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"content": "// SPDX-License-Identifier: MIT\r\n// ERC721A Contracts v4.2.3\r\n// Creator: Chiru Labs\r\n\r\npragma solidity ^0.8.4;\r\n\r\nimport './IERC721A.sol';\r\n\r\n/**\r\n * @dev Interface of ERC721 token receiver.\r\n */\r\ninterface ERC721A__IERC721Receiver {\r\n function onERC721Received(\r\n address operator,\r\n address from,\r\n uint256 tokenId,\r\n bytes calldata data\r\n ) external returns (bytes4);\r\n}\r\n\r\n/**\r\n * @title ERC721A\r\n *\r\n * @dev Implementation of the [ERC721](https://eips.ethereum.org/EIPS/eip-721)\r\n * Non-Fungible Token Standard, including the Metadata extension.\r\n * Optimized for lower gas during batch mints.\r\n *\r\n * Token IDs are minted in sequential order (e.g. 0, 1, 2, 3, ...)\r\n * starting from `_startTokenId()`.\r\n *\r\n * Assumptions:\r\n *\r\n * - An owner cannot have more than 2**64 - 1 (max value of uint64) of supply.\r\n * - The maximum token ID cannot exceed 2**256 - 1 (max value of uint256).\r\n */\r\ncontract ERC721A is IERC721A {\r\n // Bypass for a `--via-ir` bug (https://github.com/chiru-labs/ERC721A/pull/364).\r\n struct TokenApprovalRef {\r\n address value;\r\n }\r\n\r\n // =============================================================\r\n // CONSTANTS\r\n // =============================================================\r\n\r\n // Mask of an entry in packed address data.\r\n uint256 private constant _BITMASK_ADDRESS_DATA_ENTRY = (1 << 64) - 1;\r\n\r\n // The bit position of `numberMinted` in packed address data.\r\n uint256 private constant _BITPOS_NUMBER_MINTED = 64;\r\n\r\n // The bit position of `numberBurned` in packed address data.\r\n uint256 private constant _BITPOS_NUMBER_BURNED = 128;\r\n\r\n // The bit position of `aux` in packed address data.\r\n uint256 private constant _BITPOS_AUX = 192;\r\n\r\n // Mask of all 256 bits in packed address data except the 64 bits for `aux`.\r\n uint256 private constant _BITMASK_AUX_COMPLEMENT = (1 << 192) - 1;\r\n\r\n // The bit position of `startTimestamp` in packed ownership.\r\n uint256 private constant _BITPOS_START_TIMESTAMP = 160;\r\n\r\n // The bit mask of the `burned` bit in packed ownership.\r\n uint256 private constant _BITMASK_BURNED = 1 << 224;\r\n\r\n // The bit position of the `nextInitialized` bit in packed ownership.\r\n uint256 private constant _BITPOS_NEXT_INITIALIZED = 225;\r\n\r\n // The bit mask of the `nextInitialized` bit in packed ownership.\r\n uint256 private constant _BITMASK_NEXT_INITIALIZED = 1 << 225;\r\n\r\n // The bit position of `extraData` in packed ownership.\r\n uint256 private constant _BITPOS_EXTRA_DATA = 232;\r\n\r\n // Mask of all 256 bits in a packed ownership except the 24 bits for `extraData`.\r\n uint256 private constant _BITMASK_EXTRA_DATA_COMPLEMENT = (1 << 232) - 1;\r\n\r\n // The mask of the lower 160 bits for addresses.\r\n uint256 private constant _BITMASK_ADDRESS = (1 << 160) - 1;\r\n\r\n // The maximum `quantity` that can be minted with {_mintERC2309}.\r\n // This limit is to prevent overflows on the address data entries.\r\n // For a limit of 5000, a total of 3.689e15 calls to {_mintERC2309}\r\n // is required to cause an overflow, which is unrealistic.\r\n uint256 private constant _MAX_MINT_ERC2309_QUANTITY_LIMIT = 5000;\r\n\r\n // The `Transfer` event signature is given by:\r\n // `keccak256(bytes(\"Transfer(address,address,uint256)\"))`.\r\n bytes32 private constant _TRANSFER_EVENT_SIGNATURE =\r\n 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;\r\n\r\n // =============================================================\r\n // STORAGE\r\n // =============================================================\r\n\r\n // The next token ID to be minted.\r\n uint256 private _currentIndex;\r\n\r\n // The number of tokens burned.\r\n uint256 private _burnCounter;\r\n\r\n // Token name\r\n string private _name;\r\n\r\n // Token symbol\r\n string private _symbol;\r\n\r\n // Mapping from token ID to ownership details\r\n // An empty struct value does not necessarily mean the token is unowned.\r\n // See {_packedOwnershipOf} implementation for details.\r\n //\r\n // Bits Layout:\r\n // - [0..159] `addr`\r\n // - [160..223] `startTimestamp`\r\n // - [224] `burned`\r\n // - [225] `nextInitialized`\r\n // - [232..255] `extraData`\r\n mapping(uint256 => uint256) private _packedOwnerships;\r\n\r\n // Mapping owner address to address data.\r\n //\r\n // Bits Layout:\r\n // - [0..63] `balance`\r\n // - [64..127] `numberMinted`\r\n // - [128..191] `numberBurned`\r\n // - [192..255] `aux`\r\n mapping(address => uint256) private _packedAddressData;\r\n\r\n // Mapping from token ID to approved address.