feat: add balancer v2 executor

foundry/lib/balancer-labs/v2-interfaces/contracts/liquidity-mining/IChildChainGauge.sol

@@ -0,0 +1,51 @@
+// 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;
+
+import "../pool-utils/IVersion.sol";
+import "./ILiquidityGaugeFactory.sol";
+
+// For compatibility, we're keeping the same function names as in the original Curve code, including the mixed-case
+// naming convention.
+// solhint-disable func-name-mixedcase
+// solhint-disable func-param-name-mixedcase
+
+interface IChildChainGauge is IVersion {
+    /**
+     * @notice Proxy constructor.
+     * @param lpToken Pool allowed to stake in this gauge.
+     * @param version Gauge version string identifier.
+     */
+    function initialize(address lpToken, string memory version) external;
+
+    /**
+     * @notice Returns BAL liquidity emissions calculated during checkpoints for the given user.
+     * @param user User address.
+     * @return uint256 BAL amount to issue for the address.
+     */
+    function integrate_fraction(address user) external view returns (uint256);
+
+    /**
+     * @notice Records a checkpoint for a given user.
+     * @param user User address.
+     * @return bool Always true.
+     */
+    function user_checkpoint(address user) external returns (bool);
+
+    /**
+     * @notice Returns gauge factory address.
+     */
+    function factory() external view returns (ILiquidityGaugeFactory);
+}