registry

Registry.swift

import STS

final class Registry {
    // MARK: Internal

    func register<T: AnyObject>(_ value: T) {
        self.lock.execute {
            let key = ObjectIdentifier(T.self)
            assert(self.objects[key] == nil)
            assert(self.factories[key] == nil)
            self.objects[key] = value
        }
    }

    func register<T: AnyObject>(_ value: @escaping () -> T) {
        self.lock.execute {
            let key = ObjectIdentifier(T.self)
            assert(self.objects[key] == nil)
            assert(self.factories[key] == nil)
            self.factories[key] = value
        }
    }

    func resolve<T: AnyObject>() -> T {
        self.lock.execute {
            let key = ObjectIdentifier(T.self)

            if let object = self.objects[key] {
                return object as! T
            }

            if let factory = self.factories[key] {
                let object = factory()
                self.objects[key] = object
                self.factories[key] = nil
                return object as! T
            }

            fatalError("object of type \(key) is not registered")
        }
    }

    // MARK: Private

    private let lock = UnfairLock()
    private var objects: [ObjectIdentifier: AnyObject] = [:]
    private var factories: [ObjectIdentifier: () -> AnyObject] = [:]
}