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|
use proc_macro2::Span;
use quote::{quote, ToTokens};
use syn::{self, punctuated::Punctuated, token::Comma, Data, Field, FieldsNamed, Ident};
fn write_named_fields(
named: &Punctuated<Field, Comma>,
ident_name: Option<&Ident>,
) -> proc_macro2::TokenStream {
let write_fields = named.iter().map(|f| {
let field_name = &f.ident;
let field_type = &f.ty;
let ident_dot_field = match ident_name {
Some(ident) => quote! { &#ident.#field_name },
None => quote! { #field_name },
};
// 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(#ident_dot_field, buf)?;
}
} else {
quote! {
azalea_buf::McBufWritable::write_into(#ident_dot_field, buf)?;
}
}
}
_ => panic!(
"Error writing field {}: {}",
field_name.clone().unwrap(),
field_type.to_token_stream()
),
}
});
quote! { #(#write_fields)* }
}
pub fn create_impl_mcbufwritable(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 write_fields =
write_named_fields(named, Some(&Ident::new("self", Span::call_site())));
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 { variants, .. }) => {
// remember whether it's a data variant so we can do an optimization later
let mut is_data_enum = false;
let mut match_arms = quote!();
let mut match_arms_without_id = quote!();
let mut variant_discrim: u32 = 0;
let mut first = true;
for variant in variants {
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(),
// syn::Lit::Str(s) => s.value(),
_ => 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 {
first = false;
} else {
variant_discrim += 1;
}
}
}
let variant_name = &variant.ident;
// the variant number that we're going to write
let write_the_variant = quote! {
azalea_buf::McBufVarWritable::var_write_into(&#variant_discrim, buf)?;
};
match &variant.fields {
syn::Fields::Named(f) => {
is_data_enum = true;
let field_names = f
.named
.iter()
.map(|f| f.ident.clone().unwrap())
.collect::<Vec<_>>();
let write_fields = write_named_fields(&f.named, None);
match_arms.extend(quote! {
Self::#variant_name { #(#field_names),* } => {
#write_the_variant
#write_fields
}
});
match_arms_without_id.extend(quote! {
Self::#variant_name { #(#field_names),* } => {
#write_fields
}
});
}
syn::Fields::Unit => {
match_arms.extend(quote! {
Self::#variant_name => {
#write_the_variant
}
});
match_arms_without_id.extend(quote! {
Self::#variant_name => {}
});
}
syn::Fields::Unnamed(fields) => {
is_data_enum = true;
let mut writers_code = quote! {};
let mut params_code = quote! {};
for (i, f) in fields.unnamed.iter().enumerate() {
let param_ident = Ident::new(&format!("data{i}"), Span::call_site());
params_code.extend(quote! { #param_ident, });
if f.attrs.iter().any(|attr| attr.path.is_ident("var")) {
writers_code.extend(quote! {
azalea_buf::McBufVarWritable::var_write_into(#param_ident, buf)?;
});
} else {
writers_code.extend(quote! {
azalea_buf::McBufWritable::write_into(#param_ident, buf)?;
});
}
}
match_arms.extend(quote! {
Self::#variant_name(#params_code) => {
#write_the_variant
#writers_code
}
});
match_arms_without_id.extend(quote! {
Self::#variant_name(data) => {
azalea_buf::McBufWritable::write_into(data, buf)?;
}
});
}
}
}
if is_data_enum {
quote! {
impl azalea_buf::McBufWritable for #ident {
fn write_into(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
match self {
#match_arms
}
Ok(())
}
}
impl #ident {
pub fn write_without_id(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
match self {
#match_arms_without_id
}
Ok(())
}
}
}
} else {
// optimization: if it doesn't have data we can just do `as u32`
quote! {
impl azalea_buf::McBufWritable for #ident {
fn write_into(&self, buf: &mut impl std::io::Write) -> Result<(), std::io::Error> {
azalea_buf::McBufVarWritable::var_write_into(&(*self as u32), buf)
}
}
}
}
}
_ => panic!("#[derive(McBuf)] can only be used on structs"),
}
}
|
