Add FungibleAdapter (#2684)

In the move from the old `Currency` traits to the new `fungible/s` family of traits, we already had the `FungiblesAdapter` and `NonFungiblesAdapter` for multiple fungible and non fungible assets respectively. However, for handling only one fungible asset, we were missing a `FungibleAdapter`, and so used the old `CurrencyAdapter` instead. This PR aims to fill in that gap, and provide the new adapter for more updated examples. I marked the old `CurrencyAdapter` as deprecated as part of this PR, and I'll change it to the new `FungibleAdapter` in a following PR. The two stages are separated so as to not bloat this PR with some name fixes in tests. --------- Co-authored-by: command-bot <>
2026-05-31 16:51:02 +00:00 · 2023-12-14 15:34:35 +01:00
parent 3e4e8c0bd1
commit 10a91f821e
25 changed files with 479 additions and 93 deletions
@@ -0,0 +1,317 @@
+// Copyright (C) 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/>.
+
+//! Adapters to work with [`frame_support::traits::fungible`] through XCM.
+
+use super::MintLocation;
+use frame_support::traits::{
+	tokens::{
+		fungible, Fortitude::Polite, Precision::Exact, Preservation::Preserve, Provenance::Minted,
+	},
+	Get,
+};
+use sp_std::{marker::PhantomData, prelude::*, result};
+use xcm::latest::prelude::*;
+use xcm_executor::traits::{ConvertLocation, Error as MatchError, MatchesFungible, TransactAsset};
+
+/// [`TransactAsset`] implementation that allows the use of a [`fungible`] implementation for
+/// handling an asset in the XCM executor.
+/// Only works for transfers.
+pub struct FungibleTransferAdapter<Fungible, Matcher, AccountIdConverter, AccountId>(
+	PhantomData<(Fungible, Matcher, AccountIdConverter, AccountId)>,
+);
+impl<
+		Fungible: fungible::Mutate<AccountId>,
+		Matcher: MatchesFungible<Fungible::Balance>,
+		AccountIdConverter: ConvertLocation<AccountId>,
+		AccountId: Eq + Clone,
+	> TransactAsset for FungibleTransferAdapter<Fungible, Matcher, AccountIdConverter, AccountId>
+{
+	fn internal_transfer_asset(
+		what: &MultiAsset,
+		from: &MultiLocation,
+		to: &MultiLocation,
+		_context: &XcmContext,
+	) -> result::Result<xcm_executor::Assets, XcmError> {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"internal_transfer_asset what: {:?}, from: {:?}, to: {:?}",
+			what, from, to
+		);
+		// Check we handle the asset
+		let amount = Matcher::matches_fungible(what).ok_or(MatchError::AssetNotHandled)?;
+		let source = AccountIdConverter::convert_location(from)
+			.ok_or(MatchError::AccountIdConversionFailed)?;
+		let dest = AccountIdConverter::convert_location(to)
+			.ok_or(MatchError::AccountIdConversionFailed)?;
+		Fungible::transfer(&source, &dest, amount, Preserve)
+			.map_err(|error| XcmError::FailedToTransactAsset(error.into()))?;
+		Ok(what.clone().into())
+	}
+}
+
+/// [`TransactAsset`] implementation that allows the use of a [`fungible`] implementation for
+/// handling an asset in the XCM executor.
+/// Works for everything but transfers.
