73 lines
2.3 KiB
Swift
73 lines
2.3 KiB
Swift
//
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// SingleAssignmentDisposable.swift
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// RxSwift
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//
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// Created by Krunoslav Zaher on 2/15/15.
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// Copyright © 2015 Krunoslav Zaher. All rights reserved.
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//
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/**
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Represents a disposable resource which only allows a single assignment of its underlying disposable resource.
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If an underlying disposable resource has already been set, future attempts to set the underlying disposable resource will throw an exception.
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*/
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public final class SingleAssignmentDisposable : DisposeBase, Cancelable {
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private struct DisposeState: OptionSet {
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let rawValue: Int32
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static let disposed = DisposeState(rawValue: 1 << 0)
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static let disposableSet = DisposeState(rawValue: 1 << 1)
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}
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// state
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private let state = AtomicInt(0)
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private var disposable = nil as Disposable?
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/// - returns: A value that indicates whether the object is disposed.
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public var isDisposed: Bool {
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isFlagSet(self.state, DisposeState.disposed.rawValue)
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}
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/// Initializes a new instance of the `SingleAssignmentDisposable`.
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public override init() {
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super.init()
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}
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/// Gets or sets the underlying disposable. After disposal, the result of getting this property is undefined.
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///
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/// **Throws exception if the `SingleAssignmentDisposable` has already been assigned to.**
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public func setDisposable(_ disposable: Disposable) {
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self.disposable = disposable
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let previousState = fetchOr(self.state, DisposeState.disposableSet.rawValue)
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if (previousState & DisposeState.disposableSet.rawValue) != 0 {
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rxFatalError("oldState.disposable != nil")
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}
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if (previousState & DisposeState.disposed.rawValue) != 0 {
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disposable.dispose()
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self.disposable = nil
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}
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}
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/// Disposes the underlying disposable.
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public func dispose() {
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let previousState = fetchOr(self.state, DisposeState.disposed.rawValue)
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if (previousState & DisposeState.disposed.rawValue) != 0 {
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return
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}
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if (previousState & DisposeState.disposableSet.rawValue) != 0 {
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guard let disposable = self.disposable else {
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rxFatalError("Disposable not set")
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}
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disposable.dispose()
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self.disposable = nil
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}
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}
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}
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