> For the complete documentation index, see [llms.txt](https://docs.mezzanine.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.mezzanine.xyz/smart-contracts/source-code/feecontroller.md). # FeeController [Git Source](https://github.com/EntreDevelopers-Lab-Inc/Mezz-Companies/blob/f7a3e84e3dd5bb33c4bd7f77283983f9e8ba20b2/src/FeeController.sol) **Inherits:** Initializable, ERC165Upgradeable, HubOwnableUUPSUpgradeable, IFeeController **Author:** Daniel Yamagata & Naveen Ailawadi A contract to set and manage fees for the Mezzanine Protocol *All fees are denominated in 100\_000 as 100%. For example, a fee of 1\_000 is equivalent to 1% All fees in Mezzanine are transferred to the fee controller, which then can be collected by the owner of the Mezz Hub. All implementations that charge a fee are responsible for transferring the fees to the fee controller.* ## State Variables ### MAX\_IMPLEMENTATION\_FEE ```solidity uint256 public constant MAX_IMPLEMENTATION_FEE = Constants.MAX_IMPLEMENTATION_FEE; ``` ### FeeControllerStorageLocation ```solidity bytes32 private constant FeeControllerStorageLocation = 0x9980cbcd1eea9936b8d3caaf89dd2ea96db52917f1123c39e72b02e9cb513100; ``` ## Functions ### \_getFeeControllerStorage ```solidity function _getFeeControllerStorage() internal pure returns (FeeControllerStorage storage $); ``` ### constructor ```solidity constructor(address _mezzHub) HubOwnableUUPSUpgradeable(_mezzHub); ``` ### setImplementationFee Sets the fee of the 'implementation' to 'newFee'. Only callable by the 'owner' of the MezzHub ```solidity function setImplementationFee(address implementation, uint256 newFee) external virtual onlyHubOwner; ``` ### collectFees Transfers 'amount' of 'asset' to the owner of the Mezz Hub ```solidity function collectFees(address asset, uint256 amount) external virtual onlyHubOwner; ``` ### calculateFee Returns the fee for 'amount' based on the 'asset' and 'implementation' Returns zero if 'asset' is not a denomination asset or the implementation does not have a fee ```solidity function calculateFee(address asset, uint256 amount, address implementation) public view virtual returns (uint256); ``` ### getFeeByImplementation Returns the fee for 'implementation'. Returns zero if there is no fee ```solidity function getFeeByImplementation(address implementation) public view returns (uint256); ``` ### supportsInterface *ERC165 support* ```solidity function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165Upgradeable, IERC165) returns (bool); ``` ## Structs ### FeeControllerStorage ```solidity struct FeeControllerStorage { mapping(address => uint256) _feeByImplementation; } ``` --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.mezzanine.xyz/smart-contracts/source-code/feecontroller.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.