+pub struct FungibleMutateAdapter<Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount>(
+	PhantomData<(Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount)>,
+);
+
+impl<
+		Fungible: fungible::Mutate<AccountId>,
+		Matcher: MatchesFungible<Fungible::Balance>,
+		AccountIdConverter: ConvertLocation<AccountId>,
+		AccountId: Eq + Clone,
+		CheckingAccount: Get<Option<(AccountId, MintLocation)>>,
+	> FungibleMutateAdapter<Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount>
+{
+	fn can_accrue_checked(checking_account: AccountId, amount: Fungible::Balance) -> XcmResult {
+		Fungible::can_deposit(&checking_account, amount, Minted)
+			.into_result()
+			.map_err(|_| XcmError::NotDepositable)
+	}
+
+	fn can_reduce_checked(checking_account: AccountId, amount: Fungible::Balance) -> XcmResult {
+		Fungible::can_withdraw(&checking_account, amount)
+			.into_result(false)
+			.map_err(|_| XcmError::NotWithdrawable)
+			.map(|_| ())
+	}
+
+	fn accrue_checked(checking_account: AccountId, amount: Fungible::Balance) {
+		let ok = Fungible::mint_into(&checking_account, amount).is_ok();
+		debug_assert!(ok, "`can_accrue_checked` must have returned `true` immediately prior; qed");
+	}
+
+	fn reduce_checked(checking_account: AccountId, amount: Fungible::Balance) {
+		let ok = Fungible::burn_from(&checking_account, amount, Exact, Polite).is_ok();
+		debug_assert!(ok, "`can_reduce_checked` must have returned `true` immediately prior; qed");
+	}
+}
+
+impl<
+		Fungible: fungible::Mutate<AccountId>,
+		Matcher: MatchesFungible<Fungible::Balance>,
+		AccountIdConverter: ConvertLocation<AccountId>,
+		AccountId: Eq + Clone,
+		CheckingAccount: Get<Option<(AccountId, MintLocation)>>,
+	> TransactAsset
+	for FungibleMutateAdapter<Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount>
+{
+	fn can_check_in(
+		_origin: &MultiLocation,
+		what: &MultiAsset,
+		_context: &XcmContext,
+	) -> XcmResult {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"can_check_in origin: {:?}, what: {:?}",
+			_origin, what
+		);
+		// Check we handle this asset
+		let amount = Matcher::matches_fungible(what).ok_or(MatchError::AssetNotHandled)?;
+		match CheckingAccount::get() {
+			Some((checking_account, MintLocation::Local)) =>
+				Self::can_reduce_checked(checking_account, amount),
+			Some((checking_account, MintLocation::NonLocal)) =>
+				Self::can_accrue_checked(checking_account, amount),
+			None => Ok(()),
+		}
+	}
+
+	fn check_in(_origin: &MultiLocation, what: &MultiAsset, _context: &XcmContext) {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"check_in origin: {:?}, what: {:?}",
+			_origin, what
+		);
+		if let Some(amount) = Matcher::matches_fungible(what) {
+			match CheckingAccount::get() {
+				Some((checking_account, MintLocation::Local)) =>
+					Self::reduce_checked(checking_account, amount),
+				Some((checking_account, MintLocation::NonLocal)) =>
+					Self::accrue_checked(checking_account, amount),
+				None => (),
+			}
+		}
+	}
+
+	fn can_check_out(_dest: &MultiLocation, what: &MultiAsset, _context: &XcmContext) -> XcmResult {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"check_out dest: {:?}, what: {:?}",
+			_dest,
+			what
+		);
+		let amount = Matcher::matches_fungible(what).ok_or(MatchError::AssetNotHandled)?;
+		match CheckingAccount::get() {
+			Some((checking_account, MintLocation::Local)) =>
+				Self::can_accrue_checked(checking_account, amount),
+			Some((checking_account, MintLocation::NonLocal)) =>
+				Self::can_reduce_checked(checking_account, amount),
+			None => Ok(()),
+		}
+	}
+
+	fn check_out(_dest: &MultiLocation, what: &MultiAsset, _context: &XcmContext) {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"check_out dest: {:?}, what: {:?}",
+			_dest,
+			what
+		);
+		if let Some(amount) = Matcher::matches_fungible(what) {
+			match CheckingAccount::get() {
+				Some((checking_account, MintLocation::Local)) =>
+					Self::accrue_checked(checking_account, amount),
+				Some((checking_account, MintLocation::NonLocal)) =>
+					Self::reduce_checked(checking_account, amount),
+				None => (),
+			}
+		}
+	}
+
+	fn deposit_asset(
+		what: &MultiAsset,
+		who: &MultiLocation,
+		_context: Option<&XcmContext>,
+	) -> XcmResult {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"deposit_asset what: {:?}, who: {:?}",
+			what, who,
+		);
+		let amount = Matcher::matches_fungible(what).ok_or(MatchError::AssetNotHandled)?;
+		let who = AccountIdConverter::convert_location(who)
+			.ok_or(MatchError::AccountIdConversionFailed)?;
+		Fungible::mint_into(&who, amount)
+			.map_err(|error| XcmError::FailedToTransactAsset(error.into()))?;
+		Ok(())
+	}
+
+	fn withdraw_asset(
+		what: &MultiAsset,
+		who: &MultiLocation,
+		_context: Option<&XcmContext>,
+	) -> result::Result<xcm_executor::Assets, XcmError> {
+		log::trace!(
+			target: "xcm::fungible_adapter",
+			"deposit_asset what: {:?}, who: {:?}",
+			what, who,
+		);
+		let amount = Matcher::matches_fungible(what).ok_or(MatchError::AssetNotHandled)?;
+		let who = AccountIdConverter::convert_location(who)
+			.ok_or(MatchError::AccountIdConversionFailed)?;
+		Fungible::burn_from(&who, amount, Exact, Polite)
+			.map_err(|error| XcmError::FailedToTransactAsset(error.into()))?;
+		Ok(what.clone().into())
+	}
+}
+
+/// [`TransactAsset`] implementation that allows the use of a [`fungible`] implementation for
+/// handling an asset in the XCM executor.
