git.delta.rocks / unique-network / refs/commits / eebd0e2c517b

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::{84	ensure,85	pallet_prelude::{DispatchResultWithPostInfo, Pays},86	dispatch::PostDispatchInfo,87};88use pallet_evm::account::CrossAccountId;89use up_data_structs::{90	AccessMode, CollectionId, TokenId, CreateCollectionData, mapping::TokenAddressMapping,91	budget::Budget, PropertyKey, Property,92};93use pallet_common::{94	Error as CommonError, Event as CommonEvent, Pallet as PalletCommon,95	eth::collection_id_to_address, SelfWeightOf as PalletCommonWeightOf,96	weights::WeightInfo as CommonWeightInfo, helpers::add_weight_to_post_info,97};98use pallet_evm::Pallet as PalletEvm;99use pallet_structure::Pallet as PalletStructure;100use pallet_evm_coder_substrate::WithRecorder;101use sp_core::H160;102use sp_runtime::{ArithmeticError, DispatchError, DispatchResult};103use sp_std::{collections::btree_map::BTreeMap, vec::Vec};104use weights::WeightInfo;105pub use pallet::*;106107use crate::erc::ERC20Events;108#[cfg(feature = "runtime-benchmarks")]109pub mod benchmarking;110pub mod common;111pub mod erc;112pub mod weights;113114pub type CreateItemData<T> = (<T as pallet_evm::Config>::CrossAccountId, u128);115pub(crate) type SelfWeightOf<T> = <T as Config>::WeightInfo;116117#[frame_support::pallet]118pub mod pallet {119	use frame_support::{Blake2_128, Blake2_128Concat, Twox64Concat, pallet_prelude::*, storage::Key};120	use up_data_structs::CollectionId;121	use super::weights::WeightInfo;122123	#[pallet::error]124	pub enum Error<T> {125		/// Not Fungible item data used to mint in Fungible collection.126		NotFungibleDataUsedToMintFungibleCollectionToken,127		/// Fungible tokens hold no ID, and the default value of TokenId for Fungible collection is 0.128		FungibleItemsHaveNoId,129		/// Tried to set data for fungible item.130		FungibleItemsDontHaveData,131		/// Fungible token does not support nesting.132		FungibleDisallowsNesting,133		/// Setting item properties is not allowed.134		SettingPropertiesNotAllowed,135		/// Setting allowance for all is not allowed.136		SettingAllowanceForAllNotAllowed,137		/// Only a fungible collection could be possibly broken; any fungible token is valid.138		FungibleTokensAreAlwaysValid,139	}140141	#[pallet::config]142	pub trait Config:143		frame_system::Config + pallet_common::Config + pallet_structure::Config + pallet_evm::Config144	{145		type WeightInfo: WeightInfo;146	}147148	#[pallet::pallet]149	pub struct Pallet<T>(_);150151	/// Total amount of fungible tokens inside a collection.152	#[pallet::storage]153	pub type TotalSupply<T: Config> =154		StorageMap<Hasher = Twox64Concat, Key = CollectionId, Value = u128, QueryKind = ValueQuery>;155156	/// Amount of tokens owned by an account inside a collection.157	#[pallet::storage]158	pub type Balance<T: Config> = StorageNMap<159		Key = (160			Key<Twox64Concat, CollectionId>,161			Key<Blake2_128Concat, T::CrossAccountId>,162		),163		Value = u128,164		QueryKind = ValueQuery,165	>;166167	/// Storage for assets delegated to a limited extent to other users.168	#[pallet::storage]169	pub type Allowance<T: Config> = StorageNMap<170		Key = (171			Key<Twox64Concat, CollectionId>,172			Key<Blake2_128, T::CrossAccountId>,       // Owner173			Key<Blake2_128Concat, T::CrossAccountId>, // Spender174		),175		Value = u128,176		QueryKind = ValueQuery,177	>;178}179180/// Wrapper around untyped collection handle, asserting inner collection is of fungible type.181/// Required for interaction with Fungible collections, type safety and implementation [`solidity_interface`][`evm_coder::solidity_interface`].182pub struct FungibleHandle<T: Config>(pallet_common::CollectionHandle<T>);183184/// Implementation of methods required for dispatching during runtime.185impl<T: Config> FungibleHandle<T> {186	/// Casts [`CollectionHandle`][`pallet_common::CollectionHandle`] into [`FungibleHandle`].187	pub fn cast(inner: pallet_common::CollectionHandle<T>) -> Self {188		