\r\n mapping(uint256 => TokenApprovalRef) private _tokenApprovals;\r\n\r\n // Mapping from owner to operator approvals\r\n mapping(address => mapping(address => bool)) private _operatorApprovals;\r\n\r\n // =============================================================\r\n // CONSTRUCTOR\r\n // =============================================================\r\n\r\n constructor(string memory name_, string memory symbol_) {\r\n _name = name_;\r\n _symbol = symbol_;\r\n _currentIndex = _startTokenId();\r\n }\r\n\r\n // =============================================================\r\n // TOKEN COUNTING OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Returns the starting token ID.\r\n * To change the starting token ID, please override this function.\r\n */\r\n function _startTokenId() internal view virtual returns (uint256) {\r\n return 0;\r\n }\r\n\r\n /**\r\n * @dev Returns the next token ID to be minted.\r\n */\r\n function _nextTokenId() internal view virtual returns (uint256) {\r\n return _currentIndex;\r\n }\r\n\r\n /**\r\n * @dev Returns the total number of tokens in existence.\r\n * Burned tokens will reduce the count.\r\n * To get the total number of tokens minted, please see {_totalMinted}.\r\n */\r\n function totalSupply() public view virtual override returns (uint256) {\r\n // Counter underflow is impossible as _burnCounter cannot be incremented\r\n // more than `_currentIndex - _startTokenId()` times.\r\n unchecked {\r\n return _currentIndex - _burnCounter - _startTokenId();\r\n }\r\n }\r\n\r\n /**\r\n * @dev Returns the total amount of tokens minted in the contract.\r\n */\r\n function _totalMinted() internal view virtual returns (uint256) {\r\n // Counter underflow is impossible as `_currentIndex` does not decrement,\r\n // and it is initialized to `_startTokenId()`.\r\n unchecked {\r\n return _currentIndex - _startTokenId();\r\n }\r\n }\r\n\r\n /**\r\n * @dev Returns the total number of tokens burned.\r\n */\r\n function _totalBurned() internal view virtual returns (uint256) {\r\n return _burnCounter;\r\n }\r\n\r\n // =============================================================\r\n // ADDRESS DATA OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Returns the number of tokens in `owner`'s account.\r\n */\r\n function balanceOf(address owner) public view virtual override returns (uint256) {\r\n if (owner == address(0)) revert BalanceQueryForZeroAddress();\r\n return _packedAddressData[owner] & _BITMASK_ADDRESS_DATA_ENTRY;\r\n }\r\n\r\n /**\r\n * Returns the number of tokens minted by `owner`.\r\n */\r\n function _numberMinted(address owner) internal view returns (uint256) {\r\n return (_packedAddressData[owner] >> _BITPOS_NUMBER_MINTED) & _BITMASK_ADDRESS_DATA_ENTRY;\r\n }\r\n\r\n /**\r\n * Returns the number of tokens burned by or on behalf of `owner`.\r\n */\r\n function _numberBurned(address owner) internal view returns (uint256) {\r\n return (_packedAddressData[owner] >> _BITPOS_NUMBER_BURNED) & _BITMASK_ADDRESS_DATA_ENTRY;\r\n }\r\n\r\n /**\r\n * Returns the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).\r\n */\r\n function _getAux(address owner) internal view returns (uint64) {\r\n return uint64(_packedAddressData[owner] >> _BITPOS_AUX);\r\n }\r\n\r\n /**\r\n * Sets the auxiliary data for `owner`. (e.g. number of whitelist mint slots used).\r\n * If there are multiple variables, please pack them into a uint64.\r\n */\r\n function _setAux(address owner, uint64 aux) internal virtual {\r\n uint256 packed = _packedAddressData[owner];\r\n uint256 auxCasted;\r\n // Cast `aux` with assembly to avoid redundant masking.\r\n assembly {\r\n auxCasted := aux\r\n }\r\n packed = (packed & _BITMASK_AUX_COMPLEMENT) | (auxCasted << _BITPOS_AUX);\r\n _packedAddressData[owner] = packed;\r\n }\r\n\r\n // =============================================================\r\n // IERC165\r\n // =============================================================\r\n\r\n /**\r\n * @dev Returns true if this contract implements the interface defined by\r\n * `interfaceId`. See the corresponding\r\n * [EIP section](https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified)\r\n * to learn more about how these ids are created.\r\n *\r\n * This function call must use less than 30000 gas.\r\n */\r\n function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {\r\n // The interface IDs are constants representing the first 4 bytes\r\n // of the XOR of all function selectors in the interface.\r\n // See: [ERC165](https://eips.ethereum.org/EIPS/eip-165)\r\n // (e.g. `bytes4(i.functionA.selector ^ i.functionB.selector ^ ...)