Function derive

crates/csskit_derives/src/feature_metadata.rs:13–149

(input: DeriveInput)

}

pub fn derive(input: DeriveInput) -> Result<TokenStream> {
	let atom = atom_from_attrs(&input.attrs).ok_or_else(|| {
		Error::new(input.ident.span(), "#[derive(FeatureMetadata)] requires #[feature_metadata(CssAtomSet::Atom)]")
	})?;

	let ident = &input.ident;
	let (impl_generics, type_generics, where_clause) = input.generics.split_for_impl();

	let variants = match &input.data {
		Data::Enum(e) => &e.variants,
		_ => return Err(Error::new(ident.span(), "#[derive(FeatureMetadata)] requires an enum")),
	};

	let mut arms = Vec::new();

	for variant in variants {
		let vname = &variant.ident;
		match vname.to_string().as_str() {
			// discrete_feature! / boolean_feature! colon form
			"WithValue" => {
				arms.push(quote! {
					Self::WithValue(_, _, _, value, _) => {
						use css_lexer::ToSpan;
						crate::ConditionalFeature::Plain {
							name: #atom,
							value: Some(value.to_span()),
						}
					}
				});
			}
			// discrete_feature! / boolean_feature! bare form
			"Bare" => {
				arms.push(quote! {
					Self::Bare(_, _, _) => crate::ConditionalFeature::Plain {
						name: #atom,
						value: None,
					}
				});
			}
			// ranged_feature! exact colon form
			"Exact" => {
				arms.push(quote! {
					Self::Exact(_, _, _, value, _) => {
						use css_lexer::ToSpan;
						crate::ConditionalFeature::Ranged {
							name: #atom,
							form: crate::RangedForm::Exact { value: value.to_span() },
						}
					}
				});
			}
			// ranged_feature! legacy min form
			"Min" => {
				arms.push(quote! {
					Self::Min(_, _, _, value, _) => {
						use css_lexer::ToSpan;
						crate::ConditionalFeature::Ranged {
							name: #atom,