Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
interface IOperatorFilterRegistry {
function isOperatorAllowed(address registrant, address operator) external view returns (bool);
function register(address registrant) external;
function registerAndSubscribe(address registrant, address subscription) external;
function registerAndCopyEntries(address registrant, address registrantToCopy) external;
function unregister(address addr) external;
function updateOperator(address registrant, address operator, bool filtered) external;
function updateOperators(address registrant, address[] calldata operators, bool filtered) external;
function updateCodeHash(address registrant, bytes32 codehash, bool filtered) external;
function updateCodeHashes(address registrant, bytes32[] calldata codeHashes, bool filtered) external;
function subscribe(address registrant, address registrantToSubscribe) external;
function unsubscribe(address registrant, bool copyExistingEntries) external;
function subscriptionOf(address addr) external returns (address registrant);
function subscribers(address registrant) external returns (address[] memory);
function subscriberAt(address registrant, uint256 index) external returns (address);
function copyEntriesOf(address registrant, address registrantToCopy) external;
function isOperatorFiltered(address registrant, address operator) external returns (bool);
function isCodeHashOfFiltered(address registrant, address operatorWithCode) external returns (bool);
function isCodeHashFiltered(address registrant, bytes32 codeHash) external returns (bool);
function filteredOperators(address addr) external returns (address[] memory);
function filteredCodeHashes(address addr) external returns (bytes32[] memory);
function filteredOperatorAt(address registrant, uint256 index) external returns (address);
function filteredCodeHashAt(address registrant, uint256 index) external returns (bytes32);
function isRegistered(address addr) external returns (bool);
function codeHashOf(address addr) external returns (bytes32);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
import {RevokableOperatorFilterer} from "./RevokableOperatorFilterer.sol";
/**
* @title RevokableDefaultOperatorFilterer
* @notice Inherits from RevokableOperatorFilterer and automatically subscribes to the default OpenSea subscription.
* Note that OpenSea will disable creator fee enforcement if filtered operators begin fulfilling orders
* on-chain, eg, if the registry is revoked or bypassed.
*/
abstract contract RevokableDefaultOperatorFilterer is RevokableOperatorFilterer {
address constant DEFAULT_SUBSCRIPTION = address(0x3cc6CddA760b79bAfa08dF41ECFA224f810dCeB6);
constructor() RevokableOperatorFilterer(0x000000000000AAeB6D7670E522A718067333cd4E, DEFAULT_SUBSCRIPTION, true) {}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
import {UpdatableOperatorFilterer} from "./UpdatableOperatorFilterer.sol";
import {IOperatorFilterRegistry} from "./IOperatorFilterRegistry.sol";
/**
* @title RevokableOperatorFilterer
* @notice This contract is meant to allow contracts to permanently skip OperatorFilterRegistry checks if desired. The
* Registry itself has an "unregister" function, but if the contract is ownable, the owner can re-register at
* any point. As implemented, this abstract contract allows the contract owner to permanently skip the
* OperatorFilterRegistry checks by calling revokeOperatorFilterRegistry. Once done, the registry
* address cannot be further updated.
* Note that OpenSea will still disable creator fee enforcement if filtered operators begin fulfilling orders
* on-chain, eg, if the registry is revoked or bypassed.
*/
abstract contract RevokableOperatorFilterer is UpdatableOperatorFilterer {
error RegistryHasBeenRevoked();
error InitialRegistryAddressCannotBeZeroAddress();
bool public isOperatorFilterRegistryRevoked;
constructor(address _registry, address subscriptionOrRegistrantToCopy, bool subscribe)
UpdatableOperatorFilterer(_registry, subscriptionOrRegistrantToCopy, subscribe)
{
// don't allow creating a contract with a permanently revoked registry
if (_registry == address(0)) {
revert InitialRegistryAddressCannotBeZeroAddress();
}
}
function _checkFilterOperator(address operator) internal view virtual override {
if (address(operatorFilterRegistry) != address(0)) {
super._checkFilterOperator(operator);
}
}
/**
* @notice Update the address that the contract will make OperatorFilter checks against. When set to the zero
* address, checks will be permanently bypassed, and the address cannot be updated again. OnlyOwner.
*/
function updateOperatorFilterRegistryAddress(address newRegistry) public override {
if (msg.sender != owner()) {
revert OnlyOwner();
}
// if registry has been revoked, do not allow further updates
if (isOperatorFilterRegistryRevoked) {
revert RegistryHasBeenRevoked();
}
operatorFilterRegistry = IOperatorFilterRegistry(newRegistry);
}
/**
* @notice Revoke the OperatorFilterRegistry address, permanently bypassing checks. OnlyOwner.
*/
function revokeOperatorFilterRegistry() public {
if (msg.sender != owner()) {
revert OnlyOwner();
}
// if registry has been revoked, do not allow further updates
if (isOperatorFilterRegistryRevoked) {
revert RegistryHasBeenRevoked();
}
// set to zero address to bypass checks
operatorFilterRegistry = IOperatorFilterRegistry(address(0));
isOperatorFilterRegistryRevoked = true;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
import {IOperatorFilterRegistry} from "./IOperatorFilterRegistry.sol";
/**
* @title UpdatableOperatorFilterer
* @notice Abstract contract whose constructor automatically registers and optionally subscribes to or copies another
* registrant's entries in the OperatorFilterRegistry. This contract allows the Owner to update the
* OperatorFilterRegistry address via updateOperatorFilterRegistryAddress, including to the zero address,
* which will bypass registry checks.
* Note that OpenSea will still disable creator fee enforcement if filtered operators begin fulfilling orders
* on-chain, eg, if the registry is revoked or bypassed.
* @dev This smart contract is meant to be inherited by token contracts so they can use the following:
* - `onlyAllowedOperator` modifier for `transferFrom` and `safeTransferFrom` methods.
* - `onlyAllowedOperatorApproval` modifier for `approve` and `setApprovalForAll` methods.
