feat(asset-hubs): add PoolAssetsExchanger

polkadot-fellows · Jan 10, 2025 · 5840c18 · 5840c18
1 parent 80ac2e4
commit 5840c18
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Showing 2 changed files with 46 additions and 2 deletions.
diff --git a/system-parachains/asset-hubs/asset-hub-kusama/src/xcm_config.rs b/system-parachains/asset-hubs/asset-hub-kusama/src/xcm_config.rs
@@ -197,6 +197,28 @@ pub type PoolFungiblesTransactor = FungiblesAdapter<
 pub type AssetTransactors =
 	(FungibleTransactor, FungiblesTransactor, ForeignFungiblesTransactor, PoolFungiblesTransactor);
 
+/// Asset converter for pool assets.
+/// Used to convert one asset to another, when there is a pool available between the two.
+/// This type thus allows paying delivery fees with any asset as long as there is a pool between said
+/// asset and the asset required for fee payment.
+pub type PoolAssetsExchanger = SingleAssetExchangeAdapter<
+	AssetConversion,
+	NativeAndAssets,
+	(
+		TrustBackedAssetsAsLocation<TrustBackedAssetsPalletLocation, Balance, xcm::v4::Location>,
+		ForeignAssetsConvertedConcreteId,
+		// `ForeignAssetsConvertedConcreteId` excludes the relay token, so we add it back here.
+		MatchedConvertedConcreteId<
+			xcm::v4::Location,
+			Balance,
+			Equals<ParentLocation>,
+			WithLatestLocationConverter<xcm::v4::Location>,
+			TryConvertInto,
+		>,
+	),
+	AccountId,
+>;
+
 /// This is the type we use to convert an (incoming) XCM origin into a local `Origin` instance,
 /// ready for dispatching a transaction with Xcm's `Transact`.
 ///
@@ -378,7 +400,7 @@ impl xcm_executor::Config for XcmConfig {
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
 	type AssetLocker = ();
-	type AssetExchanger = ();
+	type AssetExchanger = PoolAssetsExchanger;
 	type FeeManager = XcmFeeManagerFromComponents<
 		WaivedLocations,
 		SendXcmFeeToAccount<Self::AssetTransactor, RelayTreasuryPalletAccount>,

diff --git a/system-parachains/asset-hubs/asset-hub-polkadot/src/xcm_config.rs b/system-parachains/asset-hubs/asset-hub-polkadot/src/xcm_config.rs
@@ -196,6 +196,28 @@ pub type PoolFungiblesTransactor = FungiblesAdapter<
 pub type AssetTransactors =
 	(FungibleTransactor, FungiblesTransactor, ForeignFungiblesTransactor, PoolFungiblesTransactor);
 
+/// Asset converter for pool assets.
+/// Used to convert one asset to another, when there is a pool available between the two.
+/// This type thus allows paying delivery fees with any asset as long as there is a pool between said
+/// asset and the asset required for fee payment.
+pub type PoolAssetsExchanger = SingleAssetExchangeAdapter<
+	AssetConversion,
+	NativeAndAssets,
+	(
+		TrustBackedAssetsAsLocation<TrustBackedAssetsPalletLocation, Balance, xcm::v4::Location>,
+		ForeignAssetsConvertedConcreteId,
+		// `ForeignAssetsConvertedConcreteId` excludes the relay token, so we add it back here.
+		MatchedConvertedConcreteId<
+			xcm::v4::Location,
+			Balance,
+			Equals<ParentLocation>,
+			WithLatestLocationConverter<xcm::v4::Location>,
+			TryConvertInto,
+		>,
+	),
+	AccountId,
+>;
+
 /// This is the type we use to convert an (incoming) XCM origin into a local `Origin` instance,
 /// ready for dispatching a transaction with Xcm's `Transact`.
 ///
@@ -443,7 +465,7 @@ impl xcm_executor::Config for XcmConfig {
 	type PalletInstancesInfo = AllPalletsWithSystem;
 	type MaxAssetsIntoHolding = MaxAssetsIntoHolding;
 	type AssetLocker = ();
-	type AssetExchanger = ();
+	type AssetExchanger = PoolAssetsExchanger;
 	type FeeManager = XcmFeeManagerFromComponents<
 		WaivedLocations,
 		SendXcmFeeToAccount<Self::AssetTransactor, RelayTreasuryPalletAccount>,