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1fd993b Jan 26, 2019
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@nventuro @pw94 @frangio @Skyge
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pragma solidity ^0.5.2;
import "./ERC721.sol";
import "./IERC721Metadata.sol";
import "../../introspection/ERC165.sol";
contract ERC721Metadata is ERC165, ERC721, IERC721Metadata {
// Token name
string private _name;
// Token symbol
string private _symbol;
// Optional mapping for token URIs
mapping(uint256 => string) private _tokenURIs;
bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
/*
* 0x5b5e139f ===
* bytes4(keccak256('name()')) ^
* bytes4(keccak256('symbol()')) ^
* bytes4(keccak256('tokenURI(uint256)'))
*/
/**
* @dev Constructor function
*/
constructor (string memory name, string memory symbol) public {
_name = name;
_symbol = symbol;
// register the supported interfaces to conform to ERC721 via ERC165
_registerInterface(_INTERFACE_ID_ERC721_METADATA);
}
/**
* @dev Gets the token name
* @return string representing the token name
*/
function name() external view returns (string memory) {
return _name;
}
/**
* @dev Gets the token symbol
* @return string representing the token symbol
*/
function symbol() external view returns (string memory) {
return _symbol;
}
/**
* @dev Returns an URI for a given token ID
* Throws if the token ID does not exist. May return an empty string.
* @param tokenId uint256 ID of the token to query
*/
function tokenURI(uint256 tokenId) external view returns (string memory) {
require(_exists(tokenId));
return _tokenURIs[tokenId];
}
/**
* @dev Internal function to set the token URI for a given token
* Reverts if the token ID does not exist
* @param tokenId uint256 ID of the token to set its URI
* @param uri string URI to assign
*/
function _setTokenURI(uint256 tokenId, string memory uri) internal {
require(_exists(tokenId));
_tokenURIs[tokenId] = uri;
}
/**
* @dev Internal function to burn a specific token
* Reverts if the token does not exist
* Deprecated, use _burn(uint256) instead
* @param owner owner of the token to burn
* @param tokenId uint256 ID of the token being burned by the msg.sender
*/
function _burn(address owner, uint256 tokenId) internal {
super._burn(owner, tokenId);
// Clear metadata (if any)
if (bytes(_tokenURIs[tokenId]).length != 0) {
delete _tokenURIs[tokenId];
}
}
}