/// <summary>
/// Creates an intercepted object for the specified target using the provided aspect chain.
/// </summary>
/// <param name="serviceType">Type of service object</param>
/// <param name="target">Target object to create an intercepted object for</param>
/// <param name="aspects">Aspects to be used for the service object's method calls</param>
/// <returns>Intercepted service object</returns>
public static object GetInterceptedObject(Type serviceType, object target, AspectChain aspects)
{
if (serviceType == null)
{
throw new ArgumentNullException("serviceType");
}
// --- Check the cache
InterceptedTypeDescriptor interceptor;
if (!s_Interceptors.TryGetValue(serviceType, out interceptor))
{
lock (s_Interceptors)
{
// --- Validate again to prevent a parallel type creation
if (!s_Interceptors.TryGetValue(serviceType, out interceptor))
{
// --- Validate input parameters
if (target == null)
{
throw new ArgumentNullException("target");
}
if (!serviceType.IsInterface || !serviceType.IsInstanceOfType(target))
{
throw new InvalidOperationException("Service type must be an interface" +
" type and the target object must implement that interface.");
}
// --- No generics is accepted
if (serviceType.IsGenericType ||
serviceType.GetMethods().Any(met => met.IsGenericMethod) ||
serviceType.GetInterfaces().Any(intf => intf.IsGenericType ||
intf.GetMethods().Any(met => met.IsGenericMethod)))
{
throw new InvalidOperationException(
"Service type must not have generic parameters or methods.");
}
// --- We do not have any wrapper types for the specified service type
// --- Generate the interceptor type and save it in the cache
interceptor = new InterceptedTypeDescriptor
{
InterceptedType = serviceType,
Methods = GetInterfaceMethods(serviceType)
};
GenerateWrappedType(interceptor, serviceType);
s_Interceptors[serviceType] = interceptor;
}
}
}
// --- Instantiate the wrapped type
var wrappedInstance = Activator.CreateInstance(
interceptor.WrapperType,
new[] { target, aspects });
return(wrappedInstance);
}
/// <summary>
/// Generates an intercepted type for the specified type
/// </summary>
/// <param name="descriptor">Intercepted type descriptor to generate the dynamic code into</param>
/// <param name="interfaceType">Type of interface this type is generated for</param>
/// <returns>Descriptor instance</returns>
private static void GenerateWrappedType(InterceptedTypeDescriptor descriptor, Type interfaceType)
{
// --- Create the dynamic assembly and the dynamic type holding the wrapper
EnsureModuleBuilder();
// --- Create the helper type for method information
var methodHelperType = CreateMethodHelperType(interfaceType);
var invokerHelperType = CreateInvokerHelperType(interfaceType);
var wrapper = CreateWrapperType(interfaceType, methodHelperType, invokerHelperType);
// --- Add a new type to the generated assembly
descriptor.WrapperType = wrapper;
}