`)\r\n return\r\n interfaceId == 0x01ffc9a7 || // ERC165 interface ID for ERC165.\r\n interfaceId == 0x80ac58cd || // ERC165 interface ID for ERC721.\r\n interfaceId == 0x5b5e139f; // ERC165 interface ID for ERC721Metadata.\r\n }\r\n\r\n // =============================================================\r\n // IERC721Metadata\r\n // =============================================================\r\n\r\n /**\r\n * @dev Returns the token collection name.\r\n */\r\n function name() public view virtual override returns (string memory) {\r\n return _name;\r\n }\r\n\r\n /**\r\n * @dev Returns the token collection symbol.\r\n */\r\n function symbol() public view virtual override returns (string memory) {\r\n return _symbol;\r\n }\r\n\r\n /**\r\n * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.\r\n */\r\n function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {\r\n if (!_exists(tokenId)) revert URIQueryForNonexistentToken();\r\n\r\n string memory baseURI = _baseURI();\r\n return bytes(baseURI).length != 0 ? string(abi.encodePacked(baseURI, _toString(tokenId))) : '';\r\n }\r\n\r\n /**\r\n * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each\r\n * token will be the concatenation of the `baseURI` and the `tokenId`. Empty\r\n * by default, it can be overridden in child contracts.\r\n */\r\n function _baseURI() internal view virtual returns (string memory) {\r\n return '';\r\n }\r\n\r\n // =============================================================\r\n // OWNERSHIPS OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Returns the owner of the `tokenId` token.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n */\r\n function ownerOf(uint256 tokenId) public view virtual override returns (address) {\r\n return address(uint160(_packedOwnershipOf(tokenId)));\r\n }\r\n\r\n /**\r\n * @dev Gas spent here starts off proportional to the maximum mint batch size.\r\n * It gradually moves to O(1) as tokens get transferred around over time.\r\n */\r\n function _ownershipOf(uint256 tokenId) internal view virtual returns (TokenOwnership memory) {\r\n return _unpackedOwnership(_packedOwnershipOf(tokenId));\r\n }\r\n\r\n /**\r\n * @dev Returns the unpacked `TokenOwnership` struct at `index`.\r\n */\r\n function _ownershipAt(uint256 index) internal view virtual returns (TokenOwnership memory) {\r\n return _unpackedOwnership(_packedOwnerships[index]);\r\n }\r\n\r\n /**\r\n * @dev Initializes the ownership slot minted at `index` for efficiency purposes.\r\n */\r\n function _initializeOwnershipAt(uint256 index) internal virtual {\r\n if (_packedOwnerships[index] == 0) {\r\n _packedOwnerships[index] = _packedOwnershipOf(index);\r\n }\r\n }\r\n\r\n /**\r\n * Returns the packed ownership data of `tokenId`.\r\n */\r\n function _packedOwnershipOf(uint256 tokenId) private view returns (uint256) {\r\n uint256 curr = tokenId;\r\n\r\n unchecked {\r\n if (_startTokenId() <= curr)\r\n if (curr < _currentIndex) {\r\n uint256 packed = _packedOwnerships[curr];\r\n // If not burned.\r\n if (packed & _BITMASK_BURNED == 0) {\r\n // Invariant:\r\n // There will always be an initialized ownership slot\r\n // (i.e. `ownership.addr != address(0) && ownership.burned == false`)\r\n // before an unintialized ownership slot\r\n // (i.e. `ownership.addr == address(0) && ownership.burned == false`)\r\n // Hence, `curr` will not underflow.\r\n //\r\n // We can directly compare the packed value.\r\n // If the address is zero, packed will be zero.\r\n while (packed == 0) {\r\n packed = _packedOwnerships[--curr];\r\n }\r\n return packed;\r\n }\r\n }\r\n }\r\n revert OwnerQueryForNonexistentToken();\r\n }\r\n\r\n /**\r\n * @dev Returns the unpacked `TokenOwnership` struct from `packed`.\r\n */\r\n function _unpackedOwnership(uint256 packed) private pure returns (TokenOwnership memory ownership) {\r\n ownership.addr = address(uint160(packed));\r\n ownership.startTimestamp = uint64(packed >> _BITPOS_START_TIMESTAMP);\r\n ownership.burned = packed & _BITMASK_BURNED != 0;\r\n ownership.extraData = uint24(packed >> _BITPOS_EXTRA_DATA);\r\n }\r\n\r\n /**\r\n * @dev Packs ownership data into a single uint256.\r\n */\r\n function _packOwnershipData(address owner, uint256 flags) private view returns (uint256 result) {\r\n assembly {\r\n // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.\r\n owner := and(owner, _BITMASK_ADDRESS)\r\n // `owner | (block.timestamp << _BITPOS_START_TIMESTAMP) | flags`.\r\n result := or(owner, or(shl(_BITPOS_START_TIMESTAMP, timestamp()), flags))\r\n }\r\n }\r\n\r\n /**\r\n * @dev Returns the `nextInitialized` flag set if `quantity` equals 1.