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87 lines
2.2 KiB
87 lines
2.2 KiB
pragma solidity ^0.4.24;
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import "./ERC721.sol";
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import "./IERC721Metadata.sol";
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import "../../introspection/ERC165.sol";
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contract ERC721Metadata is ERC165, ERC721, IERC721Metadata {
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// Token name
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string private _name;
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// Token symbol
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string private _symbol;
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// Optional mapping for token URIs
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mapping(uint256 => string) private _tokenURIs;
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bytes4 private constant InterfaceId_ERC721Metadata = 0x5b5e139f;
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/**
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* 0x5b5e139f ===
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* bytes4(keccak256('name()')) ^
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* bytes4(keccak256('symbol()')) ^
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* bytes4(keccak256('tokenURI(uint256)'))
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*/
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/**
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* @dev Constructor function
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*/
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constructor(string name, string symbol) public {
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_name = name;
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_symbol = symbol;
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// register the supported interfaces to conform to ERC721 via ERC165
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_registerInterface(InterfaceId_ERC721Metadata);
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}
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/**
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* @dev Gets the token name
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* @return string representing the token name
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*/
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function name() external view returns (string) {
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return _name;
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}
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/**
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* @dev Gets the token symbol
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* @return string representing the token symbol
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*/
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function symbol() external view returns (string) {
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return _symbol;
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}
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/**
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* @dev Returns an URI for a given token ID
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* Throws if the token ID does not exist. May return an empty string.
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* @param tokenId uint256 ID of the token to query
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*/
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function tokenURI(uint256 tokenId) external view returns (string) {
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require(_exists(tokenId));
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return _tokenURIs[tokenId];
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}
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/**
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* @dev Internal function to set the token URI for a given token
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* Reverts if the token ID does not exist
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* @param tokenId uint256 ID of the token to set its URI
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* @param uri string URI to assign
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*/
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function _setTokenURI(uint256 tokenId, string uri) internal {
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require(_exists(tokenId));
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_tokenURIs[tokenId] = uri;
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}
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/**
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* @dev Internal function to burn a specific token
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* Reverts if the token does not exist
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* @param owner owner of the token to burn
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* @param tokenId uint256 ID of the token being burned by the msg.sender
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*/
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function _burn(address owner, uint256 tokenId) internal {
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super._burn(owner, tokenId);
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// Clear metadata (if any)
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if (bytes(_tokenURIs[tokenId]).length != 0) {
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delete _tokenURIs[tokenId];
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}
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}
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}
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