/// <summary>
/// Builds a delegate from a synchronous action.
/// </summary>
/// <typeparam name="TAttributed">Type that contains [EventHandler] methods. This should match DeclaringType property.</typeparam>
/// <typeparam name="TEvent">Type of event that is handled by the EventHandlerAttributeMethod. This should match EventType property.</typeparam>
/// <param name="attributedObjectFactory">Factory delegate which provides an instance of a class that contains methods marked with [EventHandler] attribute.</param>
/// <returns>Delegate that handles an event.</returns>
private MessageHandlerDelegate BuildWrappedSyncDelegate <TAttributed, TEvent>(Func <object> attributedObjectFactory)
where TAttributed : class
where TEvent : class
{
// Create an expression that will invoke the event handler method of a given instance.
ParameterExpression instanceParameterExpression = Expression.Parameter(typeof(TAttributed), "instance");
ParameterExpression eventParameterExpression = Expression.Parameter(typeof(TEvent), "event");
MethodCallExpression callExpression = Expression.Call(instanceParameterExpression, MethodInfo, eventParameterExpression);
// Lambda signature:
// (instance, @event) => instance.HandleEvent(@event);
Action <TAttributed, TEvent> action = Expression.Lambda <Action <TAttributed, TEvent> >(callExpression, new[]
{
instanceParameterExpression,
eventParameterExpression
}).Compile();
return(EventHandlerDelegateBuilder.FromDelegate(attributedObjectFactory, action, yieldSynchronousExecution: YieldSynchronousExecution));
}
/// <summary>
/// Builds a delegate from an asynchronous (non-cancellable) action.
/// </summary>
/// <typeparam name="TAttributed">Type that contains [EventHandler] methods. This should match DeclaringType property.</typeparam>
/// <typeparam name="TEvent">Type of event that is handled by the EventHandlerAttributeMethod. This should match EventType property.</typeparam>
/// <param name="attributedObjectFactory">Factory delegate which provides an instance of a class that contains methods marked with [EventHandler] attribute.</param>
/// <returns>Delegate that handles an event.</returns>
private MessageHandlerDelegate BuildNonCancellableAsyncDelegate <TAttributed, TEvent>(Func <object> attributedObjectFactory)
where TAttributed : class
where TEvent : class
{
// Create an expression that will invoke the event handler method of a given instance.
ParameterExpression instanceParameterExpression = Expression.Parameter(typeof(TAttributed), "instance");
ParameterExpression eventParameterExpression = Expression.Parameter(typeof(TEvent), "event");
MethodCallExpression callExpression = Expression.Call(instanceParameterExpression, MethodInfo, eventParameterExpression);
// Lambda signature:
// (instance, @event) => instance.HandleEventAsync(@event);
Func <TAttributed, TEvent, Task> nonCancellableAsyncDelegate = Expression.Lambda <Func <TAttributed, TEvent, Task> >(callExpression, new[]
{
instanceParameterExpression,
eventParameterExpression
}).Compile();
return(EventHandlerDelegateBuilder.FromDelegate(attributedObjectFactory, nonCancellableAsyncDelegate));
}