\r\n */\r\n function _nextInitializedFlag(uint256 quantity) private pure returns (uint256 result) {\r\n // For branchless setting of the `nextInitialized` flag.\r\n assembly {\r\n // `(quantity == 1) << _BITPOS_NEXT_INITIALIZED`.\r\n result := shl(_BITPOS_NEXT_INITIALIZED, eq(quantity, 1))\r\n }\r\n }\r\n\r\n // =============================================================\r\n // APPROVAL OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Gives permission to `to` to transfer `tokenId` token to another account.\r\n * The approval is cleared when the token is transferred.\r\n *\r\n * Only a single account can be approved at a time, so approving the\r\n * zero address clears previous approvals.\r\n *\r\n * Requirements:\r\n *\r\n * - The caller must own the token or be an approved operator.\r\n * - `tokenId` must exist.\r\n *\r\n * Emits an {Approval} event.\r\n */\r\n function approve(address to, uint256 tokenId) public payable virtual override {\r\n address owner = ownerOf(tokenId);\r\n\r\n if (_msgSenderERC721A() != owner)\r\n if (!isApprovedForAll(owner, _msgSenderERC721A())) {\r\n revert ApprovalCallerNotOwnerNorApproved();\r\n }\r\n\r\n _tokenApprovals[tokenId].value = to;\r\n emit Approval(owner, to, tokenId);\r\n }\r\n\r\n /**\r\n * @dev Returns the account approved for `tokenId` token.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n */\r\n function getApproved(uint256 tokenId) public view virtual override returns (address) {\r\n if (!_exists(tokenId)) revert ApprovalQueryForNonexistentToken();\r\n\r\n return _tokenApprovals[tokenId].value;\r\n }\r\n\r\n /**\r\n * @dev Approve or remove `operator` as an operator for the caller.\r\n * Operators can call {transferFrom} or {safeTransferFrom}\r\n * for any token owned by the caller.\r\n *\r\n * Requirements:\r\n *\r\n * - The `operator` cannot be the caller.\r\n *\r\n * Emits an {ApprovalForAll} event.\r\n */\r\n function setApprovalForAll(address operator, bool approved) public virtual override {\r\n _operatorApprovals[_msgSenderERC721A()][operator] = approved;\r\n emit ApprovalForAll(_msgSenderERC721A(), operator, approved);\r\n }\r\n\r\n /**\r\n * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.\r\n *\r\n * See {setApprovalForAll}.\r\n */\r\n function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {\r\n return _operatorApprovals[owner][operator];\r\n }\r\n\r\n /**\r\n * @dev Returns whether `tokenId` exists.\r\n *\r\n * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.\r\n *\r\n * Tokens start existing when they are minted. See {_mint}.\r\n */\r\n function _exists(uint256 tokenId) internal view virtual returns (bool) {\r\n return\r\n _startTokenId() <= tokenId &&\r\n tokenId < _currentIndex && // If within bounds,\r\n _packedOwnerships[tokenId] & _BITMASK_BURNED == 0; // and not burned.\r\n }\r\n\r\n /**\r\n * @dev Returns whether `msgSender` is equal to `approvedAddress` or `owner`.\r\n */\r\n function _isSenderApprovedOrOwner(\r\n address approvedAddress,\r\n address owner,\r\n address msgSender\r\n ) private pure returns (bool result) {\r\n assembly {\r\n // Mask `owner` to the lower 160 bits, in case the upper bits somehow aren't clean.\r\n owner := and(owner, _BITMASK_ADDRESS)\r\n // Mask `msgSender` to the lower 160 bits, in case the upper bits somehow aren't clean.\r\n msgSender := and(msgSender, _BITMASK_ADDRESS)\r\n // `msgSender == owner || msgSender == approvedAddress`.\r\n result := or(eq(msgSender, owner), eq(msgSender, approvedAddress))\r\n }\r\n }\r\n\r\n /**\r\n * @dev Returns the storage slot and value for the approved address of `tokenId`.\r\n */\r\n function _getApprovedSlotAndAddress(uint256 tokenId)\r\n private\r\n view\r\n returns (uint256 approvedAddressSlot, address approvedAddress)\r\n {\r\n TokenApprovalRef storage tokenApproval = _tokenApprovals[tokenId];\r\n // The following is equivalent to `approvedAddress = _tokenApprovals[tokenId].value`.\r\n assembly {\r\n approvedAddressSlot := tokenApproval.slot\r\n approvedAddress := sload(approvedAddressSlot)\r\n }\r\n }\r\n\r\n // =============================================================\r\n // TRANSFER OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Transfers `tokenId` from `from` to `to`.\r\n *\r\n * Requirements:\r\n *\r\n * - `from` cannot be the zero address.\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must be owned by `from`.\r\n * - If the caller is not `from`, it must be approved to move this token\r\n * by either {approve} or {setApprovalForAll}.