*/
abstract contract UpdatableOperatorFilterer {
error OperatorNotAllowed(address operator);
error OnlyOwner();
IOperatorFilterRegistry public operatorFilterRegistry;
constructor(address _registry, address subscriptionOrRegistrantToCopy, bool subscribe) {
IOperatorFilterRegistry registry = IOperatorFilterRegistry(_registry);
operatorFilterRegistry = registry;
// If an inheriting token contract is deployed to a network without the registry deployed, the modifier
// will not revert, but the contract will need to be registered with the registry once it is deployed in
// order for the modifier to filter addresses.
if (address(registry).code.length > 0) {
if (subscribe) {
registry.registerAndSubscribe(address(this), subscriptionOrRegistrantToCopy);
} else {
if (subscriptionOrRegistrantToCopy != address(0)) {
registry.registerAndCopyEntries(address(this), subscriptionOrRegistrantToCopy);
} else {
registry.register(address(this));
}
}
}
}
modifier onlyAllowedOperator(address from) virtual {
// Allow spending tokens from addresses with balance
// Note that this still allows listings and marketplaces with escrow to transfer tokens if transferred
// from an EOA.
if (from != msg.sender) {
_checkFilterOperator(msg.sender);
}
_;
}
modifier onlyAllowedOperatorApproval(address operator) virtual {
_checkFilterOperator(operator);
_;
}
/**
* @notice Update the address that the contract will make OperatorFilter checks against. When set to the zero
* address, checks will be bypassed. OnlyOwner.
*/
function updateOperatorFilterRegistryAddress(address newRegistry) public virtual {
if (msg.sender != owner()) {
revert OnlyOwner();
}
operatorFilterRegistry = IOperatorFilterRegistry(newRegistry);
}
/**
* @dev assume the contract has an owner, but leave specific Ownable implementation up to inheriting contract
*/
function owner() public view virtual returns (address);
function _checkFilterOperator(address operator) internal view virtual {
IOperatorFilterRegistry registry = operatorFilterRegistry;
// Check registry code length to facilitate testing in environments without a deployed registry.
if (address(registry) != address(0) && address(registry).code.length > 0) {
if (!registry.isOperatorAllowed(address(this), operator)) {
revert OperatorNotAllowed(operator);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;
import {ERC721} from "openzeppelin-contracts/token/ERC721/ERC721.sol";
import {RevokableDefaultOperatorFilterer} from "./Base/RevokableDefaultOperatorFilterer.sol";
import {Ownable} from "openzeppelin-contracts/access/Ownable.sol";
import {Strings} from "openzeppelin-contracts/utils/Strings.sol";
import {ReentrancyGuard} from "openzeppelin-contracts/utils/ReentrancyGuard.sol";
import {MerkleProof} from "openzeppelin-contracts/cryptography/MerkleProof.sol";
import {AccessControl} from "openzeppelin-contracts/access/AccessControl.sol";
// GGGGGGGGGGGGG QQQQQQQQQ 333333333333333
// GGG::::::::::::G QQ:::::::::QQ 3:::::::::::::::33
// GG:::::::::::::::G QQ:::::::::::::QQ 3::::::33333::::::3
// G:::::GGGGGGGG::::GQ:::::::QQQ:::::::Q3333333 3:::::3
// G:::::G GGGGGGQ::::::O Q::::::Q 3:::::3
// G:::::G Q:::::O Q:::::Q 3:::::3
// G:::::G Q:::::O Q:::::Q 33333333:::::3
// G:::::G GGGGGGGGGGQ:::::O Q:::::Q 3:::::::::::3
// G:::::G G::::::::GQ:::::O Q:::::Q 33333333:::::3
// G:::::G GGGGG::::GQ:::::O Q:::::Q 3:::::3
// G:::::G G::::GQ:::::O QQQQ:::::Q 3:::::3
// G:::::G G::::GQ::::::O Q::::::::Q 3:::::3
// G:::::GGGGGGGG::::GQ:::::::QQ::::::::Q3333333 3:::::3
// GG:::::::::::::::G QQ::::::::::::::Q 3::::::33333::::::3
// GGG::::::GGG:::G QQ:::::::::::Q 3:::::::::::::::33
// GGGGGG GGGG QQQQQQQQ::::QQ 333333333333333
// Q:::::Q
// QQQQQQ
contract GQ3 is
ERC721,
RevokableDefaultOperatorFilterer,
AccessControl,
ReentrancyGuard
{
uint256 public price;
uint256 public maxSupply;
uint256 public maxAmountPerTx;
uint8 public phase;
bool private revealed;
string private contractURL;
string private notRevealedUri;
string private baseUri;
bytes32 public merkleRoot;
address private ownerAddress;
uint256 private currentTokenId;
mapping(address => uint256) private _minted;
bytes32 public constant MINTER_ROLE = keccak256("MINTER_ROLE");
constructor(
string memory _notRevealedUri,
string memory _revealedUri
) ERC721("GQ3 Issue 001: Change is Good", "GQ3") {
price = 0.1957 ether;
currentTokenId = 1;
maxSupply = 1661;
maxAmountPerTx = 1;
phase = 1; // 1, 2, or 3
revealed = false;
notRevealedUri = _notRevealedUri;
baseUri = _revealedUri;
ownerAddress = _msgSender();
_setupRole(DEFAULT_ADMIN_ROLE, _msgSender());
_setupRole(MINTER_ROLE, 0xEF0B56692F78A44CF4034b07F80204757c31Bcc9);
}
modifier onlyOwner() {
require(
hasRole(DEFAULT_ADMIN_ROLE, _msgSender()),
"Caller is not a admin"
);
_;
}
modifier onlyMinter() {
require(hasRole(MINTER_ROLE, _msgSender()), "Caller is not a minter");
_;
}
function owner() public view virtual override returns (address) {
return ownerAddress;
}
function grantMinterRole(address _account) public onlyOwner {
grantRole(MINTER_ROLE, _account);
}
function isOnAllowlist(
bytes32[] memory _proof,
address _claimer,
uint256 _amount
) public view returns (bool) {
bytes32 leaf = keccak256(abi.encodePacked(_claimer, _amount));
return MerkleProof.verify(_proof, merkleRoot, leaf);
}
function setMerkleRoot(bytes32 _merkleRoot) public onlyOwner {
merkleRoot = _merkleRoot;
}
function setPhase(uint8 _newPhase) public onlyOwner {
require(_newPhase < 4 && _newPhase > 0, "Invalid phase: 1, 2, 3");
phase = _newPhase;
}
function setPrice(uint256 _newPrice) public onlyOwner {
price = _newPrice;
}
function setMaxSupply(uint256 _maxSupply) public onlyOwner {
require(
_maxSupply > maxSupply,
"New supply should be bigger than old one"
);
maxSupply = _maxSupply;
}
function setRevealed(bool _revealed) public onlyOwner {
revealed = _revealed;
}
function setNotRevealedURI(
string memory _newNotRevealedURI
) public onlyOwner {
notRevealedUri = _newNotRevealedURI;
}
function setBaseURI(string memory _newBaseURI) public onlyOwner {
baseUri = _newBaseURI;
}
function setMaxAmountPerTx(uint256 _maxAmount) public onlyOwner {
require(_maxAmount > 0, "Invalid param provided");
maxAmountPerTx = _maxAmount;
}
function withdraw() public onlyOwner nonReentrant {
uint256 _balance = address(this).balance;
require(_balance > 0, "No amount to withdraw");
(bool success, ) = _msgSender().call{value: _balance}("");
require(success, "Transfer failed.");
}
function contractURI() public view returns (string memory) {
return contractURL;
}
function setContractURI(string memory _contractURL) public onlyOwner {
contractURL = _contractURL;
}
function mintedBalanceOf(address _address) public view returns (uint256) {
return _minted[_address];
}
function airdrop(address _to, uint256 _amount) public onlyOwner {
require(
totalSupply() + _amount <= maxSupply,
"Cannot mint that many tokens."
