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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
/// A type that tracks the number of live instances.
///
/// `LifetimeTracked` conforms to `CustomStringConvertible`, and conditionally
/// conforms to `Equatable`, `Hashable` and `Comparable` when its payload does.
///
/// `LifetimeTracked` is useful to check for leaks in algorithms and data
/// structures. The easiest way to produce instances is to use the
/// `withLifetimeTracking` function:
///
/// class FooTests: XCTestCase {
/// func testFoo() {
/// withLifetimeTracking([1, 2, 3]) { instances in
/// _ = instances.sorted(by: >)
/// }
/// }
/// }
public class LifetimeTracked<Payload> {
public let tracker: LifetimeTracker
internal var serialNumber: Int = 0
public let payload: Payload
public init(_ payload: Payload, for tracker: LifetimeTracker) {
tracker.instances += 1
tracker._nextSerialNumber += 1
self.tracker = tracker
self.serialNumber = tracker._nextSerialNumber
self.payload = payload
}
deinit {
precondition(serialNumber != 0, "Double deinit")
tracker.instances -= 1
serialNumber = -serialNumber
}
}
extension LifetimeTracked: CustomStringConvertible {
public var description: String {
return "\(payload)"
}
}
extension LifetimeTracked: Equatable where Payload: Equatable {
public static func == (left: LifetimeTracked, right: LifetimeTracked) -> Bool {
return left.payload == right.payload
}
}
extension LifetimeTracked: Hashable where Payload: Hashable {
public func _rawHashValue(seed: Int) -> Int {
payload._rawHashValue(seed: seed)
}
public func hash(into hasher: inout Hasher) {
hasher.combine(payload)
}
public var hashValue: Int {
payload.hashValue
}
}
extension LifetimeTracked: Comparable where Payload: Comparable {
public static func < (left: LifetimeTracked, right: LifetimeTracked) -> Bool {
return left.payload < right.payload
}
}
extension LifetimeTracked: Encodable where Payload: Encodable {
public func encode(to encoder: Encoder) throws {
try payload.encode(to: encoder)
}
}
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