Remove COMExportBase and introduce COMImplements<Binding> (#411)

Generator/Sources/SwiftWinRT/Extensions/WindowsFoundationCollections_IIterable_swift

@@ -9,7 +9,7 @@ extension Sequence {
     }
 }
 
-fileprivate class SequenceIterable<S: Sequence>: WinRTPrimaryExport<IInspectableBinding>, WindowsFoundationCollections_IIterableProtocol {
+fileprivate class SequenceIterable<S: Sequence>: WinRTExport<IInspectableBinding>, WindowsFoundationCollections_IIterableProtocol {
     typealias T = S.Element
 
     private let sequence: S
@@ -23,7 +23,7 @@ fileprivate class SequenceIterable<S: Sequence>: WinRTPrimaryExport<IInspectable
     }
 }
 
-internal class SequenceIterator<I: IteratorProtocol>: WinRTPrimaryExport<IInspectableBinding>, WindowsFoundationCollections_IIteratorProtocol {
+internal class SequenceIterator<I: IteratorProtocol>: WinRTExport<IInspectableBinding>, WindowsFoundationCollections_IIteratorProtocol {
     typealias T = I.Element
 
     private var iterator: I

Generator/Sources/SwiftWinRT/Extensions/WindowsFoundationCollections_IVectorView_swift

@@ -12,7 +12,7 @@ extension Collection where Index == Int, Element: Equatable {
     }
 }
 
-fileprivate class CollectionVectorView<C: Collection>: WinRTPrimaryExport<IInspectableBinding>,
+fileprivate class CollectionVectorView<C: Collection>: WinRTExport<IInspectableBinding>,
         WindowsFoundationCollections_IVectorViewProtocol
         where C.Index == Int {
     public typealias T = C.Element

Generator/Sources/SwiftWinRT/Extensions/WindowsFoundationCollections_IVector_swift

@@ -13,7 +13,7 @@ extension Array where Element: Equatable {
 }
 
 /// Wraps a Swift array into a type implementing WinRT's Windows.Foundation.Collections.IVector<T>.
-public class ArrayVector<T>: WinRTPrimaryExport<IInspectableBinding>,
+public class ArrayVector<T>: WinRTExport<IInspectableBinding>,
         WindowsFoundationCollections_IVectorProtocol, WindowsFoundationCollections_IVectorViewProtocol {
     public var array: [T]
     public var elementEquals: (T, T) -> Bool

InteropTests/Tests/EventTests.swift

@@ -28,7 +28,7 @@ class EventTests: WinRTTestCase {
         try eventSource.fire()
         XCTAssertEqual(try counter.count, 1)
 
-        class EventSource: WinRTPrimaryExport<IEventSourceBinding>, IEventSourceProtocol {
+        class EventSource: WinRTExport<IEventSourceBinding>, IEventSourceProtocol {
             private var invocationList: EventInvocationList<MinimalDelegate> = .init()
 
             @discardableResult

InteropTests/Tests/InterfaceImplementationTests.swift

@@ -4,7 +4,7 @@ import WinRTComponent
 
 class InterfaceImplementationTests: WinRTTestCase {
     func testWithSwiftObject() throws {
-        class Exported: WinRTPrimaryExport<IInspectableBinding>, IMinimalInterfaceProtocol {
+        class Exported: WinRTExport<IInspectableBinding>, IMinimalInterfaceProtocol {
             override class var queriableInterfaces: [any COMTwoWayBinding.Type] { [
                 IMinimalInterfaceBinding.self
             ] }

InteropTests/Tests/ObjectExportingTests.swift

@@ -3,7 +3,7 @@ import WindowsRuntime
 import WinRTComponent
 
 class ObjectExportingTests: WinRTTestCase {
-    class ExportedClass: WinRTPrimaryExport<IInspectableBinding> {}
+    class ExportedClass: WinRTExport<IInspectableBinding> {}
 
     func testBalancedAddRefRelease() throws {
         let obj: ExportedClass = .init()
@@ -42,7 +42,7 @@ class ObjectExportingTests: WinRTTestCase {
     }
 
     func testWeakReference() throws {
-        class Exported: WinRTPrimaryExport<IInspectableBinding> {}
+        class Exported: WinRTExport<IInspectableBinding> {}
 
         var instance: Exported? = Exported()
         let weakReferencer = try WeakReferencer(XCTUnwrap(instance))

