/// <summary>
/// Registers a dependency
/// </summary>
/// <typeparam name="TDependency">The interface / base class of the dependency</typeparam>
/// <typeparam name="TImplementation">The implementation class to use</typeparam>
public static void Register <TDependency, TImplementation>()
where TDependency : class
where TImplementation : TDependency
{
lock (dependencyLock)
{
if (dependencies.ContainsKey(typeof(TDependency)))
{
throw new AlreadyRegisteredDependencyException(typeof(TDependency)); // dependency already registered
}
dependencies[typeof(TDependency)] = new TranscientDependencyData
{
ImplementationType = typeof(TImplementation),
};
}
}
private void GetConstructorInfo(TranscientDependencyData dependencyData)
{
var constructors = dependencyData.ImplementationType.GetConstructors();
if (constructors.Length == 0)
{
throw new ImplementationNotInstanciableException(dependencyData.ImplementationType);
}
dependencyData.ConstructorInfo = TryGetFirstEligibleConstructor(dependencyData);
if (dependencyData.ConstructorInfo is null)
{
throw new NoSuitableConstructorFoundException(dependencyData.ImplementationType);
}
}
/// <summary>
/// Resovles a dependency using the type of the dependency interface / base class
/// </summary>
/// <param name="dependencyData">The data containing the implementation type and, if already resolved, the constructor</param>
/// <param name="dependencyLock">Locks the dependency service to ensure if to be thread safe</param>
/// <returns></returns>
public object Resolve(TranscientDependencyData dependencyData, object dependencyLock)
{
// lock the dependency service for it to be thread safe
// Getting the constructor info modifies the DependencyService
// the lock avoid collision and doing the same thing twice.
lock (dependencyLock)
{
if (dependencyData.ConstructorInfo is null)
{
GetConstructorInfo(dependencyData);
}
}
// Release the lock as soon and possible
// Construct(DependencyData) will not modify the DependencyInjectionService
return(Construct(dependencyData));
}
private object Construct(TranscientDependencyData dependencyData)
{
var parameters = dependencyData.ConstructorInfo.GetParameters();
List <object> constructorParameters = new List <object>();
try
{
foreach (var parameter in parameters)
{
var paramType = parameter.ParameterType;
constructorParameters.Add(DependencyInjectionService.Resolve(paramType));
}
return(Activator.CreateInstance(dependencyData.ImplementationType, constructorParameters.ToArray()));
}
catch (NotRegisteredDependencyException)
{
return(null);
}
}
private ConstructorInfo TryGetFirstEligibleConstructor(TranscientDependencyData dependencyData)
{
foreach (var constructor in dependencyData.ImplementationType.GetConstructors())
{
var eligible = true;
foreach (var parameter in constructor.GetParameters())
{
if (!DependencyInjectionService.IsRegistered(parameter.ParameterType))
{
eligible = false;
break;
}
}
if (eligible)
{
return(constructor);
}
}
return(null);
}
/// <summary>
/// Resovles a dependency using the generic as dependency interface / base class
/// </summary>
/// <typeparam name="TDependency">the dependency interface / base class</typeparam>
/// <param name="dependencyData">The data containing the implementation type and, if already resolved, the constructor</param>
/// <param name="dependencyLock">Locks the dependency service to ensure if to be thread safe</param>
/// <returns></returns>
public TDependency Resolve <TDependency>(TranscientDependencyData dependencyData, object dependencyLock)
{
return((TDependency)Resolve(dependencyData, dependencyLock));
}