Function derive

crates/csskit_derives/src/parse.rs:1152–1226

(input: DeriveInput)

}

pub fn derive(input: DeriveInput) -> Result<TokenStream> {
	let mut where_collector = WhereCollector::new();
	let ident = input.ident;
	let generics = &input.generics;
	let generic_with_a = ensure_lifetime_a(generics);
	let (impl_generics, _, _) = generic_with_a.split_for_impl();
	let (_, type_generics, _) = generics.split_for_impl();

	let mut pre_parse_steps = quote! {};
	let mut post_parse_steps = quote! {};
	let parse_arg = ParseArg::from_attributes(&input.attrs)?;
	let parse_mode = parse_arg.parse_mode();
	if let Some(crate::darling_ext::StateArg(state_ident)) = parse_arg.state {
		pre_parse_steps = quote! {
			let state = p.set_state(State::#state_ident);
			#pre_parse_steps
		};
		post_parse_steps = quote! {
			#post_parse_steps
			p.set_state(state);
		};
	}
	if let Some(stop) = parse_arg.stop {
		let kind_ident = &stop.variant;
		pre_parse_steps = if stop.prefix == "Kind" {
			quote! {
				let stop = p.set_stop(KindSet::new(&[Kind::#kind_ident]));
				#pre_parse_steps
			}
		} else {
			quote! {
				let stop = p.set_stop(KindSet::#kind_ident);
				#pre_parse_steps
			}
		};
		post_parse_steps = quote! {
			#post_parse_steps
			p.set_stop(stop);
		};
	}

	let body = match &input.data {
		Data::Union(_) => return Err(Error::new(ident.span(), "Cannot derive Parse on a Union")),
		Data::Struct(data) => derive_struct_body(data, parse_mode, &post_parse_steps, &mut where_collector)?,
		Data::Enum(data) => derive_enum_body(data, &post_parse_steps, &mut where_collector)?,
	};

	let generics = input.generics.clone();
	let mut where_clause = where_collector.extend_where_clause(&generics, parse_quote! { ::css_parse::Parse<'a> });
	// Add Peek<'a> predicate for each collected type param too.
	if let Some(ref mut wc) = where_clause {
		let additional = where_collector.extend_where_clause(&generics, parse_quote! { ::css_parse::Peek<'a> });
		if let Some(additional) = additional {
			for pred in additional.predicates {
				if !wc.predicates.iter().any(|p| p == &pred) {
					wc.predicates.push(pred);
				}
			}