pragma solidity 0.6.12; import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; import "@openzeppelin/contracts/access/Ownable.sol"; // DioneToken with Governance. contract DioneToken is ERC20("DioneToken", "DIONE"), Ownable { /// @notice Creates `_amount` token to `_to`. Must only be called by the owner (MasterChef). function mint(address _to, uint256 _amount) public onlyOwner { _mint(_to, _amount); _moveDelegates(address(0), _delegates[_to], _amount); } // Copied and modified from YAM code: // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernanceStorage.sol // https://github.com/yam-finance/yam-protocol/blob/master/contracts/token/YAMGovernance.sol // Which is copied and modified from COMPOUND: // https://github.com/compound-finance/compound-protocol/blob/master/contracts/Governance/Comp.sol /// @notice A record of each accounts delegate mapping (address => address) internal _delegates; /// @notice A checkpoint for marking number of votes from a given block struct Checkpoint { uint32 fromBlock; uint256 votes; } /// @notice A record of votes checkpoints for each account, by index mapping (address => mapping (uint32 => Checkpoint)) public checkpoints; /// @notice The number of checkpoints for each account mapping (address => uint32) public numCheckpoints; /// @notice The EIP-712 typehash for the contract's domain bytes32 public constant DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)"); /// @notice The EIP-712 typehash for the delegation struct used by the contract bytes32 public constant DELEGATION_TYPEHASH = keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)"); /// @notice A record of states for signing / validating signatures mapping (address => uint) public nonces; /// @notice An event thats emitted when an account changes its delegate event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate); /// @notice An event thats emitted when a delegate account's vote balance changes event DelegateVotesChanged(address indexed delegate, uint previousBalance, uint newBalance); /** * @notice Delegate votes from `msg.sender` to `delegatee` * @param delegator The address to get delegatee for */ function delegates(address delegator) external view returns (address) { return _delegates[delegator]; } /** * @notice Delegate votes from `msg.sender` to `delegatee` * @param delegatee The address to delegate votes to */ function delegate(address delegatee) external { return _delegate(msg.sender, delegatee); } /** * @notice Delegates votes from signatory to `delegatee` * @param delegatee The address to delegate votes to * @param nonce The contract state required to match the signature * @param expiry The time at which to expire the signature * @param v The recovery byte of the signature * @param r Half of the ECDSA signature pair * @param s Half of the ECDSA signature pair */ function delegateBySig( address delegatee, uint nonce, uint expiry, uint8 v, bytes32 r, bytes32 s ) external { bytes32 domainSeparator = keccak256( abi.encode( DOMAIN_TYPEHASH, keccak256(bytes(name())), getChainId(), address(this) ) ); bytes32 structHash = keccak256( abi.encode( DELEGATION_TYPEHASH, delegatee, nonce, expiry ) ); bytes32 digest = keccak256( abi.encodePacked( "\x19\x01", domainSeparator, structHash ) ); address signatory = ecrecover(digest, v, r, s); require(signatory != address(0), "DIONE::delegateBySig: invalid signature"); require(nonce == nonces[signatory]++, "DIONE::delegateBySig: invalid nonce"); require(now <= expiry, "DIONE::delegateBySig: signature expired"); return _delegate(signatory, delegatee); } /** * @notice Gets the current votes balance for `account` * @param account The address to get votes balance * @return The number of current votes for `account` */ function getCurrentVotes(address account) external view returns (uint256) { uint32 nCheckpoints = numCheckpoints[account]; return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0; } /** * @notice Determine the prior number of votes for an account as of a block number * @dev Block number must be a finalized block or else this function will revert to prevent misinformation. * @param account The address of the account to check * @param blockNumber The block number to get the vote balance at * @return The number of votes the account had as of the given block */ function getPriorVotes(address account, uint blockNumber) external view returns (uint256) { require(blockNumber < block.number, "DIONE::getPriorVotes: not yet determined"); uint32 nCheckpoints = numCheckpoints[account]; if (nCheckpoints == 0) { return 0; } // First check most recent balance if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) { return checkpoints[account][nCheckpoints - 1].votes; } // Next check implicit zero balance if (checkpoints[account][0].fromBlock > blockNumber) { return 0; } uint32 lower = 0; uint32 upper = nCheckpoints - 1; while (upper > lower) { uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow Checkpoint memory cp = checkpoints[account][center]; if (cp.fromBlock == blockNumber) { return cp.votes; } else if (cp.fromBlock < blockNumber) { lower = center; } else { upper = center - 1; } } return checkpoints[account][lower].votes; } function _delegate(address delegator, address delegatee) internal { address currentDelegate = _delegates[delegator]; uint256 delegatorBalance = balanceOf(delegator); _delegates[delegator] = delegatee; emit DelegateChanged(delegator, currentDelegate, delegatee); _moveDelegates(currentDelegate, delegatee, delegatorBalance); } function _moveDelegates(address srcRep, address dstRep, uint256 amount) internal { if (srcRep != dstRep && amount > 0) { if (srcRep != address(0)) { // decrease old representative uint32 srcRepNum = numCheckpoints[srcRep]; uint256 srcRepOld = srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0; uint256 srcRepNew = srcRepOld.sub(amount); _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew); } if (dstRep != address(0)) { // increase new representative uint32 dstRepNum = numCheckpoints[dstRep]; uint256 dstRepOld = dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0; uint256 dstRepNew = dstRepOld.add(amount); _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew); } } } function _writeCheckpoint( address delegatee, uint32 nCheckpoints, uint256 oldVotes, uint256 newVotes ) internal { uint32 blockNumber = safe32(block.number, "DIONE::_writeCheckpoint: block number exceeds 32 bits"); if (nCheckpoints > 0 && checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber) { checkpoints[delegatee][nCheckpoints - 1].votes = newVotes; } else { checkpoints[delegatee][nCheckpoints] = Checkpoint(blockNumber, newVotes); numCheckpoints[delegatee] = nCheckpoints + 1; } emit DelegateVotesChanged(delegatee, oldVotes, newVotes); } function safe32(uint n, string memory errorMessage) internal pure returns (uint32) { require(n < 2**32, errorMessage); return uint32(n); } function getChainId() internal pure returns (uint) { uint256 chainId; assembly { chainId := chainid() } return chainId; } }