mirror of
https://github.com/apple/swift-argument-parser.git
synced 2026-06-06 20:18:23 +00:00
Rauhul Varma
fd8ea096da
The `@_implementationOnly` attribute does not work correctly without library evolution enabled. The only possible client with this enabled is Apple, however they have updated to the Swift 6 compiler and can use `internal import` instead of this attribute. Therefore there is no need for this package to use the attribute anymore.
61 lines
2.1 KiB
Swift
61 lines
2.1 KiB
Swift
//===----------------------------------------------------------*- swift -*-===//
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//
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// This source file is part of the Swift Argument Parser 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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//
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//===----------------------------------------------------------------------===//
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#if swift(>=6.0)
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internal import Foundation
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#else
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import Foundation
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#endif
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/// A synchronization primitive that protects shared mutable state via mutual
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/// exclusion.
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///
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/// The `Mutex` type offers non-recursive exclusive access to the state it is
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/// protecting by blocking threads attempting to acquire the lock. Only one
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/// execution context at a time has access to the value stored within the
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/// `Mutex` allowing for exclusive access.
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class Mutex<T>: @unchecked Sendable {
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/// The lock used to synchronize access to the value.
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var lock: NSLock
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/// The value protected by the mutex.
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var value: T
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/// Initializes a new `Mutex` with the provided value.
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///
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/// - Parameter value: The initial value to be protected by the mutex.
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init(_ value: T) {
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self.lock = .init()
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self.value = value
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}
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/// Calls the given closure after acquiring the lock and then releases
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/// ownership.
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///
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/// - Warning: Recursive calls to `withLock` within the closure parameter has
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/// behavior that is platform dependent. Some platforms may choose to panic
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/// the process, deadlock, or leave this behavior unspecified. This will
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/// never reacquire the lock however.
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///
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/// - Parameter body: A closure with a parameter of `Value` that has exclusive
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/// access to the value being stored within this mutex. This closure is
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/// considered the critical section as it will only be executed once the
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/// calling thread has acquired the lock.
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///
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/// - Returns: The return value, if any, of the `body` closure parameter.
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func withLock<U>(
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_ body: (inout T) throws -> U
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) rethrows -> U {
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self.lock.lock()
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defer { self.lock.unlock() }
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return try body(&self.value)
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}
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}
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