Balance to Asset Balance Conversion (#9076)

* add BalanceConversion trait and implementation

* derive some useful traits on Imbalance

* Update frame/support/src/traits/tokens/fungibles/imbalance.rs

Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>

* make BalanceConversion error type configurable

* add RuntimeDebug import and derive traits on other Imbalance

* formatting

* move BalanceConversion trait to frame-support

* add necessary trait import

Co-authored-by: Xiliang Chen <xlchen1291@gmail.com>

substrate/frame/support/src/traits/tokens.rs

@@ -25,6 +25,7 @@ pub mod nonfungible;
 pub mod nonfungibles;
 mod misc;
 pub use misc::{
-	WithdrawConsequence, DepositConsequence, ExistenceRequirement, BalanceStatus, WithdrawReasons,
+	BalanceConversion, BalanceStatus,  DepositConsequence,
+	ExistenceRequirement, WithdrawConsequence, WithdrawReasons,
 };
 pub use imbalance::Imbalance;

substrate/frame/support/src/traits/tokens/fungible/imbalance.rs

@@ -20,7 +20,7 @@
 
 use super::*;
 use sp_std::marker::PhantomData;
-use sp_runtime::traits::Zero;
+use sp_runtime::{RuntimeDebug, traits::Zero};
 use super::misc::Balance;
 use super::balanced::Balanced;
 use crate::traits::misc::{TryDrop, SameOrOther};
@@ -39,6 +39,7 @@ pub trait HandleImbalanceDrop<Balance> {
 ///
 /// Importantly, it has a special `Drop` impl, and cannot be created outside of this module.
 #[must_use]
+#[derive(RuntimeDebug, Eq, PartialEq)]
 pub struct Imbalance<
 	B: Balance,
 	OnDrop: HandleImbalanceDrop<B>,

substrate/frame/support/src/traits/tokens/fungibles/imbalance.rs

@@ -20,7 +20,7 @@
 
 use super::*;
 use sp_std::marker::PhantomData;
-use sp_runtime::traits::Zero;
+use sp_runtime::{RuntimeDebug, traits::Zero};
 use super::fungibles::{AssetId, Balance};
 use super::balanced::Balanced;
 use crate::traits::misc::{TryDrop, SameOrOther};
@@ -37,6 +37,7 @@ pub trait HandleImbalanceDrop<AssetId, Balance> {
 ///
 /// Importantly, it has a special `Drop` impl, and cannot be created outside of this module.
 #[must_use]
+#[derive(RuntimeDebug, Eq, PartialEq)]
 pub struct Imbalance<
 	A: AssetId,
 	B: Balance,

substrate/frame/support/src/traits/tokens/misc.rs

@@ -167,3 +167,9 @@ impl<T: FullCodec + Copy + Eq + PartialEq + Debug> AssetId for T {}
 /// Simple amalgamation trait to collect together properties for a Balance under one roof.
 pub trait Balance: AtLeast32BitUnsigned + FullCodec + Copy + Default + Debug {}
 impl<T: AtLeast32BitUnsigned + FullCodec + Copy + Default + Debug> Balance for T {}
+
+/// Converts a balance value into an asset balance.
+pub trait BalanceConversion<InBalance, AssetId, OutBalance> {
+	type Error;
+	fn to_asset_balance(balance: InBalance, asset_id: AssetId) -> Result<OutBalance, Self::Error>;
+}