1 files changed, 108 insertions, 0 deletions
diff --git a/bzipper_macros/src/impls/serialise_enum.rs b/bzipper_macros/src/impls/serialise_enum.rs
new file mode 100644
index 0000000..8f0693a
--- /dev/null
+++ b/bzipper_macros/src/impls/serialise_enum.rs
@@ -0,0 +1,108 @@
+// 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::Capture;
+
+use proc_macro2::{Span, TokenStream};
+use quote::quote;
+use syn::{DataEnum, Fields, Ident, Token};
+use syn::punctuated::Punctuated;
+
+#[must_use]
+pub fn serialise_enum(data: &DataEnum) -> TokenStream {
+ let mut sizes = Vec::new();
+
+ let mut match_arms = Punctuated::<TokenStream, Token![,]>::new();
+
+ for (index, variant) in data.variants.iter().enumerate() {
+ let mut serialised_size = Punctuated::<TokenStream, Token![+]>::new();
+
+ let name = &variant.ident;
+
+ let discriminant = u32::try_from(index)
+ .expect("enumeration discriminants must be representable in `u32`");
+
+ // Discriminant size:
+ serialised_size.push(quote! { <u32 as ::bzipper::Serialise>::SERIALISED_SIZE });
+
+ let arm = if matches!(variant.fields, Fields::Unit) {
+ quote! { Self::#name => stream.append(&#discriminant)? }
+ } else {
+ let mut captures = Punctuated::<Capture, Token![,]>::new();
+
+ let mut chain_commands = Punctuated::<TokenStream, Token![;]>::new();
+ chain_commands.push(quote! { stream.append(&#discriminant)? });
+
+ for (index, field) in variant.fields.iter().enumerate() {
+ let field_ty = &field.ty;
+
+ let field_name = field.ident
+ .as_ref()
+ .map_or_else(|| Ident::new(&format!("v{index}"), Span::call_site()), Clone::clone);
+
+ serialised_size.push(quote! { <#field_ty as ::bzipper::Serialise>::SERIALISED_SIZE });
+
+ captures.push(Capture {
+ ref_token: Token![ref](Span::call_site()),
+ ident: field_name.clone(),
+ });
+
+ chain_commands.push(quote! { stream.append(#field_name)? });
+ }
+
+ chain_commands.push_punct(Token![;](Span::call_site()));
+
+ match variant.fields {
+ Fields::Named( ..) => quote! { Self::#name { #captures } => { #chain_commands } },
+ Fields::Unnamed(..) => quote! { Self::#name(#captures) => { #chain_commands } },
+ Fields::Unit => unreachable!(),
+ }
+ };
+
+ sizes.push(serialised_size);
+ match_arms.push(arm);
+ }
+
+ let mut size_tests = Punctuated::<TokenStream, Token![else]>::new();
+
+ for size in &sizes {
+ let mut test = Punctuated::<TokenStream, Token![&&]>::new();
+
+ for other_size in &sizes { test.push(quote! { #size >= #other_size }) }
+
+ size_tests.push(quote! { if #test { #size } });
+ }
+
+ size_tests.push(quote! { { core::unreachable!(); } });
+
+ quote! {
+ const SERIALISED_SIZE: usize = const { #size_tests };
+
+ fn serialise(&self, buf: &mut [u8]) -> ::bzipper::Result<()> {
+ ::core::debug_assert_eq!(buf.len(), Self::SERIALISED_SIZE);
+
+ let mut stream = ::bzipper::Sstream::new(buf);
+
+ match (*self) { #match_arms }
+ Ok(())
+ }
+ }
+}