feat: add balancer v2 executor

foundry/lib/balancer-labs/v2-interfaces/contracts/pool-utils/BasePoolUserData.sol

@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pragma solidity >=0.7.0 <0.9.0;
+
+library BasePoolUserData {
+    // Special ExitKind for all pools, used in Recovery Mode. Use the max 8-bit value to prevent conflicts
+    // with future additions to the ExitKind enums (or any front-end code that maps to existing values)
+    uint8 public constant RECOVERY_MODE_EXIT_KIND = 255;
+
+    // Return true if this is the special exit kind.
+    function isRecoveryModeExitKind(bytes memory self) internal pure returns (bool) {
+        // Check for the "no data" case, or abi.decode would revert
+        return self.length > 0 && abi.decode(self, (uint8)) == RECOVERY_MODE_EXIT_KIND;
+    }
+
+    // Parse the bptAmountIn out of the userData
+    function recoveryModeExit(bytes memory self) internal pure returns (uint256 bptAmountIn) {
+        (, bptAmountIn) = abi.decode(self, (uint8, uint256));
+    }
+}