git.delta.rocks / unique-network / refs/commits / c652c1eecc65

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;8283use evm_coder::ToLog;84use frame_support::{dispatch::PostDispatchInfo, ensure, pallet_prelude::*};85pub use pallet::*;86use pallet_common::{87	eth::collection_id_to_address, helpers::add_weight_to_post_info,88	weights::WeightInfo as CommonWeightInfo, Error as CommonError, Event as CommonEvent,89	Pallet as PalletCommon, SelfWeightOf as PalletCommonWeightOf,90};91use pallet_evm::{account::CrossAccountId, Pallet as PalletEvm};92use pallet_evm_coder_substrate::WithRecorder;93use pallet_structure::Pallet as PalletStructure;94use sp_core::H160;95use sp_runtime::{ArithmeticError, DispatchError, DispatchResult};96use sp_std::{collections::btree_map::BTreeMap, vec::Vec};97use up_data_structs::{98	budget::Budget, mapping::TokenAddressMapping, AccessMode, CollectionId, CreateCollectionData,99	Property, PropertyKey, TokenId,100};101use weights::WeightInfo;102103use crate::erc::ERC20Events;104#[cfg(feature = "runtime-benchmarks")]105pub mod benchmarking;106pub mod common;107pub mod erc;108pub mod weights;109110pub type CreateItemData<T> = (<T as pallet_evm::Config>::CrossAccountId, u128);111pub(crate) type SelfWeightOf<T> = <T as Config>::WeightInfo;112113#[frame_support::pallet]114pub mod pallet {115	use frame_support::{116		pallet_prelude::*, storage::Key, Blake2_128, Blake2_128Concat, Twox64Concat,117	};118	use up_data_structs::CollectionId;119120	use super::weights::WeightInfo;121122	#[pallet::error]123	pub enum Error<T> {124		/// Not Fungible item data used to mint in Fungible collection.125		NotFungibleDataUsedToMintFungibleCollectionToken,126		/// Tried to set data for fungible item.127		FungibleItemsDontHaveData,128		/// Fungible token does not support nesting.129		FungibleDisallowsNesting,130		/// Setting item properties is not allowed.131		SettingPropertiesNotAllowed,132		/// Setting allowance for all is not allowed.133		SettingAllowanceForAllNotAllowed,134		/// Only a fungible collection could be possibly broken; any fungible token is valid.135		FungibleTokensAreAlwaysValid,136	}137138	#[pallet::config]139	pub trait Config:140		frame_system::Config + pallet_common::Config + pallet_structure::Config + pallet_evm::Config141	{142		type WeightInfo: WeightInfo;143	}144145	#[pallet::pallet]146	pub struct Pallet<T>(_);147148	/// Total amount of fungible tokens inside a collection.149	#[pallet::storage]150	pub type TotalSupply<T: Config> =151		StorageMap<Hasher = Twox64Concat, Key = CollectionId, Value = u128, QueryKind = ValueQuery>;152153	/// Amount of tokens owned by an account inside a collection.154	#[pallet::storage]155	pub type Balance<T: Config> = StorageNMap<156		Key = (157			Key<Twox64Concat, CollectionId>,158			Key<Blake2_128Concat, T::CrossAccountId>,159		),160		Value = u128,161		QueryKind = ValueQuery,162	>;163164	/// Storage for assets delegated to a limited extent to other users.165	#[pallet::storage]166	pub type Allowance<T: Config> = StorageNMap<167		Key = (168			Key<Twox64Concat, CollectionId>,169			Key<Blake2_128, T::CrossAccountId>,       // Owner170			Key<Blake2_128Concat, T::CrossAccountId>, // Spender171		),172		Value = u128,173		QueryKind = ValueQuery,174	>;175}176177/// Wrapper around untyped collection handle, asserting inner collection is of fungible type.178/// Required for interaction with Fungible collections, type safety and implementation [`solidity_interface`][`evm_coder::solidity_interface`].179pub struct FungibleHandle<T: Config>(pallet_common::CollectionHandle<T>);180181/// Implementation of methods required for dispatching during runtime.182impl<T: Config> FungibleHandle<T> {183	/// Casts [`CollectionHandle`][`pallet_common::CollectionHandle`] into [`FungibleHandle`].184	pub fn cast(inner: pallet_common::CollectionHandle<T>) -> Self {185		Self(inner)186	}187188	/// Casts [`FungibleHandle`] into [`CollectionHandle`][`pallet_common::CollectionHandle`].189	pub fn into_inner(self) -> pallet_common::CollectionHandle<T> {190		self.0191	}192	/// Returns a mutable reference to the internal [`CollectionHandle`][`pallet_common::CollectionHandle`].193	pub fn common_mut(&mut self) -> &mut pallet_common::CollectionHandle<T> {194		&mut self.0195	}196}197impl<T: Config> WithRecorder<T> for FungibleHandle<T> {198	fn recorder(&self) -> &pallet_evm_coder_substrate::SubstrateRecorder<T> {199		self.0.recorder()200	}201	fn into_recorder(self) -> pallet_evm_coder_substrate::SubstrateRecorder<T> {202		self.0.into_recorder()203	}204}205impl<T: Config> Deref for FungibleHandle<T> {206	type Target = pallet_common::CollectionHandle<T>;207208	fn deref(&self) -> &Self::Target {209		&self.0210	}211}212213/// Pallet implementation for fungible assets214impl<T: Config> Pallet<T> {215	/// Destroys a collection.216	pub fn destroy_collection(217		collection: FungibleHandle<T>,218		sender: &T::CrossAccountId,219	) -> DispatchResult {220		let id = collection.id;221222		if Self::collection_has_tokens(id) {223			return Err(<CommonError<T>>::CantDestroyNotEmptyCollection.into());224		}225226		// =========227228		PalletCommon::destroy_collection(collection.0, sender)?;229230		<TotalSupply<T>>::remove(id);231		let _ = <Balance<T>>::clear_prefix((id,), u32::MAX, None);232		let _ = <Allowance<T>>::clear_prefix((id,), u32::MAX, None);233		Ok(())234	}235236	/// Add properties to the collection.237	pub fn set_collection_properties(238		collection: &FungibleHandle<T>,239		sender: &T::CrossAccountId,240		properties: Vec<Property>,241	) -> DispatchResult {242		<PalletCommon<T>>::set_collection_properties(collection, sender, properties.into_iter())243	}244245	/// Delete properties of the collection, associated with the provided keys.246	pub fn delete_collection_properties(247		collection: &FungibleHandle<T>,248		sender: &T::CrossAccountId,249		property_keys: Vec<PropertyKey>,250	) -> DispatchResult {251		<PalletCommon<T>>::delete_collection_properties(252			collection,253			sender,254			property_keys.into_iter(),255		)256	}257258	/// Checks if collection has tokens. Return `true` if it has.259	fn collection_has_tokens(collection_id: CollectionId) -> bool {260		<TotalSupply<T>>::get(collection_id) != 0261	}262263	/// Burns the specified amount of the token. If the token balance264	/// or total supply is less than the given value,265	/// it will return [DispatchError].266	pub fn burn(267		collection: &FungibleHandle<T>,268		owner: &T::CrossAccountId,269		amount: u128,270	) -> DispatchResult {271		let total_supply = <TotalSupply<T>>::get(collection.id)272			.checked_sub(amount)273			.ok_or(<CommonError<T>>::TokenValueTooLow)?;274275		let balance = <Balance<T>>::get((collection.id, owner))276			.checked_sub(amount)277			.ok_or(<CommonError<T>>::TokenValueTooLow)?;278279		// Foreign collection check280		ensure!(!collection.flags.foreign, <CommonError<T>>::NoPermission);281282		if collection.permissions.access() == AccessMode::AllowList {283			collection.check_allowlist(owner)?;284		}285286		// =========287288		if balance == 0 {289			<Balance<T>>::remove((collection.id, owner));290			<PalletStructure<T>>::unnest_if_nested(owner, collection.id, TokenId::default());291		} else {292			<Balance<T>>::insert((collection.id, owner), balance);293		}294		<TotalSupply<T>>::insert(collection.id, total_supply);295296		<PalletEvm<T>>::deposit_log(297			ERC20Events::Transfer {298				from: *owner.as_eth(),299				to: H160::default(),300				value: amount.into(),301			}302			.to_log(collection_id_to_address(collection.id)),303		);304		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(305			collection.id,306			TokenId::default(),307			owner.clone(),308			amount,309		));310		Ok(())311	}312313	/// Burns the specified amount of the token.314	pub fn burn_foreign(315		collection: &FungibleHandle<T>,316		owner: &T::CrossAccountId,317		amount: u128,318	