);
for (uint256 index = 0; index < _amount; index++) {
_mint(_to, currentTokenId);
currentTokenId += 1;
}
_minted[_to] += _amount;
}
function checkClaimEligibility(
address _to,
uint256 _ogHoldQuantity,
uint256 _mintQuantity,
bytes32[] memory _proof
) external view returns (string memory) {
return
_checkClaimEligibility(_to, _ogHoldQuantity, _mintQuantity, _proof);
}
function _checkClaimEligibility(
address _to,
uint256 _ogHoldQuantity,
uint256 _mintQuantity,
bytes32[] memory _proof
) internal view returns (string memory) {
if (phase < 3) {
if (!isOnAllowlist(_proof, _to, _ogHoldQuantity)) {
return "Wallet address is not Allowlisted";
}
}
if (phase > 1 && _mintQuantity > maxAmountPerTx) {
return "Cannot mint that many tokens per tx";
}
if (phase == 1) {
if (_minted[_to] + _mintQuantity > _ogHoldQuantity) {
return "Cannot mint that many tokens per wallet";
}
} else if (phase == 2) {
if (
_minted[_to] + _mintQuantity >
(_ogHoldQuantity + maxAmountPerTx)
) {
return "Cannot mint that many tokens per wallet";
}
}
if (totalSupply() + _mintQuantity > maxSupply) {
return "NFT is sold out";
}
return "";
}
function claimTo(
address _to,
uint256 _ogHoldQuantity, // When phase 2, 3, ignore it as 0 for non og holders
uint256 _mintQuantity,
bytes32[] memory _proof
) external payable onlyMinter {
string memory eligibility = _checkClaimEligibility(
_to,
_ogHoldQuantity,
_mintQuantity,
_proof
);
require(bytes(eligibility).length == 0, eligibility);
require(
msg.value >= _mintQuantity * price,
"Not enough to pay for that"
);
for (uint256 index = 0; index < _mintQuantity; index++) {
_safeMint(_msgSender(), currentTokenId);
currentTokenId += 1;
}
_minted[_to] += _mintQuantity;
}
function webMint(
uint256 _ogHoldQuantity, // When phase 2, 3, ignore it as 0 for non og holders
uint256 _mintQuantity,
bytes32[] memory _proof
) external payable {
string memory eligibility = _checkClaimEligibility(
_msgSender(),
_ogHoldQuantity,
_mintQuantity,
_proof
);
require(bytes(eligibility).length == 0, eligibility);
require(
msg.value >= _mintQuantity * price,
"Not enough to pay for that"
);
for (uint256 index = 0; index < _mintQuantity; index++) {
_mint(_msgSender(), currentTokenId);
currentTokenId += 1;
}
_minted[_msgSender()] += _mintQuantity;
}
function tokenURI(
uint256 _tokenId
) public view virtual override returns (string memory) {
require(_exists(_tokenId), "NFT does not exist");
if (!revealed) {
return notRevealedUri;
}
return
string(
abi.encodePacked(baseUri, Strings.toString(_tokenId), ".json")
);
}
function setApprovalForAll(
address operator,
bool approved
) public override onlyAllowedOperatorApproval(operator) {
super.setApprovalForAll(operator, approved);
}
function approve(
address operator,
uint256 tokenId
) public override onlyAllowedOperatorApproval(operator) {
super.approve(operator, tokenId);
}
function transferFrom(
address from,
address to,
uint256 tokenId
) public override onlyAllowedOperator(from) {
super.transferFrom(from, to, tokenId);
}
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) public override onlyAllowedOperator(from) {
super.safeTransferFrom(from, to, tokenId);
}
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes memory data
) public override onlyAllowedOperator(from) {
super.safeTransferFrom(from, to, tokenId, data);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../utils/EnumerableSet.sol";
import "../utils/Address.sol";
import "../GSN/Context.sol";
/**
* @dev Contract module that allows children to implement role-based access
* control mechanisms.
*
* Roles are referred to by their `bytes32` identifier. These should be exposed
* in the external API and be unique. The best way to achieve this is by
* using `public constant` hash digests:
*
* ```
* bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
* ```
*
* Roles can be used to represent a set of permissions. To restrict access to a
* function call, use {hasRole}:
*
* ```
* function foo() public {
* require(hasRole(MY_ROLE, msg.sender));
* ...
* }
* ```
*
* Roles can be granted and revoked dynamically via the {grantRole} and
* {revokeRole} functions. Each role has an associated admin role, and only
* accounts that have a role's admin role can call {grantRole} and {revokeRole}.