Self(inner)189	}190191	/// Casts [`FungibleHandle`] into [`CollectionHandle`][`pallet_common::CollectionHandle`].192	pub fn into_inner(self) -> pallet_common::CollectionHandle<T> {193		self.0194	}195	/// Returns a mutable reference to the internal [`CollectionHandle`][`pallet_common::CollectionHandle`].196	pub fn common_mut(&mut self) -> &mut pallet_common::CollectionHandle<T> {197		&mut self.0198	}199}200impl<T: Config> WithRecorder<T> for FungibleHandle<T> {201	fn recorder(&self) -> &pallet_evm_coder_substrate::SubstrateRecorder<T> {202		self.0.recorder()203	}204	fn into_recorder(self) -> pallet_evm_coder_substrate::SubstrateRecorder<T> {205		self.0.into_recorder()206	}207}208impl<T: Config> Deref for FungibleHandle<T> {209	type Target = pallet_common::CollectionHandle<T>;210211	fn deref(&self) -> &Self::Target {212		&self.0213	}214}215216/// Pallet implementation for fungible assets217impl<T: Config> Pallet<T> {218	/// Initializes the collection. Returns [CollectionId] on success, [DispatchError] otherwise.219	pub fn init_collection(220		owner: T::CrossAccountId,221		payer: T::CrossAccountId,222		data: CreateCollectionData<T::CrossAccountId>,223	) -> Result<CollectionId, DispatchError> {224		<PalletCommon<T>>::init_collection(owner, payer, data)225	}226227	/// Initializes the collection with ForeignCollection flag. Returns [CollectionId] on success, [DispatchError] otherwise.228	pub fn init_foreign_collection(229		owner: T::CrossAccountId,230		payer: T::CrossAccountId,231		data: CreateCollectionData<T::CrossAccountId>,232	) -> Result<CollectionId, DispatchError> {233		<PalletCommon<T>>::init_foreign_collection(owner, payer, data)234	}235236	/// Destroys a collection.237	pub fn destroy_collection(238		collection: FungibleHandle<T>,239		sender: &T::CrossAccountId,240	) -> DispatchResult {241		let id = collection.id;242243		if Self::collection_has_tokens(id) {244			return Err(<CommonError<T>>::CantDestroyNotEmptyCollection.into());245		}246247		// =========248249		PalletCommon::destroy_collection(collection.0, sender)?;250251		<TotalSupply<T>>::remove(id);252		let _ = <Balance<T>>::clear_prefix((id,), u32::MAX, None);253		let _ = <Allowance<T>>::clear_prefix((id,), u32::MAX, None);254		Ok(())255	}256257	/// Add properties to the collection.258	pub fn set_collection_properties(259		collection: &FungibleHandle<T>,260		sender: &T::CrossAccountId,261		properties: Vec<Property>,262	) -> DispatchResult {263		<PalletCommon<T>>::set_collection_properties(collection, sender, properties.into_iter())264	}265266	/// Delete properties of the collection, associated with the provided keys.267	pub fn delete_collection_properties(268		collection: &FungibleHandle<T>,269		sender: &T::CrossAccountId,270		property_keys: Vec<PropertyKey>,271	) -> DispatchResult {272		<PalletCommon<T>>::delete_collection_properties(273			collection,274			sender,275			property_keys.into_iter(),276		)277	}278279	/// Checks if collection has tokens. Return `true` if it has.280	fn collection_has_tokens(collection_id: CollectionId) -> bool {281		<TotalSupply<T>>::get(collection_id) != 0282	}283284	/// Burns the specified amount of the token. If the token balance285	/// or total supply is less than the given value,286	/// it will return [DispatchError].287	pub fn burn(288		collection: &FungibleHandle<T>,289		owner: &T::CrossAccountId,290		amount: u128,291	) -> DispatchResult {292		let total_supply = <TotalSupply<T>>::get(collection.id)293			.checked_sub(amount)294			.ok_or(<CommonError<T>>::TokenValueTooLow)?;295296		let balance = <Balance<T>>::get((collection.id, owner))297			.checked_sub(amount)298			.ok_or(<CommonError<T>>::TokenValueTooLow)?;299300		// Foreign collection check301		ensure!