Extract select_bridge macro. (#869)

bridges/relays/bin-substrate/src/cli/bridge.rs

@@ -0,0 +1,75 @@
+// Copyright 2019-2021 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common 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.
+
+// Parity Bridges Common 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 Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+use structopt::clap::arg_enum;
+
+arg_enum! {
+	#[derive(Debug)]
+	/// Supported full bridges (headers + messages).
+	pub enum FullBridge {
+		MillauToRialto,
+		RialtoToMillau,
+	}
+}
+
+impl FullBridge {
+	/// Return instance index of the bridge pallet in source runtime.
+	pub fn bridge_instance_index(&self) -> u8 {
+		match self {
+			Self::MillauToRialto => MILLAU_TO_RIALTO_INDEX,
+			Self::RialtoToMillau => RIALTO_TO_MILLAU_INDEX,
+		}
+	}
+}
+
+pub const RIALTO_TO_MILLAU_INDEX: u8 = 0;
+pub const MILLAU_TO_RIALTO_INDEX: u8 = 0;
+
+/// The macro allows executing bridge-specific code without going fully generic.
+///
+/// It matches on the [`FullBridge`] enum, sets bridge-specific types or imports and injects
+/// the `$generic` code at every variant.
+#[macro_export]
+macro_rules! select_full_bridge {
+	($bridge: expr, $generic: tt) => {
+		match $bridge {
+			FullBridge::MillauToRialto => {
+				type Source = relay_millau_client::Millau;
+				type Target = relay_rialto_client::Rialto;
+
+				#[allow(unused_imports)]
+				use bp_millau::derive_account_from_rialto_id as derive_account;
+
+				#[allow(unused_imports)]
+				use crate::rialto_millau::millau_messages_to_rialto::run as relay_messages;
+
+				$generic
+			}
+			FullBridge::RialtoToMillau => {
+				type Source = relay_rialto_client::Rialto;
+				type Target = relay_millau_client::Millau;
+
+				#[allow(unused_imports)]
+				use bp_rialto::derive_account_from_millau_id as derive_account;
+
+				#[allow(unused_imports)]
+				use crate::rialto_millau::rialto_messages_to_millau::run as relay_messages;
+
+				$generic
+			}
+		}
+	};
+}