git.delta.rocks / unique-network / refs/commits / 4a0df43d0b40

1// Copyright 2019-2022 Unique Network (Gibraltar) Ltd.2// This file is part of Unique Network.34// Unique Network is free software: you can redistribute it and/or modify5// it under the terms of the GNU General Public License as published by6// the Free Software Foundation, either version 3 of the License, or7// (at your option) any later version.89// Unique Network is distributed in the hope that it will be useful,10// but WITHOUT ANY WARRANTY; without even the implied warranty of11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the12// GNU General Public License for more details.1314// You should have received a copy of the GNU General Public License15// along with Unique Network. If not, see <http://www.gnu.org/licenses/>.1617//! # Fungible Pallet18//!19//! The Fungible pallet provides functionality for dealing with fungible assets.20//!21//! - [`CreateItemData`]22//! - [`Config`]23//! - [`FungibleHandle`]24//! - [`Pallet`]25//! - [`TotalSupply`]26//! - [`Balance`]27//! - [`Allowance`]28//! - [`Error`]29//!30//! ## Fungible tokens31//!32//! Fungible tokens or assets are divisible and non-unique. For instance,33//! fiat currencies like the dollar are fungible: A $1 bill34//! in New York City has the same value as a $1 bill in Miami.35//! A fungible token can also be a cryptocurrency like Bitcoin: 1 BTC is worth 1 BTC,36//! no matter where it is issued. Thus, the fungibility refers to a specific currency’s37//! ability to maintain one standard value. As well, it needs to have uniform acceptance.38//! This means that a currency’s history should not be able to affect its value,39//! and this is due to the fact that each piece that is a part of the currency is equal40//! in value when compared to every other piece of that exact same currency.41//! In the world of cryptocurrencies, this is essentially a coin or a token42//! that can be replaced by another identical coin or token, and they are43//! both mutually interchangeable. A popular implementation of fungible tokens is44//! the ERC-20 token standard.45//!46//! ### ERC-2047//!48//! The [ERC-20](https://ethereum.org/en/developers/docs/standards/tokens/erc-20/) (Ethereum Request for Comments 20), proposed by Fabian Vogelsteller in November 2015,49//! is a Token Standard that implements an API for tokens within Smart Contracts.50//!51//! Example functionalities ERC-20 provides:52//!53//! * transfer tokens from one account to another54//! * get the current token balance of an account55//! * get the total supply of the token available on the network56//! * approve whether an amount of token from an account can be spent by a third-party account57//!58//! ## Overview59//!60//! The module provides functionality for asset management of fungible asset, supports ERC-20 standart, includes:61//!62//! * Asset Issuance63//! * Asset Transferal64//! * Asset Destruction65//! * Delegated Asset Transfers66//!67//! **NOTE:** The created fungible asset always has `token_id` = 0.68//! So `tokenA` and `tokenB` will have different `collection_id`.69//!70//! ### Implementations71//!72//! The Fungible pallet provides implementations for the following traits.73//!74//! - [`WithRecorder`](pallet_evm_coder_substrate::WithRecorder): Trait for EVM support75//! - [`CommonCollectionOperations`](pallet_common::CommonCollectionOperations): Functions for dealing with collections76//!	- [`CommonWeightInfo`](pallet_common::CommonWeightInfo): Functions for retrieval of transaction weight77//! - [`CommonEvmHandler`](pallet_common::erc::CommonEvmHandler): Function for handling EVM runtime calls7879#![cfg_attr(not(feature = "std"), no_std)]8081use core::ops::Deref;82use evm_coder::ToLog;83use frame_support::{ensure};84use pallet_evm::account::CrossAccountId;85use up_data_structs::{86	AccessMode, CollectionId, CollectionFlags, TokenId, CreateCollectionData,87	mapping::TokenAddressMapping, budget::Budget,88};89use pallet_common::{90	Error as CommonError, Event as CommonEvent, Pallet as PalletCommon,91	eth::collection_id_to_address,92};93use pallet_evm::Pallet