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function transferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) public payable virtual override {\r\n uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);\r\n\r\n if (address(uint160(prevOwnershipPacked)) != from) revert TransferFromIncorrectOwner();\r\n\r\n (uint256 approvedAddressSlot, address approvedAddress) = _getApprovedSlotAndAddress(tokenId);\r\n\r\n // The nested ifs save around 20+ gas over a compound boolean condition.\r\n if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))\r\n if (!isApprovedForAll(from, _msgSenderERC721A())) revert TransferCallerNotOwnerNorApproved();\r\n\r\n if (to == address(0)) revert TransferToZeroAddress();\r\n\r\n _beforeTokenTransfers(from, to, tokenId, 1);\r\n\r\n // Clear approvals from the previous owner.\r\n assembly {\r\n if approvedAddress {\r\n // This is equivalent to `delete _tokenApprovals[tokenId]`.\r\n sstore(approvedAddressSlot, 0)\r\n }\r\n }\r\n\r\n // Underflow of the sender's balance is impossible because we check for\r\n // ownership above and the recipient's balance can't realistically overflow.\r\n // Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.\r\n unchecked {\r\n // We can directly increment and decrement the balances.\r\n --_packedAddressData[from]; // Updates: `balance -= 1`.\r\n ++_packedAddressData[to]; // Updates: `balance += 1`.\r\n\r\n // Updates:\r\n // - `address` to the next owner.\r\n // - `startTimestamp` to the timestamp of transfering.\r\n // - `burned` to `false`.\r\n // - `nextInitialized` to `true`.\r\n _packedOwnerships[tokenId] = _packOwnershipData(\r\n to,\r\n _BITMASK_NEXT_INITIALIZED | _nextExtraData(from, to, prevOwnershipPacked)\r\n );\r\n\r\n // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .\r\n if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {\r\n uint256 nextTokenId = tokenId + 1;\r\n // If the next slot's address is zero and not burned (i.e. packed value is zero).\r\n if (_packedOwnerships[nextTokenId] == 0) {\r\n // If the next slot is within bounds.\r\n if (nextTokenId != _currentIndex) {\r\n // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.\r\n _packedOwnerships[nextTokenId] = prevOwnershipPacked;\r\n }\r\n }\r\n }\r\n }\r\n\r\n emit Transfer(from, to, tokenId);\r\n _afterTokenTransfers(from, to, tokenId, 1);\r\n }\r\n\r\n /**\r\n * @dev Equivalent to `safeTransferFrom(from, to, tokenId, '')`.\r\n */\r\n function safeTransferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId\r\n ) public payable virtual override {\r\n safeTransferFrom(from, to, tokenId, '');\r\n }\r\n\r\n /**\r\n * @dev Safely transfers `tokenId` token from `from` to `to`.\r\n *\r\n * Requirements:\r\n *\r\n * - `from` cannot be the zero address.\r\n * - `to` cannot be the zero address.\r\n * - `tokenId` token must exist and be owned by `from`.\r\n * - If the caller is not `from`, it must be approved to move this token\r\n * by either {approve} or {setApprovalForAll}.\r\n * - If `to` refers to a smart contract, it must implement\r\n * {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function safeTransferFrom(\r\n address from,\r\n address to,\r\n uint256 tokenId,\r\n bytes memory _data\r\n ) public payable virtual override {\r\n transferFrom(from, to, tokenId);\r\n if (to.code.length != 0)\r\n if (!_checkContractOnERC721Received(from, to, tokenId, _data)) {\r\n revert TransferToNonERC721ReceiverImplementer();\r\n }\r\n }\r\n\r\n /**\r\n * @dev Hook that is called before a set of serially-ordered token IDs\r\n * are about to be transferred. This includes minting.\r\n * And also called before burning one token.\r\n *\r\n * `startTokenId` - the first token ID to be transferred.\r\n * `quantity` - the amount to be transferred.\r\n *\r\n * Calling conditions:\r\n *\r\n * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be\r\n * transferred to `to`.\r\n * - When `from` is zero, `tokenId` will be minted for `to`.\r\n * - When `to` is zero, `tokenId` will be burned by `from`.\r\n * - `from` and `to` are never both zero.\r\n */\r\n function _beforeTokenTransfers(\r\n address from,\r\n address to,\r\n uint256 startTokenId,\r\n uint256 quantity\r\n ) internal virtual {}\r\n\r\n /**\r\n * @dev Hook that is called after a set of serially-ordered token IDs\r\n * have been transferred. This includes minting.\r\n * And also called after one token has been burned.\r\n *\r\n * `startTokenId` - the first token ID to be transferred.\r\n * `quantity` - the amount to be transferred.\r\n *\r\n * Calling conditions:\r\n *\r\n * - When `from` and `to` are both non-zero, `from`'s `tokenId` has been\r\n * transferred to `to`.\r\n * - When `from` is zero, `tokenId` has been minted for `to`.\r\n * - When `to` is zero, `tokenId` has been burned by `from`.\r\n * - `from` and `to` are never both zero.