*
* By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
* that only accounts with this role will be able to grant or revoke other
* roles. More complex role relationships can be created by using
* {_setRoleAdmin}.
*
* WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
* grant and revoke this role. Extra precautions should be taken to secure
* accounts that have been granted it.
*/
abstract contract AccessControl is Context {
using EnumerableSet for EnumerableSet.AddressSet;
using Address for address;
struct RoleData {
EnumerableSet.AddressSet members;
bytes32 adminRole;
}
mapping (bytes32 => RoleData) private _roles;
bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
/**
* @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
*
* `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
* {RoleAdminChanged} not being emitted signaling this.
*
* _Available since v3.1._
*/
event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
/**
* @dev Emitted when `account` is granted `role`.
*
* `sender` is the account that originated the contract call, an admin role
* bearer except when using {_setupRole}.
*/
event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
/**
* @dev Emitted when `account` is revoked `role`.
*
* `sender` is the account that originated the contract call:
* - if using `revokeRole`, it is the admin role bearer
* - if using `renounceRole`, it is the role bearer (i.e. `account`)
*/
event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
/**
* @dev Returns `true` if `account` has been granted `role`.
*/
function hasRole(bytes32 role, address account) public view returns (bool) {
return _roles[role].members.contains(account);
}
/**
* @dev Returns the number of accounts that have `role`. Can be used
* together with {getRoleMember} to enumerate all bearers of a role.
*/
function getRoleMemberCount(bytes32 role) public view returns (uint256) {
return _roles[role].members.length();
}
/**
* @dev Returns one of the accounts that have `role`. `index` must be a
* value between 0 and {getRoleMemberCount}, non-inclusive.
*
* Role bearers are not sorted in any particular way, and their ordering may
* change at any point.
*
* WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
* you perform all queries on the same block. See the following
* https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
* for more information.
*/
function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
return _roles[role].members.at(index);
}
/**
* @dev Returns the admin role that controls `role`. See {grantRole} and
* {revokeRole}.
*
* To change a role's admin, use {_setRoleAdmin}.
*/
function getRoleAdmin(bytes32 role) public view returns (bytes32) {
return _roles[role].adminRole;
}
/**
* @dev Grants `role` to `account`.
*
* If `account` had not been already granted `role`, emits a {RoleGranted}
* event.
*
* Requirements:
*
* - the caller must have ``role``'s admin role.
*/
function grantRole(bytes32 role, address account) public virtual {
require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");
_grantRole(role, account);
}
/**
* @dev Revokes `role` from `account`.
*
* If `account` had been granted `role`, emits a {RoleRevoked} event.
*
* Requirements:
*
* - the caller must have ``role``'s admin role.
*/
function revokeRole(bytes32 role, address account) public virtual {
require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");
_revokeRole(role, account);
}
/**
* @dev Revokes `role` from the calling account.
*
* Roles are often managed via {grantRole} and {revokeRole}: this function's
* purpose is to provide a mechanism for accounts to lose their privileges
* if they are compromised (such as when a trusted device is misplaced).
*
* If the calling account had been granted `role`, emits a {RoleRevoked}
* event.
*
* Requirements:
*
* - the caller must be `account`.
*/
function renounceRole(bytes32 role, address account) public virtual {
require(account == _msgSender(), "AccessControl: can only renounce roles for self");
_revokeRole(role, account);
}
/**
* @dev Grants `role` to `account`.
*
* If `account` had not been already granted `role`, emits a {RoleGranted}
* event. Note that unlike {grantRole}, this function doesn't perform any
* checks on the calling account.
*
* [WARNING]
* ====
* This function should only be called from the constructor when setting
* up the initial roles for the system.
*
* Using this function in any other way is effectively circumventing the admin
* system imposed by {AccessControl}.
* ====
*/
function _setupRole(bytes32 role, address account) internal virtual {
_grantRole(role, account);
}
/**
* @dev Sets `adminRole` as ``role``'s admin role.
*
* Emits a {RoleAdminChanged} event.
*/
function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
emit RoleAdminChanged(role, _roles[role].adminRole, adminRole);
_roles[role].adminRole = adminRole;
}
function _grantRole(bytes32 role, address account) private {
if (_roles[role].members.add(account)) {
emit RoleGranted(role, account, _msgSender());
}
}
function _revokeRole(bytes32 role, address account) private {
if (_roles[role].members.remove(account)) {
emit RoleRevoked(role, account, _msgSender());
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../GSN/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor () {
address msgSender = _msgSender();
_owner = msgSender;
emit OwnershipTransferred(address(0), msgSender);
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(_owner == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
emit OwnershipTransferred(_owner, address(0));
_owner = address(0);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev These functions deal with verification of Merkle trees (hash trees),
*/
library MerkleProof {
/**
* @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
* defined by `root`. For this, a `proof` must be provided, containing
* sibling hashes on the branch from the leaf to the root of the tree. Each
* pair of leaves and each pair of pre-images are assumed to be sorted.
*/
function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
bytes32 computedHash = leaf;
for (uint256 i = 0; i < proof.length; i++) {
bytes32 proofElement = proof[i];
if (computedHash <= proofElement) {
// Hash(current computed hash + current element of the proof)
computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
} else {
// Hash(current element of the proof + current computed hash)
computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
}
}
// Check if the computed hash (root) is equal to the provided root
return computedHash == root;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with GSN meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC165.sol";
/**
* @dev Implementation of the {IERC165} interface.
*
* Contracts may inherit from this and call {_registerInterface} to declare
* their support of an interface.
*/
abstract contract ERC165 is IERC165 {
/*
* bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
*/
bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
/**
* @dev Mapping of interface ids to whether or not it's supported.
*/
mapping(bytes4 => bool) private _supportedInterfaces;
constructor () {
// Derived contracts need only register support for their own interfaces,
// we register support for ERC165 itself here
_registerInterface(_INTERFACE_ID_ERC165);
}
/**
* @dev See {IERC165-supportsInterface}.
