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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift open source project
//
// Copyright (c) 2025 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
/// Helper to provide convenient access to an AsyncStream's continuation, which is one of the few in Swift Concurrency allowed to escape.
public final class AsyncStreamController<Element: Sendable, Failure>: Sendable where Failure: Error {
private let continuation: AsyncStream<Element>.Continuation
fileprivate let task: Task<Void, Failure>
init(continuation: AsyncStream<Element>.Continuation, task: Task<Void, Failure>) {
self.continuation = continuation
self.task = task
}
deinit {
invalidate()
}
@discardableResult public func yield(_ value: Element) -> AsyncStream<Element>.Continuation.YieldResult {
continuation.yield(value)
}
public func finish() {
continuation.finish()
}
public func invalidate() {
finish()
task.cancel()
}
}
extension AsyncStreamController where Failure == any Error {
public convenience init(priority: TaskPriority? = nil, _ task: @Sendable @escaping (AsyncStream<Element>) async throws -> Void) {
let (stream, continuation) = AsyncStream<Element>.makeStream()
self.init(continuation: continuation, task: Task<Void, Failure>(priority: priority) { try await task(stream) })
}
public func wait() async throws {
try await task.value
}
}
extension AsyncStreamController where Failure == Never {
public convenience init(priority: TaskPriority? = nil, _ task: @Sendable @escaping (AsyncStream<Element>) async -> Void) {
let (stream, continuation) = AsyncStream<Element>.makeStream()
self.init(continuation: continuation, task: Task<Void, Failure>(priority: priority) { await task(stream) })
}
public func wait() async {
await task.value
}
}
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