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of adding a property. This better matches what the actual implementation expects, and it avoids some possibilities of weird mismatches. However, it also requires special-case initialization, destruction, and dynamic-layout support, none of which I've added yet. In order to get NSObject default actor subclasses to use Swift refcounting (and thus avoid the need for the default actor runtime to generally use ObjC refcounting), I've had to introduce a SwiftNativeNSObject which we substitute as the superclass when inheriting directly from NSObject. This is something we could do in all NSObject subclasses; for now, I'm just doing it in actors, although it's all actors and not just default actors. We are not yet taking advantage of our special knowledge of this class anywhere except the reference-counting code. I went around in circles exploring a number of alternatives for doing this; at one point I basically had a completely parallel "ForImplementation" superclass query. That proved to be a lot of added complexity and created more problems than it solved. We also don't *really* get any benefit from this subclassing because there still wouldn't be a consistent superclass for all actors. So instead it's very ad-hoc.
44 lines
1.5 KiB
C++
44 lines
1.5 KiB
C++
//===--- Actor.h - ABI structures for actors --------------------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Swift ABI describing actors.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_ABI_ACTOR_H
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#define SWIFT_ABI_ACTOR_H
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#include "swift/ABI/HeapObject.h"
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#include "swift/ABI/MetadataValues.h"
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namespace swift {
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/// The default actor implementation. This is the layout of both
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/// the DefaultActor and NSDefaultActor classes.
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class alignas(Alignment_DefaultActor) DefaultActor : public HeapObject {
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public:
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// These constructors do not initialize the actor instance, and the
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// destructor does not destroy the actor instance; you must call
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// swift_defaultActor_{initialize,destroy} yourself.
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constexpr DefaultActor(const HeapMetadata *metadata)
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: HeapObject(metadata), PrivateData{} {}
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constexpr DefaultActor(const HeapMetadata *metadata,
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InlineRefCounts::Immortal_t immortal)
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: HeapObject(metadata, immortal), PrivateData{} {}
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void *PrivateData[NumWords_DefaultActor];
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};
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} // end namespace swift
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#endif |