(!collection.flags.foreign, <CommonError<T>>::NoPermission);302303		if collection.permissions.access() == AccessMode::AllowList {304			collection.check_allowlist(owner)?;305		}306307		// =========308309		if balance == 0 {310			<Balance<T>>::remove((collection.id, owner));311			<PalletStructure<T>>::unnest_if_nested(owner, collection.id, TokenId::default());312		} else {313			<Balance<T>>::insert((collection.id, owner), balance);314		}315		<TotalSupply<T>>::insert(collection.id, total_supply);316317		<PalletEvm<T>>::deposit_log(318			ERC20Events::Transfer {319				from: *owner.as_eth(),320				to: H160::default(),321				value: amount.into(),322			}323			.to_log(collection_id_to_address(collection.id)),324		);325		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(326			collection.id,327			TokenId::default(),328			owner.clone(),329			amount,330		));331		Ok(())332	}333334	/// Burns the specified amount of the token.335	pub fn burn_foreign(336		collection: &FungibleHandle<T>,337		owner: &T::CrossAccountId,338		amount: u128,339	) -> DispatchResult {340		let total_supply = <TotalSupply<T>>::get(collection.id)341			.checked_sub(amount)342			.ok_or(<CommonError<T>>::TokenValueTooLow)?;343344		let balance = <Balance<T>>::get((collection.id, owner))345			.checked_sub(amount)346			.ok_or(<CommonError<T>>::TokenValueTooLow)?;347		// =========348349		if balance == 0 {350			<Balance<T>>::remove((collection.id, owner));351			<PalletStructure<T>>::unnest_if_nested(owner, collection.id, TokenId::default());352		} else {353			<Balance<T>>::insert((collection.id, owner), balance);354		}355		<TotalSupply<T>>::insert(collection.id, total_supply);356357		<PalletEvm<T>>::deposit_log(358			ERC20Events::Transfer {359				from: *owner.as_eth(),360				to: H160::default(),361				value: amount.into(),362			}363			.to_log(collection_id_to_address(collection.id)),364		);365		<PalletCommon<T>>::deposit_event(CommonEvent::ItemDestroyed(366			collection.id,367			TokenId::default(),368			owner.clone(),369			amount,370		));371		Ok(())372	}373374	/// Transfers the specified amount of tokens. Will check that375	/// the transfer is allowed for the token.376	///377	/// - `from`: Owner of tokens to transfer.378	/// - `to`: Recepient of transfered tokens.379	/// - `amount`: Amount of tokens to transfer.380	/// - `collection`: Collection that contains the token381	pub fn transfer(382		collection: &FungibleHandle<T>,383		from: &T::CrossAccountId,384		to: &T::CrossAccountId,385		amount: u128,386		nesting_budget: &dyn Budget,387	) -> DispatchResultWithPostInfo {388		ensure!(389			collection.limits.transfers_enabled(),390			<CommonError<T>>::TransferNotAllowed,391		);392393		let mut actual_weight = <SelfWeightOf<T>>::transfer_raw();394395		if collection.permissions.access() == AccessMode::AllowList {396			collection.check_allowlist(from)?;397			collection.check_allowlist(to)?;398			actual_weight += <PalletCommonWeightOf<T>>::check_accesslist() * 2;399		}400		<PalletCommon<T>>::ensure_correct_receiver(to)?;401		let balance_from = <Balance<T>>::get((collection.id, from))402			.checked_sub(amount)403			.ok_or(<CommonError<T>>::TokenValueTooLow)?;404		let balance_to = if from != to && amount != 0 {405			Some(406				<Balance<T>>::get((collection.id, to))407					.checked_add(amount)408					.ok_or(ArithmeticError::Overflow)?,409			)410		} else {411			None412		};413414		// =========415416		if let Some(balance_to) = balance_to {417			// from != to && amount != 0418419			<PalletStructure<T>>::nest_if_sent_to_token(420				from.clone(),421				to,422				collection.id,423				TokenId::default(),424				nesting_budget,425			)?;426427			if balance_from == 0 {428				<Balance<T>>::remove((collection.id, from));429				<PalletStructure<T>>::unnest_if_nested(from, collection.id, TokenId::default());430			} else {431				<Balance<T>>::insert((collection.id, from), balance_from);432			}433			<Balance<T>>::insert((collection.id, to), balance_to);434		}435436		<PalletEvm<T>>::deposit_log(437			ERC20Events::Transfer {438				from: *from.as_eth(),439				to: *to.as_eth(),440				value: amount.into(),441			}442			.to_log(collection_id_to_address(collection.id)),443		);444		<PalletCommon<T>>::deposit_event(CommonEvent::Transfer(445			collection.id,446			