Contract Address Details

pragma solidity ^0.4.24;

import "./ERC721Token.sol";
import "./Registry.sol";
import "./DSAuth.sol";

/**
 * @title Token of a Meme. Single ERC721 instance represents all memes/cards
 */

contract MemeToken is ERC721Token {
  Registry public registry;

  modifier onlyRegistryEntry() {
    require(registry.isRegistryEntry(msg.sender),"MemeToken: onlyRegistryEntry failed");
    _;
  }

  function MemeToken(Registry _registry)
  ERC721Token("MemeToken", "MEME")
  {
    registry = _registry;
  }

  function mint(address _to, uint256 _tokenId)
  onlyRegistryEntry
  public
  {
    super._mint(_to, _tokenId);
    tokenURIs[_tokenId] = msg.sender;
  }

  function safeTransferFromMulti(
    address _from,
    address _to,
    uint256[] _tokenIds,
    bytes _data
  ) {
    for (uint i = 0; i < _tokenIds.length; i++) {
      safeTransferFrom(_from, _to, _tokenIds[i], _data);
    }
  }
}
        

pragma solidity ^0.4.18;


/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  /**
  * @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}
          

pragma solidity ^0.4.24;

import "./DSAuth.sol";
import "./EternalDb.sol";
import "./MutableForwarder.sol"; // Keep it included despite not being used (for compiler)

/**
 * @title Central contract for TCR registry
 *
 * @dev Manages state about deployed registry entries and factories
 * Serves as a central point for firing all registry entry events
 * This contract is not accessed directly, but through MutableForwarder. See MutableForwarder.sol for more comments.
 */

contract Registry is DSAuth {
  address private dummyTarget; // Keep it here, because this contract is deployed as MutableForwarder

  bytes32 public constant challengePeriodDurationKey = sha3("challengePeriodDuration");
  bytes32 public constant commitPeriodDurationKey = sha3("commitPeriodDuration");
  bytes32 public constant revealPeriodDurationKey = sha3("revealPeriodDuration");
  bytes32 public constant depositKey = sha3("deposit");
  bytes32 public constant challengeDispensationKey = sha3("challengeDispensation");
  bytes32 public constant voteQuorumKey = sha3("voteQuorum");
  bytes32 public constant maxTotalSupplyKey = sha3("maxTotalSupply");
  bytes32 public constant maxAuctionDurationKey = sha3("maxAuctionDuration");

  event MemeConstructedEvent(address registryEntry, uint version, address creator, bytes metaHash, uint totalSupply, uint deposit, uint challengePeriodEnd);
  event MemeMintedEvent(address registryEntry, uint version, address creator, uint tokenStartId, uint tokenEndId, uint totalMinted);

  event ChallengeCreatedEvent(address registryEntry, uint version, address challenger, uint commitPeriodEnd, uint revealPeriodEnd, uint rewardPool, bytes metahash);
  event VoteCommittedEvent(address registryEntry, uint version, address voter, uint amount);
  event VoteRevealedEvent(address registryEntry, uint version, address voter, uint option);
  event VoteAmountClaimedEvent(address registryEntry, uint version, address voter);
  event VoteRewardClaimedEvent(address registryEntry, uint version, address voter, uint amount);
  event ChallengeRewardClaimedEvent(address registryEntry, uint version, address challenger, uint amount);

  event ParamChangeConstructedEvent(address registryEntry, uint version, address creator, address db, string key, uint value, uint deposit, uint challengePeriodEnd);
  event ParamChangeAppliedEvent(address registryEntry, uint version);

  EternalDb public db;
  bool private wasConstructed;

  /**
   * @dev Constructor for this contract.
   * Native constructor is not used, because we use a forwarder pointing to single instance of this contract,
   * therefore constructor must be called explicitly.

