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use proc_macro::TokenStream;
use quote::quote;
use syn::{
self, braced,
parse::{Parse, ParseStream, Result},
parse_macro_input, DeriveInput, FieldsNamed, Ident, LitInt, Token,
};
fn as_packet_derive(input: TokenStream, state: proc_macro2::TokenStream) -> TokenStream {
let DeriveInput { ident, data, .. } = parse_macro_input!(input);
let fields = match &data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => fields,
_ => panic!("#[derive(*Packet)] can only be used on structs"),
};
let FieldsNamed { named: _, .. } = match fields {
syn::Fields::Named(f) => f,
_ => panic!("#[derive(*Packet)] can only be used on structs with named fields"),
};
let variant_name = variant_name_from(&ident);
let contents = quote! {
impl #ident {
pub fn get(self) -> #state {
#state::#variant_name(self)
}
pub fn write(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
azalea_buf::McBufWritable::write_into(self, buf)
}
pub fn read(
buf: &mut std::io::Cursor<&[u8]>,
) -> Result<#state, azalea_buf::BufReadError> {
use azalea_buf::McBufReadable;
Ok(Self::read_from(buf)?.get())
}
}
};
contents.into()
}
#[proc_macro_derive(ServerboundGamePacket, attributes(var))]
pub fn derive_serverbound_game_packet(input: TokenStream) -> TokenStream {
as_packet_derive(input, quote! {crate::packets::game::ServerboundGamePacket})
}
#[proc_macro_derive(ServerboundHandshakePacket, attributes(var))]
pub fn derive_serverbound_handshake_packet(input: TokenStream) -> TokenStream {
as_packet_derive(
input,
quote! {crate::packets::handshake::ServerboundHandshakePacket},
)
}
#[proc_macro_derive(ServerboundLoginPacket, attributes(var))]
pub fn derive_serverbound_login_packet(input: TokenStream) -> TokenStream {
as_packet_derive(
input,
quote! {crate::packets::login::ServerboundLoginPacket},
)
}
#[proc_macro_derive(ServerboundStatusPacket, attributes(var))]
pub fn derive_serverbound_status_packet(input: TokenStream) -> TokenStream {
as_packet_derive(
input,
quote! {crate::packets::status::ServerboundStatusPacket},
)
}
#[proc_macro_derive(ClientboundGamePacket, attributes(var))]
pub fn derive_clientbound_game_packet(input: TokenStream) -> TokenStream {
as_packet_derive(input, quote! {crate::packets::game::ClientboundGamePacket})
}
#[proc_macro_derive(ClientboundHandshakePacket, attributes(var))]
pub fn derive_clientbound_handshake_packet(input: TokenStream) -> TokenStream {
as_packet_derive(
input,
quote! {crate::packets::handshake::ClientboundHandshakePacket},
)
}
#[proc_macro_derive(ClientboundLoginPacket, attributes(var))]
pub fn derive_clientbound_login_packet(input: TokenStream) -> TokenStream {
as_packet_derive(
input,
quote! {crate::packets::login::ClientboundLoginPacket},
)
}
#[proc_macro_derive(ClientboundStatusPacket, attributes(var))]
pub fn derive_clientbound_status_packet(input: TokenStream) -> TokenStream {
as_packet_derive(
input,
quote! {crate::packets::status::ClientboundStatusPacket},
)
}
#[derive(Debug)]
struct PacketIdPair {
id: u32,
module: Ident,
name: Ident,
}
#[derive(Debug)]
struct PacketIdMap {
packets: Vec<PacketIdPair>,
}
impl Parse for PacketIdMap {
fn parse(input: ParseStream) -> Result<Self> {
let mut packets = vec![];
while let Ok(packet_id) = input.parse::<LitInt>() {
let packet_id = packet_id.base10_parse::<u32>()?;
input.parse::<Token![:]>()?;
let module: Ident = input.parse()?;
input.parse::<Token![::]>()?;
let name: Ident = input.parse()?;
packets.push(PacketIdPair {
id: packet_id,
module,
name,
});
if input.parse::<Token![,]>().is_err() {
break;
}
}
Ok(PacketIdMap { packets })
}
}
#[derive(Debug)]
struct DeclareStatePackets {
name: Ident,
serverbound: PacketIdMap,
clientbound: PacketIdMap,
}
impl Parse for DeclareStatePackets {
fn parse(input: ParseStream) -> Result<Self> {
let name = input.parse()?;
input.parse::<Token![,]>()?;
let serverbound_token: Ident = input.parse()?;
if serverbound_token != "Serverbound" {
return Err(syn::Error::new(
serverbound_token.span(),
"Expected `Serverbound`",
));
}
input.parse::<Token![=>]>()?;
let content;
braced!(content in input);
let serverbound = content.parse()?;
input.parse::<Token![,]>()?;
let clientbound_token: Ident = input.parse()?;
if clientbound_token != "Clientbound" {
return Err(syn::Error::new(
clientbound_token.span(),
"Expected `Clientbound`",
));
}
input.parse::<Token![=>]>()?;
let content;
braced!(content in input);
let clientbound = content.parse()?;
Ok(DeclareStatePackets {
name,
serverbound,
clientbound,
})
}
}
#[proc_macro]
pub fn declare_state_packets(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeclareStatePackets);
let serverbound_state_name =
Ident::new(&format!("Serverbound{}", input.name), input.name.span());
let clientbound_state_name =
Ident::new(&format!("Clientbound{}", input.name), input.name.span());
let state_name_litstr = syn::LitStr::new(&input.name.to_string(), input.name.span());
let has_serverbound_packets = !input.serverbound.packets.is_empty();
let has_clientbound_packets = !input.clientbound.packets.is_empty();
