pallet_meta_tx/

extension.rs

// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use super::*;
use sp_runtime::impl_tx_ext_default;

/// This type serves as a marker extension to differentiate meta-transactions from regular
/// transactions. It implements the `TransactionExtension` trait and carries constant implicit data
/// ("_meta_tx").
#[derive(Encode, Decode, Clone, Eq, PartialEq, TypeInfo, DebugNoBound, DecodeWithMemTracking)]
#[scale_info(skip_type_params(T))]
pub struct MetaTxMarker<T> {
	_phantom: core::marker::PhantomData<T>,
}

impl<T> MetaTxMarker<T> {
	/// Creates new `TransactionExtension` with implicit meta tx marked.
	pub fn new() -> Self {
		Self { _phantom: Default::default() }
	}
}

impl<T: Config + Send + Sync> TransactionExtension<T::RuntimeCall> for MetaTxMarker<T> {
	const IDENTIFIER: &'static str = "MetaTxMarker";
	type Implicit = [u8; 8];
	type Val = ();
	type Pre = ();
	fn implicit(&self) -> Result<Self::Implicit, TransactionValidityError> {
		Ok(*b"_meta_tx")
	}
	fn weight(&self, _: &T::RuntimeCall) -> Weight {
		Weight::zero()
	}
	impl_tx_ext_default!(T::RuntimeCall; validate prepare);
}