   * @param _db Address of EternalDb related to this registry
   */
  function construct(EternalDb _db)
  external
  {
    require(address(_db) != 0x0, "Registry: Address can't be 0x0");

    db = _db;
    wasConstructed = true;
    owner = msg.sender;
  }

  modifier onlyFactory() {
    require(isFactory(msg.sender), "Registry: Sender should be factory");
    _;
  }

  modifier onlyRegistryEntry() {
    require(isRegistryEntry(msg.sender), "Registry: Sender should registry entry");
    _;
  }

  modifier notEmergency() {
    require(!isEmergency(),"Registry: Emergency mode is enable");
    _;
  }

  /**
   * @dev Sets whether address is factory allowed to add registry entries into registry
   * Must be callable only by authenticated user

   * @param _factory Address of a factory contract
   * @param _isFactory Whether the address is allowed factory
   */
  function setFactory(address _factory, bool _isFactory)
  external
  auth
  {
    db.setBooleanValue(sha3("isFactory", _factory), _isFactory);
  }

  /**
   * @dev Adds address as valid registry entry into the Registry
   * Must be callable only by allowed factory contract

   * @param _registryEntry Address of new registry entry
   */
  function addRegistryEntry(address _registryEntry)
  external
  onlyFactory
  notEmergency
  {
    db.setBooleanValue(sha3("isRegistryEntry", _registryEntry), true);
  }

  /**
   * @dev Sets emergency state to pause all trading operations
   * Must be callable only by authenticated user

   * @param _isEmergency True if emergency is happening
   */
  function setEmergency(bool _isEmergency)
  external
  auth
  {
    db.setBooleanValue("isEmergency", _isEmergency);
  }

  function fireMemeConstructedEvent(uint version, address creator, bytes metaHash, uint totalSupply, uint deposit, uint challengePeriodEnd)
  public
  onlyRegistryEntry
  {
    emit MemeConstructedEvent(msg.sender, version, creator, metaHash, totalSupply, deposit, challengePeriodEnd);
  }

  function fireMemeMintedEvent(uint version, address creator, uint tokenStartId, uint tokenEndId, uint totalMinted)
  public
  onlyRegistryEntry
  {
    emit MemeMintedEvent(msg.sender, version, creator, tokenStartId, tokenEndId, totalMinted);
  }

  function fireChallengeCreatedEvent(uint version, address challenger, uint commitPeriodEnd, uint revealPeriodEnd, uint rewardPool, bytes metahash)
  public
  onlyRegistryEntry
  {
    emit ChallengeCreatedEvent(msg.sender, version,  challenger, commitPeriodEnd, revealPeriodEnd, rewardPool, metahash);
  }

  function fireVoteCommittedEvent(uint version, address voter, uint amount)
  public
  onlyRegistryEntry
  {
    emit VoteCommittedEvent(msg.sender, version, voter, amount);
  }

  function fireVoteRevealedEvent(uint version, address voter, uint option)
  public
  onlyRegistryEntry
  {
    emit VoteRevealedEvent(msg.sender, version, voter, option);
  }

  function fireVoteAmountClaimedEvent(uint version, address voter)
  public
  onlyRegistryEntry
  {
    emit VoteAmountClaimedEvent(msg.sender, version, voter);
  }

  function fireVoteRewardClaimedEvent(uint version, address voter, uint amount)
  public
  onlyRegistryEntry
  {
    emit VoteRewardClaimedEvent(msg.sender, version, voter, amount);
  }

  function fireChallengeRewardClaimedEvent(uint version, address challenger, uint amount)
  public
  onlyRegistryEntry
  {
    emit ChallengeRewardClaimedEvent(msg.sender, version, challenger, amount);
  }

  function fireParamChangeConstructedEvent(uint version, address creator, address db, string key, uint value, uint deposit, uint challengePeriodEnd)
  public
  onlyRegistryEntry
  {
    emit ParamChangeConstructedEvent(msg.sender, version, creator, db, key, value, deposit, challengePeriodEnd);
  }

  function fireParamChangeAppliedEvent(uint version)
  public
  onlyRegistryEntry
  {
    emit ParamChangeAppliedEvent(msg.sender, version);
  }

