Swiftとメタデータ

4XJGUͱϝλσʔλ 4XJGUѪ޷ձWPM ! !OPQQFGPYXPMG

OPQQF ! ͖ͭͶ͕޷͖ʂʂ " J04ΞϓϦ։ൃ೥໨ 4XJGUѪ޷ձॳࢀઓ ! !OPQQFGPYXPMG

! !OPQQFGPYXPMG

ϝλσʔλͱ͸ ϝλ৘ใͱ͸ɺ͢ͳΘͪσʔλʹ͍ͭͯͷσʔλͱ͍͏ ҙຯͰɺ͋Δσʔλ͕෇ਵͯ࣋ͭͦ͠ͷσʔλࣗ਎ʹͭ ͍ͯͷ෇ՃతͳσʔλΛࢦ͢ɻʢ8JLJௐ΂ʣ ! IUUQTKBXJLJQFEJBPSHXJLJϝλσʔλ ! !OPQQFGPYXPMG

ϝλσʔλͱ͸ ‣ Ϋϥε໊ ‣ ΫϥεͷϓϩύςΟ໊ ‣ ܧঝݩ ‣ ४ڌ͍ͯ͠Δϓϩτίϧ FUD
! !OPQQFGPYXPMG

ϝλσʔλ͕ඞཁͳ࣌ ‣ ࠓݟ͍ͯΔϏϡʔίϯτϩʔϥΛϩάʹు͖͍ͨ ‣ ΠϯελϯεΛμϯϓͯ͠อଘ͍ͨ͠ ‣ ৄࡉͰ෼͔Γ΍͍͢ΤϥʔΛද͍ࣔͨ͠ ‣ ͍͍ײ͡ͷ03.࡞Γ͍ͨͱ͔ FUD
! !OPQQFGPYXPMG

4XJGUͰϝλσʔλΛऔಘ͢Δʹ͸Ͳ͏͢Ε͹͍͍ʁ ! !OPQQFGPYXPMG

ͦ͏͍͑͹0CKFDUJWF$Ͱ͸Ͳ͏͍ͯͨ͠ͷ͔ʁ ! !OPQQFGPYXPMG

ϓϩύςΟҰཡΛऔಘ͢Δ 0CKFDUJWF$SVOUJNF"1* class_copyPropertyList(_:_:) IUUQTEFWFMPQFSBQQMFDPNEPDVNFOUBUJPO PCKFDUJWFDDMBTT@DPQZQSPQFSUZMJTU ! !OPQQFGPYXPMG

ϓϩύςΟҰཡΛऔಘ͢Δ unsigned int propertyCount = 0; objc_property_t * properties =
class_copyPropertyList([self class], &propertyCount); NSMutableArray * propertyNames = [NSMutableArray array]; for (unsigned int i = 0; i < propertyCount; ++i) { objc_property_t property = properties[i]; const char * name = property_getName(property); [propertyNames addObject:[NSString stringWithUTF8String:name]]; } free(properties); NSLog(@"Names: %@", propertyNames); ! !OPQQFGPYXPMG

ϓϩύςΟҰཡΛऔಘ͢Δ 0CK$SVOUJNF"1*͸4XJGUͰ΋࢖͏͜ͱ͕Ͱ͖Δɻ import ObjectiveC ! !OPQQFGPYXPMG

ϓϩύςΟҰཡΛऔಘ͢Δ var count: UInt32 = 0 let properties = class_copyPropertyList(MyClass.self,
&count) for i in 0..<Int(count) { let prop = properties![i] let propName = String(cString: property_getName(prop)) print(propName) } ! !OPQQFGPYXPMG

