versions))
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(define version-getter (cond
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[(procedure? @type) @type]
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[(symbol? @type) (λ (parent) (dict-ref parent @type))]))
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(define version-setter (cond
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[(procedure? @type) @type]
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[(symbol? @type) (λ (parent version) (dict-set! parent @type version))]))
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(define (extract-fields-dict val)
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(define field-object (dict-ref @versions (dict-ref val 'version #f) #f))
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(unless field-object
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(raise-argument-error 'xversioned-struct-encode "valid version key" version))
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(if (xstruct? field-object) (get-field fields field-object) field-object))
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(define/override (xxdecode port parent [length 0])
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(define res (xstruct-setup port parent length))
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(dict-set! res 'version
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(cond
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[(integer? @type) @type]
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[(or (symbol? @type) (procedure? @type))
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(unless parent
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(raise-argument-error 'xversioned-struct-decode "valid parent" parent))
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(version-getter parent)]
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[else (send @type xxdecode port)]))
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(when (dict-ref @versions 'header #f)
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(xstruct-parse-fields port res (dict-ref @versions 'header)))
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(define fields
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(or (dict-ref @versions (dict-ref res 'version #f) #f)
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(raise-argument-error 'xversioned-struct-decode "valid version key" (cons version @versions))))
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(cond
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[(xversioned-struct? fields) (send fields xxdecode port parent)]
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[else (xstruct-parse-fields port res fields)
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res]))
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(define/override (xxencode encode-me port [parent-arg #f])
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(unless (dict? encode-me)
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(raise-argument-error 'xversioned-struct-encode "dict" encode-me))
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(define parent (mhash 'pointers null
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'startOffset (pos port)
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'parent parent-arg
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'val encode-me
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'pointerSize 0))
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(dict-set! parent 'pointerOffset (+ (pos port) (xxsize encode-me parent #f)))
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(unless (or (symbol? @type) (procedure? @type))
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(send @type xxencode (dict-ref encode-me 'version #f) port parent))
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(define maybe-header-dict (dict-ref @versions 'header #f))
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(when maybe-header-dict
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(for ([(key type) (in-dict maybe-header-dict)])
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(send type xxencode (dict-ref encode-me key) port parent)))
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(define fields (extract-fields-dict encode-me))
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(unless (andmap (λ (key) (member key (dict-keys encode-me))) (dict-keys fields))
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(raise-argument-error 'xversioned-struct-encode (format "hash that contains superset of xversioned-struct keys: ~a" (dict-keys fields)) (hash-keys encode-me)))
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(for ([(key type) (in-dict fields)])
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(send type xxencode (dict-ref encode-me key) port parent))
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(for ([ptr (in-list (dict-ref parent 'pointers))])
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(send (dict-ref ptr 'type) xxencode (dict-ref ptr 'val) port (dict-ref ptr 'parent))))
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(define/override (xxsize [val #f] [parent-arg #f] [include-pointers #t])
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(unless val
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(raise-argument-error 'xversioned-struct-size "value" val))
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(define parent (mhash 'parent parent-arg 'val val 'pointerSize 0))
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(define version-size
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(let ([struct-type @type])
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(if (or (symbol? struct-type) (procedure? struct-type))
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0
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(send @type xxsize (dict-ref val 'version) parent))))
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(define header-size
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(for/sum ([(key type) (in-dict (or (dict-ref @versions 'header #f) null))])
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(send type xxsize (and val (dict-ref val key)) parent)))
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(define fields-size
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(for/sum ([(key type) (in-dict (extract-fields-dict val))])
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(send type xxsize (and val (dict-ref val key)) parent)))
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(define pointer-size (if include-pointers (dict-ref parent 'pointerSize) 0))
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(+ version-size header-size fields-size pointer-size))))
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(define (xversioned-struct? x) (is-a? x xversioned-struct%))
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(define (+xversioned-struct #:subclass [class xversioned-struct%] type [versions (dictify)])
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(new class [type type] [versions versions][fields #f]))
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