  /**
   * @dev Returns whether address is valid registry entry factory

   * @return True if address is factory
   */
  function isFactory(address factory) public constant returns (bool) {
    return db.getBooleanValue(sha3("isFactory", factory));
  }

  /**
   * @dev Returns whether address is valid registry entry

   * @return True if address is registry entry
   */
  function isRegistryEntry(address registryEntry) public constant returns (bool) {
    return db.getBooleanValue(sha3("isRegistryEntry", registryEntry));
  }

  /**
   * @dev Returns whether emergency stop is happening

   * @return True if emergency is happening
   */
  function isEmergency() public constant returns (bool) {
    return db.getBooleanValue("isEmergency");
  }
}
          

pragma solidity ^0.4.18;

import "./DelegateProxy.sol";
import "./DSAuth.sol";

/**
 * @title Forwarder proxy contract with editable target
 *
 * @dev For TCR Registry contracts (Registry.sol, ParamChangeRegistry.sol) we use mutable forwarders instead of using
 * contracts directly. This is for better upgradeability. Since registry contracts fire all events related to registry
 * entries, we want to be able to access whole history of events always on the same address. Which would be address of
 * a MutableForwarder. When a registry contract is replaced with updated one, mutable forwarder just replaces target
 * and all events stay still accessible on the same address.
 */

contract MutableForwarder is DelegateProxy, DSAuth {

  address public target = 0xBEeFbeefbEefbeEFbeEfbEEfBEeFbeEfBeEfBeef; // checksumed to silence warning

  /**
   * @dev Replaces targer forwarder contract is pointing to
   * Only authenticated user can replace target

   * @param _target New target to proxy into
  */
  function setTarget(address _target) public auth {
    target = _target;
  }

  function() payable {
    delegatedFwd(target, msg.data);
  }

}
          

pragma solidity ^0.4.18;

import "./DSAuth.sol";

/**
 * @title Contract to store arbitrary state data, decoupled from any logic related to it
 *
 * @dev Original implementation: https://blog.colony.io/writing-upgradeable-contracts-in-solidity-6743f0eecc88
 * In addition to original implementation, this contract uses DSAuth for more advanced authentication options
 * It also provides way set/get multiple values in single transaction
 */

contract EternalDb is DSAuth {

  enum Types {UInt, String, Address, Bytes, Bytes32, Boolean, Int}

  event EternalDbEvent(bytes32[] records, uint[] values, uint timestamp);

  function EternalDb(){
  }

  ////////////
  //UInt
  ////////////

  mapping(bytes32 => uint) UIntStorage;

  function getUIntValue(bytes32 record) constant returns (uint){
    return UIntStorage[record];
  }

  function getUIntValues(bytes32[] records) constant returns (uint[] results){
    results = new uint[](records.length);
    for (uint i = 0; i < records.length; i++) {
      results[i] = UIntStorage[records[i]];
    }
  }

  function setUIntValue(bytes32 record, uint value)
  auth
  {
    UIntStorage[record] = value;
    bytes32[] memory records = new bytes32[](1);
    records[0] = record;
    uint[] memory values = new uint[](1);
    values[0] = value;
    emit EternalDbEvent(records, values, now);
  }

  function setUIntValues(bytes32[] records, uint[] values)
  auth
  {
    for (uint i = 0; i < records.length; i++) {
      UIntStorage[records[i]] = values[i];
    }
    emit EternalDbEvent(records, values, now);
  }

  function deleteUIntValue(bytes32 record)
  auth
  {
    delete UIntStorage[record];
  }

  ////////////
  //Strings
  ////////////

  mapping(bytes32 => string) StringStorage;

  function getStringValue(bytes32 record) constant returns (string){
    return StringStorage[record];
  }

  function setStringValue(bytes32 record, string value)
  auth
  {
    StringStorage[record] = value;
  }

  function deleteStringValue(bytes32 record)
  auth
  {
    delete StringStorage[record];
  }