TokenId::default(),447			from.clone(),448			to.clone(),449			amount,450		));451452		Ok(PostDispatchInfo {453			actual_weight: Some(actual_weight),454			pays_fee: Pays::Yes,455		})456	}457458	/// Minting tokens for multiple IDs.459	/// It is a utility function used in [`create_multiple_items`][`Pallet::create_multiple_items`]460	/// and [`create_multiple_items_foreign`][`Pallet::create_multiple_items_foreign`]461	pub fn create_multiple_items_common(462		collection: &FungibleHandle<T>,463		sender: &T::CrossAccountId,464		data: BTreeMap<T::CrossAccountId, u128>,465		nesting_budget: &dyn Budget,466	) -> DispatchResult {467		let total_supply = data468			.values()469			.copied()470			.try_fold(<TotalSupply<T>>::get(collection.id), |acc, v| {471				acc.checked_add(v)472			})473			.ok_or(ArithmeticError::Overflow)?;474475		for (to, _) in data.iter() {476			<PalletStructure<T>>::check_nesting(477				sender.clone(),478				to,479				collection.id,480				TokenId::default(),481				nesting_budget,482			)?;483		}484485		let updated_balances = data486			.into_iter()487			.map(|(user, amount)| {488				let updated_balance = <Balance<T>>::get((collection.id, &user))489					.checked_add(amount)490					.ok_or(ArithmeticError::Overflow)?;491				Ok((user, amount, updated_balance))492			})493			.collect::<Result<Vec<_>, DispatchError>>()?;494495		// =========496497		<TotalSupply<T>>::insert(collection.id, total_supply);498		for (user, amount, updated_balance) in updated_balances {499			<Balance<T>>::insert((collection.id, &user), updated_balance);500			<PalletStructure<T>>::nest_if_sent_to_token_unchecked(501				&user,502				collection.id,503				TokenId::default(),504			);505			<PalletEvm<T>>::deposit_log(506				ERC20Events::Transfer {507					from: H160::default(),508					to: *user.as_eth(),509					value: amount.into(),510				}511				.to_log(collection_id_to_address(collection.id)),512			);513			<PalletCommon<T>>::deposit_event(CommonEvent::ItemCreated(514				collection.id,515				TokenId::default(),516				user.clone(),517				amount,518			));519		}520521		Ok(())522	}523524	/// Minting tokens for multiple IDs.525	/// See [`create_item`][`Pallet::create_item`] for more details.526	pub fn create_multiple_items(527		collection: &FungibleHandle<T>,528		sender: &T::CrossAccountId,529		data: BTreeMap<T::CrossAccountId, u128>,530		nesting_budget: &dyn Budget,531	) -> DispatchResult {532		// Foreign collection check533		ensure!(!collection.flags.foreign, <CommonError<T>>::NoPermission);534535		if !collection.is_owner_or_admin(sender) {536			ensure!(537				collection.permissions.mint_mode(),538				<CommonError<T>>::PublicMintingNotAllowed539			);540			collection.check_allowlist(sender)?;541542			for (owner, _) in data.iter() {543				collection.check_allowlist(owner)?;544			}545		}546547		Self::create_multiple_items_common(collection, sender, data, nesting_budget)548	}549550	/// Minting tokens for multiple IDs.551	/// See [`create_item_foreign`][`Pallet::create_item_foreign`] for more details.552	pub fn create_multiple_items_foreign(553		collection: &FungibleHandle<T>,554		sender: &T::CrossAccountId,555		data: BTreeMap<T::CrossAccountId, u128>,556		nesting_budget: &dyn Budget,557	) -> DispatchResult {558		Self::create_multiple_items_common(collection, sender, data, nesting_budget)559	}560561	fn set_allowance_unchecked(562		collection: &FungibleHandle<T>,563		owner: &T::CrossAccountId,564		spender: &T::CrossAccountId,565		amount: u128,566	) {567		if amount == 0 {568			<Allowance<T>>::remove((collection.id, owner, spender));569		} else {570			<Allowance<T>>::insert((collection.id, owner, spender), amount);571		}572573		<PalletEvm<T>>::deposit_log(574			ERC20Events::Approval {575				owner: *owner.as_eth(),576				spender: *spender.as_eth(),577				value: amount.into(),578			}579			.to_log(collection_id_to_address(collection.id)),580		);581		<PalletCommon<T>>::deposit_event(CommonEvent::Approved(582			collection.id,583			TokenId(0),584			owner.clone(),585			