as PalletEvm;94use pallet_structure::Pallet as PalletStructure;95use pallet_evm_coder_substrate::WithRecorder;96use sp_core::H160;97use sp_runtime::{ArithmeticError, DispatchError, DispatchResult};98use sp_std::{collections::btree_map::BTreeMap, vec::Vec};99100pub use pallet::*;101102use crate::erc::ERC20Events;103#[cfg(feature = "runtime-benchmarks")]104pub mod benchmarking;105pub mod common;106pub mod erc;107pub mod weights;108109pub type CreateItemData<T> = (<T as pallet_evm::Config>::CrossAccountId, u128);110pub(crate) type SelfWeightOf<T> = <T as Config>::WeightInfo;111112#[frame_support::pallet]113pub mod pallet {114	use frame_support::{Blake2_128, Blake2_128Concat, Twox64Concat, pallet_prelude::*, storage::Key};115	use up_data_structs::CollectionId;116	use super::weights::WeightInfo;117118	#[pallet::error]119	pub enum Error<T> {120		/// Not Fungible item data used to mint in Fungible collection.121		NotFungibleDataUsedToMintFungibleCollectionToken,122		/// Fungible tokens hold no ID, and the default value of TokenId for Fungible collection is 0.123		FungibleItemsHaveNoId,124		/// Tried to set data for fungible item.125		FungibleItemsDontHaveData,126		/// Fungible token does not support nesting.127		FungibleDisallowsNesting,128		/// Setting item properties is not allowed.129		SettingPropertiesNotAllowed,130		/// Setting allowance for all is not allowed.131		SettingAllowanceForAllNotAllowed,132		/// Only a fungible collection could be possibly broken; any fungible token is valid.133		FungibleTokensAreAlwaysValid,134	}135136	#[pallet::config]137	pub trait Config:138		frame_system::Config + pallet_common::Config + pallet_structure::Config + pallet_evm::Config139	{140		type WeightInfo: WeightInfo;141	}142143	#[pallet::pallet]144	#[pallet::generate_store(pub(super) trait Store)]145	pub struct Pallet<T>(_);146147	/// Total amount of fungible tokens inside a collection.148	#[pallet::storage]149	pub type TotalSupply<T: Config> =150		StorageMap<Hasher = Twox64Concat, Key = CollectionId, Value = u128, QueryKind = ValueQuery>;151152	/// Amount of tokens owned by an account inside a collection.153	#[pallet::storage]154	pub type Balance<T: Config> = StorageNMap<155		Key = (156			Key<Twox64Concat, CollectionId>,157			Key<Blake2_128Concat, T::CrossAccountId>,158		),159		Value = u128,160		QueryKind = ValueQuery,161	>;162163	/// Storage for assets delegated to a limited extent to other users.164	#[pallet::storage]165	pub type Allowance<T: Config> = StorageNMap<166		Key = (167			Key<Twox64Concat, CollectionId>,168			Key<Blake2_128, T::CrossAccountId>,169			Key<Blake2_128Concat, T::CrossAccountId>,170		),171		Value = u128,172		QueryKind = ValueQuery,173	>;174}175176/// Wrapper around untyped collection handle, asserting inner collection is of fungible type.177/// Required for interaction with Fungible collections, type safety and implementation [`solidity_interface`][`evm_coder::solidity_interface`].178pub struct FungibleHandle<T: Config>(pallet_common::CollectionHandle<T>);179180/// Implementation of methods required for dispatching during runtime.181impl<T: Config> FungibleHandle<T> {182	/// Casts [`CollectionHandle`][`pallet_common::CollectionHandle`] into [`FungibleHandle`].183	pub fn cast(inner: pallet_common::CollectionHandle<T>) -> Self {184		Self(inner)185	}186187	/// Casts [`FungibleHandle`] into [`CollectionHandle`][`pallet_common::CollectionHandle`].188	pub fn into_inner(self) -> pallet_common::CollectionHandle<T> {189		self.0190	}191	/// Returns a mutable reference to the internal [`CollectionHandle`][`pallet_common::CollectionHandle`].192	pub fn common_mut(&mut self) -> &mut pallet_common::CollectionHandle<T> {193		&mut self.0194	}195}196impl<T: Config> WithRecorder<T> for FungibleHandle<T> {197	fn recorder(&self) -> &pallet_evm_coder_substrate::SubstrateRecorder<T> {198		self.0.recorder()199	}200	fn into_recorder(self) -> pallet_evm_coder_substrate::SubstrateRecorder<T> {201		self.0.into_recorder()202	}203}204impl<T: Config> Deref for FungibleHandle<T> {205	type Target = pallet_common::CollectionHandle<T>;206207	fn