) -> DispatchResult {319		let total_supply = <TotalSupply<T>>::get(collection.id)320			.checked_sub(amount)321			.ok_or(<CommonError<T>>::TokenValueTooLow)?;322323		let balance = <Balance<T>>::get((collection.id, owner))324			.checked_sub(amount)325			.ok_or(<CommonError<T>>::TokenValueTooLow)?;326		// =========327328		if balance == 0 {329			<Balance<T>>::remove((collection.id, owner));330			<PalletStructure<T>>::unnest_if_nested(owner, collection.id, TokenId::default());331		} else {332			<Balance<T>>::insert((collection.id, owner), balance);333		}334		<TotalSupply<T>>::insert(collection.id, total_supply);335336		<PalletEvm<T>>::deposit_log(337			ERC20Events::Transfer {338				from: *owner.as_eth(),339				to: H160::default(),340				value: amount.into(),341			}342			.to_log(collection_id_to_address(collection.id)),343		);344		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(345			collection.id,346			TokenId::default(),347			owner.clone(),348			amount,349		));350		Ok(())351	}352353	/// Transfers the specified amount of tokens. Will check that354	/// the transfer is allowed for the token.355	///356	/// - `from`: Owner of tokens to transfer.357	/// - `to`: Recepient of transfered tokens.358	/// - `amount`: Amount of tokens to transfer.359	/// - `collection`: Collection that contains the token360	pub fn transfer(361		collection: &FungibleHandle<T>,362		from: &T::CrossAccountId,363		to: &T::CrossAccountId,364		amount: u128,365		nesting_budget: &dyn Budget,366	) -> DispatchResultWithPostInfo {367		let depositor = from;368		Self::transfer_internal(collection, depositor, from, to, amount, nesting_budget)369	}370371	/// Transfers tokens from the `from` account to the `to` account.372	/// The `depositor` is the account who deposits the tokens.373	/// For instance, the nesting rules will be checked against the `depositor`'s permissions.374	fn transfer_internal(375		collection: &FungibleHandle<T>,376		depositor: &T::CrossAccountId,377		from: &T::CrossAccountId,378		to: &T::CrossAccountId,379		amount: u128,380		nesting_budget: &dyn Budget,381	) -> DispatchResultWithPostInfo {382		ensure!(383			collection.limits.transfers_enabled(),384			<CommonError<T>>::TransferNotAllowed,385		);386387		let mut actual_weight = <SelfWeightOf<T>>::transfer_raw();388389		if collection.permissions.access() == AccessMode::AllowList {390			collection.check_allowlist(from)?;391			collection.check_allowlist(to)?;392			actual_weight += <PalletCommonWeightOf<T>>::check_accesslist() * 2;393		}394		<PalletCommon<T>>::ensure_correct_receiver(to)?;395		let balance_from = <Balance<T>>::get((collection.id, from))396			.checked_sub(amount)397			.ok_or(<CommonError<T>>::TokenValueTooLow)?;398		let balance_to = if from != to && amount != 0 {399			Some(400				<Balance<T>>::get((collection.id, to))401					.checked_add(amount)402					.ok_or(ArithmeticError::Overflow)?,403			)404		} else {405			None406		};407408		// =========409410		if let Some(balance_to) = balance_to {411			// from != to && amount != 0412413			<PalletStructure<T>>::nest_if_sent_to_token(414				depositor,415				to,416				collection.id,417				TokenId::default(),418				nesting_budget,419			)?;420421			if balance_from == 0 {422				<Balance<T>>::remove((collection.id, from));423				<PalletStructure<T>>::unnest_if_nested(from, collection.id, TokenId::default());424			} else {425				<Balance<T>>::insert((collection.id, from), balance_from);426			}427			<Balance<T>>::insert((collection.id, to), balance_to);428		}429430		<PalletEvm<T>>::deposit_log(431			ERC20Events::Transfer {432				from: *from.as_eth(),433				to: *to.as_eth(),434				value: amount.into(),435			}436			.to_log(collection_id_to_address(collection.id)),437		);438		<PalletCommon<T>>::deposit_event(CommonEvent::Transfer(439			collection.id,440			TokenId::default(),441			from.clone(),442			to.clone(),443			amount,444		));445446		Ok(PostDispatchInfo {447			actual_weight: Some(actual_weight),448			