/// <summary>
/// Registers <see cref="KeyedServiceCollection{TService, TKey}"/> instance in <see cref="IServiceCollection"/> as singleton.
/// </summary>
/// <typeparam name="TService">Implementation contract of registrations kept in collection</typeparam>
/// <typeparam name="TKey">Type of key we will distinguish implementations with</typeparam>
/// <param name="services">Services collection</param>
/// <returns>Registered instance</returns>
public static KeyedServiceCollection <TService, TKey> AddKeyedServiceCollection <TService, TKey>(
this IServiceCollection services)
{
var collection = new KeyedServiceCollection <TService, TKey>();
services.AddSingleton(collection);
return(collection);
}
/// <summary>
/// Creates instance <see cref="KeyedServiceCollection{TService, TKey}"/>.
/// This is generaly meant to be used with <see cref="IServiceProvider"/>.
/// The <see cref="KeyedServiceProvider{TService, TKey}"/> instance is registered with the first service of <see cref="TService"/> inside <see cref="KeyedServiceProviderExtensions.AddKeyedService{TService, TImplementation, TKey}(Extensions.DependencyInjection.IServiceCollection, TKey, Action{Extensions.DependencyInjection.IServiceCollection})"/>.
/// </summary>
/// <param name="serviceProvider">Instance of <see cref="IServiceProvider"/>. The <see cref="IServiceProvider"/> can injects itself.</param>
/// <param name="implementations">Registered implementations collection under the same contract. The collection should be registered in services collection as singleton. You can do that with <see cref="KeyedServiceProviderExtensions.AddKeyedServiceCollection{TService, TKey}(Extensions.DependencyInjection.IServiceCollection)"/> extension.</param>
public KeyedServiceProvider(IServiceProvider serviceProvider, KeyedServiceCollection <TService, TKey> implementations)
{
_lookUp = key =>
{
Type resolvedServiceType = implementations[key];
return((TService)serviceProvider.GetService(resolvedServiceType));
};
}