InteropTests/Tests/ValueOutParamRoundtripTests.swift

@@ -107,7 +107,7 @@ class ValueOutParamRoundtripTests: WinRTTestCase {
         XCTAssertNil(roundtripped)
     }
 
-    class OutputArgumentImplementation: WinRTPrimaryExport<IOutputArgumentBinding>, IOutputArgumentProtocol {
+    class OutputArgumentImplementation: WinRTExport<IOutputArgumentBinding>, IOutputArgumentProtocol {
         func int32(_ value: Int32, _ result: inout Int32) throws { result = value }
         func string(_ value: String, _ result: inout String) throws { result = value }
         func object(_ value: WindowsRuntime.IInspectable?, _ result: inout WindowsRuntime.IInspectable?) throws { result = value }

InteropTests/Tests/ValueReturnRoundtripTests.swift

@@ -86,7 +86,7 @@ class ValueReturnRoundtripTests: WinRTTestCase {
         XCTAssertNil(try twoWay.reference(nil))
     }
 
-    class ReturnArgumentImplementation: WinRTPrimaryExport<IReturnArgumentBinding>, IReturnArgumentProtocol {
+    class ReturnArgumentImplementation: WinRTExport<IReturnArgumentBinding>, IReturnArgumentProtocol {
         func int32(_ value: Int32) throws -> Int32 { value }
         func string(_ value: String) throws -> String { value }
         func object(_ value: WindowsRuntime.IInspectable?) throws -> WindowsRuntime.IInspectable { try NullResult.unwrap(value) }

Support/Sources/COM/COMEmbedding.swift

@@ -24,10 +24,12 @@ public struct COMEmbedding: ~Copyable {
 
     public mutating func initialize(embedder: AnyObject, virtualTable: UnsafeRawPointer) {
         comObject.virtualTable = virtualTable
-        comObject.swiftSelf = Unmanaged<AnyObject>.passUnretained(embedder).toOpaque()
+        comObject.swiftEmbedder = Unmanaged<AnyObject>.passUnretained(embedder).toOpaque()
     }
 
-    public var isInitialized: Bool { comObject.swiftSelf != nil }
+    public var isInitialized: Bool { comObject.swiftEmbedder != nil }
+
+    public var embedder: AnyObject? { comObject.swiftEmbedder == nil ? nil : Unmanaged<AnyObject>.fromOpaque(comObject.swiftEmbedder).takeUnretainedValue() }
 
     public var unknownPointer: IUnknownPointer {
         mutating get {
@@ -41,7 +43,7 @@ public struct COMEmbedding: ~Copyable {
 
     fileprivate static func toUnmanagedUnsafe<ABIStruct>(_ this: UnsafeMutablePointer<ABIStruct>) -> Unmanaged<AnyObject> {
         this.withMemoryRebound(to: SWRT_SwiftCOMObject.self, capacity: 1) {
-            Unmanaged<AnyObject>.fromOpaque($0.pointee.swiftSelf)
+            Unmanaged<AnyObject>.fromOpaque($0.pointee.swiftEmbedder)
         }
     }
 

Support/Sources/COM/COMError+SwiftErrorInfo.swift

@@ -1,6 +1,6 @@
 extension COMError {
     /// Wraps a Swift Error object into an `IErrorInfo` to preserve it across COM boundaries.
-    internal final class SwiftErrorInfo: COMPrimaryExport<IErrorInfoBinding>, IErrorInfoProtocol {
+    internal final class SwiftErrorInfo: COMExport<IErrorInfoBinding>, IErrorInfoProtocol {
         public let error: Error
 
         public init(error: Error) {

Support/Sources/COM/COMPrimaryExport.swift → Support/Sources/COM/COMExport.swift

@@ -1,19 +1,24 @@
 /// Base for Swift classes that implement one or more COM interfaces and owns the COM object identity,
 /// meaning that they own the object returned when using QueryInterface for IUnknown.
 /// The generic Binding parameter determines the virtual table of the identity object.
-open class COMPrimaryExport<Binding: COMTwoWayBinding>: COMExportBase<Binding> {
+open class COMExport<PrimaryInterfaceBinding: COMTwoWayBinding>: IUnknownProtocol {
     /// Gets the interfaces that can be queried for using queryInterface.
     open class var queriableInterfaces: [any COMTwoWayBinding.Type] { [] }
     open class var implementIAgileObject: Bool { true }
     open class var implementFreeThreadedMarshaling: Bool { implementIAgileObject }
 
