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