let mut serverbound_enum_contents = quote!();
let mut clientbound_enum_contents = quote!();
let mut serverbound_id_match_contents = quote!();
let mut clientbound_id_match_contents = quote!();
let mut serverbound_write_match_contents = quote!();
let mut clientbound_write_match_contents = quote!();
let mut serverbound_read_match_contents = quote!();
let mut clientbound_read_match_contents = quote!();
for PacketIdPair { id, module, name } in input.serverbound.packets {
let variant_name = variant_name_from(&name);
let name_litstr = syn::LitStr::new(&name.to_string(), name.span());
serverbound_enum_contents.extend(quote! {
#variant_name(#module::#name),
});
serverbound_id_match_contents.extend(quote! {
#serverbound_state_name::#variant_name(_packet) => #id,
});
serverbound_write_match_contents.extend(quote! {
#serverbound_state_name::#variant_name(packet) => packet.write(buf),
});
serverbound_read_match_contents.extend(quote! {
#id => {
let data = #module::#name::read(buf).map_err(|e| crate::read::ReadPacketError::Parse {
source: e,
packet_id: #id,
backtrace: Box::new(std::backtrace::Backtrace::capture()),
packet_name: #name_litstr.to_string(),
})?;
#[cfg(debug_assertions)]
{
let mut leftover = Vec::new();
let _ = std::io::Read::read_to_end(buf, &mut leftover);
if !leftover.is_empty() {
return Err(Box::new(crate::read::ReadPacketError::LeftoverData { packet_name: #name_litstr.to_string(), data: leftover }));
}
}
data
},
});
}
for PacketIdPair { id, module, name } in input.clientbound.packets {
let name_litstr = syn::LitStr::new(&name.to_string(), name.span());
let variant_name = variant_name_from(&name);
clientbound_enum_contents.extend(quote! {
#variant_name(#module::#name),
});
clientbound_id_match_contents.extend(quote! {
#clientbound_state_name::#variant_name(_packet) => #id,
});
clientbound_write_match_contents.extend(quote! {
#clientbound_state_name::#variant_name(packet) => packet.write(buf),
});
clientbound_read_match_contents.extend(quote! {
#id => {
let data = #module::#name::read(buf).map_err(|e| crate::read::ReadPacketError::Parse {
source: e,
packet_id: #id,
backtrace: Box::new(std::backtrace::Backtrace::capture()),
packet_name: #name_litstr.to_string(),
})?;
#[cfg(debug_assertions)]
{
let mut leftover = Vec::new();
let _ = std::io::Read::read_to_end(buf, &mut leftover);
if !leftover.is_empty() {
return Err(
Box::new(
crate::read::ReadPacketError::LeftoverData {
packet_name: #name_litstr.to_string(),
data: leftover
}
)
);
}
}
data
},
});
}
if !has_serverbound_packets {
serverbound_id_match_contents.extend(quote! {
_ => unreachable!("This enum is empty and can't exist.")
});
serverbound_write_match_contents.extend(quote! {
_ => unreachable!("This enum is empty and can't exist.")
});
}
if !has_clientbound_packets {
clientbound_id_match_contents.extend(quote! {
_ => unreachable!("This enum is empty and can't exist.")
});
clientbound_write_match_contents.extend(quote! {
_ => unreachable!("This enum is empty and can't exist.")
});
}
let mut contents = quote! {
#[derive(Clone, Debug)]
pub enum #serverbound_state_name
where
Self: Sized,
{
#serverbound_enum_contents
}
#[derive(Clone, Debug)]
pub enum #clientbound_state_name
where
Self: Sized,
{
#clientbound_enum_contents
}
};
contents.extend(quote! {
#[allow(unreachable_code)]
impl crate::packets::ProtocolPacket for #serverbound_state_name {
fn id(&self) -> u32 {
match self {
#serverbound_id_match_contents
}
}
fn write(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
match self {
#serverbound_write_match_contents
}
}
fn read(
id: u32,
buf: &mut std::io::Cursor<&[u8]>,
) -> Result<#serverbound_state_name, Box<crate::read::ReadPacketError>>
where
Self: Sized,
{
Ok(match id {
#serverbound_read_match_contents
_ => return Err(Box::new(crate::read::ReadPacketError::UnknownPacketId { state_name: #state_name_litstr.to_string(), id })),
})
}
}
});
contents.extend(quote! {
#[allow(unreachable_code)]
impl crate::packets::ProtocolPacket for #clientbound_state_name {
fn id(&self) -> u32 {
match self {
#clientbound_id_match_contents
}
}
fn write(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
match self {
#clientbound_write_match_contents
}
}
fn read(
id: u32,
buf: &mut std::io::Cursor<&[u8]>,
) -> Result<#clientbound_state_name, Box<crate::read::ReadPacketError>>
where
Self: Sized,
{
Ok(match id {
#clientbound_read_match_contents
_ => return Err(Box::new(crate::read::ReadPacketError::UnknownPacketId { state_name: #state_name_litstr.to_string(), id })),
})
}
}
});
contents.into()
}
fn variant_name_from(name: &syn::Ident) -> syn::Ident {
let mut variant_name = name.to_string();
if variant_name.starts_with("Clientbound") {
variant_name = variant_name["Clientbound".len()..].to_string();
} else if variant_name.starts_with("Serverbound") {
variant_name = variant_name["Serverbound".len()..].to_string();
}
if variant_name.ends_with("Packet") {
variant_name = variant_name[..variant_name.len() - "Packet".len()].to_string();
}
syn::Ident::new(&variant_name, name.span())
}