Update README.md

README.md

@@ -1,4 +1,4 @@
-# Core Contracts
+# child chain
 
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rootERC20predecate

@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.19;
+
+import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@openzeppelin/contracts/proxy/Clones.sol";
+import "../interfaces/root/IRootERC20Predicate.sol";
+import "../interfaces/IStateSender.sol";
+
+// solhint-disable reason-string
+contract RootERC20Predicate is Initializable, IRootERC20Predicate {
+    using SafeERC20 for IERC20Metadata;
+
+    IStateSender public stateSender;
+    address public exitHelper;
+    address public childERC20Predicate;
+    address public childTokenTemplate;
+    bytes32 public constant DEPOSIT_SIG = keccak256("DEPOSIT");
+    bytes32 public constant WITHDRAW_SIG = keccak256("WITHDRAW");
+    bytes32 public constant MAP_TOKEN_SIG = keccak256("MAP_TOKEN");
+    mapping(address => address) public rootTokenToChildToken;
+
+    /**
+     * @notice Initialization function for RootERC20Predicate
+     * @param newStateSender Address of StateSender to send deposit information to
+     * @param newExitHelper Address of ExitHelper to receive withdrawal information from
+     * @param newChildERC20Predicate Address of child ERC20 predicate to communicate with
+     * @dev Can only be called once.
+     */
+    function initialize(
+        address newStateSender,
+        address newExitHelper,
+        address newChildERC20Predicate,
+        address newChildTokenTemplate,
+        address nativeTokenRootAddress
+    ) external initializer {
+        require(
+            newStateSender != address(0) &&
+                newExitHelper != address(0) &&
+                newChildERC20Predicate != address(0) &&
+                newChildTokenTemplate != address(0),
+            "RootERC20Predicate: BAD_INITIALIZATION"
+        );
+        stateSender = IStateSender(newStateSender);
+        exitHelper = newExitHelper;
+        childERC20Predicate = newChildERC20Predicate;
+        childTokenTemplate = newChildTokenTemplate;
+        if (nativeTokenRootAddress != address(0)) {
+            rootTokenToChildToken[nativeTokenRootAddress] = 0x0000000000000000000000000000000000001010;
+            emit TokenMapped(nativeTokenRootAddress, 0x0000000000000000000000000000000000001010);
+        }
+    }
+
+    /**
+     * @inheritdoc IL2StateReceiver
+     * @notice Function to be used for token withdrawals
+     * @dev Can be extended to include other signatures for more functionality
+     */
+    function onL2StateReceive(uint256 /* id */, address sender, bytes calldata data) external {
+        require(msg.sender == exitHelper, "RootERC20Predicate: ONLY_EXIT_HELPER");
+        require(sender == childERC20Predicate, "RootERC20Predicate: ONLY_CHILD_PREDICATE");
+
+        if (bytes32(data[:32]) == WITHDRAW_SIG) {
+            _withdraw(data[32:]);
+        } else {
+            revert("RootERC20Predicate: INVALID_SIGNATURE");
+        }
+    }
+
+    /**
+     * @inheritdoc IRootERC20Predicate
+     */
+    function deposit(IERC20Metadata rootToken, uint256 amount) external {
+        _deposit(rootToken, msg.sender, amount);
+    }
+
+    /**
+     * @inheritdoc IRootERC20Predicate
+     */
+    function depositTo(IERC20Metadata rootToken, address receiver, uint256 amount) external {
+        _deposit(rootToken, receiver, amount);
+    }
+
+    /**
+     * @inheritdoc IRootERC20Predicate
+     */
+    function mapToken(IERC20Metadata rootToken) public returns (address) {
+        require(address(rootToken) != address(0), "RootERC20Predicate: INVALID_TOKEN");
+        require(rootTokenToChildToken[address(rootToken)] == address(0), "RootERC20Predicate: ALREADY_MAPPED");
+
+        address childPredicate = childERC20Predicate;
+
+        address childToken = Clones.predictDeterministicAddress(
+            childTokenTemplate,
+            keccak256(abi.encodePacked(rootToken)),
+            childPredicate
+        );
+
+        rootTokenToChildToken[address(rootToken)] = childToken;
+
+        stateSender.syncState(
+            childPredicate,
+            abi.encode(MAP_TOKEN_SIG, rootToken, rootToken.name(), rootToken.symbol(), rootToken.decimals())
+        );
+        // slither-disable-next-line reentrancy-events
+        emit TokenMapped(address(rootToken), childToken);
+
+        return childToken;
+    }
+
+    function _deposit(IERC20Metadata rootToken, address receiver, uint256 amount) private {
+        address childToken = rootTokenToChildToken[address(rootToken)];
+
+        if (childToken == address(0)) {
+            childToken = mapToken(rootToken);
+        }
+
+        assert(childToken != address(0)); // invariant because we map the token if mapping does not exist
+
+        rootToken.safeTransferFrom(msg.sender, address(this), amount);
+
+        stateSender.syncState(childERC20Predicate, abi.encode(DEPOSIT_SIG, rootToken, msg.sender, receiver, amount));
+        // slither-disable-next-line reentrancy-events
+        emit ERC20Deposit(address(rootToken), childToken, msg.sender, receiver, amount);
+    }
+
+    function _withdraw(bytes calldata data) private {
+        (address rootToken, address withdrawer, address receiver, uint256 amount) = abi.decode(
+            data,
+            (address, address, address, uint256)
+        );
+        address childToken = rootTokenToChildToken[rootToken];
+        assert(childToken != address(0)); // invariant because child predicate should have already mapped tokens
+
+        IERC20Metadata(rootToken).safeTransfer(receiver, amount);
+        // slither-disable-next-line reentrancy-events
+        emit ERC20Withdraw(address(rootToken), childToken, withdrawer, receiver, amount);
+    }
+
+    // slither-disable-next-line unused-state,naming-convention
+    uint256[50] private __gap;
+}