*
* Time complexity O(1), guaranteed to always use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) public virtual view override returns (bool) {
return _supportedInterfaces[interfaceId];
}
/**
* @dev Registers the contract as an implementer of the interface defined by
* `interfaceId`. Support of the actual ERC165 interface is automatic and
* registering its interface id is not required.
*
* See {IERC165-supportsInterface}.
*
* Requirements:
*
* - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
*/
function _registerInterface(bytes4 interfaceId) internal virtual {
require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
_supportedInterfaces[interfaceId] = true;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC165 standard, as defined in the
* https://eips.ethereum.org/EIPS/eip-165[EIP].
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({ERC165Checker}).
*
* For an implementation, see {ERC165}.
*/
interface IERC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`. See the corresponding
* https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
* to learn more about how these ids are created.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../../GSN/Context.sol";
import "./IERC721.sol";
import "./IERC721Metadata.sol";
import "./IERC721Enumerable.sol";
import "./IERC721Receiver.sol";
import "../../introspection/ERC165.sol";
import "../../utils/Address.sol";
import "../../utils/EnumerableSet.sol";
import "../../utils/EnumerableMap.sol";
import "../../utils/Strings.sol";
/**
* @title ERC721 Non-Fungible Token Standard basic implementation
* @dev see https://eips.ethereum.org/EIPS/eip-721
*/
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable {
using Address for address;
using EnumerableSet for EnumerableSet.UintSet;
using EnumerableMap for EnumerableMap.UintToAddressMap;
using Strings for uint256;
// Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
// which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;
// Mapping from holder address to their (enumerable) set of owned tokens
mapping (address => EnumerableSet.UintSet) private _holderTokens;
// Enumerable mapping from token ids to their owners
EnumerableMap.UintToAddressMap private _tokenOwners;
// Mapping from token ID to approved address
mapping (uint256 => address) private _tokenApprovals;
// Mapping from owner to operator approvals
mapping (address => mapping (address => bool)) private _operatorApprovals;
// Token name
string private _name;
// Token symbol
string private _symbol;
// Optional mapping for token URIs
mapping (uint256 => string) private _tokenURIs;
// Base URI
string private _baseURI;
/*
* bytes4(keccak256('balanceOf(address)')) == 0x70a08231
* bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e
* bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
* bytes4(keccak256('getApproved(uint256)')) == 0x081812fc
* bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465
* bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5
* bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
* bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e
* bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
*
* => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
* 0xa22cb465 ^ 0xe985e9c5 ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
*/
bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;
/*
* bytes4(keccak256('name()')) == 0x06fdde03
* bytes4(keccak256('symbol()')) == 0x95d89b41
* bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd
*
* => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f
*/
bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
/*
* bytes4(keccak256('totalSupply()')) == 0x18160ddd
* bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59
* bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7
*
* => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63
*/
bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
/**
* @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
*/
constructor (string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
// register the supported interfaces to conform to ERC721 via ERC165
_registerInterface(_INTERFACE_ID_ERC721);
_registerInterface(_INTERFACE_ID_ERC721_METADATA);
_registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
}
/**
* @dev See {IERC721-balanceOf}.
*/
function balanceOf(address owner) public view override returns (uint256) {
require(owner != address(0), "ERC721: balance query for the zero address");
return _holderTokens[owner].length();
}
/**
* @dev See {IERC721-ownerOf}.
*/
function ownerOf(uint256 tokenId) public view override returns (address) {
return _tokenOwners.get(tokenId, "ERC721: owner query for nonexistent token");
}
/**
* @dev See {IERC721Metadata-name}.
*/
function name() public view override returns (string memory) {
return _name;
}
/**
* @dev See {IERC721Metadata-symbol}.
*/
function symbol() public view override returns (string memory) {
return _symbol;
}
/**
* @dev See {IERC721Metadata-tokenURI}.
*/
function tokenURI(uint256 tokenId) public virtual view override returns (string memory) {
require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
string memory _tokenURI = _tokenURIs[tokenId];
// If there is no base URI, return the token URI.
if (bytes(_baseURI).length == 0) {
return _tokenURI;
}
// If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
if (bytes(_tokenURI).length > 0) {
return string(abi.encodePacked(_baseURI, _tokenURI));
}
// If there is a baseURI but no tokenURI, concatenate the tokenID to the baseURI.
return string(abi.encodePacked(_baseURI, tokenId.toString()));
}
/**
* @dev Returns the base URI set via {_setBaseURI}. This will be
* automatically added as a prefix in {tokenURI} to each token's URI, or
* to the token ID if no specific URI is set for that token ID.
*/
function baseURI() public view returns (string memory) {
return _baseURI;
}
/**
* @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
*/
function tokenOfOwnerByIndex(address owner, uint256 index) public view override returns (uint256) {
return _holderTokens[owner].at(index);
}
/**
* @dev See {IERC721Enumerable-totalSupply}.
*/
function totalSupply() public view override returns (uint256) {
// _tokenOwners are indexed by tokenIds, so .length() returns the number of tokenIds
return _tokenOwners.length();
}
/**
* @dev See {IERC721Enumerable-tokenByIndex}.
*/
function tokenByIndex(uint256 index) public view override returns (uint256) {
(uint256 tokenId, ) = _tokenOwners.at(index);
return tokenId;
}
/**
* @dev See {IERC721-approve}.
*/
function approve(address to, uint256 tokenId) public virtual override {
address owner = ownerOf(tokenId);
require(to != owner, "ERC721: approval to current owner");
require(_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
"ERC721: approve caller is not owner nor approved for all"
);
_approve(to, tokenId);
}
/**
* @dev See {IERC721-getApproved}.
*/
function getApproved(uint256 tokenId) public view override returns (address) {
require(_exists(tokenId), "ERC721: approved query for nonexistent token");
return _tokenApprovals[tokenId];
}
/**
* @dev See {IERC721-setApprovalForAll}.
*/
function setApprovalForAll(address operator, bool approved) public virtual override {
require(operator != _msgSender(), "ERC721: approve to caller");
_operatorApprovals[_msgSender()][operator] = approved;
emit ApprovalForAll(_msgSender(), operator, approved);
}
/**
* @dev See {IERC721-isApprovedForAll}.
