private static GenericHandlerDelegate GetHandlerMethod(IExportEvent exportEvent)
{
return(HandlerMethodMap.GetOrAdd(exportEvent.GetType(), type =>
{
var payloadType = GetPayloadType(type);
if (payloadType == null)
{
return null;
}
var handlersType = typeof(IEnumerable <>).MakeGenericType(
typeof(IExportEventHandler <>).MakeGenericType(payloadType)
);
var eventType = typeof(IExportEvent <>).MakeGenericType(payloadType);
var method = HandleGenericEventMethod.MakeGenericMethod(payloadType);
var handlersParam = Expression.Parameter(typeof(object), "handlers");
var eventParam = Expression.Parameter(typeof(IExportEvent), "exportEvent");
var tokenParam = Expression.Parameter(typeof(CancellationToken), "token");
var castHandlers = Expression.Convert(handlersParam, handlersType);
var castEvent = Expression.Convert(eventParam, eventType);
var callExpression = Expression.Call(method, castHandlers, castEvent, tokenParam);
var lambda = Expression.Lambda <GenericHandlerDelegate>(callExpression, handlersParam, eventParam, tokenParam);
return lambda.Compile();
}));
}
private static Type GetHandlerType(IExportEvent exportEvent)
{
return(EventHandlerTypeMap.GetOrAdd(exportEvent.GetType(), type =>
{
var payloadType = GetPayloadType(type);
if (payloadType == null)
{
return null;
}
var handlerType = typeof(IExportEventHandler <>).MakeGenericType(payloadType);
var enumerableType = typeof(IEnumerable <>).MakeGenericType(handlerType);
return enumerableType;
}));
}