ERC721

Git Source

Inherits: Context, ERC165, IERC721, IERC721Metadata

Doesn't track balances.

Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including the Metadata extension, but not including the Enumerable extension, which is available separately as ERC721Enumerable.

State Variables

_name

string private _name;

_symbol

string private _symbol;

_owners

mapping(uint256 => address) internal _owners;

_tokenApprovals

mapping(uint256 => address) private _tokenApprovals;

_operatorApprovals

mapping(address => mapping(address => bool)) private _operatorApprovals;

Functions

_initialize

Initializes the contract by setting a name and a symbol to the token collection.

function _initialize(string memory name_, string memory symbol_) internal;

supportsInterface

See IERC165-supportsInterface.

function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool);

balanceOf

Balance tracking to be overriden by childs

function balanceOf(address owner) external view virtual override returns (uint256 balance);

ownerOf

See IERC721-ownerOf.

function ownerOf(uint256 tokenId) public view virtual override returns (address);

name

See IERC721Metadata-name.

function name() public view virtual override returns (string memory);

symbol

See IERC721Metadata-symbol.

function symbol() public view virtual override returns (string memory);

tokenURI

See IERC721Metadata-tokenURI.

function tokenURI(uint256 tokenId) public view virtual override returns (string memory);

_baseURI

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, can be overridden in child contracts.

function _baseURI() internal view virtual returns (string memory);

approve

See IERC721-approve.

function approve(address to, uint256 tokenId) public virtual override;

getApproved

See IERC721-getApproved.

function getApproved(uint256 tokenId) public view virtual override returns (address);

setApprovalForAll

See IERC721-setApprovalForAll.

function setApprovalForAll(address operator, bool approved) public virtual override;

isApprovedForAll

See IERC721-isApprovedForAll.

function isApprovedForAll(address owner, address operator) public view virtual override returns (bool);

transferFrom

See IERC721-transferFrom.

function transferFrom(address from, address to, uint256 tokenId) public virtual override;

safeTransferFrom

See IERC721-safeTransferFrom.

function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override;

safeTransferFrom

See IERC721-safeTransferFrom.

function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public virtual override;

_safeTransfer

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;

_exists

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 virtual returns (bool);

_isApprovedOrOwner

Returns whether spender is allowed to manage tokenId. Requirements:

• tokenId must exist.

function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool);

_mint

Mints tokenId and transfers it to to. Requirements:

• tokenId must not exist.
• to cannot be the zero address. Emits a Transfer event.

function _mint(address to, uint256 tokenId) internal virtual;

_burn

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;

_transfer

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;

_approve

Approve to to operate on tokenId Emits an Approval event.

function _approve(address to, uint256 tokenId) internal virtual;

_setApprovalForAll

Approve operator to operate on all of owner tokens Emits an ApprovalForAll event.

function _setApprovalForAll(address owner, address operator, bool approved) internal virtual;

_requireMinted

Reverts if the tokenId has not been minted yet.

function _requireMinted(uint256 tokenId) internal view virtual;

_checkOnERC721Received

Internal function to invoke IERC721Receiver-onERC721Received on a target address. The call is not executed if the target address is not a contract.

function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory data) private returns (bool);

Parameters

Name	Type	Description
from	address	address representing the previous owner of the given token ID
to	address	target address that will receive the tokens
tokenId	uint256	uint256 ID of the token to be transferred
data	bytes	bytes optional data to send along with the call

Returns

Name	Type	Description
<none>	bool	bool whether the call correctly returned the expected magic value

_beforeTokenTransfer

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 and to are never both zero. 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;

_afterTokenTransfer

Hook that is called after any transfer of tokens. This includes minting and burning. Calling conditions:

• when from and to are both non-zero.
• from and to are never both zero. To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].

function _afterTokenTransfer(address from, address to, uint256 tokenId) internal virtual;

Errors

ALEADY_MINTED

error ALEADY_MINTED();

APPROVE_TO_CALLER

error APPROVE_TO_CALLER();

APPROVAL_TO_CURRENT_OWNER

error APPROVAL_TO_CURRENT_OWNER();

CALLER_NOT_OWNER_OR_APPROVED

error CALLER_NOT_OWNER_OR_APPROVED();

INVALID_TOKEN_ID

error INVALID_TOKEN_ID();

INCORRECT_OWNER

error INCORRECT_OWNER();

MINT_TO_ZERO

error MINT_TO_ZERO();

TRANSFER_TO_NON_IMPLEMENTER

error TRANSFER_TO_NON_IMPLEMENTER();

TRANSFER_TO_ZERO_ADDRESS

error TRANSFER_TO_ZERO_ADDRESS();