*/
function isApprovedForAll(address owner, address operator) public view override returns (bool) {
return _operatorApprovals[owner][operator];
}
/**
* @dev See {IERC721-transferFrom}.
*/
function transferFrom(address from, address to, uint256 tokenId) public virtual override {
//solhint-disable-next-line max-line-length
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_transfer(from, to, tokenId);
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
safeTransferFrom(from, to, tokenId, "");
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_safeTransfer(from, to, tokenId, _data);
}
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* `_data` is additional data, it has no specified format and it is sent in call to `to`.
*
* This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
* implement alternative mechanisms to perform token transfer, such as signature-based.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {
_transfer(from, to, tokenId);
require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
/**
* @dev Returns whether `tokenId` exists.
*
* Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
*
* Tokens start existing when they are minted (`_mint`),
* and stop existing when they are burned (`_burn`).
*/
function _exists(uint256 tokenId) internal view returns (bool) {
return _tokenOwners.contains(tokenId);
}
/**
* @dev Returns whether `spender` is allowed to manage `tokenId`.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool) {
require(_exists(tokenId), "ERC721: operator query for nonexistent token");
address owner = ownerOf(tokenId);
return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
}
/**
* @dev Safely mints `tokenId` and transfers it to `to`.
*
* Requirements:
d*
* - `tokenId` must not exist.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeMint(address to, uint256 tokenId) internal virtual {
_safeMint(to, tokenId, "");
}
/**
* @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
* forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
*/
function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
_mint(to, tokenId);
require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
/**
* @dev Mints `tokenId` and transfers it to `to`.
*
* WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
*
* Requirements:
*
* - `tokenId` must not exist.
* - `to` cannot be the zero address.
*
* Emits a {Transfer} event.
*/
function _mint(address to, uint256 tokenId) internal virtual {
require(to != address(0), "ERC721: mint to the zero address");
require(!_exists(tokenId), "ERC721: token already minted");
_beforeTokenTransfer(address(0), to, tokenId);
_holderTokens[to].add(tokenId);
_tokenOwners.set(tokenId, to);
emit Transfer(address(0), to, tokenId);
}
/**
* @dev Destroys `tokenId`.
* The approval is cleared when the token is burned.
*
* Requirements:
*
* - `tokenId` must exist.
*
* Emits a {Transfer} event.
*/
function _burn(uint256 tokenId) internal virtual {
address owner = ownerOf(tokenId);
_beforeTokenTransfer(owner, address(0), tokenId);
// Clear approvals
_approve(address(0), tokenId);
// Clear metadata (if any)
if (bytes(_tokenURIs[tokenId]).length != 0) {
delete _tokenURIs[tokenId];
}
_holderTokens[owner].remove(tokenId);
_tokenOwners.remove(tokenId);
emit Transfer(owner, address(0), tokenId);
}
/**
* @dev Transfers `tokenId` from `from` to `to`.
* As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
*
* Emits a {Transfer} event.
*/
function _transfer(address from, address to, uint256 tokenId) internal virtual {
require(ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
require(to != address(0), "ERC721: transfer to the zero address");
_beforeTokenTransfer(from, to, tokenId);
// Clear approvals from the previous owner
_approve(address(0), tokenId);
_holderTokens[from].remove(tokenId);
_holderTokens[to].add(tokenId);
_tokenOwners.set(tokenId, to);
emit Transfer(from, to, tokenId);
}
/**
* @dev Sets `_tokenURI` as the tokenURI of `tokenId`.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
require(_exists(tokenId), "ERC721Metadata: URI set of nonexistent token");
_tokenURIs[tokenId] = _tokenURI;
}
/**
* @dev Internal function to set the base URI for all token IDs. It is
* automatically added as a prefix to the value returned in {tokenURI},
* or to the token ID if {tokenURI} is empty.
*/
function _setBaseURI(string memory baseURI_) internal virtual {
_baseURI = baseURI_;
}
/**
* @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
* The call is not executed if the target address is not a contract.
*
* @param from address representing the previous owner of the given token ID
* @param to target address that will receive the tokens
* @param tokenId uint256 ID of the token to be transferred
* @param _data bytes optional data to send along with the call
* @return bool whether the call correctly returned the expected magic value
*/
function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
private returns (bool)
{
if (!to.isContract()) {
return true;
}
bytes memory returndata = to.functionCall(abi.encodeWithSelector(
IERC721Receiver(to).onERC721Received.selector,
_msgSender(),
from,
tokenId,
_data
), "ERC721: transfer to non ERC721Receiver implementer");
bytes4 retval = abi.decode(returndata, (bytes4));
return (retval == _ERC721_RECEIVED);
}
function _approve(address to, uint256 tokenId) private {
_tokenApprovals[tokenId] = to;
emit Approval(ownerOf(tokenId), to, tokenId);
}
/**
* @dev Hook that is called before any token transfer. This includes minting
* and burning.
*
* Calling conditions:
*
* - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
* transferred to `to`.
* - When `from` is zero, `tokenId` will be minted for `to`.
* - When `to` is zero, ``from``'s `tokenId` will be burned.
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual { }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../../introspection/IERC165.sol";
/**
* @dev Required interface of an ERC721 compliant contract.
*/
interface IERC721 is IERC165 {
/**
* @dev Emitted when `tokenId` token is transferred from `from` to `to`.
*/
event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
*/
event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
*/
event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
/**
* @dev Returns the number of tokens in ``owner``'s account.
*/
function balanceOf(address owner) external view returns (uint256 balance);
/**
* @dev Returns the owner of the `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function ownerOf(uint256 tokenId) external view returns (address owner);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(address from, address to, uint256 tokenId) external;
/**
* @dev Transfers `tokenId` token from `from` to `to`.
*
* WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
*
* Emits a {Transfer} event.
*/
function transferFrom(address from, address to, uint256 tokenId) external;
/**
* @dev Gives permission to `to` to transfer `tokenId` token to another account.
* The approval is cleared when the token is transferred.
*
* Only a single account can be approved at a time, so approving the zero address clears previous approvals.
*
* Requirements:
*
* - The caller must own the token or be an approved operator.
* - `tokenId` must exist.
