Derivability

Smart contract interface

In comparison with legacy NFT, NFT2.0 possesses derivability attribute, i.e. it can be derived in term of time space or data space. Some use cases for this novel derivative assets is rental, time-bound perk, etc. The exhibition of derivative assets consequently gain usability and liquidity for underlying assets, thus increase the value of NFT2.0 item.

IDerivable interface is the following:

interface IDerivableV2 {
  /**
    * @dev The registry MUST emit the Derive event upon successful wildcard deriving NFT.
    * This event is persisted in order to comply with v1 interface
    * It should be replaced by DeriveByKeys event.
    */
  event Derive(address underlyingCollection, uint256 underlyingTokenId, address derivedCollection, uint256 derivedTokenId, uint256 startTime, uint256 endTime);

  /**
    * @dev The registry MUST emit the DeriveByKeys event upon successful deriving NFT by specified keys.
    */
  event DeriveByKeys(address underlyingCollection, uint256 underlyingTokenId, address derivedCollection, uint256 derivedTokenId, uint256 startTime, uint256 endTime, bytes32[] keyHashes);

  /**
    * @dev Derive NFT from an underlying NFT by all keys.
    *   
    * Emits Derive event.
    * @param underlyingCollection collection address of the underlying NFT
    * @param underlyingTokenId token ID of the underlying NFT
    * @param startTime Unix timestamp from which the derived NFT is usable
    * @param endTime Unix timestamp beyond which the derived NFT is unusable
    * @param royaltyRate royalty rate in basis point of derived NFT
    */
  function derive(address underlyingCollection, uint256 underlyingTokenId, uint256 startTime, uint256 endTime, uint256 royaltyRate) external payable returns (uint256 tokenId);

  /**
    * @dev Derive NFT from an underlying NFT by specified keys.
    *   
    * Emits DeriveByKeys event.
    * @param underlyingCollection collection address of the underlying NFT
    * @param underlyingTokenId token ID of the underlying NFT
    * @param startTime Unix timestamp from which the derived NFT is usable
    * @param endTime Unix timestamp beyond which the derived NFT is unusable
    * @param royaltyRate royalty rate in basis point of derived NFT
    * @param keyHashes list of keys
    */
  function deriveByKeys(address underlyingCollection, uint256 underlyingTokenId, uint256 startTime, uint256 endTime, uint256 royaltyRate, bytes32[] calldata keyHashes) external payable returns (uint256 tokenId);

  /**
    * @dev Returns the derived NFT of a underlying NFT by all keys.
    *       
    * @param underlyingCollection collection address of the underlying NFT
    * @param underlyingTokenId token ID of the underlying NFT    
    */
  function derivedOf(address underlyingCollection, uint256 underlyingTokenId) external view returns (DerivedToken memory);

  /**
    * @dev Returns the derived NFT of a underlying NFT by specified key.
    *       
    * @param underlyingCollection collection address of the underlying NFT
    * @param underlyingTokenId token ID of the underlying NFT
    * @param key the key hash
    */
  function derivedByKeyOf(address underlyingCollection, uint256 underlyingTokenId, bytes32 key) external view returns (DerivedToken memory);

  /**
    * @dev Returns the underlying NFT of a specific derived NFT.
    *           
    * @param derivedTokenId token ID of the derived NFT    
    */
  function underlyingOf(uint256 derivedTokenId) external view returns (address, uint256);

  /**
    * @dev Returns boolean indicates whether the NFT is usable by all keys or not.
    *   
    * @param collection collection address of the NFT        
    * @param tokenId token ID of the NFT
    */
  function isUsable(address collection, uint256 tokenId) external view returns (bool);

  /**
    * @dev Returns boolean indicates whether the NFT is usable by specified key or not.
    *   
    * @param collection collection address of the NFT
    * @param tokenId token ID of the NFT
    * @param key the key hash need to lookup
    */
  function isUsableByKey(address collection, uint256 tokenId, bytes32 key) external view returns (bool);

  /**
    * @dev Returns boolean indicates whether the NFT is derivable or not
    *   
    * @param collection collection address of the NFT        
    * @param tokenId token ID of the NFT    
    */
  function isDerivable(address collection, uint256 tokenId) external view returns (bool);
  
  /**
    * @dev Returns boolean indicates whether the NFT is derivable by specified key or not.
    *   
    * @param collection collection address of the NFT        
    * @param tokenId token ID of the NFT
    * @param key the key hash need to lookup    
    */
  function isDerivableByKey(address collection, uint256 tokenId, bytes32 key) external view returns (bool);
}