dexorder

lib_openzeppelin_contracts/contracts/utils/structs/BitMaps.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.0.0) (utils/structs/BitMaps.sol)
+pragma solidity ^0.8.20;
+
+/**
+ * @dev Library for managing uint256 to bool mapping in a compact and efficient way, provided the keys are sequential.
+ * Largely inspired by Uniswap's https://github.com/Uniswap/merkle-distributor/blob/master/contracts/MerkleDistributor.sol[merkle-distributor].
+ *
+ * BitMaps pack 256 booleans across each bit of a single 256-bit slot of `uint256` type.
+ * Hence booleans corresponding to 256 _sequential_ indices would only consume a single slot,
+ * unlike the regular `bool` which would consume an entire slot for a single value.
+ *
+ * This results in gas savings in two ways:
+ *
+ * - Setting a zero value to non-zero only once every 256 times
+ * - Accessing the same warm slot for every 256 _sequential_ indices
+ */
+library BitMaps {
+    struct BitMap {
+        mapping(uint256 bucket => uint256) _data;
+    }
+
+    /**
+     * @dev Returns whether the bit at `index` is set.
+     */
+    function get(BitMap storage bitmap, uint256 index) internal view returns (bool) {
+        uint256 bucket = index >> 8;
+        uint256 mask = 1 << (index & 0xff);
+        return bitmap._data[bucket] & mask != 0;
+    }
+
+    /**
+     * @dev Sets the bit at `index` to the boolean `value`.
+     */
+    function setTo(BitMap storage bitmap, uint256 index, bool value) internal {
+        if (value) {
+            set(bitmap, index);
+        } else {
+            unset(bitmap, index);
+        }
+    }
+
+    /**
+     * @dev Sets the bit at `index`.
+     */
+    function set(BitMap storage bitmap, uint256 index) internal {
+        uint256 bucket = index >> 8;
+        uint256 mask = 1 << (index & 0xff);
+        bitmap._data[bucket] |= mask;
+    }
+
+    /**
+     * @dev Unsets the bit at `index`.
+     */
+    function unset(BitMap storage bitmap, uint256 index) internal {
+        uint256 bucket = index >> 8;
+        uint256 mask = 1 << (index & 0xff);
+        bitmap._data[bucket] &= ~mask;
+    }
+}