Update currency adapter to work with new xtokens impl (#436)

* Xcm support implementations rework.

* Update xtokens mock.

Author: shaunxw

xcm-support/src/currency_adapter.rs

@@ -2,6 +2,7 @@ use codec::FullCodec;
 use sp_runtime::traits::{MaybeSerializeDeserialize, SaturatedConversion};
 use sp_std::{
 	cmp::{Eq, PartialEq},
+	convert::{TryFrom, TryInto},
 	fmt::Debug,
 	marker::PhantomData,
 	prelude::*,
@@ -11,7 +12,7 @@ use sp_std::{
 use xcm::v0::{Error as XcmError, MultiAsset, MultiLocation, Result};
 use xcm_executor::traits::{LocationConversion, MatchesFungible, TransactAsset};
 
-use crate::{CurrencyIdConversion, UnknownAsset as UnknownAssetT};
+use crate::UnknownAsset as UnknownAssetT;
 
 /// Asset transaction errors.
 enum Error {
@@ -37,22 +38,13 @@ impl From<Error> for XcmError {
 ///
 /// If the asset is known, deposit/withdraw will be handled by `MultiCurrency`,
 /// else by `UnknownAsset` if unknown.
-pub struct MultiCurrencyAdapter<
-	MultiCurrency,
-	UnknownAsset,
-	Matcher,
-	AccountIdConverter,
-	AccountId,
-	CurrencyIdConverter,
-	CurrencyId,
->(
+pub struct MultiCurrencyAdapter<MultiCurrency, UnknownAsset, Matcher, AccountIdConverter, AccountId, CurrencyId>(
 	PhantomData<(
 		MultiCurrency,
 		UnknownAsset,
 		Matcher,
 		AccountIdConverter,
 		AccountId,
-		CurrencyIdConverter,
 		CurrencyId,
 	)>,
 );
@@ -63,27 +55,18 @@ impl<
 		Matcher: MatchesFungible<MultiCurrency::Balance>,
 		AccountIdConverter: LocationConversion<AccountId>,
 		AccountId: sp_std::fmt::Debug,
-		CurrencyIdConverter: CurrencyIdConversion<CurrencyId>,
-		CurrencyId: FullCodec + Eq + PartialEq + Copy + MaybeSerializeDeserialize + Debug,
+		CurrencyId: FullCodec + Eq + PartialEq + Copy + MaybeSerializeDeserialize + Debug + TryFrom<MultiAsset>,
 	> TransactAsset
-	for MultiCurrencyAdapter<
-		MultiCurrency,
-		UnknownAsset,
-		Matcher,
-		AccountIdConverter,
-		AccountId,
-		CurrencyIdConverter,
-		CurrencyId,
-	>
+	for MultiCurrencyAdapter<MultiCurrency, UnknownAsset, Matcher, AccountIdConverter, AccountId, CurrencyId>
 {
 	fn deposit_asset(asset: &MultiAsset, location: &MultiLocation) -> Result {
 		match (
 			AccountIdConverter::from_location(location),
-			CurrencyIdConverter::from_asset(asset),
+			asset.clone().try_into(),
 			Matcher::matches_fungible(&asset),
 		) {
 			// known asset
-			(Some(who), Some(currency_id), Some(amount)) => {
+			(Some(who), Ok(currency_id), Some(amount)) => {
 				MultiCurrency::deposit(currency_id, &who, amount).map_err(|e| XcmError::FailedToTransactAsset(e.into()))
 			}
 			// unknown asset
@@ -95,8 +78,10 @@ impl<
 		UnknownAsset::withdraw(asset, location).or_else(|_| {
 			let who = AccountIdConverter::from_location(location)
 				.ok_or_else(|| XcmError::from(Error::AccountIdConversionFailed))?;
-			let currency_id = CurrencyIdConverter::from_asset(asset)
-				.ok_or_else(|| XcmError::from(Error::CurrencyIdConversionFailed))?;
+			let currency_id = asset
+				.clone()
+				.try_into()
+				.map_err(|_| XcmError::from(Error::CurrencyIdConversionFailed))?;
 			let amount: MultiCurrency::Balance = Matcher::matches_fungible(&asset)
 				.ok_or_else(|| XcmError::from(Error::FailedToMatchFungible))?
 				.saturated_into();

xcm-support/src/lib.rs

@@ -9,20 +9,12 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![allow(clippy::unused_unit)]
 
-use frame_support::{
-	dispatch::{DispatchError, DispatchResult},
-	traits::Get,
-};
-use sp_runtime::traits::{CheckedConversion, Convert};
-use sp_std::{
-	collections::btree_set::BTreeSet,
-	convert::{TryFrom, TryInto},
-	marker::PhantomData,
-	prelude::*,
-};
+use frame_support::dispatch::{DispatchError, DispatchResult};
+use sp_runtime::traits::CheckedConversion;
+use sp_std::{convert::TryFrom, marker::PhantomData, prelude::*};
 