  ////////////
  //Address
  ////////////

  mapping(bytes32 => address) AddressStorage;

  function getAddressValue(bytes32 record) constant returns (address){
    return AddressStorage[record];
  }

  function setAddressValues(bytes32[] records, address[] values)
  auth
  {
    for (uint i = 0; i < records.length; i++) {
      AddressStorage[records[i]] = values[i];
    }
  }

  function setAddressValue(bytes32 record, address value)
  auth
  {
    AddressStorage[record] = value;
  }

  function deleteAddressValue(bytes32 record)
  auth
  {
    delete AddressStorage[record];
  }

  ////////////
  //Bytes
  ////////////

  mapping(bytes32 => bytes) BytesStorage;

  function getBytesValue(bytes32 record) constant returns (bytes){
    return BytesStorage[record];
  }

  function setBytesValue(bytes32 record, bytes value)
  auth
  {
    BytesStorage[record] = value;
  }

  function deleteBytesValue(bytes32 record)
  auth
  {
    delete BytesStorage[record];
  }

  ////////////
  //Bytes32
  ////////////

  mapping(bytes32 => bytes32) Bytes32Storage;

  function getBytes32Value(bytes32 record) constant returns (bytes32){
    return Bytes32Storage[record];
  }

  function getBytes32Values(bytes32[] records) constant returns (bytes32[] results){
    results = new bytes32[](records.length);
    for (uint i = 0; i < records.length; i++) {
      results[i] = Bytes32Storage[records[i]];
    }
  }

  function setBytes32Value(bytes32 record, bytes32 value)
  auth
  {
    Bytes32Storage[record] = value;
  }

  function setBytes32Values(bytes32[] records, bytes32[] values)
  auth
  {
    for (uint i = 0; i < records.length; i++) {
      Bytes32Storage[records[i]] = values[i];
    }
  }

  function deleteBytes32Value(bytes32 record)
  auth
  {
    delete Bytes32Storage[record];
  }

  ////////////
  //Boolean
  ////////////

  mapping(bytes32 => bool) BooleanStorage;

  function getBooleanValue(bytes32 record) constant returns (bool){
    return BooleanStorage[record];
  }

  function getBooleanValues(bytes32[] records) constant returns (bool[] results){
    results = new bool[](records.length);
    for (uint i = 0; i < records.length; i++) {
      results[i] = BooleanStorage[records[i]];
    }
  }

  function setBooleanValue(bytes32 record, bool value)
  auth
  {
    BooleanStorage[record] = value;
  }

  function setBooleanValues(bytes32[] records, bool[] values)
  auth
  {
    for (uint i = 0; i < records.length; i++) {
      BooleanStorage[records[i]] = values[i];
    }
  }

  function deleteBooleanValue(bytes32 record)
  auth
  {
    delete BooleanStorage[record];
  }

  ////////////
  //Int
  ////////////
  mapping(bytes32 => int) IntStorage;

  function getIntValue(bytes32 record) constant returns (int){
    return IntStorage[record];
  }

  function getIntValues(bytes32[] records) constant returns (int[] results){
    results = new int[](records.length);
    for (uint i = 0; i < records.length; i++) {
      results[i] = IntStorage[records[i]];
    }
  }

  function setIntValue(bytes32 record, int value)
  auth
  {
    IntStorage[record] = value;
  }

  function setIntValues(bytes32[] records, int[] values)
  auth
  {
    for (uint i = 0; i < records.length; i++) {
      IntStorage[records[i]] = values[i];
    }
  }

  function deleteIntValue(bytes32 record)
  auth
  {
    delete IntStorage[record];
  }

}
          

pragma solidity ^0.4.18;

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 ERC721, ERC721BasicToken {
  // 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 => address) internal tokenURIs;

  /**
  * @dev Constructor function
  */
  function ERC721Token(string _name, string _symbol) public {
    name_ = _name;
    symbol_ = _symbol;
  }

  /**
  * @dev Gets the token name
  * @return string representing the token name
  */
  function name() public view returns (string) {
    return name_;
  }

