Utilize Rust Macros

[john-bv]

Issue / Question:
We should utilize rust Macros.

Relevance:
Rust macros would save us time when writing protocol implementation, for instance, instead of repeatedly writing implementations for ProtocolEncoder/Decoder we can utilize macros, which will be able to do this for us.

Solution:

#[mcpe_packet(1)]
pub struct LoginPacket {
	pub protocol: u8;
	pub data: BinaryStream;
}

or more advanced:

#[derive(encoder, decoder)]
pub struct BehaviorPack {
	... props
}
#[mcpe_packet(7, "custom")]
pub struct ResourcePacksInfo {
	pub required: bool,
	pub has_scripts: bool,
	pub bpacks: Vec<BehaviorPack>
}

[umaYnit]

This looks like a fun issue 😄 mind if I give this a go?

[john-bv]

go for it

[umaYnit]

should we change ProtocolEncoder trait to

pub trait ProtocolEncoder {
     fn write(&self, dst: &mut BinaryStream);
}

so that some memory copy can be avoided

[john-bv]

Sure, I feel like this won't hurt anything. This was originally recommended by @buchwasa for raknet, which we decided against just because of how often we need to make new streams in raknet.