ϓϩύςΟҰཡΛऔಘ͢Δ 4XJGUͰDMBTT@DPQZ1SPQFSUZ-JTUΛ࢖͏ʹ͸੍ݶ͕͋Δ class MyClass: NSObject { @objc var prop1 =
"" @objc var prop2 = "" } ϓϩύςΟʹ@objcΛ͚ͭΔ͜ͱʂ˞ ˞!PCKD͕ඞཁͰ͋Γɺ/40CKFDUΛܧঝ͢Δඞཁ͸ͳ͍ɻ·ͨ!PCKDΛ͚ͭΔʹ͸DMBTTͰ͋Δඞཁ͕͋Δ ! !OPQQFGPYXPMG

!PCKDΛ෇͚ͣʹϓϩύ ςΟҰཡΛऔಘ͢Δํ๏͸ ͳ͍Ͱ͠ΐ͏͔ʜʁ ! !OPQQFGPYXPMG

ϓϩύςΟҰཡΛऔಘ͢Δ &ODPEBCMF class MyClass: Encodable { var prop1 = ""
var prop2 = "" } let data = try! JSONEncoder().encode(MyClass()) let json = try! JSONSerialization.jsonObject(with: data, options: .allowFragments) print((json as! [String : Any]).keys) ‣ <QSPQ QSPQ> ! !OPQQFGPYXPMG

SFqFDUJPO let mirror = Mirror(reflecting: MyClass()) let propNames = mirror.children.compactMap({
$0.label }) ! !OPQQFGPYXPMG

0CKFDUJWF$SVOUJNF "1*ʹ૬౰͢Δ GSBNFXPSL͸ແ͍ͷ͔ʜ ! !OPQQFGPYXPMG

TXJGUEPDT3VOUJNFNE 5IFpOBMSVOUJNFJOUFSGBDFJTDVSSFOUMZ BXPSLJOQSPHSFTT ͳͦ͞͏ IUUQTHJUIVCDPNBQQMFTXJGUCMPCNBTUFSEPDT3VOUJNFNE ! !OPQQFGPYXPMG

5IJSEQBSUZSVOUJNF"1* IUUQTHJUIVCDPNXJDLXJSFX3VOUJNF IUUQTHJUIVCDPN;FXP3FqFDUJPO ! !OPQQFGPYXPMG

XJDLXJSFX3VOUJNF var md = ClassMetadata(type: MyClass<Int>.self) let info = md.toTypeInfo()
info.properties.compactMap { $0.name } ! !OPQQFGPYXPMG

1SPT$POT !PCKD JOTUBODF NFUBEBUB 0CK$SVOUJNF Y P P &ODPEBCMF P
Y Y SFqFDUJPO P Y ˚ UIJSEQBSUZBQJ P P P ! !OPQQFGPYXPMG

☺ ͡Ό͋5IJSEQBSUZͷ࢖͓͏ʙʙ ! !OPQQFGPYXPMG

3VOUJNF΍3FqFDUJPO͸ Ͳ͏΍ͬͯϝλσʔλΛऔ ಘ͍ͯ͠Δͷ͔ʁ ! !OPQQFGPYXPMG

3VOUJNFͷॲཧ 5ZQF͕อ࣋͞Ε͍ͯΔϝϞϦΛ௚઀ࢀরͯ͠ϝλσʔ λΛऔಘ͍ͯ͠Δɻ ͜ΕΒΛߏ଄ମʹ౰ͯቕΊͯ࢖͍΍͍͢Α͏ʹͨ͠ϥΠ ϒϥϦ ϝϞϦͷϨΠΞ΢τߏ଄͸υΩϡϝϯτ͕͋Δ ! !OPQQFGPYXPMG

! !OPQQFGPYXPMG

45&1 var type: Any.Type = Kind.self let typeAsPointer = unsafeBitCast(type,
to: UnsafeMutablePointer<Int64>.self) let metadataPointer = typeAsPointer.advanced(by: -1) let metadataRawPointer = UnsafeMutableRawPointer(metadataPointer) UZQFࣗମͷϙΠϯλ͔ΒੜϙΠϯλΛऔಘ͢Δ ! !OPQQFGPYXPMG

