private static HandlerExecutor GetExecutor(Type handlerType, Type messageType, MethodInfo action)
{
Type objectType = typeof (object);
ParameterExpression handlerParameter = Expression.Parameter(objectType, "handler");
ParameterExpression messageParameter = Expression.Parameter(objectType, "message");
MethodCallExpression methodCall =
Expression.Call(
Expression.Convert(handlerParameter, handlerType),
action,
Expression.Convert(messageParameter, messageType));
if (action.ReturnType == typeof (void))
{
var lambda = Expression.Lambda<Action<object, object>>(
methodCall,
handlerParameter,
messageParameter);
Action<object, object> voidExecutor = lambda.Compile();
return (handler, message) =>
{
voidExecutor(handler, message);
return null;
};
}
else
{
var lambda = Expression.Lambda<HandlerExecutor>(
Expression.Convert(methodCall, typeof(object)),
handlerParameter,
messageParameter);
return lambda.Compile();
}
}