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openzeppelin-contracts/contracts/token/ERC721/extensions/ERC721Votes.sol

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1.8 KiB

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC721/extensions/ERC721Votes.sol)
pragma solidity ^0.8.20;
import {ERC721} from "../ERC721.sol";
import {Votes} from "../../../governance/utils/Votes.sol";
/**
* @dev Extension of ERC-721 to support voting and delegation as implemented by {Votes}, where each individual NFT counts
* as 1 vote unit.
*
* Tokens do not count as votes until they are delegated, because votes must be tracked which incurs an additional cost
* on every transfer. Token holders can either delegate to a trusted representative who will decide how to make use of
* the votes in governance decisions, or they can delegate to themselves to be their own representative.
*/
abstract contract ERC721Votes is ERC721, Votes {
/**
* @dev See {ERC721-_update}. Adjusts votes when tokens are transferred.
*
* Emits a {IVotes-DelegateVotesChanged} event.
*/
function _update(address to, uint256 tokenId, address auth) internal virtual override returns (address) {
address previousOwner = super._update(to, tokenId, auth);
_transferVotingUnits(previousOwner, to, 1);
return previousOwner;
}
/**
* @dev Returns the balance of `account`.
*
* WARNING: Overriding this function will likely result in incorrect vote tracking.
*/
function _getVotingUnits(address account) internal view virtual override returns (uint256) {
return balanceOf(account);
}
/**
* @dev See {ERC721-_increaseBalance}. We need that to account tokens that were minted in batch.
*/
function _increaseBalance(address account, uint128 amount) internal virtual override {
super._increaseBalance(account, amount);
_transferVotingUnits(address(0), account, amount);
}
}