Swinject+OneOf.swift

import Swinject

private let prefix = "<asOneOf:"

private func nameOf<T>(_ serviceType: T) -> String {
    return "\(prefix):\(String(reflecting: serviceType))>"
}

class AggregateBehavior<Common> : Behavior {
    private var factories: [(Resolver) -> Common?] = []
    
    func container<Type, Service>(_ container: Container, didRegisterType type: Type.Type, toService entry: ServiceEntry<Service>, withName name: String?) {
        guard Type.self == Common.self, let name = name, name.starts(with: prefix) else { return }
        
        if factories.isEmpty {
            container.register([Common].self) { resolver in
                return self.factories.map { factory in factory(resolver)! }
            }
        }
        
        factories.append({ resolver in
            let name = nameOf(Service.self)
            return resolver.resolve(Type.self, name: name) as? Common
        })
    }
}

extension Container {
    func aggregate<Service>(_ serviceType: Service.Type) {
        addBehavior(AggregateBehavior<Service>())
    }
}

extension ServiceEntry {
    @discardableResult
    func asOneOf<T>(_ serviceType: T.Type) -> ServiceEntry<Service> {
        let name = nameOf(Service.self)
        return implements(serviceType, name: name)
    }
}