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8a27fb8178
We're going to use it for Array internals. When we do, it should be expected to cause a performance hit on arrays of value types until rdar://18125016 is handled. Swift SVN r22784
108 lines
2.9 KiB
Swift
108 lines
2.9 KiB
Swift
//===--- BridgeStorage.swift - Discriminated storage for bridged types ----===//
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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 - 2015 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 http://swift.org/LICENSE.txt for license information
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// See http://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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// Types that are bridged to Objective-C need to manage an object
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// that may be either some native class or the @objc Cocoa
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// equivalent. Ideally we would have a Builtin type that could
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// discriminate between these two possibilities and store a few extra
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// bits when the stored type is native. _BridgeStorage is an
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// abstraction layer that will allow us to seamlessly integrate that
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// type, when it becomes available.
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//
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//===----------------------------------------------------------------------===//
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import SwiftShims
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public // @testable
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enum _BridgeStorage<
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NativeType: AnyObject, CocoaType: AnyObject
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> {
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public // @testable
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typealias Native = NativeType
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public // @testable
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typealias Cocoa = CocoaType
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public // @testable
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init(_ native: Native, bits: Int) {
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_sanityCheck(_usesNativeSwiftReferenceCounting(NativeType.self))
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_sanityCheck(!_usesNativeSwiftReferenceCounting(CocoaType.self))
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switch bits {
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case 0: self = .Native0(native)
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case 1: self = .Native1(native)
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case 2: self = .Native2(native)
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default:
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// on i386, we have 2 spare bits. Other platforms have more.
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_sanityCheckFailure(
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"BridgeStorage can't store bits outside the range 0-2")
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}
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}
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public // @testable
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init(_ cocoa: Cocoa) {
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_sanityCheck(_usesNativeSwiftReferenceCounting(NativeType.self))
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_sanityCheck(!_usesNativeSwiftReferenceCounting(CocoaType.self))
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self = .Cocoa0(cocoa)
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}
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public // @testable
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var native: Native? {
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switch self {
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case Native0(let x):
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return x
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case Native1(let x):
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return x
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case Native2(let x):
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return x
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default:
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return nil
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}
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}
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public // @testable
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var cocoa: Cocoa? {
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switch self {
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case Cocoa0(let x):
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return x
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default:
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return nil
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}
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}
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public // @testable
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var spareBits: Int {
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switch self {
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case Native1:
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return 1
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case Native2:
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return 2
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default:
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return 0
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}
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}
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public // @testable
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mutating func isUniquelyReferenced() -> Bool {
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if let raw = native.map({ Builtin.bridgeToRawPointer($0) }) {
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return _swift_isUniquelyReferenced_nonNull_native(UnsafePointer(raw)) != 0
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}
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return false
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}
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//===--- private/internal -----------------------------------------------===//
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case Native0(Native)
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case Native1(Native)
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case Native2(Native)
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case Cocoa0(CocoaType)
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}
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