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pragma solidity ^0.4.21;
import "./ERC721.sol";
import "./ERC721BasicToken.sol";
/**
* @title Full ERC721 Token
* This implementation includes all the required and some optional functionality of the ERC721 standard
* Moreover, it includes approve all functionality using operator terminology
* @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
*/
contract ERC721Token is ERC721BasicToken, ERC721 {
bytes4 private constant InterfaceId_ERC721Enumerable = 0x780e9d63;
/**
* 0x780e9d63 ===
* bytes4(keccak256('totalSupply()')) ^
* bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) ^
* bytes4(keccak256('tokenByIndex(uint256)'))
*/
bytes4 private constant InterfaceId_ERC721Metadata = 0x5b5e139f;
/**
* 0x5b5e139f ===
* bytes4(keccak256('name()')) ^
* bytes4(keccak256('symbol()')) ^
* bytes4(keccak256('tokenURI(uint256)'))
*/
// Token name
string internal name_;
// Token symbol
string internal symbol_;
// Mapping from owner to list of owned token IDs
mapping(address => uint256[]) internal ownedTokens;
// Mapping from token ID to index of the owner tokens list
mapping(uint256 => uint256) internal ownedTokensIndex;
// Array with all token ids, used for enumeration
uint256[] internal allTokens;
// Mapping from token id to position in the allTokens array
mapping(uint256 => uint256) internal allTokensIndex;
// Optional mapping for token URIs
mapping(uint256 => string) internal tokenURIs;
/**
* @dev Constructor function
*/
function initialize(string _name, string _symbol) public {
name_ = _name;
symbol_ = _symbol;
}
/**
* @dev Gets the token name
* @return string representing the token name
*/
function name() external view returns (string) {
return name_;
}
/**
* @dev Gets the token symbol
* @return string representing the token symbol
*/
function symbol() external view returns (string) {
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) public view returns (string) {
require(exists(_tokenId));
return tokenURIs[_tokenId];
}
/**
* @dev Gets the token ID at a given index of the tokens list of the requested owner
* @param _owner address owning the tokens list to be accessed
* @param _index uint256 representing the index to be accessed of the requested tokens list
* @return uint256 token ID at the given index of the tokens list owned by the requested address
*/
function tokenOfOwnerByIndex(
address _owner,
uint256 _index
)
public
view
returns (uint256)
{
require(_index < balanceOf(_owner));
return ownedTokens[_owner][_index];
}
/**
* @dev Gets the total amount of tokens stored by the contract
* @return uint256 representing the total amount of tokens
*/
function totalSupply() public view returns (uint256) {
return allTokens.length;
}
/**
* @dev Gets the token ID at a given index of all the tokens in this contract
* Reverts if the index is greater or equal to the total number of tokens
* @param _index uint256 representing the index to be accessed of the tokens list
* @return uint256 token ID at the given index of the tokens list
*/
function tokenByIndex(uint256 _index) public view returns (uint256) {
require(_index < totalSupply());
return allTokens[_index];
}
/**
* @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 _uri) internal {
require(exists(_tokenId));
tokenURIs[_tokenId] = _uri;
}
/**
* @dev Internal function to add a token ID to the list of a given address
* @param _to address representing the new owner of the given token ID
* @param _tokenId uint256 ID of the token to be added to the tokens list of the given address
*/
function addTokenTo(address _to, uint256 _tokenId) internal {
super.addTokenTo(_to, _tokenId);
uint256 length = ownedTokens[_to].length;
ownedTokens[_to].push(_tokenId);
ownedTokensIndex[_tokenId] = length;
}
/**
* @dev Internal function to remove a token ID from the list of a given address
* @param _from address representing the previous owner of the given token ID
* @param _tokenId uint256 ID of the token to be removed from the tokens list of the given address
*/
function removeTokenFrom(address _from, uint256 _tokenId) internal {
super.removeTokenFrom(_from, _tokenId);
uint256 tokenIndex = ownedTokensIndex[_tokenId];
uint256 lastTokenIndex = safeSub(ownedTokens[_from].length, 1);
uint256 lastToken = ownedTokens[_from][lastTokenIndex];
ownedTokens[_from][tokenIndex] = lastToken;
ownedTokens[_from][lastTokenIndex] = 0;
// Note that this will handle single-element arrays. In that case, both tokenIndex and lastTokenIndex are going to
// be zero. Then we can make sure that we will remove _tokenId from the ownedTokens list since we are first swapping
// the lastToken to the first position, and then dropping the element placed in the last position of the list
ownedTokens[_from].length--;
ownedTokensIndex[_tokenId] = 0;
ownedTokensIndex[lastToken] = tokenIndex;
}
/**
* @dev Internal function to mint a new token
* Reverts if the given token ID already exists
* @param _to address the beneficiary that will own the minted token
* @param _tokenId uint256 ID of the token to be minted by the msg.sender
*/
function _mint(address _to, uint256 _tokenId) internal {
super._mint(_to, _tokenId);
allTokensIndex[_tokenId] = allTokens.length;
allTokens.push(_tokenId);
}
/**
* @dev Internal function to burn a specific token
* Reverts if the token does not exist
* @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];
}
// Reorg all tokens array
uint256 tokenIndex = allTokensIndex[_tokenId];
uint256 lastTokenIndex = safeSub(allTokens.length, 1);
uint256 lastToken = allTokens[lastTokenIndex];
allTokens[tokenIndex] = lastToken;
allTokens[lastTokenIndex] = 0;
allTokens.length--;
allTokensIndex[_tokenId] = 0;
allTokensIndex[lastToken] = tokenIndex;
}
}
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