deref(&self) -> &Self::Target {208		&self.0209	}210}211212/// Pallet implementation for fungible assets213impl<T: Config> Pallet<T> {214	/// Initializes the collection. Returns [CollectionId] on success, [DispatchError] otherwise.215	pub fn init_collection(216		owner: T::CrossAccountId,217		payer: T::CrossAccountId,218		data: CreateCollectionData<T::AccountId>,219		flags: CollectionFlags,220	) -> Result<CollectionId, DispatchError> {221		<PalletCommon<T>>::init_collection(owner, payer, data, flags)222	}223224	/// Initializes the collection with ForeignCollection flag. Returns [CollectionId] on success, [DispatchError] otherwise.225	pub fn init_foreign_collection(226		owner: T::CrossAccountId,227		payer: T::CrossAccountId,228		data: CreateCollectionData<T::AccountId>,229	) -> Result<CollectionId, DispatchError> {230		let id = <PalletCommon<T>>::init_collection(231			owner,232			payer,233			data,234			CollectionFlags {235				foreign: true,236				..Default::default()237			},238		)?;239		Ok(id)240	}241242	/// Destroys a collection.243	pub fn destroy_collection(244		collection: FungibleHandle<T>,245		sender: &T::CrossAccountId,246	) -> DispatchResult {247		let id = collection.id;248249		if Self::collection_has_tokens(id) {250			return Err(<CommonError<T>>::CantDestroyNotEmptyCollection.into());251		}252253		// =========254255		PalletCommon::destroy_collection(collection.0, sender)?;256257		<TotalSupply<T>>::remove(id);258		let _ = <Balance<T>>::clear_prefix((id,), u32::MAX, None);259		let _ = <Allowance<T>>::clear_prefix((id,), u32::MAX, None);260		Ok(())261	}262263	///Checks if collection has tokens. Return `true` if it has.264	fn collection_has_tokens(collection_id: CollectionId) -> bool {265		<TotalSupply<T>>::get(collection_id) != 0266	}267268	/// Burns the specified amount of the token. If the token balance269	/// or total supply is less than the given value,270	/// it will return [DispatchError].271	pub fn burn(272		collection: &FungibleHandle<T>,273		owner: &T::CrossAccountId,274		amount: u128,275	) -> DispatchResult {276		let total_supply = <TotalSupply<T>>::get(collection.id)277			.checked_sub(amount)278			.ok_or(<CommonError<T>>::TokenValueTooLow)?;279280		let balance = <Balance<T>>::get((collection.id, owner))281			.checked_sub(amount)282			.ok_or(<CommonError<T>>::TokenValueTooLow)?;283284		// Foreign collection check285		ensure!(!collection.flags.foreign, <CommonError<T>>::NoPermission);286287		if collection.permissions.access() == AccessMode::AllowList {288			collection.check_allowlist(owner)?;289		}290291		// =========292293		if balance == 0 {294			<Balance<T>>::remove((collection.id, owner));295			<PalletStructure<T>>::unnest_if_nested(owner, collection.id, TokenId::default());296		} else {297			<Balance<T>>::insert((collection.id, owner), balance);298		}299		<TotalSupply<T>>::insert(collection.id, total_supply);300301		<PalletEvm<T>>::deposit_log(302			ERC20Events::Transfer {303				from: *owner.as_eth(),304				to: H160::default(),305				value: amount.into(),306			}307			.to_log(collection_id_to_address(collection.id)),308		);309		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(310			collection.id,311			TokenId::default(),312			owner.clone(),313			amount,314		));315		Ok(())316	}317318	/// Burns the specified amount of the token.319	pub fn burn_foreign(320		collection: &FungibleHandle<T>,321		owner: &T::CrossAccountId,322		amount: u128,323	) -> DispatchResult {324		let total_supply = <TotalSupply<T>>::get(collection.id)325			.checked_sub(amount)326			.ok_or(<CommonError<T>>::TokenValueTooLow)?;327328		let balance = <Balance<T>>::get((collection.id, owner))329			.checked_sub(amount)330			.ok_or(<CommonError<T>>::TokenValueTooLow)?;331		// =========332333		if balance == 0 {334			<Balance<T>>::remove((collection.id, owner));335			<PalletStructure<T>>::unnest_if_nested(owner, collection.id, TokenId::default());336		} else {337			<Balance<T>>::insert((collection.id, owner), balance);338		}339		<TotalSupply<T>>::insert(collection.id, total_supply);340341		<PalletEvm<T>>::deposit_log(342			ERC20Events::Transfer {343				from: *owner.as_eth(),344				to: H160::default(),345				value: amount.into(),346			}347			.to_log(collection_id_to_address(collection.id)),348		);349		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(350			collection.id,351			TokenId::default(),352			owner.clone(),353			amount,354		));355		Ok(())356	}357358	/// Transfers the specified amount of tokens. Will check that359	/// the transfer is allowed for the token.360	///361	/// - `from`: Owner of tokens to transfer.362	/// - `to`: Recepient of transfered tokens.363	/// - `amount`: Amount of tokens to transfer.364	/// - `collection`: Collection that contains the token365	pub fn transfer(366		collection: &FungibleHandle<T>,367		from: &T::CrossAccountId,368		to: &T::CrossAccountId,369		amount: u128,370		nesting_budget: &dyn Budget,371	) -> DispatchResult {372		ensure!(373			collection.limits.transfers_enabled(),374			<CommonError<T>>::TransferNotAllowed,375		);376377		if collection.permissions.access() == AccessMode::AllowList {378			collection.check_allowlist(from)?;379			collection.check_allowlist(to)?;380		}381		<PalletCommon<T>>::ensure_correct_receiver(to)?;382383		let balance_from = <Balance<T>>::get((collection.id, from))384			.checked_sub(amount)385			.ok_or(<CommonError<T>>::TokenValueTooLow)?;386		let balance_to = if from != to && amount != 0 {387			Some(388				<Balance<T>>::get((collection.id, to))389					.checked_add(amount)390					.ok_or(ArithmeticError::Overflow)?,391			)392		} else {393			None394		};395396		// =========397398		if let Some(balance_to) = balance_to {399			// from != to && amount != 0400401			<PalletStructure<T>>::nest_if_sent_to_token(402				from.clone(),403				to,404				collection.id,405				TokenId::default(),406				nesting_budget,407			)?;408409			if balance_from == 0 {410				<Balance<T>>::remove((collection.id, from));411				<PalletStructure<T>>::unnest_if_nested(from, collection.id, TokenId::default());412			} else {413				<Balance<T>>::insert((collection.id, from), balance_from);414			}415			<Balance<T>>::insert((collection.id, to), balance_to);416		}417418		<PalletEvm<T>>::deposit_log(419			ERC20Events::Transfer {420				from: *from.as_eth(),421				to: *to.as_eth(),422				value: amount.into(),423			}424			.to_log(collection_id_to_address(collection.id)),425		);426		<PalletCommon<T>>::deposit_event(CommonEvent::Transfer(427			collection.id,428			TokenId::default(),429			from.clone(),430			to.clone(),431			amount,432		));433		Ok(())434	}435436	/// Minting tokens for multiple IDs.437	/// It is a utility function used in [`create_multiple_items`][`Pallet::create_multiple_items`]438	/// and [`create_multiple_items_foreign`][`Pallet::create_multiple_items_foreign`]439	pub fn create_multiple_items_common(440		collection: &FungibleHandle<T>,441		sender: &T::CrossAccountId,442		data: BTreeMap<T::CrossAccountId, u128>,443		nesting_budget: &dyn Budget,444	) -> DispatchResult {445		let total_supply = data446			.iter()447			.map(|(_, v)| *v)448			.try_fold(<TotalSupply<T>>::get(collection.id), |acc, v| {449				acc.checked_add(v)450			})451			.ok_or(ArithmeticError::Overflow)?;452453		for (to, _) in data.iter() {454			<PalletStructure<T>>::check_nesting(455				sender.clone(),456				to,457				collection.id,458				TokenId::default(),459				nesting_budget,460			)?;461		}462463		let updated_balances = data464			.into_iter()465			.map(|(user, amount)| {466				let updated_balance = <Balance<T>>::get((collection.id, &user))467					.checked_add(amount)468					.ok_or(ArithmeticError::Overflow)?;469				Ok((user, amount, updated_balance))470			})471			.collect::<Result<Vec<_>, DispatchError>>()?;472473		// =========474475		<TotalSupply<T>>::insert(collection.id, total_supply);476		for (user, amount, updated_balance) in updated_balances {477			<Balance<T>>::insert((collection.id, &user), updated_balance);478			<PalletStructure<T>>::nest_if_sent_to_token_unchecked(479				&user,480				collection.id,481				TokenId::default(),482			);483			<PalletEvm<T>>::deposit_log(484				ERC20Events::Transfer {485					from: H160::default(),486					to: *user.as_eth(),487					value: amount.into(),488				}489				.to_log(collection_id_to_address(collection.id)),490			);491			<PalletCommon<T>>::deposit_event(CommonEvent::ItemCreated(492				collection.id,493				TokenId::default(),494				user.clone(),495				amount,496			));497		}498499		Ok(())500	}501502	/// Minting tokens for multiple IDs.503	/// See [`create_item`][`Pallet::create_item`] for more details.504	pub fn create_multiple_items(505		collection: &FungibleHandle<T>,506		sender: &T::CrossAccountId,507		data: BTreeMap<T::CrossAccountId, u128>,508		nesting_budget: &dyn Budget,509	) -> DispatchResult {510		// Foreign collection check511		ensure!