-    public override init() {
-        super.init()
+    /// The COM identity object exposing the implementation of the primary interface.
+    private var primaryImplements: COMImplements<PrimaryInterfaceBinding> = .init()
+
+    public init() {}
+
+    public func toCOM() -> PrimaryInterfaceBinding.ABIReference {
+        primaryImplements.toCOM(embedder: self)
     }
 
-    open override func _queryInterface(_ id: COMInterfaceID) throws -> IUnknownReference {
+    open func _queryInterface(_ id: COMInterfaceID) throws -> IUnknownReference {
         switch id {
-            case Binding.interfaceID:
+            case PrimaryInterfaceBinding.interfaceID:
                 return toCOM().cast()
             case IUnknownBinding.interfaceID:
                 return toCOM().cast()

Support/Sources/COM/COMImplements.swift

@@ -0,0 +1,24 @@
+/// Use as a stored property of a class to allow the object to be referenced
+/// as a COM object exposing a given interface.
+public struct COMImplements<InterfaceBinding: COMTwoWayBinding>: ~Copyable {
+    private var embedding: COMEmbedding = .uninitialized
+
+    public mutating func toCOM(embedder: InterfaceBinding.SwiftObject) -> InterfaceBinding.ABIReference {
+        // The embedder should conform to IUnknownProtocol and hence be an AnyObject,
+        // but this cannot be expressed in the type system.
+        toCOM(embedder: embedder as! IUnknown)
+    }
+
+    internal mutating func toCOM(embedder: AnyObject) -> InterfaceBinding.ABIReference {
+        if embedding.isInitialized {
+            assert(embedding.embedder === embedder, "COM object already embedded in another object.")
+        } else {
+            // Thread safe since every initialization will produce the same state and has no side-effects.
+            assert(embedder is InterfaceBinding.SwiftObject || embedder is COMEmbedderWithDelegatedImplementation,
+                "Embedder \(type(of: embedder)) does not conform to the expected interface \(InterfaceBinding.self).")
+            embedding.initialize(embedder: embedder, virtualTable: InterfaceBinding.virtualTablePointer)
+        }
+
+        return embedding.toCOM().cast()
+    }
+}

Support/Sources/COM/COMSecondaryExport.swift

@@ -1,14 +1,19 @@
 /// A COM-exported object providing a secondary interface to a primary exported object.
-open class COMSecondaryExport<Binding: COMTwoWayBinding>: COMExportBase<Binding> {
+open class COMSecondaryExport<InterfaceBinding: COMTwoWayBinding>: IUnknownProtocol {
+    private var implements: COMImplements<InterfaceBinding> = .init()
     public let identity: IUnknown
 
     public init(identity: IUnknown) {
         self.identity = identity
     }
 
-    open override func _queryInterface(_ id: COMInterfaceID) throws -> IUnknownReference {
+    public func toCOM() -> InterfaceBinding.ABIReference {
+        implements.toCOM(embedder: self)
+    }
+
+    open func _queryInterface(_ id: COMInterfaceID) throws -> IUnknownReference {
         switch id {
-            case Binding.interfaceID: return toCOM().cast()
+            case InterfaceBinding.interfaceID: return toCOM().cast()
             default: return try identity._queryInterface(id)
         }
     }

Support/Sources/COM_ABI/include/SwiftCOMObject.h

@@ -9,5 +9,5 @@ typedef struct SWRT_SwiftCOMObject {
     const void* virtualTable;
     // The Unmanaged<AnyObject> pointer to the Swift object that embeds this structure.
     // This object is retained and released by AddRef/Release calls.
-    void* swiftSelf;
+    void* swiftEmbedder;
 } SWRT_SwiftCOMObject;