*
* Emits an {Approval} event.
*/
function approve(address to, uint256 tokenId) external;
/**
* @dev Returns the account approved for `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function getApproved(uint256 tokenId) external view returns (address operator);
/**
* @dev Approve or remove `operator` as an operator for the caller.
* Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
*
* Requirements:
*
* - The `operator` cannot be the caller.
*
* Emits an {ApprovalForAll} event.
*/
function setApprovalForAll(address operator, bool _approved) external;
/**
* @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
*
* See {setApprovalForAll}
*/
function isApprovedForAll(address owner, address operator) external view returns (bool);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC721.sol";
/**
* @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Enumerable is IERC721 {
/**
* @dev Returns the total amount of tokens stored by the contract.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns a token ID owned by `owner` at a given `index` of its token list.
* Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
*/
function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);
/**
* @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
* Use along with {totalSupply} to enumerate all tokens.
*/
function tokenByIndex(uint256 index) external view returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC721.sol";
/**
* @title ERC-721 Non-Fungible Token Standard, optional metadata extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Metadata is IERC721 {
/**
* @dev Returns the token collection name.
*/
function name() external view returns (string memory);
/**
* @dev Returns the token collection symbol.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
*/
function tokenURI(uint256 tokenId) external view returns (string memory);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @title ERC721 token receiver interface
* @dev Interface for any contract that wants to support safeTransfers
* from ERC721 asset contracts.
*/
interface IERC721Receiver {
/**
* @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
* by `operator` from `from`, this function is called.
*
* It must return its Solidity selector to confirm the token transfer.
* If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
*
* The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
*/
function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
// solhint-disable-next-line no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain`call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: value }(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.3._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.3._
*/
function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Library for managing an enumerable variant of Solidity's
* https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
* type.
*
* Maps have the following properties:
*
* - Entries are added, removed, and checked for existence in constant time
* (O(1)).
* - Entries are enumerated in O(n). No guarantees are made on the ordering.
*
* ```
* contract Example {
* // Add the library methods
* using EnumerableMap for EnumerableMap.UintToAddressMap;
*
* // Declare a set state variable
* EnumerableMap.UintToAddressMap private myMap;
* }
* ```
*
* As of v3.0.0, only maps of type `uint256 -> address` (`UintToAddressMap`) are
* supported.
*/
library EnumerableMap {
// To implement this library for multiple types with as little code
// repetition as possible, we write it in terms of a generic Map type with
// bytes32 keys and values.
// The Map implementation uses private functions, and user-facing
// implementations (such as Uint256ToAddressMap) are just wrappers around
// the underlying Map.
// This means that we can only create new EnumerableMaps for types that fit
// in bytes32.
struct MapEntry {
bytes32 _key;
bytes32 _value;
}
struct Map {
// Storage of map keys and values
MapEntry[] _entries;
// Position of the entry defined by a key in the `entries` array, plus 1
// because index 0 means a key is not in the map.
mapping (bytes32 => uint256) _indexes;
}
/**
* @dev Adds a key-value pair to a map, or updates the value for an existing
* key. O(1).
*
* Returns true if the key was added to the map, that is if it was not
* already present.
*/
function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {
// We read and store the key's index to prevent multiple reads from the same storage slot
uint256 keyIndex = map._indexes[key];
if (keyIndex == 0) { // Equivalent to !contains(map, key)
map._entries.push(MapEntry({ _key: key, _value: value }));
// The entry is stored at length-1, but we add 1 to all indexes
// and use 0 as a sentinel value
map._indexes[key] = map._entries.length;
return true;
} else {
map._entries[keyIndex - 1]._value = value;
return false;
}
}
/**
* @dev Removes a key-value pair from a map. O(1).
*
* Returns true if the key was removed from the map, that is if it was present.
*/
function _remove(Map storage map, bytes32 key) private returns (bool) {
// We read and store the key's index to prevent multiple reads from the same storage slot
uint256 keyIndex = map._indexes[key];
if (keyIndex != 0) { // Equivalent to contains(map, key)
// To delete a key-value pair from the _entries array in O(1), we swap the entry to delete with the last one
// in the array, and then remove the last entry (sometimes called as 'swap and pop').
// This modifies the order of the array, as noted in {at}.
uint256 toDeleteIndex = keyIndex - 1;
uint256 lastIndex = map._entries.length - 1;
// When the entry to delete is the last one, the swap operation is unnecessary. However, since this occurs
// so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
MapEntry storage lastEntry = map._entries[lastIndex];
// Move the last entry to the index where the entry to delete is
map._entries[toDeleteIndex] = lastEntry;
// Update the index for the moved entry
map._indexes[lastEntry._key] = toDeleteIndex + 1; // All indexes are 1-based
// Delete the slot where the moved entry was stored
map._entries.pop();
// Delete the index for the deleted slot
delete map._indexes[key];
return true;
} else {
return false;
}
}
/**
* @dev Returns true if the key is in the map. O(1).
*/
function _contains(Map storage map, bytes32 key) private view returns (bool) {
return map._indexes[key] != 0;
}
/**
* @dev Returns the number of key-value pairs in the map. O(1).
*/
function _length(Map storage map) private view returns (uint256) {
return map._entries.length;
}
/**
* @dev Returns the key-value pair stored at position `index` in the map. O(1).
*
* Note that there are no guarantees on the ordering of entries inside the
* array, and it may change when more entries are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {
require(map._entries.length > index, "EnumerableMap: index out of bounds");
MapEntry storage entry = map._entries[index];
return (entry._key, entry._value);
}
/**
* @dev Returns the value associated with `key`. O(1).
*
* Requirements:
*
* - `key` must be in the map.
*/
function _get(Map storage map, bytes32 key) private view returns (bytes32) {
return _get(map, key, "EnumerableMap: nonexistent key");
}
/**
* @dev Same as {_get}, with a custom error message when `key` is not in the map.
*/
function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {
uint256 keyIndex = map._indexes[key];
require(keyIndex != 0, errorMessage); // Equivalent to contains(map, key)
return map._entries[keyIndex - 1]._value; // All indexes are 1-based
}
// UintToAddressMap
struct UintToAddressMap {
Map _inner;
}
/**
* @dev Adds a key-value pair to a map, or updates the value for an existing
* key. O(1).