\r\n */\r\n function _afterTokenTransfers(\r\n address from,\r\n address to,\r\n uint256 startTokenId,\r\n uint256 quantity\r\n ) internal virtual {}\r\n\r\n /**\r\n * @dev Private function to invoke {IERC721Receiver-onERC721Received} on a target contract.\r\n *\r\n * `from` - Previous owner of the given token ID.\r\n * `to` - Target address that will receive the token.\r\n * `tokenId` - Token ID to be transferred.\r\n * `_data` - Optional data to send along with the call.\r\n *\r\n * Returns whether the call correctly returned the expected magic value.\r\n */\r\n function _checkContractOnERC721Received(\r\n address from,\r\n address to,\r\n uint256 tokenId,\r\n bytes memory _data\r\n ) private returns (bool) {\r\n try ERC721A__IERC721Receiver(to).onERC721Received(_msgSenderERC721A(), from, tokenId, _data) returns (\r\n bytes4 retval\r\n ) {\r\n return retval == ERC721A__IERC721Receiver(to).onERC721Received.selector;\r\n } catch (bytes memory reason) {\r\n if (reason.length == 0) {\r\n revert TransferToNonERC721ReceiverImplementer();\r\n } else {\r\n assembly {\r\n revert(add(32, reason), mload(reason))\r\n }\r\n }\r\n }\r\n }\r\n\r\n // =============================================================\r\n // MINT OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Mints `quantity` tokens and transfers them to `to`.\r\n *\r\n * Requirements:\r\n *\r\n * - `to` cannot be the zero address.\r\n * - `quantity` must be greater than 0.\r\n *\r\n * Emits a {Transfer} event for each mint.\r\n */\r\n function _mint(address to, uint256 quantity) internal virtual {\r\n uint256 startTokenId = _currentIndex;\r\n if (quantity == 0) revert MintZeroQuantity();\r\n\r\n _beforeTokenTransfers(address(0), to, startTokenId, quantity);\r\n\r\n // Overflows are incredibly unrealistic.\r\n // `balance` and `numberMinted` have a maximum limit of 2**64.\r\n // `tokenId` has a maximum limit of 2**256.\r\n unchecked {\r\n // Updates:\r\n // - `balance += quantity`.\r\n // - `numberMinted += quantity`.\r\n //\r\n // We can directly add to the `balance` and `numberMinted`.\r\n _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);\r\n\r\n // Updates:\r\n // - `address` to the owner.\r\n // - `startTimestamp` to the timestamp of minting.\r\n // - `burned` to `false`.\r\n // - `nextInitialized` to `quantity == 1`.\r\n _packedOwnerships[startTokenId] = _packOwnershipData(\r\n to,\r\n _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)\r\n );\r\n\r\n uint256 toMasked;\r\n uint256 end = startTokenId + quantity;\r\n\r\n // Use assembly to loop and emit the `Transfer` event for gas savings.\r\n // The duplicated `log4` removes an extra check and reduces stack juggling.\r\n // The assembly, together with the surrounding Solidity code, have been\r\n // delicately arranged to nudge the compiler into producing optimized opcodes.\r\n assembly {\r\n // Mask `to` to the lower 160 bits, in case the upper bits somehow aren't clean.\r\n toMasked := and(to, _BITMASK_ADDRESS)\r\n // Emit the `Transfer` event.\r\n log4(\r\n 0, // Start of data (0, since no data).\r\n 0, // End of data (0, since no data).\r\n _TRANSFER_EVENT_SIGNATURE, // Signature.\r\n 0, // `address(0)`.\r\n toMasked, // `to`.\r\n startTokenId // `tokenId`.\r\n )\r\n\r\n // The `iszero(eq(,))` check ensures that large values of `quantity`\r\n // that overflows uint256 will make the loop run out of gas.\r\n // The compiler will optimize the `iszero` away for performance.\r\n for {\r\n let tokenId := add(startTokenId, 1)\r\n } iszero(eq(tokenId, end)) {\r\n tokenId := add(tokenId, 1)\r\n } {\r\n // Emit the `Transfer` event. Similar to above.\r\n log4(0, 0, _TRANSFER_EVENT_SIGNATURE, 0, toMasked, tokenId)\r\n }\r\n }\r\n if (toMasked == 0) revert MintToZeroAddress();\r\n\r\n _currentIndex = end;\r\n }\r\n _afterTokenTransfers(address(0), to, startTokenId, quantity);\r\n }\r\n\r\n /**\r\n * @dev Mints `quantity` tokens and transfers them to `to`.\r\n *\r\n * This function is intended for efficient minting only during contract creation.\r\n *\r\n * It emits only one {ConsecutiveTransfer} as defined in\r\n * [ERC2309](https://eips.ethereum.org/EIPS/eip-2309),\r\n * instead of a sequence of {Transfer} event(s).\r\n *\r\n * Calling this function outside of contract creation WILL make your contract\r\n * non-compliant with the ERC721 standard.\r\n * For full ERC721 compliance, substituting ERC721 {Transfer} event(s) with the ERC2309\r\n * {ConsecutiveTransfer} event is only permissible during contract creation.\r\n *\r\n * Requirements:\r\n *\r\n * - `to` cannot be the zero address.\r\n * - `quantity` must be greater than 0.\r\n *\r\n * Emits a {ConsecutiveTransfer} event.