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|
use proc_macro::TokenStream;
use quote::{quote, ToTokens};
use syn::{self, parse_macro_input, Data, DeriveInput, FieldsNamed, Ident};
fn create_impl_mcbufreadable(ident: &Ident, data: &Data) -> proc_macro2::TokenStream {
match data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => {
let FieldsNamed { named, .. } = match fields {
syn::Fields::Named(f) => f,
_ => panic!("#[derive(McBuf)] can only be used on structs with named fields"),
};
let read_fields = named
.iter()
.map(|f| {
let field_name = &f.ident;
let field_type = &f.ty;
// do a different buf.write_* for each field depending on the type
// if it's a string, use buf.write_string
match field_type {
syn::Type::Path(_) | syn::Type::Array(_) => {
if f.attrs.iter().any(|a| a.path.is_ident("var")) {
quote! {
let #field_name = azalea_buf::McBufVarReadable::var_read_from(buf)?;
}
} else {
quote! {
let #field_name = azalea_buf::McBufReadable::read_from(buf)?;
}
}
}
_ => panic!(
"Error reading field {}: {}",
field_name.clone().unwrap(),
field_type.to_token_stream()
),
}
})
.collect::<Vec<_>>();
let read_field_names = named.iter().map(|f| &f.ident).collect::<Vec<_>>();
quote! {
impl azalea_buf::McBufReadable for #ident {
fn read_from(buf: &mut impl std::io::Read) -> Result<Self, azalea_buf::BufReadError> {
#(#read_fields)*
Ok(#ident {
#(#read_field_names: #read_field_names),*
})
}
}
}
}
syn::Data::Enum(syn::DataEnum { variants, .. }) => {
let mut match_contents = quote!();
let mut variant_discrim: u32 = 0;
for variant in variants {
let variant_name = &variant.ident;
match &variant.discriminant.as_ref() {
Some(d) => {
variant_discrim = match &d.1 {
syn::Expr::Lit(e) => match &e.lit {
syn::Lit::Int(i) => i.base10_parse().unwrap(),
_ => panic!("Error parsing enum discriminant as int"),
},
syn::Expr::Unary(_) => {
panic!("Negative enum discriminants are not supported")
}
_ => {
panic!("Error parsing enum discriminant as literal (is {:?})", d.1)
}
}
}
None => {
variant_discrim += 1;
}
}
match_contents.extend(quote! {
#variant_discrim => Ok(Self::#variant_name),
});
}
quote! {
impl azalea_buf::McBufReadable for #ident {
fn read_from(buf: &mut impl std::io::Read) -> Result<Self, azalea_buf::BufReadError>
{
let id = azalea_buf::McBufVarReadable::var_read_from(buf)?;
match id {
#match_contents
_ => Err(azalea_buf::BufReadError::UnexpectedEnumVariant { id: id as i32 }),
}
}
}
}
}
_ => panic!("#[derive(McBuf)] can only be used on structs"),
}
}
fn create_impl_mcbufwritable(ident: &Ident, data: &Data) -> proc_macro2::TokenStream {
match data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => {
let FieldsNamed { named, .. } = match fields {
syn::Fields::Named(f) => f,
_ => panic!("#[derive(McBuf)] can only be used on structs with named fields"),
};
let write_fields = named
.iter()
.map(|f| {
let field_name = &f.ident;
let field_type = &f.ty;
// do a different buf.write_* for each field depending on the type
// if it's a string, use buf.write_string
match field_type {
syn::Type::Path(_) | syn::Type::Array(_) => {
if f.attrs.iter().any(|attr| attr.path.is_ident("var")) {
quote! {
azalea_buf::McBufVarWritable::var_write_into(&self.#field_name, buf)?;
}
} else {
quote! {
azalea_buf::McBufWritable::write_into(&self.#field_name, buf)?;
}
}
}
_ => panic!(
"Error writing field {}: {}",
field_name.clone().unwrap(),
field_type.to_token_stream()
),
}
})
.collect::<Vec<_>>();
quote! {
impl azalea_buf::McBufWritable for #ident {
fn write_into(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
#(#write_fields)*
Ok(())
}
}
}
}
syn::Data::Enum(syn::DataEnum { .. }) => {
quote! {
impl azalea_buf::McBufWritable for #ident {
fn write_into(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
azalea_buf::Writable::write_varint(buf, *self as i32)
}
}
}
}
_ => panic!("#[derive(McBuf)] can only be used on structs"),
}
}
#[proc_macro_derive(McBufReadable, attributes(var))]
pub fn derive_mcbufreadable(input: TokenStream) -> TokenStream {
let DeriveInput { ident, data, .. } = parse_macro_input!(input);
create_impl_mcbufreadable(&ident, &data).into()
}
#[proc_macro_derive(McBufWritable, attributes(var))]
pub fn derive_mcbufwritable(input: TokenStream) -> TokenStream {
let DeriveInput { ident, data, .. } = parse_macro_input!(input);
create_impl_mcbufwritable(&ident, &data).into()
}
#[proc_macro_derive(McBuf, attributes(var))]
pub fn derive_mcbuf(input: TokenStream) -> TokenStream {
let DeriveInput { ident, data, .. } = parse_macro_input!(input);
let writable = create_impl_mcbufwritable(&ident, &data);
let readable = create_impl_mcbufreadable(&ident, &data);
quote! {
#writable
#readable
}
.into()
}
|