*
* Returns true if the key was added to the map, that is if it was not
* already present.
*/
function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {
return _set(map._inner, bytes32(key), bytes32(uint256(uint160(value))));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the key was removed from the map, that is if it was present.
*/
function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
return _remove(map._inner, bytes32(key));
}
/**
* @dev Returns true if the key is in the map. O(1).
*/
function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
return _contains(map._inner, bytes32(key));
}
/**
* @dev Returns the number of elements in the map. O(1).
*/
function length(UintToAddressMap storage map) internal view returns (uint256) {
return _length(map._inner);
}
/**
* @dev Returns the element stored at position `index` in the set. O(1).
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
(bytes32 key, bytes32 value) = _at(map._inner, index);
return (uint256(key), address(uint160(uint256(value))));
}
/**
* @dev Returns the value associated with `key`. O(1).
*
* Requirements:
*
* - `key` must be in the map.
*/
function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
return address(uint160(uint256(_get(map._inner, bytes32(key)))));
}
/**
* @dev Same as {get}, with a custom error message when `key` is not in the map.
*/
function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {
return address(uint160(uint256(_get(map._inner, bytes32(key), errorMessage))));
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Library for managing
* https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
* types.
*
* Sets have the following properties:
*
* - Elements are added, removed, and checked for existence in constant time
* (O(1)).
* - Elements are enumerated in O(n). No guarantees are made on the ordering.
*
* ```
* contract Example {
* // Add the library methods
* using EnumerableSet for EnumerableSet.AddressSet;
*
* // Declare a set state variable
* EnumerableSet.AddressSet private mySet;
* }
* ```
*
* As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
* and `uint256` (`UintSet`) are supported.
*/
library EnumerableSet {
// To implement this library for multiple types with as little code
// repetition as possible, we write it in terms of a generic Set type with
// bytes32 values.
// The Set implementation uses private functions, and user-facing
// implementations (such as AddressSet) are just wrappers around the
// underlying Set.
// This means that we can only create new EnumerableSets for types that fit
// in bytes32.
struct Set {
// Storage of set values
bytes32[] _values;
// Position of the value in the `values` array, plus 1 because index 0
// means a value is not in the set.
mapping (bytes32 => uint256) _indexes;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function _add(Set storage set, bytes32 value) private returns (bool) {
if (!_contains(set, value)) {
set._values.push(value);
// The value is stored at length-1, but we add 1 to all indexes
// and use 0 as a sentinel value
set._indexes[value] = set._values.length;
return true;
} else {
return false;
}
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function _remove(Set storage set, bytes32 value) private returns (bool) {
// We read and store the value's index to prevent multiple reads from the same storage slot
uint256 valueIndex = set._indexes[value];
if (valueIndex != 0) { // Equivalent to contains(set, value)
// To delete an element from the _values array in O(1), we swap the element to delete with the last one in
// the array, and then remove the last element (sometimes called as 'swap and pop').
// This modifies the order of the array, as noted in {at}.
uint256 toDeleteIndex = valueIndex - 1;
uint256 lastIndex = set._values.length - 1;
// When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
// so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
bytes32 lastvalue = set._values[lastIndex];
// Move the last value to the index where the value to delete is
set._values[toDeleteIndex] = lastvalue;
// Update the index for the moved value
set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based
// Delete the slot where the moved value was stored
set._values.pop();
// Delete the index for the deleted slot
delete set._indexes[value];
return true;
} else {
return false;
}
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function _contains(Set storage set, bytes32 value) private view returns (bool) {
return set._indexes[value] != 0;
}
/**
* @dev Returns the number of values on the set. O(1).
*/
function _length(Set storage set) private view returns (uint256) {
return set._values.length;
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function _at(Set storage set, uint256 index) private view returns (bytes32) {
require(set._values.length > index, "EnumerableSet: index out of bounds");
return set._values[index];
}
// Bytes32Set
struct Bytes32Set {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
return _add(set._inner, value);
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
return _remove(set._inner, value);
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
return _contains(set._inner, value);
}
/**
* @dev Returns the number of values in the set. O(1).
*/
function length(Bytes32Set storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
return _at(set._inner, index);
}
// AddressSet
struct AddressSet {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(AddressSet storage set, address value) internal returns (bool) {
return _add(set._inner, bytes32(uint256(uint160(value))));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(AddressSet storage set, address value) internal returns (bool) {
return _remove(set._inner, bytes32(uint256(uint160(value))));
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(AddressSet storage set, address value) internal view returns (bool) {
return _contains(set._inner, bytes32(uint256(uint160(value))));
}
/**
* @dev Returns the number of values in the set. O(1).
*/
function length(AddressSet storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(AddressSet storage set, uint256 index) internal view returns (address) {
return address(uint160(uint256(_at(set._inner, index))));
}
// UintSet
struct UintSet {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(UintSet storage set, uint256 value) internal returns (bool) {
return _add(set._inner, bytes32(value));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(UintSet storage set, uint256 value) internal returns (bool) {
return _remove(set._inner, bytes32(value));
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(UintSet storage set, uint256 value) internal view returns (bool) {
return _contains(set._inner, bytes32(value));
}
/**
* @dev Returns the number of values on the set. O(1).
*/
function length(UintSet storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(UintSet storage set, uint256 index) internal view returns (uint256) {
return uint256(_at(set._inner, index));
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor () {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev String operations.
*/
library Strings {
/**
* @dev Converts a `uint256` to its ASCII `string` representation.
*/
function toString(uint256 value) internal pure returns (string memory) {
// Inspired by OraclizeAPI's implementation - MIT licence
// https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
if (value == 0) {
return "0";
}
uint256 temp = value;
uint256 digits;
while (temp != 0) {
digits++;
temp /= 10;
}
bytes memory buffer = new bytes(digits);
uint256 index = digits;
temp = value;
while (temp != 0) {
buffer[--index] = bytes1(uint8(48 + uint256(temp % 10)));
temp /= 10;
}
return string(buffer);
}
}