ghostgram/submodules/SSignalKit/SwiftSignalKit2/Source/Signal.swift

import Foundation

let doNothing: () -> Void = { }

public enum NoValue {
}

public enum NoError {
}

public func identity<A>(a: A) -> A {
    return a
}

precedencegroup PipeRight {
    associativity: left
    higherThan: DefaultPrecedence
}

infix operator |> : PipeRight

@inlinable
public func |> <T, U>(value: T, function: ((T) -> U)) -> U {
    return function(value)
}

public final class Signal<T, E> {
    private let generator: (Subscriber<T, E>) -> Disposable

    public init(_ generator: @escaping(Subscriber<T, E>) -> Disposable) {
        self.generator = generator
    }

    public func start(next: ((T) -> Void)! = nil, error: ((E) -> Void)! = nil, completed: (() -> Void)! = nil) -> Disposable {
        let subscriber = Subscriber<T, E>(next: next, error: error, completed: completed)
        let disposable = self.generator(subscriber)
        let wrappedDisposable = subscriber.core.assignDisposable(disposable)
        withExtendedLifetime(subscriber, {})
        return wrappedDisposable
    }

    public func startStandalone(next: ((T) -> Void)! = nil, error: ((E) -> Void)! = nil, completed: (() -> Void)! = nil) -> Disposable {
        let subscriber = Subscriber<T, E>(next: next, error: error, completed: completed)
        let disposable = self.generator(subscriber)
        let wrappedDisposable = subscriber.core.assignDisposable(disposable)
        withExtendedLifetime(subscriber, {})
        return wrappedDisposable
    }

    public func startStrict(next: ((T) -> Void)! = nil, error: ((E) -> Void)! = nil, completed: (() -> Void)! = nil, file: String = #file, line: Int = #line) -> Disposable {
        let subscriber = Subscriber<T, E>(next: next, error: error, completed: completed)
        let disposable = self.generator(subscriber)
        let wrappedDisposable = subscriber.core.assignDisposable(disposable)
        withExtendedLifetime(subscriber, {})
        return wrappedDisposable.strict(file: file, line: line)
    }

    public static func single(_ value: T) -> Signal<T, E> {
        return Signal<T, E> { subscriber in
            subscriber.putNext(value)
            subscriber.putCompletion()

            return EmptyDisposable
        }
    }

    public static func complete() -> Signal<T, E> {
        return Signal<T, E> { subscriber in
            subscriber.putCompletion()

            return EmptyDisposable
        }
    }

    public static func fail(_ error: E) -> Signal<T, E> {
        return Signal<T, E> { subscriber in
            subscriber.putError(error)

            return EmptyDisposable
        }
    }

    public static func never() -> Signal<T, E> {
        return Signal<T, E> { _ in
            return EmptyDisposable
        }
    }
}

@available(iOS 13.0, macOS 10.15, *)
public extension Signal where E == NoError {
    func get() async -> T {
        let disposable = MetaDisposable()
        return await withTaskCancellationHandler(operation: {
            return await withCheckedContinuation { continuation in
                disposable.set((self |> take(1)).startStandalone(next: { value in
                    continuation.resume(returning: value)
                }))
            }
        }, onCancel: {
            disposable.dispose()
        })
    }
}