feat: add balancer v2 executor

foundry/lib/balancer-labs/v2-interfaces/contracts/vault/IFlashLoanRecipient.sol

@@ -0,0 +1,37 @@
+// 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;
+
+// Inspired by Aave Protocol's IFlashLoanReceiver.
+
+import "../solidity-utils/openzeppelin/IERC20.sol";
+
+interface IFlashLoanRecipient {
+    /**
+     * @dev When `flashLoan` is called on the Vault, it invokes the `receiveFlashLoan` hook on the recipient.
+     *
+     * At the time of the call, the Vault will have transferred `amounts` for `tokens` to the recipient. Before this
+     * call returns, the recipient must have transferred `amounts` plus `feeAmounts` for each token back to the
+     * Vault, or else the entire flash loan will revert.
+     *
+     * `userData` is the same value passed in the `IVault.flashLoan` call.
+     */
+    function receiveFlashLoan(
+        IERC20[] memory tokens,
+        uint256[] memory amounts,
+        uint256[] memory feeAmounts,
+        bytes memory userData
+    ) external;
+}