Support/Sources/WindowsRuntime/ExportedDelegate.swift

@@ -1,6 +1,6 @@
 
 /// A COM-exported object delegating its implementation to a Swift object.
-public class ExportedDelegate<Binding: DelegateBinding>: COMPrimaryExport<Binding>, COMEmbedderWithDelegatedImplementation {
+public class ExportedDelegate<Binding: DelegateBinding>: COMExport<Binding>, COMEmbedderWithDelegatedImplementation {
     public let closure: Binding.SwiftObject
 
     public init(_ closure: Binding.SwiftObject) {

Support/Sources/WindowsRuntime/ReferenceArrayImpl.swift

@@ -2,7 +2,7 @@ import WindowsRuntime_ABI
 
 /// Implements IReferenceArray<T> for any boxable T not provided by the UWP PropertyValue class (value types and delegates).
 internal class ReferenceArrayImpl<TBinding: IReferenceableBinding>
-        : WinRTPrimaryExport<WindowsFoundation_IReferenceArrayBinding<TBinding>>,
+        : WinRTExport<WindowsFoundation_IReferenceArrayBinding<TBinding>>,
         WindowsFoundation_IReferenceArrayProtocol {
     public typealias T = TBinding.SwiftValue
 

Support/Sources/WindowsRuntime/ReferenceImpl.swift

@@ -2,7 +2,7 @@ import WindowsRuntime_ABI
 
 /// Implements IReference<T> for any boxable T not provided by the UWP PropertyValue class (value types and delegates).
 internal class ReferenceImpl<TBinding: IReferenceableBinding>
-        : WinRTPrimaryExport<WindowsFoundation_IReferenceBinding<TBinding>>,
+        : WinRTExport<WindowsFoundation_IReferenceBinding<TBinding>>,
         WindowsFoundation_IReferenceProtocol {
     public typealias T = TBinding.SwiftValue
 

Support/Sources/WindowsRuntime/WinRTError+LanguageException.swift

@@ -1,6 +1,6 @@
 extension WinRTError {
     /// Wraps a Swift Error object so it can be associated with an `IRestrictedErrorInfo`.
-    internal final class LanguageException: COMPrimaryExport<IUnknownBinding> {
+    internal final class LanguageException: COMExport<IUnknownBinding> {
         public let error: Error
 
         public init(error: Error) {

Support/Sources/WindowsRuntime/WinRTExport.swift

@@ -1,21 +1,17 @@
 import COM
 
 /// Base for classes exported to WinRT and COM consumers.
-open class WinRTPrimaryExport<Binding: InterfaceBinding>: COMPrimaryExport<Binding>, IInspectableProtocol {
+open class WinRTExport<PrimaryInterfaceBinding: InterfaceBinding>: COMExport<PrimaryInterfaceBinding>, IInspectableProtocol {
     open class var _runtimeClassName: String { String(describing: Self.self) }
     open class var _trustLevel: TrustLevel { .base }
     open class var implementIStringable: Bool { true }
     open class var implementIWeakReferenceSource: Bool { true }
 
-    public var inspectablePointer: IInspectableBinding.ABIPointer {
-        unknownPointer.withMemoryRebound(to: IInspectableBinding.ABIStruct.self, capacity: 1) { $0 }
-    }
-
     open override func _queryInterface(_ id: COMInterfaceID) throws -> IUnknownReference {
         switch id {
             // QI for IInspectable should return the identity interface just like IUnknown.
             case IInspectableBinding.interfaceID:
-                return .init(addingRef: unknownPointer)
+                return toCOM().cast()
             case IWeakReferenceSourceBinding.interfaceID where Self.implementIWeakReferenceSource:
                 return ExportedWeakReferenceSource(target: self).toCOM().cast()
             case WindowsFoundation_IStringableBinding.interfaceID where Self.implementIStringable:
@@ -29,16 +25,11 @@ open class WinRTPrimaryExport<Binding: InterfaceBinding>: COMPrimaryExport<Bindi
     }
 
