[WIP] ERC20 with library storage implementation

contracts/erc20/LibERC20.sol

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: Apache-2.0
+pragma solidity ^0.8.9;
+
+library LibDiamond {
+    bytes32 constant ERC20_STORAGE_POSITION =
+        keccak256("moonstreamdao.eth.storage.erc20");
+
+    struct ERC20Storage {
+        address controller;
+        uint256 totalSupply;
+        string name;
+        string symbol;
+        mapping(address => uint256) balances;
+        mapping(address => mapping(address => uint256)) allowances;
+    }
+
+    function erc20Storage() internal pure returns (ERC20Storage storage es) {
+        bytes32 position = ERC20_STORAGE_POSITION;
+        assembly {
+            es.slot := position
+        }
+    }
+
+    event ControlTransferred(
+        address indexed previousController,
+        address indexed newController
+    );
+
+    function setController(address _newController) internal {
+        ERC20Storage storage es = erc20Storage();
+        address previousController = es.controller;
+        es.controller = _newController;
+        emit ControlTransferred(previousController, _newController);
+    }
+
+    function getController()
+        internal
+        view
+        returns (address contractController_)
+    {
+        contractController_ = erc20Storage().controller;
+    }
+
+    function enforceIsController() internal view {
+        ERC20Storage storage es = erc20Storage();
+        require(msg.sender == es.controller, "LibERC20: Must be controller");
+    }
+}