  /**
  * @dev Gets the token symbol
  * @return string representing the token symbol
  */
  function symbol() public view returns (string) {
    return symbol_;
  }

  /**
  * @dev Returns an URI for a given token ID
  * @dev 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 (address) {
    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
  * @dev 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
  * @dev 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, address _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 = ownedTokens[_from].length.sub(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
  * @dev 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);
  }
}
          

pragma solidity ^0.4.21;


/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 *  from ERC721 asset contracts.
 */
contract ERC721Receiver {
  /**
   * @dev Magic value to be returned upon successful reception of an NFT
   *  Equals to `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`,
   *  which can be also obtained as `ERC721Receiver(0).onERC721Received.selector`
   */
  bytes4 constant ERC721_RECEIVED = 0xf0b9e5ba;

  /**
   * @notice Handle the receipt of an NFT
   * @dev The ERC721 smart contract calls this function on the recipient
   *  after a `safetransfer`. This function MAY throw to revert and reject the
   *  transfer. This function MUST use 50,000 gas or less. Return of other
   *  than the magic value MUST result in the transaction being reverted.
   *  Note: the contract address is always the message sender.
   * @param _from The sending address
   * @param _tokenId The NFT identifier which is being transfered
   * @param _data Additional data with no specified format
   * @return `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
   */
  function onERC721Received(address _from, uint256 _tokenId, bytes _data) public returns(bytes4);
}
          

pragma solidity ^0.4.21;

import "./ERC721Receiver.sol";


contract ERC721Holder is ERC721Receiver {
  function onERC721Received(address, uint256, bytes) public returns(bytes4) {
    return ERC721_RECEIVED;
  }
}
          

pragma solidity ^0.4.18;

import "./ERC721Basic.sol";
import "./ERC721Receiver.sol";
import "./SafeMath.sol";
import "./AddressUtils.sol";


/**
 * @title ERC721 Non-Fungible Token Standard basic implementation
 * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721BasicToken is ERC721Basic {
  using SafeMath for uint256;
  using AddressUtils for address;

  // Equals to `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`
  // which can be also obtained as `ERC721Receiver(0).onERC721Received.selector`
  bytes4 constant ERC721_RECEIVED = 0xf0b9e5ba;

  // Mapping from token ID to owner
  mapping (uint256 => address) internal tokenOwner;

  // Mapping from token ID to approved address
  mapping (uint256 => address) internal tokenApprovals;

  // Mapping from owner to number of owned token
  mapping (address => uint256) internal ownedTokensCount;

  // Mapping from owner to operator approvals
  mapping (address => mapping (address => bool)) internal operatorApprovals;

  /**
  * @dev Guarantees msg.sender is owner of the given token
  * @param _tokenId uint256 ID of the token to validate its ownership belongs to msg.sender
  */
  modifier onlyOwnerOf(uint256 _tokenId) {
    require(ownerOf(_tokenId) == msg.sender);
    _;
  }

  /**
  * @dev Checks msg.sender can transfer a token, by being owner, approved, or operator
  * @param _tokenId uint256 ID of the token to validate
  */
  modifier canTransfer(uint256 _tokenId) {
    require(isApprovedOrOwner(msg.sender, _tokenId));
    _;
  }

  /**
  * @dev Gets the balance of the specified address
  * @param _owner address to query the balance of
  * @return uint256 representing the amount owned by the passed address
  */
  function balanceOf(address _owner) public view returns (uint256) {
    require(_owner != address(0));
    return ownedTokensCount[_owner];
  }

  /**
  * @dev Gets the owner of the specified token ID
  * @param _tokenId uint256 ID of the token to query the owner of
  * @return owner address currently marked as the owner of the given token ID
  */
  function ownerOf(uint256 _tokenId) public view returns (address) {
    address owner = tokenOwner[_tokenId];
    require(owner != address(0));
    return owner;
  }

