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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::Discriminant;
use proc_macro2::TokenStream;
use quote::quote;
use syn::{DataEnum, Fields, Token};
use syn::punctuated::Punctuated;
#[must_use]
pub fn deserialise_enum(data: &DataEnum) -> TokenStream {
let mut match_arms = Punctuated::<TokenStream, Token![,]>::new();
for (index, variant) in data.variants.iter().enumerate() {
let variant_name = &variant.ident;
let discriminant = Discriminant::unwrap_from(index);
let block = if matches!(variant.fields, Fields::Unit) {
quote! { Self }
} else {
let mut chain_commands = Punctuated::<TokenStream, Token![,]>::new();
for field in &variant.fields {
let field_ty = &field.ty;
let command = field.ident
.as_ref()
.map_or_else(
|| quote! { stream.take::<#field_ty>()? },
|field_name| quote! { #field_name: stream.take::<#field_ty>()? }
);
chain_commands.push(command);
}
match variant.fields {
Fields::Named( ..) => quote! { Self::#variant_name { #chain_commands } },
Fields::Unnamed(..) => quote! { Self::#variant_name(#chain_commands) },
Fields::Unit => unreachable!(),
}
};
match_arms.push(quote! { #discriminant => #block });
}
match_arms.push(quote! { value => return Err(::bzipper::Error::InvalidDiscriminant { value }) });
quote! {
fn deserialise(data: &[u8]) -> ::bzipper::Result<Self> {
::core::debug_assert_eq!(data.len(), <Self as ::bzipper::Serialise>::SERIALISED_SIZE);
let mut stream = ::bzipper::Dstream::new(data);
let value = match (stream.take::<u32>()?) { #match_arms };
Ok(value)
}
}
}
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