+/// Works for everything, transfers and teleport bookkeeping.
+pub struct FungibleAdapter<Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount>(
+	PhantomData<(Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount)>,
+);
+impl<
+		Fungible: fungible::Mutate<AccountId>,
+		Matcher: MatchesFungible<Fungible::Balance>,
+		AccountIdConverter: ConvertLocation<AccountId>,
+		AccountId: Eq + Clone,
+		CheckingAccount: Get<Option<(AccountId, MintLocation)>>,
+	> TransactAsset
+	for FungibleAdapter<Fungible, Matcher, AccountIdConverter, AccountId, CheckingAccount>
+{
+	fn can_check_in(origin: &MultiLocation, what: &MultiAsset, context: &XcmContext) -> XcmResult {
+		FungibleMutateAdapter::<
+			Fungible,
+			Matcher,
+			AccountIdConverter,
+			AccountId,
+			CheckingAccount,
+		>::can_check_in(origin, what, context)
+	}
+
+	fn check_in(origin: &MultiLocation, what: &MultiAsset, context: &XcmContext) {
+		FungibleMutateAdapter::<
+			Fungible,
+			Matcher,
+			AccountIdConverter,
+			AccountId,
+			CheckingAccount,
+		>::check_in(origin, what, context)
+	}
+
+	fn can_check_out(dest: &MultiLocation, what: &MultiAsset, context: &XcmContext) -> XcmResult {
+		FungibleMutateAdapter::<
+			Fungible,
+			Matcher,
+			AccountIdConverter,
+			AccountId,
+			CheckingAccount,
+		>::can_check_out(dest, what, context)
+	}
+
+	fn check_out(dest: &MultiLocation, what: &MultiAsset, context: &XcmContext) {
+		FungibleMutateAdapter::<
+			Fungible,
+			Matcher,
+			AccountIdConverter,
+			AccountId,
+			CheckingAccount,
+		>::check_out(dest, what, context)
+	}
+
+	fn deposit_asset(
+		what: &MultiAsset,
+		who: &MultiLocation,
+		context: Option<&XcmContext>,
+	) -> XcmResult {
+		FungibleMutateAdapter::<
+			Fungible,
+			Matcher,
+			AccountIdConverter,
+			AccountId,
+			CheckingAccount,
+		>::deposit_asset(what, who, context)
+	}
+
+	fn withdraw_asset(
+		what: &MultiAsset,
+		who: &MultiLocation,
+		maybe_context: Option<&XcmContext>,
+	) -> result::Result<xcm_executor::Assets, XcmError> {
+		FungibleMutateAdapter::<
+			Fungible,
+			Matcher,
+			AccountIdConverter,
+			AccountId,
+			CheckingAccount,
+		>::withdraw_asset(what, who, maybe_context)
+	}
+
+	fn internal_transfer_asset(
+		what: &MultiAsset,
+		from: &MultiLocation,
+		to: &MultiLocation,
+		context: &XcmContext,
+	) -> result::Result<xcm_executor::Assets, XcmError> {
+		FungibleTransferAdapter::<Fungible, Matcher, AccountIdConverter, AccountId>::internal_transfer_asset(
+			what, from, to, context
+		)
+	}
+}