Files
openzeppelin-contracts/contracts/utils/Nonces.sol
Hadrien Croubois 00cbf5a236 Update pragma to 0.8.20 (#4489)
Co-authored-by: Francisco Giordano <fg@frang.io>
Co-authored-by: ernestognw <ernestognw@gmail.com>
2023-07-31 17:25:45 -03:00

47 lines
1.4 KiB
Solidity

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
/**
* @dev Provides tracking nonces for addresses. Nonces will only increment.
*/
abstract contract Nonces {
/**
* @dev The nonce used for an `account` is not the expected current nonce.
*/
error InvalidAccountNonce(address account, uint256 currentNonce);
mapping(address => uint256) private _nonces;
/**
* @dev Returns an the next unused nonce for an address.
*/
function nonces(address owner) public view virtual returns (uint256) {
return _nonces[owner];
}
/**
* @dev Consumes a nonce.
*
* Returns the current value and increments nonce.
*/
function _useNonce(address owner) internal virtual returns (uint256) {
// For each account, the nonce has an initial value of 0, can only be incremented by one, and cannot be
// decremented or reset. This guarantees that the nonce never overflows.
unchecked {
// It is important to do x++ and not ++x here.
return _nonces[owner]++;
}
}
/**
* @dev Same as {_useNonce} but checking that `nonce` is the next valid for `owner`.
*/
function _useCheckedNonce(address owner, uint256 nonce) internal virtual returns (uint256) {
uint256 current = _useNonce(owner);
if (nonce != current) {
revert InvalidAccountNonce(owner, current);
}
return current;
}
}