     open func getIids() throws -> [COMInterfaceID] {
-        var iids = [COMInterfaceID]()
-        try _appendIids(&iids)
-        return iids
-    }
-
-    open func _appendIids(_ iids: inout [COMInterfaceID]) throws {
-        for interfaceBinding in Self.queriableInterfaces { iids.append(interfaceBinding.interfaceID) }
+        var iids = Self.queriableInterfaces.map { $0.interfaceID }
         if Self.implementIAgileObject { iids.append(IAgileObjectBinding.interfaceID) }
         if Self.implementIWeakReferenceSource { iids.append(IWeakReferenceSourceBinding.interfaceID) }
         if Self.implementIStringable, self is CustomStringConvertible { iids.append(WindowsFoundation_IStringableBinding.interfaceID) }
+        return iids
     }
 
     public final func getRuntimeClassName() throws -> String { Self._runtimeClassName }
@@ -72,7 +63,7 @@ fileprivate class ExportedWeakReferenceSource: COMSecondaryExport<IWeakReference
     func getWeakReference() throws -> IWeakReference { ExportedWeakReference(target: identity as! IInspectable) }
 }
 
-fileprivate class ExportedWeakReference: COMPrimaryExport<IWeakReferenceBinding>, IWeakReferenceProtocol {
+fileprivate class ExportedWeakReference: COMExport<IWeakReferenceBinding>, IWeakReferenceProtocol {
     weak var target: IInspectable?
     init(target: IInspectable) { self.target = target }
     func resolve() throws -> IInspectable? { target }

Support/Tests/Tests/COMExportTests.swift

@@ -2,7 +2,7 @@ import XCTest
 import WindowsRuntime
 
 internal final class COMExportTests: XCTestCase {
-    final class TestObject: COMPrimaryExport<IUnknownBinding>, ICOMTestProtocol, ICOMTest2Protocol {
+    final class TestObject: COMExport<IUnknownBinding>, ICOMTestProtocol, ICOMTest2Protocol {
         override class var queriableInterfaces: [any COMTwoWayBinding.Type] { [
             ICOMTestBinding.self,
             ICOMTest2Binding.self
@@ -38,11 +38,11 @@ internal final class COMExportTests: XCTestCase {
     }
 
     func testIAgileObject() throws {
-        final class AgileObject: COMPrimaryExport<IUnknownBinding> {
+        final class AgileObject: COMExport<IUnknownBinding> {
             override class var implementIAgileObject: Bool { true }
         }
 
-        final class NonAgileObject: COMPrimaryExport<IUnknownBinding> {
+        final class NonAgileObject: COMExport<IUnknownBinding> {
             override class var implementIAgileObject: Bool { false }
         }
 
@@ -51,11 +51,11 @@ internal final class COMExportTests: XCTestCase {
     }
 
     func testFreeThreadedMarshalability() throws {
-        final class Marshalable: COMPrimaryExport<IUnknownBinding> {
+        final class Marshalable: COMExport<IUnknownBinding> {
             override class var implementFreeThreadedMarshaling: Bool { true }
         }
 
-        final class NonMarshalable: COMPrimaryExport<IUnknownBinding> {
+        final class NonMarshalable: COMExport<IUnknownBinding> {
             override class var implementFreeThreadedMarshaling: Bool { false }
         }
 
@@ -65,7 +65,7 @@ internal final class COMExportTests: XCTestCase {
     }
 
     func testImplementsSecondaryInterface() throws {
-        final class CallCounter: COMPrimaryExport<IUnknownBinding>, ICOMTestProtocol {
+        final class CallCounter: COMExport<IUnknownBinding>, ICOMTestProtocol {
             override class var queriableInterfaces: [any COMTwoWayBinding.Type] { [
                 ICOMTestBinding.self
             ] }
@@ -84,7 +84,7 @@ internal final class COMExportTests: XCTestCase {
     }
 
     func testEmbeddedSecondaryInterface() throws {
-        final class CallCounter: COMPrimaryExport<IUnknownBinding>, ICOMTestProtocol {
+        final class CallCounter: COMExport<IUnknownBinding>, ICOMTestProtocol {
             override class var queriableInterfaces: [any COMTwoWayBinding.Type] { [
                 ICOMTestBinding.self
             ] }