Update EIP-6551: Preventing circular lock situation with initialize

EIPS/eip-6551.md

@@ -156,6 +156,34 @@ interface IERC6551Account {
      */
     receive() external payable;
 
+    /**
+     * @dev initialize function is used to initialize the tken bound account
+     *  after any ownership change
+     * 
+     *  The function can only be called by current owner of token
+     * 
+     *  The function is used to tract current and previous owner of the NFT
+     *  which is used during circular locks and to prevent previous owner to call 
+     *  the functions of the contract
+     * 
+     *  @return the status of the call in boolean format
+     */
+    function initialize() external returns (bool);
+
+    /**
+     * @dev the function is used to transfer token during the situations 
+     *  of circular lock
+     * 
+     *  The function first checks the circular lock condition i.e. when 
+     *  address(this) equals to the address returned by owner() function
+     * 
+     *  The function checks if the call is created by previous owner or not
+     *  and transfer ownership of token to the previous owner
+     * 
+     *  @return the status of the call in boolean format
+     */
+    function unlockCircularLock() external returns (bool);
+
     /**
      * @dev Returns the identifier of the non-fungible token which owns the account
      *
@@ -324,6 +352,43 @@ contract ExampleERC6551Account is IERC165, IERC1271, IERC6551Account, IERC6551Ex
 
     receive() external payable {}
 
+    address public _prevOwner;
+    address public _currOwner;
+
+    function initialize() external returns (bool) {
+        require(
+            owner() == msg.sender,
+            "only new owner could call this function"
+        );
+        if (_prevOwner == address(0)) {
+            _prevOwner = _currOwner = msg.sender;
+        } else {
+            _prevOwner = _currOwner;
+            _currOwner = msg.sender;
+        }
+
+        return true;
+    }
+
+    function unlockCircularLock() external returns (bool) {
+        require(
+            owner() == address(this),
+            "circular lock condition is not present"
+        );
+        require(
+            msg.sender == _prevOwner,
+            "could only be called by previous owner"
+        );
+        (, address _tokenAddr, uint256 _tokenId) = token();
+        IERC721(_tokenAddr).safeTransferFrom(
+            address(this),
+            _prevOwner,
+            _tokenId
+        );
+
+        return true;
+    }
+
     function execute(
         address to,
         uint256 value,