DiamondLoupeFacet.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/******************************************************************************\
* Author: Nick Mudge <nick@perfectabstractions.com> (https://twitter.com/mudgen)
* EIP-2535 Diamonds: https://eips.ethereum.org/EIPS/eip-2535
/******************************************************************************/

import { LibDiamond } from  "../libraries/LibDiamond.sol";
import { IDiamondLoupe } from "../interfaces/IDiamondLoupe.sol";
import { IERC165 } from "../interfaces/IERC165.sol";

// The functions in DiamondLoupeFacet MUST be added to a diamond.
// The EIP-2535 Diamond standard requires these functions.

contract DiamondLoupeFacet is IDiamondLoupe, IERC165 {
    // Diamond Loupe Functions
    ////////////////////////////////////////////////////////////////////
    /// These functions are expected to be called frequently by tools.
    //
    // struct Facet {
    //     address facetAddress;
    //     bytes4[] functionSelectors;
    // }

    /// @notice Gets all facets and their selectors.
    /// @return facets_ Facet
    function facets() external override view returns (Facet[] memory facets_) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        uint256 numFacets = ds.facetAddresses.length;
        facets_ = new Facet[](numFacets);
        for (uint256 i; i < numFacets; i++) {
            address facetAddress_ = ds.facetAddresses[i];
            facets_[i].facetAddress = facetAddress_;
            facets_[i].functionSelectors = ds.facetFunctionSelectors[facetAddress_].functionSelectors;
        }
    }

    /// @notice Gets all the function selectors provided by a facet.
    /// @param _facet The facet address.
    /// @return facetFunctionSelectors_
    function facetFunctionSelectors(address _facet) external override view returns (bytes4[] memory facetFunctionSelectors_) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        facetFunctionSelectors_ = ds.facetFunctionSelectors[_facet].functionSelectors;
    }

    /// @notice Get all the facet addresses used by a diamond.
    /// @return facetAddresses_
    function facetAddresses() external override view returns (address[] memory facetAddresses_) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        facetAddresses_ = ds.facetAddresses;
    }

    /// @notice Gets the facet that supports the given selector.
    /// @dev If facet is not found return address(0).
    /// @param _functionSelector The function selector.
    /// @return facetAddress_ The facet address.
    function facetAddress(bytes4 _functionSelector) external override view returns (address facetAddress_) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        facetAddress_ = ds.selectorToFacetAndPosition[_functionSelector].facetAddress;
    }

    // This implements ERC-165.
    function supportsInterface(bytes4 _interfaceId) external override view returns (bool) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        return ds.supportedInterfaces[_interfaceId];
    }
}