  /**
  * @dev Returns whether the specified token exists
  * @param _tokenId uint256 ID of the token to query the existance of
  * @return whether the token exists
  */
  function exists(uint256 _tokenId) public view returns (bool) {
    address owner = tokenOwner[_tokenId];
    return owner != address(0);
  }

  /**
  * @dev Approves another address to transfer the given token ID
  * @dev The zero address indicates there is no approved address.
  * @dev There can only be one approved address per token at a given time.
  * @dev Can only be called by the token owner or an approved operator.
  * @param _to address to be approved for the given token ID
  * @param _tokenId uint256 ID of the token to be approved
  */
  function approve(address _to, uint256 _tokenId) public {
    address owner = ownerOf(_tokenId);
    require(_to != owner);
    require(msg.sender == owner || isApprovedForAll(owner, msg.sender));

    if (getApproved(_tokenId) != address(0) || _to != address(0)) {
      tokenApprovals[_tokenId] = _to;
      Approval(owner, _to, _tokenId);
    }
  }

  /**
   * @dev Gets the approved address for a token ID, or zero if no address set
   * @param _tokenId uint256 ID of the token to query the approval of
   * @return address currently approved for a the given token ID
   */
  function getApproved(uint256 _tokenId) public view returns (address) {
    return tokenApprovals[_tokenId];
  }

  /**
  * @dev Sets or unsets the approval of a given operator
  * @dev An operator is allowed to transfer all tokens of the sender on their behalf
  * @param _to operator address to set the approval
  * @param _approved representing the status of the approval to be set
  */
  function setApprovalForAll(address _to, bool _approved) public {
    require(_to != msg.sender);
    operatorApprovals[msg.sender][_to] = _approved;
    ApprovalForAll(msg.sender, _to, _approved);
  }

  /**
   * @dev Tells whether an operator is approved by a given owner
   * @param _owner owner address which you want to query the approval of
   * @param _operator operator address which you want to query the approval of
   * @return bool whether the given operator is approved by the given owner
   */
  function isApprovedForAll(address _owner, address _operator) public view returns (bool) {
    return operatorApprovals[_owner][_operator];
  }

  /**
  * @dev Transfers the ownership of a given token ID to another address
  * @dev Usage of this method is discouraged, use `safeTransferFrom` whenever possible
  * @dev Requires the msg sender to be the owner, approved, or operator
  * @param _from current owner of the token
  * @param _to address to receive the ownership of the given token ID
  * @param _tokenId uint256 ID of the token to be transferred
  */
  function transferFrom(address _from, address _to, uint256 _tokenId) public canTransfer(_tokenId) {
    require(_from != address(0));
    require(_to != address(0));

    clearApproval(_from, _tokenId);
    removeTokenFrom(_from, _tokenId);
    addTokenTo(_to, _tokenId);

    Transfer(_from, _to, _tokenId, now);
  }

  /**
  * @dev Safely transfers the ownership of a given token ID to another address
  * @dev If the target address is a contract, it must implement `onERC721Received`,
  *  which is called upon a safe transfer, and return the magic value
  *  `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`; otherwise,
  *  the transfer is reverted.
  * @dev Requires the msg sender to be the owner, approved, or operator
  * @param _from current owner of the token
  * @param _to address to receive the ownership of the given token ID
  * @param _tokenId uint256 ID of the token to be transferred
  */
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId
  )
  public
  canTransfer(_tokenId)
  {
    safeTransferFrom(_from, _to, _tokenId, "");
  }

  /**
  * @dev Safely transfers the ownership of a given token ID to another address
  * @dev If the target address is a contract, it must implement `onERC721Received`,
  *  which is called upon a safe transfer, and return the magic value
  *  `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`; otherwise,
  *  the transfer is reverted.
  * @dev Requires the msg sender to be the owner, approved, or operator
  * @param _from current owner of the token
  * @param _to address to receive the ownership of the given token ID
  * @param _tokenId uint256 ID of the token to be transferred
  * @param _data bytes data to send along with a safe transfer check
  */
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId,
    bytes _data
  )
  public
  canTransfer(_tokenId)
  {
    transferFrom(_from, _to, _tokenId);
    require(checkAndCallSafeTransfer(_from, _to, _tokenId, _data));
  }