pays_fee: Pays::Yes,449		})450	}451452	/// Minting tokens for multiple IDs.453	/// It is a utility function used in [`create_multiple_items`][`Pallet::create_multiple_items`]454	/// and [`create_multiple_items_foreign`][`Pallet::create_multiple_items_foreign`]455	pub fn create_multiple_items_common(456		collection: &FungibleHandle<T>,457		sender: &T::CrossAccountId,458		data: BTreeMap<T::CrossAccountId, u128>,459		nesting_budget: &dyn Budget,460	) -> DispatchResult {461		let total_supply = data462			.values()463			.copied()464			.try_fold(<TotalSupply<T>>::get(collection.id), |acc, v| {465				acc.checked_add(v)466			})467			.ok_or(ArithmeticError::Overflow)?;468469		for (to, _) in data.iter() {470			<PalletStructure<T>>::check_nesting(471				sender,472				to,473				collection.id,474				TokenId::default(),475				nesting_budget,476			)?;477		}478479		let updated_balances = data480			.into_iter()481			.map(|(user, amount)| {482				let updated_balance = <Balance<T>>::get((collection.id, &user))483					.checked_add(amount)484					.ok_or(ArithmeticError::Overflow)?;485				Ok((user, amount, updated_balance))486			})487			.collect::<Result<Vec<_>, DispatchError>>()?;488489		// =========490491		<TotalSupply<T>>::insert(collection.id, total_supply);492		for (user, amount, updated_balance) in updated_balances {493			<Balance<T>>::insert((collection.id, &user), updated_balance);494			<PalletStructure<T>>::nest_if_sent_to_token_unchecked(495				&user,496				collection.id,497				TokenId::default(),498			);499			<PalletEvm<T>>::deposit_log(500				ERC20Events::Transfer {501					from: H160::default(),502					to: *user.as_eth(),503					value: amount.into(),504				}505				.to_log(collection_id_to_address(collection.id)),506			);507			<PalletCommon<T>>::deposit_event(CommonEvent::ItemCreated(508				collection.id,509				TokenId::default(),510				user.clone(),511				amount,512			));513		}514515		Ok(())516	}517518	/// Minting tokens for multiple IDs.519	/// See [`create_item`][`Pallet::create_item`] for more details.520	pub fn create_multiple_items(521		collection: &FungibleHandle<T>,522		sender: &T::CrossAccountId,523		data: BTreeMap<T::CrossAccountId, u128>,524		nesting_budget: &dyn Budget,525	) -> DispatchResult {526		// Foreign collection check527		ensure!(!collection.flags.foreign, <CommonError<T>>::NoPermission);528529		if !collection.is_owner_or_admin(sender) {530			ensure!(531				collection.permissions.mint_mode(),532				<CommonError<T>>::PublicMintingNotAllowed533			);534			collection.check_allowlist(sender)?;535536			for (owner, _) in data.iter() {537				collection.check_allowlist(owner)?;538			}539		}540541		Self::create_multiple_items_common(collection, sender, data, nesting_budget)542	}543544	/// Minting tokens for multiple IDs.545	/// See [`create_item_foreign`][`Pallet::create_item_foreign`] for more details.546	pub fn create_multiple_items_foreign(547		collection: &FungibleHandle<T>,548		sender: &T::CrossAccountId,549		data: BTreeMap<T::CrossAccountId, u128>,550		nesting_budget: &dyn Budget,551	) -> DispatchResult {552		Self::create_multiple_items_common(collection, sender, data, nesting_budget)553	}554555	fn set_allowance_unchecked(556		collection: &FungibleHandle<T>,557		owner: &T::CrossAccountId,558		spender: &T::CrossAccountId,559		amount: u128,560	) {561		if amount == 0 {562			<Allowance<T>>::remove((collection.id, owner, spender));563		} else {564			<Allowance<T>>::insert((collection.id, owner, spender), amount);565		}566567		<PalletEvm<T>>::deposit_log(568			ERC20Events::Approval {569				owner: *owner.as_eth(),570				spender: *spender.as_eth(),571				value: amount.into(),572			}573			.to_log(collection_id_to_address(collection.id)),574		);575		<PalletCommon<T>>::deposit_event(CommonEvent::Approved(576			collection.id,577			TokenId(0),578			owner.clone(),579			spender.clone(),580			amount,581		));582	}583584	/// Set allowance for the spender to `transfer` or `burn` owner's tokens.585	///586	/// - `collection`: Collection that contains the token587	/// - `owner`: Owner of tokens that sets the allowance.588	/// - `spender`: Recipient of the allowance rights.589	/// - `amount`: Amount of tokens the spender is allowed to `transfer` or `burn`.590	pub fn set_allowance(591		collection: &FungibleHandle<T>,592		owner: &T::CrossAccountId,593		spender: &T::CrossAccountId,594		amount: u128,595	) -> DispatchResult {596		if collection.permissions.access() == AccessMode::AllowList {597			collection.check_allowlist(owner)?;598			collection.check_allowlist(spender)?;599		}600601		if <Balance<T>>::get((collection.id, owner)) < amount {602			ensure!(603				collection.ignores_owned_amount(owner),604				<CommonError<T>>::CantApproveMoreThanOwned605			);606		}607608		// =========609610		Self::set_allowance_unchecked(collection, owner, spender, amount);611		Ok(())612	}613614	/// Set allowance for the spender to `transfer` or `burn` owner's tokens from eth mirror.615	///616	/// - `collection`: Collection that contains the token617	/// - `sender`: Owner of tokens that sets the allowance.618	/// - `from`: Owner's eth mirror.619	/// - `to`: Recipient of the allowance rights.620	/// - `amount`: Amount of tokens the spender is allowed to `transfer` or `burn`.621	pub fn set_allowance_from(622		collection: &FungibleHandle<T>,623		sender: &T::CrossAccountId,624		from: &T::CrossAccountId,625		to: &T::CrossAccountId,626		amount: u128,627	) -> DispatchResult {628		if collection.permissions.access() == AccessMode::AllowList {629			collection.check_allowlist(sender)?;630			collection.check_allowlist(from)?;631			collection.check_allowlist(to)?;632		}633634		ensure!(635			sender.conv_eq(from),636			<CommonError<T>>::AddressIsNotEthMirror637		);638639		if <Balance<T>>::get((collection.id, from)) < amount {640			ensure!(641				collection.limits.owner_can_transfer()642					&& (collection.is_owner_or_admin(sender) || collection.is_owner_or_admin(from)),643				<CommonError<T>>::CantApproveMoreThanOwned644			);645		}646647		// =========648649		Self::set_allowance_unchecked(collection, from, to, amount);650		Ok(())651	}652653	/// Checks if a non-owner has (enough) allowance from the owner to perform operations on the tokens.654	/// Returns the expected remaining allowance - it should be set manually if the transaction proceeds.655	///656	/// - `collection`: Collection that contains the token.657	/// - `spender`: CrossAccountId who has the allowance rights.658	/// - `from`: The owner of the tokens who sets the allowance.659	/// - `amount`: Amount of tokens by which the allowance sholud be reduced.660	fn check_allowed(661		collection: &FungibleHandle<T>,662		spender: &T::CrossAccountId,663		from: &T::CrossAccountId,664		amount: u128,665		nesting_budget: &dyn Budget,666	) -> Result<Option<u128>, DispatchError> {667		if spender.conv_eq(from) {668			return Ok(None);669		}670		if collection.permissions.access() == AccessMode::AllowList {671			// `from`, `to` checked in [`transfer`]672			collection.check_allowlist(spender)?;673		}674675		if collection.ignores_token_restrictions(spender) {676			return Ok(Self::compute_allowance_decrease(677				collection, from, spender, amount,678			));679		}680681		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {682			ensure!(683				<PalletStructure<T>>::check_indirectly_owned(684					spender.clone(),685					source.0,686					source.1,687					None,688					nesting_budget689				)?,690				<CommonError<T>>::ApprovedValueTooLow,691			);692			return Ok(None);693		}694695		let allowance = Self::compute_allowance_decrease(collection, from, spender, amount);696		ensure!