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// Copyright 2024 Gabriel Bjørnager Jensen.
//
// This file is part of bZipper.
//
// bZipper is free software: you can redistribute
// it and/or modify it under the terms of the GNU
// Lesser General Public License as published by
// the Free Software Foundation, either version 3
// of the License, or (at your option) any later
// version.
//
// bZipper is distributed in the hope that it will
// be useful, but WITHOUT ANY WARRANTY; without
// even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Less-
// er General Public License along with bZipper. If
// not, see <https://www.gnu.org/licenses/>.
use crate::DiscriminantIter;
use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::{
DataEnum,
Fields,
Ident,
Variant,
};
#[must_use]
pub fn encode_enum(data: &DataEnum) -> TokenStream {
let mut match_arms = Vec::new();
// Iterate over each variant and give it a unique
// encoding scheme.
for (discriminant, variant) in DiscriminantIter::new(&data.variants) {
// The original identifiers of the fields:
let mut field_names = Vec::new();
// The captured field identifiers:
let mut field_captures = Vec::new();
for (index, field) in variant.fields.iter().enumerate() {
let capture = Ident::new(&format!("v{index}"), Span::call_site());
field_names.push(&field.ident);
field_captures.push(capture);
}
let pattern = match *variant {
Variant { ident: ref variant_name, fields: Fields::Named( ..), .. } => quote! { Self::#variant_name { #(#field_names: ref #field_captures, )* } },
Variant { ident: ref variant_name, fields: Fields::Unnamed(..), .. } => quote! { Self::#variant_name(#(ref #field_captures)*) },
Variant { ident: ref variant_name, fields: Fields::Unit, .. } => quote! { Self::#variant_name },
};
match_arms.push(quote! {
#pattern => {
::bzipper::Encode::encode(&#discriminant, stream)?;
#(::bzipper::Encode::encode(#field_captures, stream)?;)*
}
});
}
quote! {
#[inline]
fn encode(&self, stream: &mut ::bzipper::OStream) -> ::core::result::Result<(), ::bzipper::error::EncodeError> {
match *self {
#(#match_arms)*
}
Ok(())
}
}
}
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