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The `try await` ordering is both easier to read and indicates the order of operations better, because the suspension point occurs first and then one can observe a thrown error.
105 lines
2.9 KiB
Swift
105 lines
2.9 KiB
Swift
//===----------------------------------------------------------------------===//
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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) 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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import Swift
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@_implementationOnly import _SwiftConcurrencyShims
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/// A partial task is a unit of scheduleable work.
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@frozen
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public struct PartialAsyncTask {
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private var context: Builtin.Job
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public func run() { }
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}
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@frozen
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public struct UnsafeContinuation<T> {
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@usableFromInline internal var context: Builtin.RawUnsafeContinuation
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@_alwaysEmitIntoClient
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internal init(_ context: Builtin.RawUnsafeContinuation) {
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self.context = context
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}
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@_silgen_name("swift_continuation_resume")
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public func resume(returning value: __owned T)
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}
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@frozen
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public struct UnsafeThrowingContinuation<T> {
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@usableFromInline internal var context: Builtin.RawUnsafeContinuation
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@_alwaysEmitIntoClient
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internal init(_ context: Builtin.RawUnsafeContinuation) {
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self.context = context
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}
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@_silgen_name("swift_continuation_throwingResume")
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public func resume(returning: __owned T)
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@_silgen_name("swift_continuation_throwingResumeWithError")
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public func resume(throwing: __owned Error)
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}
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#if _runtime(_ObjC)
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// Intrinsics used by SILGen to resume or fail continuations
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// for
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@_alwaysEmitIntoClient
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internal func _resumeUnsafeContinuation<T>(
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_ continuation: UnsafeContinuation<T>,
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_ value: __owned T
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) {
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continuation.resume(returning: value)
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}
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@_alwaysEmitIntoClient
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internal func _resumeUnsafeThrowingContinuation<T>(
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_ continuation: UnsafeThrowingContinuation<T>,
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_ value: __owned T
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) {
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continuation.resume(returning: value)
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}
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@_alwaysEmitIntoClient
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internal func _resumeUnsafeThrowingContinuationWithError<T>(
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_ continuation: UnsafeThrowingContinuation<T>,
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_ error: __owned Error
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) {
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continuation.resume(throwing: error)
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}
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#endif
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/// The operation functions must resume the continuation *exactly once*.
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///
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/// The continuation will not begin executing until the operation function returns.
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@_alwaysEmitIntoClient
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public func withUnsafeContinuation<T>(
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_ fn: (UnsafeContinuation<T>) -> Void
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) async -> T {
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return await Builtin.withUnsafeContinuation {
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fn(UnsafeContinuation<T>($0))
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}
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}
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/// The operation functions must resume the continuation *exactly once*.
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///
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/// The continuation will not begin executing until the operation function returns.
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@_alwaysEmitIntoClient
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public func withUnsafeThrowingContinuation<T>(
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_ fn: (UnsafeThrowingContinuation<T>) -> Void
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) async throws -> T {
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return try await Builtin.withUnsafeThrowingContinuation {
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fn(UnsafeThrowingContinuation<T>($0))
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}
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}
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