dexorder

lib_openzeppelin_contracts/contracts/utils/Nonces.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (utils/Nonces.sol)
+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 account => uint256) private _nonces;
+
+    /**
+     * @dev Returns 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 {
+        uint256 current = _useNonce(owner);
+        if (nonce != current) {
+            revert InvalidAccountNonce(owner, current);
+        }
+    }
+}