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|
use quote::{quote, ToTokens};
use syn::{self, punctuated::Punctuated, token::Comma, Data, Field, FieldsNamed, Ident};
fn read_named_fields(
named: &Punctuated<Field, Comma>,
) -> (Vec<proc_macro2::TokenStream>, Vec<&Option<Ident>>) {
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<_>>();
(read_fields, read_field_names)
}
pub fn create_impl_mcbufreadable(ident: &Ident, data: &Data) -> proc_macro2::TokenStream {
match data {
syn::Data::Struct(syn::DataStruct { fields, .. }) => {
let syn::Fields::Named(FieldsNamed { named, .. }) = fields else {
panic!("#[derive(McBuf)] can only be used on structs with named fields")
};
let (read_fields, read_field_names) = read_named_fields(named);
quote! {
impl azalea_buf::McBufReadable for #ident {
fn read_from(buf: &mut std::io::Cursor<&[u8]>) -> 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;
let mut first = true;
let mut first_reader = None;
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 (is {e:?})"),
},
syn::Expr::Unary(_) => {
panic!("Negative enum discriminants are not supported")
}
_ => {
panic!("Error parsing enum discriminant as literal (is {:?})", d.1)
}
}
}
None => {
if !first {
variant_discrim += 1;
}
}
}
let reader = match &variant.fields {
syn::Fields::Named(f) => {
let (read_fields, read_field_names) = read_named_fields(&f.named);
quote! {
#(#read_fields)*
Ok(#ident::#variant_name {
#(#read_field_names: #read_field_names),*
})
}
}
syn::Fields::Unnamed(fields) => {
let mut reader_code = quote! {};
for f in &fields.unnamed {
if f.attrs.iter().any(|attr| attr.path.is_ident("var")) {
reader_code.extend(quote! {
Self::#variant_name(azalea_buf::McBufVarReadable::var_read_from(buf)?),
});
} else {
reader_code.extend(quote! {
Self::#variant_name(azalea_buf::McBufReadable::read_from(buf)?),
});
}
}
quote! { Ok(#reader_code) }
}
syn::Fields::Unit => quote! {
Ok(Self::#variant_name)
},
};
if first {
first_reader = Some(reader.clone());
first = false;
};
match_contents.extend(quote! {
#variant_discrim => {
#reader
},
});
}
let first_reader = first_reader.expect("There should be at least one variant");
quote! {
impl azalea_buf::McBufReadable for #ident {
fn read_from(buf: &mut std::io::Cursor<&[u8]>) -> Result<Self, azalea_buf::BufReadError> {
let id = azalea_buf::McBufVarReadable::var_read_from(buf)?;
Self::read_from_id(buf, id)
}
}
impl #ident {
pub fn read_from_id(buf: &mut std::io::Cursor<&[u8]>, id: u32) -> Result<Self, azalea_buf::BufReadError> {
match id {
#match_contents
// you'd THINK this throws an error, but mojang decided to make it default for some reason
_ => {#first_reader}
}
}
}
}
}
_ => panic!("#[derive(McBuf)] can only be used on structs"),
}
}
|
