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use super::*;
use syn::punctuated::Iter;
impl Expand<'_, '_> {
pub fn encoder(&mut self) {
let crate_path = &self.crate_path;
let enum_repr = self.enum_repr.as_ref();
let is_unit_enum = &self.is_unit_enum;
let output = &mut self.output;
let DeriveInput {
data,
ident,
generics,
..
} = self.input;
let body = quote(|o| {
match data {
Data::Struct(object) => match &object.fields {
Fields::Named(fields) => fields.named.iter().for_each(|f| {
encode_field(f, field(&f.ident), o);
}),
Fields::Unnamed(fields) => {
fields.unnamed.iter().enumerate().for_each(|(idx, f)| {
encode_field(f, field(Index::from(idx)), o);
})
}
Fields::Unit => {}
},
Data::Enum(enum_data) => {
let items = quote(|o| {
let mut discriminator = Discriminator::new(false);
let repr = match enum_repr {
Some(repr) => repr,
None => "isize",
};
for Variant {
ident,
fields,
discriminant,
..
} in &enum_data.variants
{
let mut encoders = Token(TokenStream::new());
let alias = quote(|o| {
match &fields {
Fields::Named(f) => {
let alias = make_alias(true, f.named.iter(), &mut encoders);
quote!(o, {{ #alias }});
}
Fields::Unnamed(f) => {
let alias =
make_alias(false, f.unnamed.iter(), &mut encoders);
quote!(o, {( #alias )});
}
Fields::Unit => {}
};
});
let index = discriminator.get(discriminant);
let encode_index = quote(|o| {
if enum_repr.is_none() && !is_unit_enum {
quote!(o, {
E::encode::<C>(&BEU15(#index), c)?;
});
return;
}
let repr = Ident::new(repr, Span::call_site());
quote!(o, {
#repr::encode::<C>(&(#index), c)?;
});
});
quote!(o, {
Self:: #ident #alias => {
#encode_index
#encoders
}
});
}
});
if !is_unit_enum && enum_repr.is_none() {
quote!(o, {
use #crate_path::var_int::BEU15;
});
}
quote!(o, {
match self {
#items
}
});
}
Data::Union(_) => {
panic!("`Encode` implementation for `union` is not yet stabilized")
}
};
});
let (_, ty_generics, where_clause) = generics.split_for_impl();
let bound: TypeParamBound = parse_quote!(#crate_path::Encode);
let mut params = generics.params.clone();
for param in params.iter_mut() {
if let GenericParam::Type(ty) = param {
ty.bounds.push(bound.clone())
}
}
quote!(output, {
impl<#params> #crate_path::Encode for #ident #ty_generics #where_clause {
fn encode<const C: u16>(&self, c: &mut (impl ::std::io::Write + ?::std::marker::Sized)) -> ::std::io::Result<()> {
use #crate_path::Encode as E;
#body
::std::result::Result::Ok(())
}
}
});
}
}
fn make_alias<'a>(
is_named: bool,
fields: Iter<'a, Field>,
encoders: &'a mut TokenStream,
) -> Token<impl FnOnce(&mut TokenStream) + 'a> {
quote(move |o| {
for (i, f) in fields.enumerate() {
let alias = Ident::new(&format!("_{i}"), Span::call_site());
encode_field(f, &alias, encoders);
if is_named {
let name = &f.ident;
quote!(o, {
#name: #alias,
});
} else {
quote!(o, { #alias, });
}
}
})
}
fn field(name: impl IntoTokens) -> Token<impl FnOnce(&mut TokenStream)> {
quote(move |o| {
quote!(o, { self.#name });
})
}
fn encode_field(f: &Field, field: impl IntoTokens, o: &mut TokenStream) {
let maybe_ref = match &f.ty {
Type::Reference(_) => None,
ty => Some(Token)),
};
quote!(o, {
E::encode::<C>(#maybe_ref #field, c)?;
});
}