Transpile 7bce2b72

contracts/token/ERC20/extensions/draft-ERC20PermitUpgradeable.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-ERC20Permit.sol)
+
+pragma solidity ^0.8.0;
+
+import "./draft-IERC20PermitUpgradeable.sol";
+import "../ERC20Upgradeable.sol";
+import "../../../utils/cryptography/draft-EIP712Upgradeable.sol";
+import "../../../utils/cryptography/ECDSAUpgradeable.sol";
+import "../../../utils/CountersUpgradeable.sol";
+import "../../../proxy/utils/Initializable.sol";
+
+/**
+ * @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
+ * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
+ *
+ * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
+ * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
+ * need to send a transaction, and thus is not required to hold Ether at all.
+ *
+ * _Available since v3.4._
+ */
+abstract contract ERC20PermitUpgradeable is Initializable, ERC20Upgradeable, IERC20PermitUpgradeable, EIP712Upgradeable {
+    using CountersUpgradeable for CountersUpgradeable.Counter;
+
+    mapping(address => CountersUpgradeable.Counter) private _nonces;
+
+    // solhint-disable-next-line var-name-mixedcase
+    bytes32 private _PERMIT_TYPEHASH;
+
+    /**
+     * @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
+     *
+     * It's a good idea to use the same `name` that is defined as the ERC20 token name.
+     */
+    function __ERC20Permit_init(string memory name) internal onlyInitializing {
+        __Context_init_unchained();
+        __EIP712_init_unchained(name, "1");
+        __ERC20Permit_init_unchained(name);
+    }
+
+    function __ERC20Permit_init_unchained(string memory) internal onlyInitializing {
+        _PERMIT_TYPEHASH = keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");}
+
+    /**
+     * @dev See {IERC20Permit-permit}.
+     */
+    function permit(
+        address owner,
+        address spender,
+        uint256 value,
+        uint256 deadline,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public virtual override {
+        require(block.timestamp <= deadline, "ERC20Permit: expired deadline");
+
+        bytes32 structHash = keccak256(abi.encode(_PERMIT_TYPEHASH, owner, spender, value, _useNonce(owner), deadline));
+
+        bytes32 hash = _hashTypedDataV4(structHash);
+
+        address signer = ECDSAUpgradeable.recover(hash, v, r, s);
+        require(signer == owner, "ERC20Permit: invalid signature");
+
+        _approve(owner, spender, value);
+    }
+
+    /**
+     * @dev See {IERC20Permit-nonces}.
+     */
+    function nonces(address owner) public view virtual override returns (uint256) {
+        return _nonces[owner].current();
+    }
+
+    /**
+     * @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
+     */
+    // solhint-disable-next-line func-name-mixedcase
+    function DOMAIN_SEPARATOR() external view override returns (bytes32) {
+        return _domainSeparatorV4();
+    }
+
+    /**
+     * @dev "Consume a nonce": return the current value and increment.
+     *
+     * _Available since v4.1._
+     */
+    function _useNonce(address owner) internal virtual returns (uint256 current) {
+        CountersUpgradeable.Counter storage nonce = _nonces[owner];
+        current = nonce.current();
+        nonce.increment();
+    }
+    uint256[49] private __gap;
+}