\r\n */\r\n function _mintERC2309(address to, uint256 quantity) internal virtual {\r\n uint256 startTokenId = _currentIndex;\r\n if (to == address(0)) revert MintToZeroAddress();\r\n if (quantity == 0) revert MintZeroQuantity();\r\n if (quantity > _MAX_MINT_ERC2309_QUANTITY_LIMIT) revert MintERC2309QuantityExceedsLimit();\r\n\r\n _beforeTokenTransfers(address(0), to, startTokenId, quantity);\r\n\r\n // Overflows are unrealistic due to the above check for `quantity` to be below the limit.\r\n unchecked {\r\n // Updates:\r\n // - `balance += quantity`.\r\n // - `numberMinted += quantity`.\r\n //\r\n // We can directly add to the `balance` and `numberMinted`.\r\n _packedAddressData[to] += quantity * ((1 << _BITPOS_NUMBER_MINTED) | 1);\r\n\r\n // Updates:\r\n // - `address` to the owner.\r\n // - `startTimestamp` to the timestamp of minting.\r\n // - `burned` to `false`.\r\n // - `nextInitialized` to `quantity == 1`.\r\n _packedOwnerships[startTokenId] = _packOwnershipData(\r\n to,\r\n _nextInitializedFlag(quantity) | _nextExtraData(address(0), to, 0)\r\n );\r\n\r\n emit ConsecutiveTransfer(startTokenId, startTokenId + quantity - 1, address(0), to);\r\n\r\n _currentIndex = startTokenId + quantity;\r\n }\r\n _afterTokenTransfers(address(0), to, startTokenId, quantity);\r\n }\r\n\r\n /**\r\n * @dev Safely mints `quantity` tokens and transfers them to `to`.\r\n *\r\n * Requirements:\r\n *\r\n * - If `to` refers to a smart contract, it must implement\r\n * {IERC721Receiver-onERC721Received}, which is called for each safe transfer.\r\n * - `quantity` must be greater than 0.\r\n *\r\n * See {_mint}.\r\n *\r\n * Emits a {Transfer} event for each mint.\r\n */\r\n function _safeMint(\r\n address to,\r\n uint256 quantity,\r\n bytes memory _data\r\n ) internal virtual {\r\n _mint(to, quantity);\r\n\r\n unchecked {\r\n if (to.code.length != 0) {\r\n uint256 end = _currentIndex;\r\n uint256 index = end - quantity;\r\n do {\r\n if (!_checkContractOnERC721Received(address(0), to, index++, _data)) {\r\n revert TransferToNonERC721ReceiverImplementer();\r\n }\r\n } while (index < end);\r\n // Reentrancy protection.\r\n if (_currentIndex != end) revert();\r\n }\r\n }\r\n }\r\n\r\n /**\r\n * @dev Equivalent to `_safeMint(to, quantity, '')`.\r\n */\r\n function _safeMint(address to, uint256 quantity) internal virtual {\r\n _safeMint(to, quantity, '');\r\n }\r\n\r\n // =============================================================\r\n // BURN OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Equivalent to `_burn(tokenId, false)`.\r\n */\r\n function _burn(uint256 tokenId) internal virtual {\r\n _burn(tokenId, false);\r\n }\r\n\r\n /**\r\n * @dev Destroys `tokenId`.\r\n * The approval is cleared when the token is burned.\r\n *\r\n * Requirements:\r\n *\r\n * - `tokenId` must exist.\r\n *\r\n * Emits a {Transfer} event.\r\n */\r\n function _burn(uint256 tokenId, bool approvalCheck) internal virtual {\r\n uint256 prevOwnershipPacked = _packedOwnershipOf(tokenId);\r\n\r\n address from = address(uint160(prevOwnershipPacked));\r\n\r\n (uint256 approvedAddressSlot, address approvedAddress) = _getApprovedSlotAndAddress(tokenId);\r\n\r\n if (approvalCheck) {\r\n // The nested ifs save around 20+ gas over a compound boolean condition.\r\n if (!_isSenderApprovedOrOwner(approvedAddress, from, _msgSenderERC721A()))\r\n if (!isApprovedForAll(from, _msgSenderERC721A())) revert TransferCallerNotOwnerNorApproved();\r\n }\r\n\r\n _beforeTokenTransfers(from, address(0), tokenId, 1);\r\n\r\n // Clear approvals from the previous owner.\r\n assembly {\r\n if approvedAddress {\r\n // This is equivalent to `delete _tokenApprovals[tokenId]`.\r\n sstore(approvedAddressSlot, 0)\r\n }\r\n }\r\n\r\n // Underflow of the sender's balance is impossible because we check for\r\n // ownership above and the recipient's balance can't realistically overflow.\r\n // Counter overflow is incredibly unrealistic as `tokenId` would have to be 2**256.\r\n unchecked {\r\n // Updates:\r\n // - `balance -= 1`.\r\n // - `numberBurned += 1`.\r\n //\r\n // We can directly decrement the balance, and increment the number burned.\r\n // This is equivalent to `packed -= 1; packed += 1 << _BITPOS_NUMBER_BURNED;`.\r\n _packedAddressData[from] += (1 << _BITPOS_NUMBER_BURNED) - 1;\r\n\r\n // Updates:\r\n // - `address` to the last owner.\r\n // - `startTimestamp` to the timestamp of burning.\r\n // - `burned` to `true`.\r\n // - `nextInitialized` to `true`.\r\n _packedOwnerships[tokenId] = _packOwnershipData(\r\n from,\r\n (_BITMASK_BURNED | _BITMASK_NEXT_INITIALIZED) | _nextExtraData(from, address(0), prevOwnershipPacked)\r\n );\r\n\r\n // If the next slot may not have been initialized (i.e. `nextInitialized == false`) .