refactor overseer into proc-macro based pattern (#2962)

polkadot/node/overseer/overseer-gen/proc-macro/src/lib.rs

@@ -0,0 +1,94 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot 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 General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+#![deny(unused_crate_dependencies)]
+
+use proc_macro2::{Span, Ident, TokenStream};
+use syn::{parse2, Result};
+use quote::{quote, ToTokens};
+
+mod impl_builder;
+mod impl_misc;
+mod impl_overseer;
+mod parse_attr;
+mod parse_struct;
+mod impl_channels_out;
+mod impl_dispatch;
+mod impl_message_wrapper;
+
+use impl_builder::*;
+use impl_channels_out::*;
+use impl_dispatch::*;
+use impl_message_wrapper::*;
+use impl_misc::*;
+use impl_overseer::*;
+use parse_attr::*;
+use parse_struct::*;
+
+#[cfg(test)]
+mod tests;
+
+#[proc_macro_attribute]
+pub fn overlord(attr: proc_macro::TokenStream, item: proc_macro::TokenStream) -> proc_macro::TokenStream {
+	let attr: TokenStream = attr.into();
+	let item: TokenStream = item.into();
+	impl_overseer_gen(attr, item).unwrap_or_else(|err| err.to_compile_error()).into()
+}
+
+pub(crate) fn impl_overseer_gen(attr: TokenStream, orig: TokenStream) -> Result<proc_macro2::TokenStream> {
+	let args: AttrArgs = parse2(attr)?;
+	let message_wrapper = args.message_wrapper;
+
+	let of: OverseerGuts = parse2(orig)?;
+
+	let support_crate_name = if cfg!(test) {
+		quote!{crate}
+	} else {
+		use proc_macro_crate::{crate_name, FoundCrate};
+		let crate_name = crate_name("polkadot-overseer-gen")
+			.expect("Support crate polkadot-overseer-gen is present in `Cargo.toml`. qed");
+		match crate_name {
+		   FoundCrate::Itself => quote!{crate},
+		   FoundCrate::Name(name) => Ident::new(&name, Span::call_site()).to_token_stream(),
+	   	}
+	};
+	let info = OverseerInfo {
+		support_crate_name,
+		subsystems: of.subsystems,
+		baggage: of.baggage,
+		overseer_name: of.name,
+		message_wrapper,
+		message_channel_capacity: args.message_channel_capacity,
+		signal_channel_capacity: args.signal_channel_capacity,
+		extern_event_ty: args.extern_event_ty,
+		extern_signal_ty: args.extern_signal_ty,
+		extern_error_ty: args.extern_error_ty,
+		extern_network_ty: args.extern_network_ty,
+		outgoing_ty: args.outgoing_ty,
+	};
+
+	let mut additive = impl_overseer_struct(&info);
+	additive.extend(impl_builder(&info));
+
+	additive.extend(impl_overseen_subsystem(&info));
+	additive.extend(impl_channels_out_struct(&info));
+	additive.extend(impl_misc(&info));
+
+	additive.extend(impl_message_wrapper_enum(&info)?);
+	additive.extend(impl_dispatch(&info));
+
+	Ok(additive)
+}