forked from DecentralizedClimateFoundation/DCIPs
233 lines
8.1 KiB
Solidity
233 lines
8.1 KiB
Solidity
// SPDX-License-Identifier: CC0-1.0
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pragma solidity ^0.8.16;
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import {IERC721} from "@openzeppelin/contracts/token/ERC721/IERC721.sol";
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import {IERC721Receiver} from "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";
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import {IERC721Errors} from "../interfaces/IERC721Errors.sol";
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/// @title Reference Minimal ERC-721 Contract
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contract ERC721 is IERC721, IERC721Errors {
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/// @notice The total number of NFTs in circulation.
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uint256 public totalSupply;
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/// @notice Gets the approved address for an NFT.
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/// @dev This implementation does not throw for zero-address queries.
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mapping(uint256 => address) public getApproved;
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/// @notice Gets the number of NFTs owned by an address.
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mapping(address => uint256) internal _balanceOf;
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/// @dev Tracks the assigned owner of an address.
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mapping(uint256 => address) internal _ownerOf;
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/// @dev Checks for an owner if an address is an authorized operator.
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mapping(address => mapping(address => bool)) internal _operatorApprovals;
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/// @dev EIP-165 identifiers for all supported interfaces.
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bytes4 private constant _ERC165_INTERFACE_ID = 0x01ffc9a7;
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bytes4 private constant _ERC721_INTERFACE_ID = 0x80ac58cd;
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/// @notice Gets the assigned owner for token `id`.
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/// @param id The id of the NFT being queried.
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/// @return The address of the owner of the NFT of id `id`.
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function ownerOf(uint256 id) external view virtual returns (address) {
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return _ownerOf[id];
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}
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/// @notice Gets number of NFTs owned by address `owner`.
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/// @param owner The address whose balance is being queried.
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/// @return The number of NFTs owned by address `owner`.
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function balanceOf(address owner) external view virtual returns (uint256) {
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return _balanceOf[owner];
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}
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/// @notice Sets approved address of NFT of id `id` to address `approved`.
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/// @param approved The new approved address for the NFT.
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/// @param id The id of the NFT to approve.
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function approve(address approved, uint256 id) external virtual {
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address owner = _ownerOf[id];
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if (msg.sender != owner && !_operatorApprovals[owner][msg.sender]) {
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revert SenderUnauthorized();
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}
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getApproved[id] = approved;
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emit Approval(owner, approved, id);
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}
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/// @notice Checks if `operator` is an authorized operator for `owner`.
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/// @param owner The address of the owner.
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/// @param operator The address of the owner's operator.
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/// @return True if `operator` is approved operator of `owner`, else False.
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function isApprovedForAll(address owner, address operator)
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external
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view
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virtual returns (bool)
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{
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return _operatorApprovals[owner][operator];
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}
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/// @notice Sets the operator for `msg.sender` to `operator`.
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/// @param operator The operator address that will manage the sender's NFTs.
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/// @param approved Whether operator is allowed to operate sender's NFTs.
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function setApprovalForAll(address operator, bool approved) external virtual {
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_operatorApprovals[msg.sender][operator] = approved;
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emit ApprovalForAll(msg.sender, operator, approved);
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}
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/// @notice Checks if interface of identifier `id` is supported.
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/// @param id The ERC-165 interface identifier.
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/// @return True if interface id `id` is supported, false otherwise.
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function supportsInterface(bytes4 id) public pure virtual returns (bool) {
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return
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id == _ERC165_INTERFACE_ID ||
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id == _ERC721_INTERFACE_ID;
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}
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/// @notice Transfers NFT of id `id` from address `from` to address `to`,
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/// with safety checks ensuring `to` is capable of receiving the NFT.
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/// @dev Safety checks are only performed if `to` is a smart contract.
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/// @param from The existing owner address of the NFT to be transferred.
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/// @param to The new owner address of the NFT being transferred.
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/// @param id The id of the NFT being transferred.