  /**
   * @dev Returns whether the given spender can transfer a given token ID
   * @param _spender address of the spender to query
   * @param _tokenId uint256 ID of the token to be transferred
   * @return bool whether the msg.sender is approved for the given token ID,
   *  is an operator of the owner, or is the owner of the token
   */
  function isApprovedOrOwner(address _spender, uint256 _tokenId) internal view returns (bool) {
    address owner = ownerOf(_tokenId);
    return _spender == owner || getApproved(_tokenId) == _spender || isApprovedForAll(owner, _spender);
  }

  /**
  * @dev Internal function to mint a new token
  * @dev Reverts if the given token ID already exists
  * @param _to The address 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 {
    require(_to != address(0));
    addTokenTo(_to, _tokenId);
    Transfer(address(0), _to, _tokenId, now);
  }

  /**
  * @dev Internal function to burn a specific token
  * @dev Reverts if the token does not exist
  * @param _tokenId uint256 ID of the token being burned by the msg.sender
  */
  function _burn(address _owner, uint256 _tokenId) internal {
    clearApproval(_owner, _tokenId);
    removeTokenFrom(_owner, _tokenId);
    Transfer(_owner, address(0), _tokenId, now);
  }

  /**
  * @dev Internal function to clear current approval of a given token ID
  * @dev Reverts if the given address is not indeed the owner of the token
  * @param _owner owner of the token
  * @param _tokenId uint256 ID of the token to be transferred
  */
  function clearApproval(address _owner, uint256 _tokenId) internal {
    require(ownerOf(_tokenId) == _owner);
    if (tokenApprovals[_tokenId] != address(0)) {
      tokenApprovals[_tokenId] = address(0);
      Approval(_owner, address(0), _tokenId);
    }
  }

  /**
  * @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 {
    require(tokenOwner[_tokenId] == address(0));
    tokenOwner[_tokenId] = _to;
    ownedTokensCount[_to] = ownedTokensCount[_to].add(1);
  }

  /**
  * @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 {
    require(ownerOf(_tokenId) == _from);
    ownedTokensCount[_from] = ownedTokensCount[_from].sub(1);
    tokenOwner[_tokenId] = address(0);
  }

  /**
  * @dev Internal function to invoke `onERC721Received` on a target address
  * @dev The call is not executed if the target address is not a contract
  * @param _from address representing the previous owner of the given token ID
  * @param _to target address that will receive the tokens
  * @param _tokenId uint256 ID of the token to be transferred
  * @param _data bytes optional data to send along with the call
  * @return whether the call correctly returned the expected magic value
  */
  function checkAndCallSafeTransfer(
    address _from,
    address _to,
    uint256 _tokenId,
    bytes _data
  )
  internal
  returns (bool)
  {
    if (!_to.isContract()) {
      return true;
    }
    bytes4 retval = ERC721Receiver(_to).onERC721Received(_from, _tokenId, _data);
    return (retval == ERC721_RECEIVED);
  }
}
          

pragma solidity ^0.4.18;


/**
 * @title ERC721 Non-Fungible Token Standard basic interface
 * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721Basic {
  event Transfer(address indexed _from, address indexed _to, uint256 _tokenId, uint256 _timestamp);
  event Approval(address indexed _owner, address indexed _approved, uint256 _tokenId);
  event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);

  function balanceOf(address _owner) public view returns (uint256 _balance);
  function ownerOf(uint256 _tokenId) public view returns (address _owner);
  function exists(uint256 _tokenId) public view returns (bool _exists);

  function approve(address _to, uint256 _tokenId) public;
  function getApproved(uint256 _tokenId) public view returns (address _operator);

  function setApprovalForAll(address _operator, bool _approved) public;
  function isApprovedForAll(address _owner, address _operator) public view returns (bool);

  function transferFrom(address _from, address _to, uint256 _tokenId) public;
  function safeTransferFrom(address _from, address _to, uint256 _tokenId) public;
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId,
    bytes _data
  )
  public;
}
          

pragma solidity ^0.4.18;

import "./ERC721Basic.sol";


