IERC6464.sol

// SPDX-License-Identifier: CC0-1.0
pragma solidity ^0.8.0;

import "./IERC721.sol";

/**
 * @notice Extends ERC-721 to include per-token approval for multiple operators.
 * @dev Off-chain indexers of approvals SHOULD assume that an operator is approved if either of `ERC721.Approval(…)` or
 * `ERC721.ApprovalForAll(…, true)` events are witnessed without the corresponding revocation(s), even if an
 * `ExplicitApprovalFor(…, false)` is emitted.
 * @dev TODO: the ERC-165 identifier for this interface is TBD.
 */
interface IERC6464 is ERC721 {
    /**
     * @notice Emitted when approval is explicitly granted or revoked for a token.
     */
    event ExplicitApprovalFor(
        address indexed operator,
        uint256 indexed tokenId,
        bool approved
    );

    /**
     * @notice Emitted when all explicit approvals, as granted by either `setExplicitApprovalFor()` function, are
     * revoked for all tokens.
     * @dev MUST be emitted upon calls to `revokeAllExplicitApprovals()`.
     */
    event AllExplicitApprovalsRevoked(address indexed owner);

    /**
     * @notice Emitted when all explicit approvals, as granted by either `setExplicitApprovalFor()` function, are
     * revoked for the specific token.
     * @param owner MUST be `ownerOf(tokenId)` as per ERC721; in the case of revocation due to transfer, this MUST be
     * the `from` address expected to be emitted in the respective `ERC721.Transfer()` event.
     */
    event AllExplicitApprovalsRevoked(
        address indexed owner,
        uint256 indexed tokenId
    );

    /**
     * @notice Approves the operator to manage the asset on behalf of its owner.
     * @dev Throws if `msg.sender` is not the current NFT owner, or an authorised operator of the current owner.
     * @dev Approvals set via this method MUST be revoked upon transfer of the token to a new owner; equivalent to
     * calling `revokeAllExplicitApprovals(tokenId)`, including associated events.
     * @dev MUST emit `ApprovalFor(operator, tokenId, approved)`.
     * @dev MUST NOT have an effect on any standard ERC721 approval setters / getters.
     */
    function setExplicitApproval(
        address operator,
        uint256 tokenId,
        bool approved
    ) external;

    /**
     * @notice Approves the operator to manage the token(s) on behalf of their owner.
     * @dev MUST be equivalent to calling `setExplicitApprovalFor(operator, tokenId, approved)` for each `tokenId` in
     * the array.
     */
    function setExplicitApproval(
        address operator,
        uint256[] memory tokenIds,
        bool approved
    ) external;

    /**
     * @notice Revokes all explicit approvals granted by `msg.sender`.
     * @dev MUST emit `AllExplicitApprovalsRevoked(msg.sender)`.
     */
    function revokeAllExplicitApprovals() external;

    /**
     * @notice Revokes all explicit approvals granted for the specified token.
     * @dev Throws if `msg.sender` is not the current NFT owner, or an authorised operator of the current owner.
     * @dev MUST emit `AllExplicitApprovalsRevoked(msg.sender, tokenId)`.
     */
    function revokeAllExplicitApprovals(uint256 tokenId) external;

    /**
     * @notice Query whether an address is an approved operator for a token.
     */
    function isExplicitlyApprovedFor(address operator, uint256 tokenId)
        external
        view
        returns (bool);
}

interface IERC6464AnyApproval is ERC721 {
    /**
     * @notice Returns true if any of the following criteria are met:
     * 1. `isExplicitlyApprovedFor(operator, tokenId) == true`; OR
     * 2. `isApprovedForAll(ownerOf(tokenId), operator) == true`; OR
     * 3. `getApproved(tokenId) == operator`.
     * @dev The criteria MUST be extended if other mechanism(s) for approving operators are introduced. The criteria
     * MUST include all approval approaches.
     */
    function isApprovedFor(address operator, uint256 tokenId)
        external
        view
        returns (bool);
}