Add FungibleAdapter

polkadot/xcm/xcm-builder/src/fungible_adapter.rs

@@ -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
+		)
+	}
+}

polkadot/xcm/xcm-builder/src/lib.rs

@@ -72,6 +72,9 @@ pub use fee_handling::{
 	deposit_or_burn_fee, HandleFee, XcmFeeManagerFromComponents, XcmFeeToAccount,
 };
 
+mod fungible_adapter;
+pub use fungible_adapter::{FungibleAdapter, FungibleMutateAdapter, FungibleTransferAdapter};
+
 mod fungibles_adapter;
 pub use fungibles_adapter::{
 	AssetChecking, DualMint, FungiblesAdapter, FungiblesMutateAdapter, FungiblesTransferAdapter,

polkadot/xcm/xcm-simulator/example/src/parachain.rs

@@ -40,10 +40,9 @@ use polkadot_parachain_primitives::primitives::{
 use xcm::{latest::prelude::*, VersionedXcm};
 use xcm_builder::{
 	Account32Hash, AccountId32Aliases, AllowUnpaidExecutionFrom, ConvertedConcreteId,
-	CurrencyAdapter as XcmCurrencyAdapter, EnsureXcmOrigin, FixedRateOfFungible, FixedWeightBounds,
-	IsConcrete, NativeAsset, NoChecking, NonFungiblesAdapter, ParentIsPreset,
-	SiblingParachainConvertsVia, SignedAccountId32AsNative, SignedToAccountId32,
-	SovereignSignedViaLocation,
+	EnsureXcmOrigin, FixedRateOfFungible, FixedWeightBounds, FungibleAdapter, IsConcrete,
+	NativeAsset, NoChecking, NonFungiblesAdapter, ParentIsPreset, SiblingParachainConvertsVia,
+	SignedAccountId32AsNative, SignedToAccountId32, SovereignSignedViaLocation,
 };
 use xcm_executor::{
 	traits::{ConvertLocation, JustTry},
@@ -202,7 +201,7 @@ parameter_types! {
 }
 
 pub type LocalAssetTransactor = (
-	XcmCurrencyAdapter<Balances, IsConcrete<KsmLocation>, LocationToAccountId, AccountId, ()>,
+	FungibleAdapter<Balances, IsConcrete<KsmLocation>, LocationToAccountId, AccountId, ()>,
 	NonFungiblesAdapter<
 		ForeignUniques,
 		ConvertedConcreteId<MultiLocation, AssetInstance, JustTry, JustTry>,

polkadot/xcm/xcm-simulator/example/src/relay_chain.rs

@@ -36,9 +36,9 @@ use xcm::latest::prelude::*;
 use xcm_builder::{
 	Account32Hash, AccountId32Aliases, AllowUnpaidExecutionFrom, AsPrefixedGeneralIndex,
 	ChildParachainAsNative, ChildParachainConvertsVia, ChildSystemParachainAsSuperuser,
-	ConvertedConcreteId, CurrencyAdapter as XcmCurrencyAdapter, FixedRateOfFungible,
-	FixedWeightBounds, IsConcrete, NoChecking, NonFungiblesAdapter, SignedAccountId32AsNative,
-	SignedToAccountId32, SovereignSignedViaLocation,
+	ConvertedConcreteId, FixedRateOfFungible, FixedWeightBounds, FungibleAdapter, IsConcrete,
+	NoChecking, NonFungiblesAdapter, SignedAccountId32AsNative, SignedToAccountId32,
+	SovereignSignedViaLocation,
 };
 use xcm_executor::{traits::JustTry, Config, XcmExecutor};
 
@@ -141,7 +141,7 @@ pub type LocationToAccountId = (
 );
 
 pub type LocalAssetTransactor = (
-	XcmCurrencyAdapter<Balances, IsConcrete<TokenLocation>, LocationToAccountId, AccountId, ()>,
+	FungibleAdapter<Balances, IsConcrete<TokenLocation>, LocationToAccountId, AccountId, ()>,
 	NonFungiblesAdapter<
 		Uniques,
 		ConvertedConcreteId<u32, u32, AsPrefixedGeneralIndex<(), u32, JustTry>, JustTry>,

prdoc/pr_2684.prdoc

@@ -0,0 +1,14 @@
+title: Add XCM FungibleAdapter
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      A new AssetTransactor has been added to xcm-builder: FungibleAdapter.
+      It's meant to be used instead of the old CurrencyAdapter for configuring the XCM executor
+      to handle only one asset.
+
+crates:
+  - name: "xcm-builder"
+
+migrations: []
+host_functions: []