// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./nf-token.sol";
import "./erc721-metadata.sol";
/**
* @dev Optional metadata implementation for ERC-721 non-fungible token standard.
*/
contract NFTokenMetadata is
NFToken,
ERC721Metadata
{
/**
* @dev A descriptive name for a collection of NFTs.
*/
string internal nftName;
/**
* @dev An abbreviated name for NFTokens.
*/
string internal nftSymbol;
/**
* @dev Mapping from NFT ID to metadata uri.
*/
mapping (uint256 => string) internal idToUri;
/**
* @notice When implementing this contract don't forget to set nftName and nftSymbol.
* @dev Contract constructor.
*/
constructor()
{
supportedInterfaces[0x5b5e139f] = true; // ERC721Metadata
}
/**
* @dev Returns a descriptive name for a collection of NFTokens.
* @return _name Representing name.
*/
function name()
external
override
view
returns (string memory _name)
{
_name = nftName;
}
/**
* @dev Returns an abbreviated name for NFTokens.
* @return _symbol Representing symbol.
*/
function symbol()
external
override
view
returns (string memory _symbol)
{
_symbol = nftSymbol;
}
/**
* @dev A distinct URI (RFC 3986) for a given NFT.
* @param _tokenId Id for which we want uri.
* @return URI of _tokenId.
*/
function tokenURI(
uint256 _tokenId
)
external
override
view
validNFToken(_tokenId)
returns (string memory)
{
return _tokenURI(_tokenId);
}
/**
* @notice This is an internal function that can be overriden if you want to implement a different
* way to generate token URI.
* @param _tokenId Id for which we want uri.
* @return URI of _tokenId.
*/
function _tokenURI(
uint256 _tokenId
)
internal
virtual
view
returns (string memory)
{
return idToUri[_tokenId];
}
/**
* @notice This is an internal function which should be called from user-implemented external
* burn function. Its purpose is to show and properly initialize data structures when using this
* implementation. Also, note that this burn implementation allows the minter to re-mint a burned
* NFT.
* @dev Burns a NFT.
* @param _tokenId ID of the NFT to be burned.
*/
function _burn(
uint256 _tokenId
)
internal
override
virtual
{
super._burn(_tokenId);
delete idToUri[_tokenId];
}
/**
* @notice This is an internal function which should be called from user-implemented external
* function. Its purpose is to show and properly initialize data structures when using this
* implementation.
* @dev Set a distinct URI (RFC 3986) for a given NFT ID.
* @param _tokenId Id for which we want URI.
* @param _uri String representing RFC 3986 URI.
*/
function _setTokenUri(
uint256 _tokenId,
string memory _uri
)
internal
validNFToken(_tokenId)
{
idToUri[_tokenId] = _uri;
}
}
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