implement children and iterative burning

pallets/rmrk-core/src/functions.rs

@@ -0,0 +1,29 @@
+use super::*;
+
+impl<T: Config> Pallet<T> {
+	pub fn is_x_descendent_of_y(
+		child_collection_id: T::CollectionId,
+		child_nft_id: T::NftId,
+		parent_collection_id: T::CollectionId,
+		parent_nft_id: T::NftId,
+	) -> bool {
+		let mut found_child = false;
+		if let Some(children) = Children::<T>::get(parent_collection_id, parent_nft_id) {
+			for child in children {
+				if child == (child_collection_id, child_nft_id) {
+					return true;
+				} else {
+					if Pallet::<T>::is_x_descendent_of_y(
+						child_collection_id,
+						child_nft_id,
+						child.0,
+						child.1,
+					) {
+						found_child = true;
+					}
+				}
+			}
+		}
+		found_child
+	}
+}

pallets/rmrk-core/src/lib.rs

@@ -20,6 +20,8 @@ use sp_std::{convert::TryInto, vec::Vec};
 
 use types::{AccountIdOrCollectionNftTuple, ClassInfo, InstanceInfo};
 
+mod functions;
+
 #[cfg(test)]
 mod mock;
 
@@ -107,6 +109,18 @@ pub mod pallet {
 		InstanceInfoOf<T>,
 	>;
 
+	#[pallet::storage]
+	#[pallet::getter(fn children)]
+	/// Stores nft info
+	pub type Children<T: Config> = StorageDoubleMap<
+		_,
+		Twox64Concat,
+		T::CollectionId,
+		Twox64Concat,
+		T::NftId,
+		Vec<(T::CollectionId, T::NftId)>,
+	>;
+
 	#[pallet::storage]
 	#[pallet::getter(fn resources)]
 	/// Stores resource info
@@ -163,6 +177,7 @@ pub mod pallet {
 		NoPermission,
 		NoWitness,
 		CollectionNotEmpty,
+		CannotSendToDescendent,
 	}
 
 	#[pallet::call]
@@ -270,19 +285,23 @@ pub mod pallet {
 		}
 
 		/// burn nft
-		/// TODO: If an NFT that contains other NFTs is being burnt, the owned NFTs are also burned.
 		#[pallet::weight(10_000 + T::DbWeight::get().reads_writes(1,1))]
 		#[transactional]
 		pub fn burn_nft(
 			origin: OriginFor<T>,
 			collection_id: T::CollectionId,
 			nft_id: T::NftId,
 		) -> DispatchResult {
-			let sender = ensure_signed(origin)?;
+			let sender = ensure_signed(origin.clone())?;
 			pallet_uniques::Pallet::<T>::do_burn(collection_id.into(), nft_id.into(), |_, _| {
 				Ok(())
 			})?;
 			NFTs::<T>::remove(collection_id, nft_id);
+			if let Some(kids) = Children::<T>::take(collection_id, nft_id) {
+				for child in kids {
+					Pallet::<T>::burn_nft(origin.clone(), child.0, child.1)?;
+				}
+			}
 			Self::deposit_event(Event::NFTBurned(sender, nft_id));
 			Ok(())
 		}
@@ -339,15 +358,48 @@ pub mod pallet {
 
 			match new_owner.clone() {
 				AccountIdOrCollectionNftTuple::AccountId(account_id) => {
+					// Remove previous parental relationship
+					if let AccountIdOrCollectionNftTuple::CollectionAndNftTuple(cid, nid) =
+						sending_nft.owner
+					{
+						if let Some(mut kids) = Children::<T>::take(cid, nid) {
+							kids.retain(|&kid| kid != (collection_id, nft_id));
+							Children::<T>::insert(cid, nid, kids);
+						}
+					}
 					sending_nft.rootowner = account_id.clone();
-				},
+				}
 				AccountIdOrCollectionNftTuple::CollectionAndNftTuple(cid, nid) => {
 					let recipient_nft =
 						NFTs::<T>::get(cid, nid).ok_or(Error::<T>::NoAvailableNftId)?;
+					// Check if sending NFT is already a child of recipient NFT
+					ensure!(
+						!Pallet::<T>::is_x_descendent_of_y(cid, nid, collection_id, nft_id),
+						Error::<T>::CannotSendToDescendent
+					);
+
+					// Remove parent if exists: first we only care if the owner is a non-AccountId)
+					if let AccountIdOrCollectionNftTuple::CollectionAndNftTuple(cid, nid) =
+						sending_nft.owner
+					{
+						// second we only care if the parent has children (it should)
+						if let Some(mut kids) = Children::<T>::take(cid, nid) {
+							// third we only "retain" the other children
+							kids.retain(|&kid| kid != (collection_id, nft_id));
+							Children::<T>::insert(cid, nid, kids);
+						}
+					}
 					if sending_nft.rootowner != recipient_nft.rootowner {
 						sending_nft.rootowner = recipient_nft.rootowner
 					}
-				},
+					match Children::<T>::take(cid, nid) {
+						None => Children::<T>::insert(cid, nid, vec![(collection_id, nft_id)]),
+						Some(mut kids) => {
+							kids.push((collection_id, nft_id));
+							Children::<T>::insert(cid, nid, kids);
+						}
+					}
+				}
 			};
 			sending_nft.owner = new_owner.clone();
 
@@ -383,7 +435,7 @@ pub mod pallet {
 			// 	collection.issuer = dest.clone();
 			// 	Collections::<T>::insert(collection_id, collection);
 			// 	Ok(())
-			// })?;
+			// })?; 
 
 			// Check that sender is current issuer
 			let mut collection =