(allowance.is_some(), <CommonError<T>>::ApprovedValueTooLow);697698		Ok(allowance)699	}700701	/// Returns `Some(amount)` if the `spender` have allowance to spend this amount.702	/// Otherwise, it returns `None`.703	fn compute_allowance_decrease(704		collection: &FungibleHandle<T>,705		from: &T::CrossAccountId,706		spender: &T::CrossAccountId,707		amount: u128,708	) -> Option<u128> {709		<Allowance<T>>::get((collection.id, from, spender)).checked_sub(amount)710	}711712	/// Transfer fungible tokens from one account to another.713	/// Same as the [`transfer`][`Pallet::transfer`] but spender doesn't needs to be an owner of the token pieces.714	/// The owner should set allowance for the spender to transfer pieces.715	/// See [`set_allowance`][`Pallet::set_allowance`] for more details.716	pub fn transfer_from(717		collection: &FungibleHandle<T>,718		spender: &T::CrossAccountId,719		from: &T::CrossAccountId,720		to: &T::CrossAccountId,721		amount: u128,722		nesting_budget: &dyn Budget,723	) -> DispatchResultWithPostInfo {724		let allowance = Self::check_allowed(collection, spender, from, amount, nesting_budget)?;725726		// =========727728		let mut result =729			Self::transfer_internal(collection, spender, from, to, amount, nesting_budget);730		add_weight_to_post_info(&mut result, <SelfWeightOf<T>>::check_allowed_raw());731		result?;732733		if let Some(allowance) = allowance {734			Self::set_allowance_unchecked(collection, from, spender, allowance);735			add_weight_to_post_info(736				&mut result,737				<SelfWeightOf<T>>::set_allowance_unchecked_raw(),738			)739		}740		result741	}742743	/// Burn fungible tokens from the account.744	///745	/// Same as the [`burn`][`Pallet::burn`] but spender doesn't need to be an owner of the tokens. The `from` should746	/// set allowance for the spender to burn tokens.747	/// See [`set_allowance`][`Pallet::set_allowance`] for more details.748	pub fn burn_from(749		collection: &FungibleHandle<T>,750		spender: &T::CrossAccountId,751		from: &T::CrossAccountId,752		amount: u128,753		nesting_budget: &dyn Budget,754	) -> DispatchResult {755		let allowance = Self::check_allowed(collection, spender, from, amount, nesting_budget)?;756757		// =========758759		Self::burn(collection, from, amount)?;760		if let Some(allowance) = allowance {761			Self::set_allowance_unchecked(collection, from, spender, allowance);762		}763		Ok(())764	}765766	/// Creates fungible token.767	///768	/// The sender should be the owner/admin of the collection or collection should be configured769	/// to allow public minting.770	///771	/// - `data`: Contains user who will become the owners of the tokens and amount772	///   of tokens he will receive.773	pub fn create_item(774		collection: &FungibleHandle<T>,775		sender: &T::CrossAccountId,776		data: CreateItemData<T>,777		nesting_budget: &dyn Budget,778	) -> DispatchResult {779		Self::create_multiple_items(780			collection,781			sender,782			[(data.0, data.1)].into_iter().collect(),783			nesting_budget,784		)785	}786787	/// Creates fungible token.788	///789	/// - `data`: Contains user who will become the owners of the tokens and amount790	///   of tokens he will receive.791	pub fn create_item_foreign(792		collection: &FungibleHandle<T>,793		sender: &T::CrossAccountId,794		data: CreateItemData<T>,795		nesting_budget: &dyn Budget,796	) -> DispatchResult {797		Self::create_multiple_items_foreign(798			collection,799			sender,800			[(data.0, data.1)].into_iter().collect(),801			nesting_budget,802		)803	}804805	/// Returns 10 tokens owners in no particular order806	///807	/// There is no direct way to get token holders in ascending order,808	/// since `iter_prefix` returns values in no particular order.809	/// Therefore, getting the 10 largest holders with a large value of holders810	/// can lead to impact memory allocation + sorting with  `n * log (n)`.811	pub fn token_owners(812		collection: CollectionId,813		_token: TokenId,814	) -> Option<Vec<T::CrossAccountId>> {815		let res: Vec<T::CrossAccountId> = <Balance<T>>::iter_prefix((collection,))816			.map(|(owner, _amount)| owner)817			.take(10)818			.collect();819820		if res.is_empty() {821			None822		} else {823			Some(res)824		}825	}826}