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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::TokenStream;
use quote::quote;
use syn::{DataEnum, Fields, Token, Variant};
use syn::punctuated::Punctuated;
#[must_use]
pub fn decode_enum(data: &DataEnum) -> TokenStream {
let mut match_arms = Punctuated::<TokenStream, Token![,]>::new();
for (discriminant, variant) in DiscriminantIter::new(&data.variants) {
let mut chain_commands = Punctuated::<TokenStream, Token![,]>::new();
for field in &variant.fields {
let command = field.ident
.as_ref()
.map_or_else(
|| quote! { ::bzipper::Decode::decode(stream)? },
|field_name| quote! { #field_name: ::bzipper::Decode::decode(stream)? },
);
chain_commands.push(command);
}
let value = match *variant {
Variant { ident: ref variant_name, fields: Fields::Named( ..), .. } => quote! { Self::#variant_name { #chain_commands } },
Variant { ident: ref variant_name, fields: Fields::Unnamed(..), .. } => quote! { Self::#variant_name(#chain_commands) },
Variant { ident: ref variant_name, fields: Fields::Unit, .. } => quote! { Self::#variant_name },
};
match_arms.push(quote! { #discriminant => #value });
}
match_arms.push(quote! {
value => return ::core::result::Result::Err(::bzipper::error::DecodeError::InvalidDiscriminant(value))
});
quote! {
#[inline]
fn decode(stream: &mut ::bzipper::IStream) -> ::core::result::Result<Self, ::bzipper::error::DecodeError> {
let value = match (<isize as ::bzipper::Decode>::decode(stream)?) { #match_arms };
Ok(value)
}
}
}
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