/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721Enumerable is ERC721Basic {
  function totalSupply() public view returns (uint256);
  function tokenOfOwnerByIndex(address _owner, uint256 _index) public view returns (uint256 _tokenId);
  function tokenByIndex(uint256 _index) public view returns (uint256);
}


/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721Metadata is ERC721Basic {
  function name() public view returns (string _name);
  function symbol() public view returns (string _symbol);
  function tokenURI(uint256 _tokenId) public view returns (address);
}


/**
 * @title ERC-721 Non-Fungible Token Standard, full implementation interface
 * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721 is ERC721Basic, ERC721Enumerable, ERC721Metadata {
}
          

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.4.13;

contract DSAuthority {
  function canCall(
    address src, address dst, bytes4 sig
  ) public view returns (bool);
}

contract DSAuthEvents {
  event LogSetAuthority (address indexed authority);
  event LogSetOwner     (address indexed owner);
}

contract DSAuth is DSAuthEvents {
  DSAuthority  public  authority;
  address      public  owner;

  function DSAuth() public {
    owner = msg.sender;
    LogSetOwner(msg.sender);
  }

  function setOwner(address owner_)
  public
  auth
  {
    owner = owner_;
    LogSetOwner(owner);
  }

  function setAuthority(DSAuthority authority_)
  public
  auth
  {
    authority = authority_;
    LogSetAuthority(authority);
  }

  modifier auth {
    require(isAuthorized(msg.sender, msg.sig));
    _;
  }

  function isAuthorized(address src, bytes4 sig) internal view returns (bool) {
    if (src == address(this)) {
      return true;
    } else if (src == owner) {
      return true;
    } else if (authority == DSAuthority(0)) {
      return false;
    } else {
      return authority.canCall(src, this, sig);
    }
  }
}
          

pragma solidity ^0.4.18;

contract DelegateProxy {
  /**
  * @dev Performs a delegatecall and returns whatever the delegatecall returned (entire context execution will return!)
  * @param _dst Destination address to perform the delegatecall
  * @param _calldata Calldata for the delegatecall
  */
  function delegatedFwd(address _dst, bytes _calldata) internal {
    require(isContract(_dst));
    assembly {
      let result := delegatecall(sub(gas, 10000), _dst, add(_calldata, 0x20), mload(_calldata), 0, 0)
      let size := returndatasize

      let ptr := mload(0x40)
      returndatacopy(ptr, 0, size)

    // revert instead of invalid() bc if the underlying call failed with invalid() it already wasted gas.
    // if the call returned error data, forward it
      switch result case 0 {revert(ptr, size)}
      default {return (ptr, size)}
    }
  }

  function isContract(address _target) internal view returns (bool) {
    uint256 size;
    assembly {size := extcodesize(_target)}
    return size > 0;
  }
}
          

pragma solidity ^0.4.18;


/**
 * Utility library of inline functions on addresses
 */
library AddressUtils {

  /**
   * Returns whether the target address is a contract
   * @dev This function will return false if invoked during the constructor of a contract,
   *  as the code is not actually created until after the constructor finishes.
   * @param addr address to check
   * @return whether the target address is a contract
   */
  function isContract(address addr) internal view returns (bool) {
    uint256 size;
    // XXX Currently there is no better way to check if there is a contract in an address
    // than to check the size of the code at that address.
    // See https://ethereum.stackexchange.com/a/14016/36603
    // for more details about how this works.
    // TODO Check this again before the Serenity release, because all addresses will be
    // contracts then.
    assembly { size := extcodesize(addr) }  // solium-disable-line security/no-inline-assembly
    return size > 0;
  }

}