(!collection.flags.foreign, <CommonError<T>>::NoPermission);512513		if !collection.is_owner_or_admin(sender) {514			ensure!(515				collection.permissions.mint_mode(),516				<CommonError<T>>::PublicMintingNotAllowed517			);518			collection.check_allowlist(sender)?;519520			for (owner, _) in data.iter() {521				collection.check_allowlist(owner)?;522			}523		}524525		Self::create_multiple_items_common(collection, sender, data, nesting_budget)526	}527528	/// Minting tokens for multiple IDs.529	/// See [`create_item_foreign`][`Pallet::create_item_foreign`] for more details.530	pub fn create_multiple_items_foreign(531		collection: &FungibleHandle<T>,532		sender: &T::CrossAccountId,533		data: BTreeMap<T::CrossAccountId, u128>,534		nesting_budget: &dyn Budget,535	) -> DispatchResult {536		Self::create_multiple_items_common(collection, sender, data, nesting_budget)537	}538539	fn set_allowance_unchecked(540		collection: &FungibleHandle<T>,541		owner: &T::CrossAccountId,542		spender: &T::CrossAccountId,543		amount: u128,544	) {545		if amount == 0 {546			<Allowance<T>>::remove((collection.id, owner, spender));547		} else {548			<Allowance<T>>::insert((collection.id, owner, spender), amount);549		}550551		<PalletEvm<T>>::deposit_log(552			ERC20Events::Approval {553				owner: *owner.as_eth(),554				spender: *spender.as_eth(),555				value: amount.into(),556			}557			.to_log(collection_id_to_address(collection.id)),558		);559		<PalletCommon<T>>::deposit_event(CommonEvent::Approved(560			collection.id,561			TokenId(0),562			owner.clone(),563			spender.clone(),564			amount,565		));566	}567568	/// Set allowance for the spender to `transfer` or `burn` owner's tokens.569	///570	/// - `collection`: Collection that contains the token571	/// - `owner`: Owner of tokens that sets the allowance.572	/// - `spender`: Recipient of the allowance rights.573	/// - `amount`: Amount of tokens the spender is allowed to `transfer` or `burn`.574	pub fn set_allowance(575		collection: &FungibleHandle<T>,576		owner: &T::CrossAccountId,577		spender: &T::CrossAccountId,578		amount: u128,579	) -> DispatchResult {580		if collection.permissions.access() == AccessMode::AllowList {581			collection.check_allowlist(owner)?;582			collection.check_allowlist(spender)?;583		}584585		if <Balance<T>>::get((collection.id, owner)) < amount {586			ensure!(587				collection.ignores_owned_amount(owner),588				<CommonError<T>>::CantApproveMoreThanOwned589			);590		}591592		// =========593594		Self::set_allowance_unchecked(collection, owner, spender, amount);595		Ok(())596	}597598	/// Checks if a non-owner has (enough) allowance from the owner to perform operations on the tokens.599	/// Returns the expected remaining allowance - it should be set manually if the transaction proceeds.600	///601	/// - `collection`: Collection that contains the token.602	/// - `spender`: CrossAccountId who has the allowance rights.603	/// - `from`: The owner of the tokens who sets the allowance.604	/// - `amount`: Amount of tokens by which the allowance sholud be reduced.605	fn check_allowed(606		collection: &FungibleHandle<T>,607		spender: &T::CrossAccountId,608		from: &T::CrossAccountId,609		amount: u128,610		nesting_budget: &dyn Budget,611	) -> Result<Option<u128>, DispatchError> {612		if spender.conv_eq(from) {613			return Ok(None);614		}615		if collection.permissions.access() == AccessMode::AllowList {616			// `from`, `to` checked in [`transfer`]617			collection.check_allowlist(spender)?;618		}619		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {620			// TODO: should collection owner be allowed to perform this transfer?621			ensure!