Fungibles and Non-Fungibles Create and Destroy Traits + Assets and Uniques Implementation (#9844)

* refactor `do_destroy`

* destroy trait

* refactor do_force_create

* impl create trait

* do not bleed weight into api

* Do the same for uniques

* add docs

substrate/frame/uniques/src/functions.rs

@@ -80,6 +80,41 @@ impl<T: Config<I>, I: 'static> Pallet<T, I> {
 		Ok(())
 	}
 
+	pub(super) fn do_destroy_class(
+		class: T::ClassId,
+		witness: DestroyWitness,
+		maybe_check_owner: Option<T::AccountId>,
+	) -> Result<DestroyWitness, DispatchError> {
+		Class::<T, I>::try_mutate_exists(class, |maybe_details| {
+			let class_details = maybe_details.take().ok_or(Error::<T, I>::Unknown)?;
+			if let Some(check_owner) = maybe_check_owner {
+				ensure!(class_details.owner == check_owner, Error::<T, I>::NoPermission);
+			}
+			ensure!(class_details.instances == witness.instances, Error::<T, I>::BadWitness);
+			ensure!(
+				class_details.instance_metadatas == witness.instance_metadatas,
+				Error::<T, I>::BadWitness
+			);
+			ensure!(class_details.attributes == witness.attributes, Error::<T, I>::BadWitness);
+
+			for (instance, details) in Asset::<T, I>::drain_prefix(&class) {
+				Account::<T, I>::remove((&details.owner, &class, &instance));
+			}
+			InstanceMetadataOf::<T, I>::remove_prefix(&class, None);
+			ClassMetadataOf::<T, I>::remove(&class);
+			Attribute::<T, I>::remove_prefix((&class,), None);
+			T::Currency::unreserve(&class_details.owner, class_details.total_deposit);
+
+			Self::deposit_event(Event::Destroyed(class));
+
+			Ok(DestroyWitness {
+				instances: class_details.instances,
+				instance_metadatas: class_details.instance_metadatas,
+				attributes: class_details.attributes,
+			})
+		})
+	}
+
 	pub(super) fn do_mint(
 		class: T::ClassId,
 		instance: T::InstanceId,

substrate/frame/uniques/src/impl_nonfungibles.rs

@@ -19,13 +19,10 @@
 
 use super::*;
 use frame_support::{
-	traits::{
-		tokens::nonfungibles::{Create, Inspect, InspectEnumerable, Mutate, Transfer},
-		Get,
-	},
+	traits::{tokens::nonfungibles::*, Get},
 	BoundedSlice,
 };
-use sp_runtime::DispatchResult;
+use sp_runtime::{DispatchError, DispatchResult};
 use sp_std::convert::TryFrom;
 
 impl<T: Config<I>, I: 'static> Inspect<<T as SystemConfig>::AccountId> for Pallet<T, I> {
@@ -106,6 +103,22 @@ impl<T: Config<I>, I: 'static> Create<<T as SystemConfig>::AccountId> for Pallet
 	}
 }
 
+impl<T: Config<I>, I: 'static> Destroy<<T as SystemConfig>::AccountId> for Pallet<T, I> {
+	type DestroyWitness = DestroyWitness;
+
+	fn get_destroy_witness(class: &Self::ClassId) -> Option<DestroyWitness> {
+		Class::<T, I>::get(class).map(|a| a.destroy_witness())
+	}
+
+	fn destroy(
+		class: Self::ClassId,
+		witness: Self::DestroyWitness,
+		maybe_check_owner: Option<T::AccountId>,
+	) -> Result<Self::DestroyWitness, DispatchError> {
+		Self::do_destroy_class(class, witness, maybe_check_owner)
+	}
+}
+
 impl<T: Config<I>, I: 'static> Mutate<<T as SystemConfig>::AccountId> for Pallet<T, I> {
 	fn mint_into(
 		class: &Self::ClassId,

substrate/frame/uniques/src/lib.rs

@@ -381,37 +381,19 @@ pub mod pallet {
 			origin: OriginFor<T>,
 			#[pallet::compact] class: T::ClassId,
 			witness: DestroyWitness,
-		) -> DispatchResult {
+		) -> DispatchResultWithPostInfo {
 			let maybe_check_owner = match T::ForceOrigin::try_origin(origin) {
 				Ok(_) => None,
 				Err(origin) => Some(ensure_signed(origin)?),
 			};
-			Class::<T, I>::try_mutate_exists(class, |maybe_details| {
-				let class_details = maybe_details.take().ok_or(Error::<T, I>::Unknown)?;
-				if let Some(check_owner) = maybe_check_owner {
-					ensure!(class_details.owner == check_owner, Error::<T, I>::NoPermission);
-				}
-				ensure!(class_details.instances == witness.instances, Error::<T, I>::BadWitness);
-				ensure!(
-					class_details.instance_metadatas == witness.instance_metadatas,
-					Error::<T, I>::BadWitness
-				);
-				ensure!(class_details.attributes == witness.attributes, Error::<T, I>::BadWitness);
+			let details = Self::do_destroy_class(class, witness, maybe_check_owner)?;
 
-				for (instance, details) in Asset::<T, I>::drain_prefix(&class) {
-					Account::<T, I>::remove((&details.owner, &class, &instance));
-				}
-				InstanceMetadataOf::<T, I>::remove_prefix(&class, None);
-				ClassMetadataOf::<T, I>::remove(&class);
-				Attribute::<T, I>::remove_prefix((&class,), None);
-				T::Currency::unreserve(&class_details.owner, class_details.total_deposit);
-
-				Self::deposit_event(Event::Destroyed(class));
-
-				// NOTE: could use postinfo to reflect the actual number of
-				// accounts/sufficient/approvals
-				Ok(())
-			})
+			Ok(Some(T::WeightInfo::destroy(
+				details.instances,
+				details.instance_metadatas,
+				details.attributes,
+			))
+			.into())
 		}
 
 		/// Mint an asset instance of a particular class.