Add transient ReentrancyGuard lib

Author: k06a

contracts/libraries/ReentrancyGuard.sol

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import { TransientLib, tuint256 } from "./Transient.sol";
+
+struct ReentrancyGuard {
+    tuint256 _raw;
+}
+
+library ReentrancyGuardLib {
+    using TransientLib for tuint256;
+
+    error ReentrantCallDetected();
+    error EnterLeaveDisbalance();
+
+    function enter(ReentrancyGuard storage self) internal {
+        if (self._raw.inc() != 1) revert ReentrantCallDetected();
+    }
+
+    function enterNoIncrement(ReentrancyGuard storage self) internal view {
+        if (self._raw.tload() != 0) revert ReentrantCallDetected();
+    }
+
+    function leave(ReentrancyGuard storage self) internal {
+        self._raw.dec(EnterLeaveDisbalance.selector);
+    }
+}

contracts/libraries/ReentrancyGuardBase.sol

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+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import { ReentrancyGuard, ReentrancyGuardLib } from "./ReentrancyGuard.sol";
+
+contract ReentrancyGuardBase {
+    using ReentrancyGuardLib for ReentrancyGuard;
+
+    ReentrancyGuard private _lock;
+
+    modifier nonReentrant {
+        _lock.enter();
+        _;
+        _lock.leave();
+    }
+
+    modifier nonReentrantView {
+        _lock.enterNoIncrement();
+        _;
+    }
+
+    modifier nonReentrantGuard(ReentrancyGuard storage lock) {
+        lock.enter();
+        _;
+        lock.leave();
+    }
+
+    modifier nonReentrantViewGuard(ReentrancyGuard storage lock) {
+        lock.enterNoIncrement();
+        _;
+    }
+}