Merge pull request #10 from sogipec/4626-provider

feat: add an ERC4626 rate provider

contracts/ERC4626RateProvider.sol

@@ -0,0 +1,44 @@
+// 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 ^0.8.0;
+
+import "@openzeppelin/contracts/interfaces/IERC4626.sol";
+
+import "./interfaces/IRateProvider.sol";
+
+/**
+ * @title ERC4626 Rate Provider
+ * @notice Returns an 18 decimal fixed point number that is the exchange rate of the
+ * shares of an ERC4626 to the underlying asset
+ */
+contract ERC4626RateProvider is IRateProvider {
+    IERC4626 public immutable erc4626;
+    uint256 public immutable fixedPointOne;
+
+    constructor(IERC4626 _erc4626) {
+        erc4626 = _erc4626;
+        uint256 underlyingDecimals = IERC4626(_erc4626.asset()).decimals();
+        // Balancer does not support tokens with more than 18 decimals so this will never underflow
+        fixedPointOne = 10**(18 + _erc4626.decimals() - underlyingDecimals);
+    }
+
+    /**
+     * @return An 18 decimal fixed point number that is the exchange rate of the
+     * shares of an ERC4626 to the underlying asset
+     */
+    function getRate() external view override returns (uint256) {
+        return erc4626.convertToAssets(fixedPointOne);
+    }
+}

contracts/ERC4626RateProviderFactory.sol

@@ -0,0 +1,35 @@
+// 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 ^0.8.0;
+
+import "./BaseRateProviderFactory.sol";
+import "./ERC4626RateProvider.sol";
+
+/**
+ * @title ERC4626 Rate Provider Factory
+ * @notice Factory for creating ERC4626RateProviders
+ * @dev This contract is used to create ERC4626RateProvider contracts.
+ */
+contract ERC4626RateProviderFactory is BaseRateProviderFactory {
+    /**
+     * @notice Deploys a new ERC4626RateProvider contract using an ERC4626 contract.
+     * @param erc4626 - The ERC4626 contract.
+     */
+    function create(IERC4626 erc4626) external returns (ERC4626RateProvider) {
+        ERC4626RateProvider rateProvider = new ERC4626RateProvider(erc4626);
+        _onCreate(address(rateProvider));
+        return rateProvider;
+    }
+}

package.json

@@ -44,7 +44,7 @@
     "@chainlink/contracts": "^0.2.1",
     "@nomiclabs/hardhat-ethers": "^2.0.1",
     "@nomiclabs/hardhat-waffle": "^2.0.0",
-    "@openzeppelin/contracts": "^4.3.0",
+    "@openzeppelin/contracts": "^4.7.3",
     "@types/chai": "^4.2.12",
     "@types/mocha": "^8.0.3",
     "@types/node": "^14.6.0",

yarn.lock

@@ -620,10 +620,10 @@
     "@types/sinon-chai" "^3.2.3"
     "@types/web3" "1.0.19"
 
-"@openzeppelin/contracts@^4.3.0":
-  version "4.3.0"
-  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-4.3.0.tgz#345236d4ec73ef381ab4907c6ef66fd55e5dedad"
-  integrity sha512-+uBDl/TrmR0Kch6mq3tuxMex/fK7huR6+fQMae+zJk1K5T+dp0pFl12Hbc+1L6oYMXoyDSBJ8zqhRIntrREDFA==
+"@openzeppelin/contracts@^4.7.3":
+  version "4.9.3"
+  resolved "https://registry.yarnpkg.com/@openzeppelin/contracts/-/contracts-4.9.3.tgz#00d7a8cf35a475b160b3f0293a6403c511099364"
+  integrity sha512-He3LieZ1pP2TNt5JbkPA4PNT9WC3gOTOlDcFGJW4Le4QKqwmiNJCRt44APfxMxvq7OugU/cqYuPcSBzOw38DAg==
 
 "@resolver-engine/core@^0.3.3":
   version "0.3.3"