1 files changed, 77 insertions, 0 deletions
diff --git a/bzipper_macros/src/impls/encode_enum.rs b/bzipper_macros/src/impls/encode_enum.rs
new file mode 100644
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--- /dev/null
+++ b/bzipper_macros/src/impls/encode_enum.rs
@@ -0,0 +1,77 @@
+// 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(())
+		}
+	}
+}