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/// @param data Additional transfer data to pass to the receiving contract.
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function safeTransferFrom(
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address from,
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address to,
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uint256 id,
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bytes memory data
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) public virtual {
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transferFrom(from, to, id);
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if (
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to.code.length != 0 &&
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IERC721Receiver(to).onERC721Received(msg.sender, from, id, data)
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!=
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IERC721Receiver.onERC721Received.selector
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) {
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revert SafeTransferUnsupported();
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}
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}
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/// @notice Transfers NFT of id `id` from address `from` to address `to`,
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/// with safety checks ensuring `to` is capable of receiving the NFT.
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/// @dev Safety checks are only performed if `to` is a smart contract.
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/// @param from The existing owner address of the NFT to be transferred.
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/// @param to The new owner address of the NFT being transferred.
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/// @param id The id of the NFT being transferred.
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function safeTransferFrom(
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address from,
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address to,
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uint256 id
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) public virtual {
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transferFrom(from, to, id);
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if (
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to.code.length != 0 &&
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IERC721Receiver(to).onERC721Received(msg.sender, from, id, "")
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!=
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IERC721Receiver.onERC721Received.selector
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) {
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revert SafeTransferUnsupported();
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}
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}
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/// @notice Transfers NFT of id `id` from address `from` to address `to`,
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/// without performing any safety checks.
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/// @dev Existence of an NFT is inferred by having a non-zero owner address.
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/// Transfers clear owner approvals, but `Approval` events are omitted.
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/// @param from The existing owner address of the NFT being transferred.
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/// @param to The new owner address of the NFT being transferred.
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/// @param id The id of the NFT being transferred.
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function transferFrom(
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address from,
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address to,
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uint256 id
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) public virtual {
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if (from != _ownerOf[id]) {
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revert OwnerInvalid();
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}
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if (
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msg.sender != from &&
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msg.sender != getApproved[id] &&
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!_operatorApprovals[from][msg.sender]
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) {
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revert SenderUnauthorized();
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}
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if (to == address(0)) {
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revert ReceiverInvalid();
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}
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_beforeTokenTransfer(from, to, id);
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delete getApproved[id];
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unchecked {
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_balanceOf[from]--;
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_balanceOf[to]++;
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}
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_ownerOf[id] = to;
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emit Transfer(from, to, id);
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}
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/// @dev Mints NFT of id `id` to address `to`. To save gas, it is assumed
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/// that `maxSupply` < `type(uint256).max` (ex. for tabs, cap is very low).
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/// @param to Address receiving the minted NFT.
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/// @param id Identifier of the NFT being minted.
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/// @return The id of the minted NFT.
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function _mint(address to, uint256 id) internal virtual returns (uint256) {
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if (to == address(0)) {
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revert ReceiverInvalid();
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}
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if (_ownerOf[id] != address(0)) {
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revert TokenAlreadyMinted();
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}
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_beforeTokenTransfer(address(0), to, id);
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unchecked {
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totalSupply++;
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_balanceOf[to]++;
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}
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_ownerOf[id] = to;
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emit Transfer(address(0), to, id);
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return id;
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}
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/// @dev Burns NFT of id `id`, removing it from existence.
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/// @param id Identifier of the NFT being burned
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function _burn(uint256 id) internal virtual {
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address owner = _ownerOf[id];
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if (owner == address(0)) {
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revert TokenNonExistent();
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}
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_beforeTokenTransfer(owner, address(0), id);
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unchecked {
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totalSupply--;
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_balanceOf[owner]--;
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}
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delete _ownerOf[id];
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emit Transfer(owner, address(0), id);
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}
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/// @notice Pre-transfer hook for embedding additional transfer behavior.
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/// @param from The address of the existing owner of the NFT.
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/// @param to The address of the new owner of the NFT.
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/// @param id The id of the NFT being transferred.
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function _beforeTokenTransfer(address from, address to, uint256 id)
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internal
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virtual
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{}
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}
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