spender.clone(),586			amount,587		));588	}589590	/// Set allowance for the spender to `transfer` or `burn` owner's tokens.591	///592	/// - `collection`: Collection that contains the token593	/// - `owner`: Owner of tokens that sets the allowance.594	/// - `spender`: Recipient of the allowance rights.595	/// - `amount`: Amount of tokens the spender is allowed to `transfer` or `burn`.596	pub fn set_allowance(597		collection: &FungibleHandle<T>,598		owner: &T::CrossAccountId,599		spender: &T::CrossAccountId,600		amount: u128,601	) -> DispatchResult {602		if collection.permissions.access() == AccessMode::AllowList {603			collection.check_allowlist(owner)?;604			collection.check_allowlist(spender)?;605		}606607		if <Balance<T>>::get((collection.id, owner)) < amount {608			ensure!(609				collection.ignores_owned_amount(owner),610				<CommonError<T>>::CantApproveMoreThanOwned611			);612		}613614		// =========615616		Self::set_allowance_unchecked(collection, owner, spender, amount);617		Ok(())618	}619620	/// Set allowance for the spender to `transfer` or `burn` owner's tokens from eth mirror.621	///622	/// - `collection`: Collection that contains the token623	/// - `sender`: Owner of tokens that sets the allowance.624	/// - `from`: Owner's eth mirror.625	/// - `to`: Recipient of the allowance rights.626	/// - `amount`: Amount of tokens the spender is allowed to `transfer` or `burn`.627	pub fn set_allowance_from(628		collection: &FungibleHandle<T>,629		sender: &T::CrossAccountId,630		from: &T::CrossAccountId,631		to: &T::CrossAccountId,632		amount: u128,633	) -> DispatchResult {634		if collection.permissions.access() == AccessMode::AllowList {635			collection.check_allowlist(sender)?;636			collection.check_allowlist(from)?;637			collection.check_allowlist(to)?;638		}639640		ensure!(641			sender.conv_eq(from),642			<CommonError<T>>::AddressIsNotEthMirror643		);644645		if <Balance<T>>::get((collection.id, from)) < amount {646			ensure!(647				collection.limits.owner_can_transfer()648					&& (collection.is_owner_or_admin(sender) || collection.is_owner_or_admin(from)),649				<CommonError<T>>::CantApproveMoreThanOwned650			);651		}652653		// =========654655		Self::set_allowance_unchecked(collection, from, to, amount);656		Ok(())657	}658659	/// Checks if a non-owner has (enough) allowance from the owner to perform operations on the tokens.660	/// Returns the expected remaining allowance - it should be set manually if the transaction proceeds.661	///662	/// - `collection`: Collection that contains the token.663	/// - `spender`: CrossAccountId who has the allowance rights.664	/// - `from`: The owner of the tokens who sets the allowance.665	/// - `amount`: Amount of tokens by which the allowance sholud be reduced.666	fn check_allowed(667		collection: &FungibleHandle<T>,668		spender: &T::CrossAccountId,669		from: &T::CrossAccountId,670		amount: u128,671		nesting_budget: &dyn Budget,672	) -> Result<Option<u128>, DispatchError> {673		if spender.conv_eq(from) {674			return Ok(None);675		}676		if collection.permissions.access() == AccessMode::AllowList {677			// `from`, `to` checked in [`transfer`]678			collection.check_allowlist(spender)?;679		}680681		if collection.ignores_token_restrictions(spender) {682			return Ok(Self::compute_allowance_decrease(683				collection, from, spender, amount,684			));685		}686687		if let Some(source) = T::CrossTokenAddressMapping::address_to_token(from) {688			ensure!(689				<PalletStructure<T>>::check_indirectly_owned(690					spender.clone(),691					source.0,692					source.1,693					None,694					nesting_budget695				)?,696				<CommonError<T>>::ApprovedValueTooLow,697			);698			return Ok(None);699		}700701		let allowance = Self::compute_allowance_decrease(collection, from, spender, amount);702		ensure!