\r\n if (prevOwnershipPacked & _BITMASK_NEXT_INITIALIZED == 0) {\r\n uint256 nextTokenId = tokenId + 1;\r\n // If the next slot's address is zero and not burned (i.e. packed value is zero).\r\n if (_packedOwnerships[nextTokenId] == 0) {\r\n // If the next slot is within bounds.\r\n if (nextTokenId != _currentIndex) {\r\n // Initialize the next slot to maintain correctness for `ownerOf(tokenId + 1)`.\r\n _packedOwnerships[nextTokenId] = prevOwnershipPacked;\r\n }\r\n }\r\n }\r\n }\r\n\r\n emit Transfer(from, address(0), tokenId);\r\n _afterTokenTransfers(from, address(0), tokenId, 1);\r\n\r\n // Overflow not possible, as _burnCounter cannot be exceed _currentIndex times.\r\n unchecked {\r\n _burnCounter++;\r\n }\r\n }\r\n\r\n // =============================================================\r\n // EXTRA DATA OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Directly sets the extra data for the ownership data `index`.\r\n */\r\n function _setExtraDataAt(uint256 index, uint24 extraData) internal virtual {\r\n uint256 packed = _packedOwnerships[index];\r\n if (packed == 0) revert OwnershipNotInitializedForExtraData();\r\n uint256 extraDataCasted;\r\n // Cast `extraData` with assembly to avoid redundant masking.\r\n assembly {\r\n extraDataCasted := extraData\r\n }\r\n packed = (packed & _BITMASK_EXTRA_DATA_COMPLEMENT) | (extraDataCasted << _BITPOS_EXTRA_DATA);\r\n _packedOwnerships[index] = packed;\r\n }\r\n\r\n /**\r\n * @dev Called during each token transfer to set the 24bit `extraData` field.\r\n * Intended to be overridden by the cosumer contract.\r\n *\r\n * `previousExtraData` - the value of `extraData` before transfer.\r\n *\r\n * Calling conditions:\r\n *\r\n * - When `from` and `to` are both non-zero, `from`'s `tokenId` will be\r\n * transferred to `to`.\r\n * - When `from` is zero, `tokenId` will be minted for `to`.\r\n * - When `to` is zero, `tokenId` will be burned by `from`.\r\n * - `from` and `to` are never both zero.\r\n */\r\n function _extraData(\r\n address from,\r\n address to,\r\n uint24 previousExtraData\r\n ) internal view virtual returns (uint24) {}\r\n\r\n /**\r\n * @dev Returns the next extra data for the packed ownership data.\r\n * The returned result is shifted into position.\r\n */\r\n function _nextExtraData(\r\n address from,\r\n address to,\r\n uint256 prevOwnershipPacked\r\n ) private view returns (uint256) {\r\n uint24 extraData = uint24(prevOwnershipPacked >> _BITPOS_EXTRA_DATA);\r\n return uint256(_extraData(from, to, extraData)) << _BITPOS_EXTRA_DATA;\r\n }\r\n\r\n // =============================================================\r\n // OTHER OPERATIONS\r\n // =============================================================\r\n\r\n /**\r\n * @dev Returns the message sender (defaults to `msg.sender`).\r\n *\r\n * If you are writing GSN compatible contracts, you need to override this function.\r\n */\r\n function _msgSenderERC721A() internal view virtual returns (address) {\r\n return msg.sender;\r\n }\r\n\r\n /**\r\n * @dev Converts a uint256 to its ASCII string decimal representation.\r\n */\r\n function _toString(uint256 value) internal pure virtual returns (string memory str) {\r\n assembly {\r\n // The maximum value of a uint256 contains 78 digits (1 byte per digit), but\r\n // we allocate 0xa0 bytes to keep the free memory pointer 32-byte word aligned.\r\n // We will need 1 word for the trailing zeros padding, 1 word for the length,\r\n // and 3 words for a maximum of 78 digits. Total: 5 * 0x20 = 0xa0.\r\n let m := add(mload(0x40), 0xa0)\r\n // Update the free memory pointer to allocate.\r\n mstore(0x40, m)\r\n // Assign the `str` to the end.\r\n str := sub(m, 0x20)\r\n // Zeroize the slot after the string.\r\n mstore(str, 0)\r\n\r\n // Cache the end of the memory to calculate the length later.\r\n let end := str\r\n\r\n // We write the string from rightmost digit to leftmost digit.\r\n // The following is essentially a do-while loop that also handles the zero case.\r\n // prettier-ignore\r\n for { let temp := value } 1 {} {\r\n str := sub(str, 1)\r\n // Write the character to the pointer.\r\n // The ASCII index of the '0' character is 48.\r\n mstore8(str, add(48, mod(temp, 10)))\r\n // Keep dividing `temp` until zero.\r\n temp := div(temp, 10)\r\n // prettier-ignore\r\n if iszero(temp) { break }\r\n }\r\n\r\n let length := sub(end, str)\r\n // Move the pointer 32 bytes leftwards to make room for the length.\r\n str := sub(str, 0x20)\r\n // Store the length.\r\n mstore(str, length)\r\n }\r\n }\r\n}"
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