-use xcm::v0::{Junction, MultiAsset, MultiLocation, Xcm};
-use xcm_executor::traits::{FilterAssetLocation, MatchesFungible, NativeAsset};
+use xcm::v0::{MultiAsset, MultiLocation, Xcm};
+use xcm_executor::traits::{FilterAssetLocation, MatchesFungible};
 
 use orml_traits::location::Reserve;
 
@@ -37,61 +29,24 @@ pub trait XcmHandler<AccountId> {
 	fn execute_xcm(origin: AccountId, xcm: Xcm) -> DispatchResult;
 }
 
-/// Convert `MultiAsset` to `CurrencyId`.
-pub trait CurrencyIdConversion<CurrencyId> {
-	/// Get `CurrencyId` from `MultiAsset`. Returns `None` if conversion failed.
-	fn from_asset(asset: &MultiAsset) -> Option<CurrencyId>;
-}
-
-/// A `MatchesFungible` implementation. It matches relay chain tokens or
-/// parachain tokens that could be decoded from a general key.
-pub struct IsConcreteWithGeneralKey<CurrencyId, FromRelayChainBalance>(
-	PhantomData<(CurrencyId, FromRelayChainBalance)>,
-);
-impl<CurrencyId, B, FromRelayChainBalance> MatchesFungible<B>
-	for IsConcreteWithGeneralKey<CurrencyId, FromRelayChainBalance>
+/// A `MatchesFungible` implementation. It matches concrete fungible assets
+/// whose `id` could be converted into `CurrencyId`.
+pub struct IsNativeConcrete<CurrencyId>(PhantomData<CurrencyId>);
+impl<CurrencyId, Amount> MatchesFungible<Amount> for IsNativeConcrete<CurrencyId>
 where
-	CurrencyId: TryFrom<Vec<u8>>,
-	B: TryFrom<u128>,
-	FromRelayChainBalance: Convert<u128, u128>,
+	CurrencyId: TryFrom<MultiLocation>,
+	Amount: TryFrom<u128>,
 {
-	fn matches_fungible(a: &MultiAsset) -> Option<B> {
+	fn matches_fungible(a: &MultiAsset) -> Option<Amount> {
 		if let MultiAsset::ConcreteFungible { id, amount } = a {
-			if id == &MultiLocation::X1(Junction::Parent) {
-				// Convert relay chain decimals to local chain
-				let local_amount = FromRelayChainBalance::convert(*amount);
-				return CheckedConversion::checked_from(local_amount);
-			}
-			if let Some(Junction::GeneralKey(key)) = id.last() {
-				if TryInto::<CurrencyId>::try_into(key.clone()).is_ok() {
-					return CheckedConversion::checked_from(*amount);
-				}
+			if CurrencyId::try_from(id.clone()).is_ok() {
+				return CheckedConversion::checked_from(*amount);
 			}
 		}
 		None
 	}
 }
 
-/// A `FilterAssetLocation` implementation. Filters native assets and ORML
-/// tokens via provided general key to `MultiLocation` pairs.
-pub struct NativePalletAssetOr<Pairs>(PhantomData<Pairs>);
-impl<Pairs: Get<BTreeSet<(Vec<u8>, MultiLocation)>>> FilterAssetLocation for NativePalletAssetOr<Pairs> {
-	fn filter_asset_location(asset: &MultiAsset, origin: &MultiLocation) -> bool {
-		if NativeAsset::filter_asset_location(asset, origin) {
-			return true;
-		}
-
-		// native orml-tokens with a general key
-		if let MultiAsset::ConcreteFungible { ref id, .. } = asset {
-			if let Some(Junction::GeneralKey(key)) = id.last() {
-				return Pairs::get().contains(&(key.clone(), origin.clone()));
-			}
-		}
-
-		false
-	}
-}
-
 /// A `FilterAssetLocation` implementation. Filters multi native assets whose
 /// reserve is same with `origin`.
 pub struct MultiNativeAsset;
@@ -106,31 +61,6 @@ impl FilterAssetLocation for MultiNativeAsset {
 	}
 }
 
-/// `CurrencyIdConversion` implementation. Converts relay chain tokens, or
-/// parachain tokens that could be decoded from a general key.
-pub struct CurrencyIdConverter<CurrencyId, RelayChainCurrencyId>(
-	PhantomData<CurrencyId>,
-	PhantomData<RelayChainCurrencyId>,
-);
-impl<CurrencyId, RelayChainCurrencyId> CurrencyIdConversion<CurrencyId>
-	for CurrencyIdConverter<CurrencyId, RelayChainCurrencyId>
-where
-	CurrencyId: TryFrom<Vec<u8>>,
-	RelayChainCurrencyId: Get<CurrencyId>,
-{
-	fn from_asset(asset: &MultiAsset) -> Option<CurrencyId> {
-		if let MultiAsset::ConcreteFungible { id: location, .. } = asset {
-			if location == &MultiLocation::X1(Junction::Parent) {
-				return Some(RelayChainCurrencyId::get());
-			}
-			if let Some(Junction::GeneralKey(key)) = location.last() {
-				return CurrencyId::try_from(key.clone()).ok();
-			}
-		}
-		None
-	}
-}
-
 /// Handlers unknown asset deposit and withdraw.
 pub trait UnknownAsset {
 	/// Deposit unknown asset.