(622				<PalletStructure<T>>::check_indirectly_owned(623					spender.clone(),624					source.0,625					source.1,626					None,627					nesting_budget628				)?,629				<CommonError<T>>::ApprovedValueTooLow,630			);631			return Ok(None);632		}633		let allowance = <Allowance<T>>::get((collection.id, from, spender)).checked_sub(amount);634		if allowance.is_none() {635			ensure!(636				collection.ignores_allowance(spender),637				<CommonError<T>>::ApprovedValueTooLow638			);639		}640641		Ok(allowance)642	}643644	/// Transfer fungible tokens from one account to another.645	/// Same as the [`transfer`][`Pallet::transfer`] but spender doesn't needs to be an owner of the token pieces.646	/// The owner should set allowance for the spender to transfer pieces.647	///	See [`set_allowance`][`Pallet::set_allowance`] for more details.648649	pub fn transfer_from(650		collection: &FungibleHandle<T>,651		spender: &T::CrossAccountId,652		from: &T::CrossAccountId,653		to: &T::CrossAccountId,654		amount: u128,655		nesting_budget: &dyn Budget,656	) -> DispatchResult {657		let allowance = Self::check_allowed(collection, spender, from, amount, nesting_budget)?;658659		// =========660661		Self::transfer(collection, from, to, amount, nesting_budget)?;662		if let Some(allowance) = allowance {663			Self::set_allowance_unchecked(collection, from, spender, allowance);664		}665		Ok(())666	}667668	/// Burn fungible tokens from the account.669	///670	/// Same as the [`burn`][`Pallet::burn`] but spender doesn't need to be an owner of the tokens. The `from` should671	/// set allowance for the spender to burn tokens.672	/// See [`set_allowance`][`Pallet::set_allowance`] for more details.673	pub fn burn_from(674		collection: &FungibleHandle<T>,675		spender: &T::CrossAccountId,676		from: &T::CrossAccountId,677		amount: u128,678		nesting_budget: &dyn Budget,679	) -> DispatchResult {680		let allowance = Self::check_allowed(collection, spender, from, amount, nesting_budget)?;681682		// =========683684		Self::burn(collection, from, amount)?;685		if let Some(allowance) = allowance {686			Self::set_allowance_unchecked(collection, from, spender, allowance);687		}688		Ok(())689	}690691	///	Creates fungible token.692	///693	/// The sender should be the owner/admin of the collection or collection should be configured694	/// to allow public minting.695	///696	/// - `data`: Contains user who will become the owners of the tokens and amount697	///   of tokens he will receive.698	pub fn create_item(699		collection: &FungibleHandle<T>,700		sender: &T::CrossAccountId,701		data: CreateItemData<T>,702		nesting_budget: &dyn Budget,703	) -> DispatchResult {704		Self::create_multiple_items(705			collection,706			sender,707			[(data.0, data.1)].into_iter().collect(),708			nesting_budget,709		)710	}711712	///	Creates fungible token.713	///714	/// - `data`: Contains user who will become the owners of the tokens and amount715	///   of tokens he will receive.716	pub fn create_item_foreign(717		collection: &FungibleHandle<T>,718		sender: &T::CrossAccountId,719		data: CreateItemData<T>,720		nesting_budget: &dyn Budget,721	) -> DispatchResult {722		Self::create_multiple_items_foreign(723			collection,724			sender,725			[(data.0, data.1)].into_iter().collect(),726			nesting_budget,727		)728	}729730	/// Returns 10 tokens owners in no particular order731	///732	/// There is no direct way to get token holders in ascending order,733	/// since `iter_prefix` returns values in no particular order.734	/// Therefore, getting the 10 largest holders with a large value of holders735	/// can lead to impact memory allocation + sorting with  `n * log (n)`.736	pub fn token_owners(737		collection: CollectionId,738		_token: TokenId,739	) -> Option<Vec<T::CrossAccountId>> {740		let res: Vec<T::CrossAccountId> = <Balance<T>>::iter_prefix((collection,))741			.map(|(owner, _amount)| owner)742			.take(10)743			.collect();744745		if res.is_empty() {746			None747		} else {748			Some(res)749		}750	}751}