(allowance.is_some(), <CommonError<T>>::ApprovedValueTooLow);703704		Ok(allowance)705	}706707	/// Returns `Some(amount)` if the `spender` have allowance to spend this amount.708	/// Otherwise, it returns `None`.709	fn compute_allowance_decrease(710		collection: &FungibleHandle<T>,711		from: &T::CrossAccountId,712		spender: &T::CrossAccountId,713		amount: u128,714	) -> Option<u128> {715		<Allowance<T>>::get((collection.id, from, spender)).checked_sub(amount)716	}717718	/// Transfer fungible tokens from one account to another.719	/// Same as the [`transfer`][`Pallet::transfer`] but spender doesn't needs to be an owner of the token pieces.720	/// The owner should set allowance for the spender to transfer pieces.721	/// See [`set_allowance`][`Pallet::set_allowance`] for more details.722	pub fn transfer_from(723		collection: &FungibleHandle<T>,724		spender: &T::CrossAccountId,725		from: &T::CrossAccountId,726		to: &T::CrossAccountId,727		amount: u128,728		nesting_budget: &dyn Budget,729	) -> DispatchResultWithPostInfo {730		let allowance = Self::check_allowed(collection, spender, from, amount, nesting_budget)?;731732		// =========733734		let mut result = Self::transfer(collection, from, to, amount, nesting_budget);735		add_weight_to_post_info(&mut result, <SelfWeightOf<T>>::check_allowed_raw());736		result?;737738		if let Some(allowance) = allowance {739			Self::set_allowance_unchecked(collection, from, spender, allowance);740			add_weight_to_post_info(741				&mut result,742				<SelfWeightOf<T>>::set_allowance_unchecked_raw(),743			)744		}745		result746	}747748	/// Burn fungible tokens from the account.749	///750	/// Same as the [`burn`][`Pallet::burn`] but spender doesn't need to be an owner of the tokens. The `from` should751	/// set allowance for the spender to burn tokens.752	/// See [`set_allowance`][`Pallet::set_allowance`] for more details.753	pub fn burn_from(754		collection: &FungibleHandle<T>,755		spender: &T::CrossAccountId,756		from: &T::CrossAccountId,757		amount: u128,758		nesting_budget: &dyn Budget,759	) -> DispatchResult {760		let allowance = Self::check_allowed(collection, spender, from, amount, nesting_budget)?;761762		// =========763764		Self::burn(collection, from, amount)?;765		if let Some(allowance) = allowance {766			Self::set_allowance_unchecked(collection, from, spender, allowance);767		}768		Ok(())769	}770771	/// Creates fungible token.772	///773	/// The sender should be the owner/admin of the collection or collection should be configured774	/// to allow public minting.775	///776	/// - `data`: Contains user who will become the owners of the tokens and amount777	///   of tokens he will receive.778	pub fn create_item(779		collection: &FungibleHandle<T>,780		sender: &T::CrossAccountId,781		data: CreateItemData<T>,782		nesting_budget: &dyn Budget,783	) -> DispatchResult {784		Self::create_multiple_items(785			collection,786			sender,787			[(data.0, data.1)].into_iter().collect(),788			nesting_budget,789		)790	}791792	/// Creates fungible token.793	///794	/// - `data`: Contains user who will become the owners of the tokens and amount795	///   of tokens he will receive.796	pub fn create_item_foreign(797		collection: &FungibleHandle<T>,798		sender: &T::CrossAccountId,799		data: CreateItemData<T>,800		nesting_budget: &dyn Budget,801	) -> DispatchResult {802		Self::create_multiple_items_foreign(803			collection,804			sender,805			[(data.0, data.1)].into_iter().collect(),806			nesting_budget,807		)808	}809810	/// Returns 10 tokens owners in no particular order811	///812	/// There is no direct way to get token holders in ascending order,813	/// since `iter_prefix` returns values in no particular order.814	/// Therefore, getting the 10 largest holders with a large value of holders815	/// can lead to impact memory allocation + sorting with  `n * log (n)`.816	pub fn token_owners(817		collection: CollectionId,818		_token: TokenId,819	) -> Option<Vec<T::CrossAccountId>> {820		let res: Vec<T::CrossAccountId> = <Balance<T>>::iter_prefix((collection,))821			.map(|(owner, _amount)| owner)822			.take(10)823			.collect();824825		if res.is_empty() {826			None827		} else {828			Some(res)829		}830	}831}