! !OPQQFGPYXPMG

<ิ଍>WBMVFXJUOFTTUBCMF ؔ਺Λݺͼग़࣌͢ʹܦ༝͢Δςʔϒϧ 3VOUJNFͰ͸͜ͷαΠζ΍ॱংΛݩʹΠϯελϯεͷϝ ϞϦߏ଄Λ࡞Γग़ͯ͠ແཧ΍Γੜ੒͢Δػೳ͕͋Δ ! !OPQQFGPYXPMG

45&1 let layout = metadataRawPointer.assumingMemoryBound(to: StructMetadataLayout.self) assumingMemoryBoundͰϙΠϯλΛ .FUBEBUB-BZPVUͷߏ଄΁ͷϙΠϯλͱղऍ͠·͢ɻ ! !OPQQFGPYXPMG

45&1 4USVDU.FUBEBUB-BZPVUTXJGU struct StructMetadataLayout: NominalMetadataLayoutType { var valueWitnessTable: UnsafePointer<ValueWitnessTable> var
kind: Int var nominalTypeDescriptor: UnsafeMutablePointer<NominalTypeDescriptor> } ! !OPQQFGPYXPMG

45&1 structLayout.kind //1 enumLayout.kind //2 protocolLayout.kind //12 ͜ΕͰϝϞϦͷߏ଄ΛTUSVDUʹϚοϐϯά͢Δࣄ͕ग़དྷ ͨ !
!OPQQFGPYXPMG

45&1 Nominal Type Descriptorͷoffset: ͕̐field namesͳͷͰͦ͜ͷ࣮ମΛࢀর͢ΔͱɺϓϩύςΟ໊ͷ $4USJOHͷ഑ྻ͕औಘͰ͖Δɻ ! !OPQQFGPYXPMG

45&1 struct Animal { var name: String } let cString
= metadata.pointee.nominalTypeDescriptor.pointee.fieldNames.advanced() String(cString: cString) → name $4USJOHͷࢀরΛ4USJOHʹม׵͢ΔͱɺϓϩύςΟ໊͕ औಘͰ͖Δɻ ! !OPQQFGPYXPMG

45&1 ͋ͱ͸͜ͷ$4USJOHͷࢀরΛϓϩύςΟ෼ζϥͯ͠औಘ ͍͚ͯ͠͹ɺશͯͷϓϩύςΟ໊͕औಘͰ͖Δɻ ࣮ࡍ͸ଞͷϙΠϯλ͔ΒϓϩύςΟͷ਺Λऔಘͯͦ͠ͷ෼Λऔಘ͍ͯ͠Δ ! !OPQQFGPYXPMG

8BSOJOH ͜ͷํ๏͸౰વ4XJGUͷ࢓༷มߋͰϝϞϦͷϨΠΞ΢τ ͕มΘΔͱ࢖͑ͳ͘ͳΔɻ 4XJGU"#*4UBCJMJUZ.BOJGFTUP IUUQTHJUIVCDPNBQQMFTXJGUCMPCNBTUFSEPDT"#*4UBCJMJUZ.BOJGFTUPNE ! !OPQQFGPYXPMG

&YBNQMFQSPKFDU IUUQTHJUIVCDPNOPQQFGPYXPMG.FUBEBUB&YBNQMF ! !OPQQFGPYXPMG

·ͱΊ ‣ ϝλσʔλʹΞΫηε͢Δํ๏͸ෳ਺͋ΓҰ௕Ұ୹ Ͱ͋Δ ‣ ७4XJGUͳߏ଄ମͷ.FUBEBUBΛ҆શʹಘΔํ๏͸· ͩແ͍ɻ ‣ ϝϞϦΛࢀর͢ΔࣄͰɺ௨ৗऔಘग़དྷͳ͍ଟ͘ͷ৘ ใʹΞΫηεͰ͖Δ
! !OPQQFGPYXPMG

Swiftとメタデータ

Swiftとメタデータ

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