interface ERC165 { /// @notice Query if a contract implements an interface /// @param interfaceID The interface identifier, as specified in ERC-165 /// @dev Interface identification is specified in ERC-165. This function /// uses less than 30,000 gas. /// @return `true` if the contract implements `interfaceID` and /// `interfaceID` is not 0xffffffff, `false` otherwise function supportsInterface(bytes4 interfaceID) external view returns (bool); } abstract contract ERC165MappingImplementation is ERC165 { /// @dev You must not set element 0xffffffff to true mapping(bytes4 => bool) internal supportedInterfaces; constructor() { supportedInterfaces[this.supportsInterface.selector] = true; } function supportsInterface(bytes4 interfaceID) external view override returns (bool) { return supportedInterfaces[interfaceID]; } } interface Simpson { function is2D() external returns (bool); function skinColor() external returns (string memory); } contract Lisa is ERC165MappingImplementation, Simpson { constructor() { supportedInterfaces[this.is2D.selector ^ this.skinColor.selector] = true; } function is2D() external override returns (bool) { return true; } function skinColor() external override returns (string memory) { return "yellow"; } } // ==== // compileViaYul: also // ---- // supportsInterface(bytes4): left(0x01ffc9a0) -> false // supportsInterface(bytes4): left(0x01ffc9a7) -> true // supportsInterface(bytes4): left(0x73b6b492) -> true // supportsInterface(bytes4): left(0x70b6b492) -> false