Enable splitting protocol in multiple places about lightyear HOT 2 CLOSED

Some ideas to accomplish this:

• use bevy_reflect and reflection extensively
• provide some kind of macro to merge various ComponentProtocols or MessageProtocols into a single enum
• maybe make it possible for ComponentProtocol to be a struct containing enums (or other structs), and provide function to iterate through the different variants (should be doable)

from lightyear.

I read a bit more about reflection.
General idea:

• every Message is registered in the TypeRegistry via Reflection. We also additional type metadata for each message via a TypeData

MessageMetadata {
  frequency: usize
}

Maybe the type data can contain pointers to other useful type functions?
The reflected types might need to have ReflectSerialize and ReflectDeserialize as extra TypeData?

• the frequency is how much we think we'll write this message. Higher frequency messages need to have their types serialized with fewer bytes.

• the bevy::reflect ReflectSerializer reflects &dyn Reflect as a type: value value pair, which is not what we want. However it looks like we can use the TypedReflectSerializer, which just serializes the value itself.

• When we call Protocol::finalize at some point, we go through the registry, get all the types that have MessageMetadata and order them by frequency. Then use Huffman coding to serialize the enum variant, in order to minimize the number of bits written. Maybe have a LightyearSerializer which wraps around TypedReflectSerializer (to have registry access), it starts by serializing the type (With huffman coding) and then serializes the value.

from lightyear.