instanceManagerFinalizerTemplate function

String instanceManagerFinalizerTemplate(SwiftOptions options)

Template for an object that tracks when an object is deallocated.

Implementation

String instanceManagerFinalizerTemplate(SwiftOptions options) => '''
// Attaches to an object to receive a callback when the object is deallocated.
internal final class ${_instanceManagerFinalizerName(options)} {
  private static let associatedObjectKey = malloc(1)!

  private let identifier: Int64
  // Reference to the delegate is weak because the callback should be ignored if the
  // `InstanceManager` is deallocated.
  private weak var delegate: ${instanceManagerFinalizerDelegateName(options)}?

  private init(identifier: Int64, delegate: ${instanceManagerFinalizerDelegateName(options)}) {
    self.identifier = identifier
    self.delegate = delegate
  }

  internal static func attach(
    to instance: AnyObject, identifier: Int64, delegate: ${instanceManagerFinalizerDelegateName(options)}
  ) {
    let finalizer = ${_instanceManagerFinalizerName(options)}(identifier: identifier, delegate: delegate)
    objc_setAssociatedObject(instance, associatedObjectKey, finalizer, .OBJC_ASSOCIATION_RETAIN)
  }

  static func detach(from instance: AnyObject) {
    objc_setAssociatedObject(instance, associatedObjectKey, nil, .OBJC_ASSOCIATION_ASSIGN)
  }

  deinit {
    delegate?.onDeinit(identifier: identifier)
  }
}

''';