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

EVM Smart Contract

Contract

1. approve

2. mint

3. safeTransferFrom

4. safeTransferFrom

5. setApprovalForAll

6. transferFrom