Compound Style Governance Token (TOMP) Tally Comp

TOMP

pragma solidity ^0.5.16;
    pragma experimental ABIEncoderV2;
    
    contract Comp {
        /// @notice EIP-20 token name for this token
        string public constant name = "Compound";
    
        /// @notice EIP-20 token symbol for this token
        string public constant symbol = "TOMP";
    
        /// @notice EIP-20 token decimals for this token
        uint8 public constant decimals = 18;
    
        /// @notice Total number of tokens in circulation
        uint public constant totalSupply = 10000000e18; // 10 million Comp

        /// @notice Allowance amounts on behalf of others
        mapping (address => mapping (address => uint96)) internal allowances;
    
        /// @notice Official record of token balances for each account
        mapping (address => uint96) internal balances;
    
        /// @notice A record of each accounts delegate
        mapping (address => address) public delegates;
    
        /// @notice A checkpoint for marking number of votes from a given block
        struct Checkpoint {
            uint32 fromBlock;
            uint96 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 The standard EIP-20 transfer event
        event Transfer(address indexed from, address indexed to, uint256 amount);
    
        /// @notice The standard EIP-20 approval event
        event Approval(address indexed owner, address indexed spender, uint256 amount);
    
        /**
         * @notice Construct a new TOMP token
         * @param account The initial account to grant all the tokens
         */
        constructor(address account) public {
            balances[account] = uint96(totalSupply);
            emit Transfer(address(0), account, totalSupply);
        }
    
        /**
         * @notice Get the number of tokens `spender` is approved to spend on behalf of `account`
         * @param account The address of the account holding the funds
         * @param spender The address of the account spending the funds
         * @return The number of tokens approved
         */
        function allowance(address account, address spender) external view returns (uint) {
            return allowances[account][spender];
        }
    
        /**
         * @notice Approve `spender` to transfer up to `amount` from `src`
         * @dev This will overwrite the approval amount for `spender`
         *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
         * @param spender The address of the account which may transfer tokens
         * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
         * @return Whether or not the approval succeeded
         */
        function approve(address spender, uint rawAmount) external returns (bool) {
            uint96 amount;
            if (rawAmount == uint(-1)) {
                amount = uint96(-1);
            } else {
                amount = safe96(rawAmount, "TOMP::approve: amount exceeds 96 bits");
            }
    
            allowances[msg.sender][spender] = amount;
    
            emit Approval(msg.sender, spender, amount);
            return true;
        }
    
        /**
         * @notice Get the number of tokens held by the `account`
         * @param account The address of the account to get the balance of
         * @return The number of tokens held
         */
        function balanceOf(address account) external view returns (uint) {
            return balances[account];
        }
    
        /**
         * @notice Transfer `amount` tokens from `msg.sender` to `dst`
         * @param dst The address of the destination account
         * @param rawAmount The number of tokens to transfer
         * @return Whether or not the transfer succeeded
         */
        function transfer(address dst, uint rawAmount) external returns (bool) {
            uint96 amount = safe96(rawAmount, "TOMP::transfer: amount exceeds 96 bits");
            _transferTokens(msg.sender, dst, amount);
            return true;
        }
    
        /**
         * @notice Transfer `amount` tokens from `src` to `dst`
         * @param src The address of the source account
         * @param dst The address of the destination account
         * @param rawAmount The number of tokens to transfer
         * @return Whether or not the transfer succeeded
         */
        function transferFrom(address src, address dst, uint rawAmount) external returns (bool) {
            address spender = msg.sender;
            uint96 spenderAllowance = allowances[src][spender];
            uint96 amount = safe96(rawAmount, "TOMP::approve: amount exceeds 96 bits");
    
            if (spender != src && spenderAllowance != uint96(-1)) {
                uint96 newAllowance = sub96(spenderAllowance, amount, "TOMP::transferFrom: transfer amount exceeds spender allowance");
                allowances[src][spender] = newAllowance;
    
                emit Approval(src, spender, newAllowance);
            }
    
            _transferTokens(src, dst, amount);
            return true;
        }
    
        /**
         * @notice Delegate votes from `msg.sender` to `delegatee`
         * @param delegatee The address to delegate votes to
         */
        function delegate(address delegatee) public {
            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) public {
            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("
", domainSeparator, structHash));
            address signatory = ecrecover(digest, v, r, s);
            require(signatory != address(0), "TOMP::delegateBySig: invalid signature");
            require(nonce == nonces[signatory]++, "TOMP::delegateBySig: invalid nonce");
            require(now <= expiry, "TOMP::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 (uint96) {
            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) public view returns (uint96) {
            require(blockNumber < block.number, "TOMP::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];
            uint96 delegatorBalance = balances[delegator];
            delegates[delegator] = delegatee;
    
            emit DelegateChanged(delegator, currentDelegate, delegatee);
    
            _moveDelegates(currentDelegate, delegatee, delegatorBalance);
        }
    
        function _transferTokens(address src, address dst, uint96 amount) internal {
            require(src != address(0), "TOMP::_transferTokens: cannot transfer from the zero address");
            require(dst != address(0), "TOMP::_transferTokens: cannot transfer to the zero address");
    
            balances[src] = sub96(balances[src], amount, "TOMP::_transferTokens: transfer amount exceeds balance");
            balances[dst] = add96(balances[dst], amount, "TOMP::_transferTokens: transfer amount overflows");
            emit Transfer(src, dst, amount);
    
            _moveDelegates(delegates[src], delegates[dst], amount);
        }
    
        function _moveDelegates(address srcRep, address dstRep, uint96 amount) internal {
            if (srcRep != dstRep && amount > 0) {
                if (srcRep != address(0)) {
                    uint32 srcRepNum = numCheckpoints[srcRep];
                    uint96 srcRepOld = srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0;
                    uint96 srcRepNew = sub96(srcRepOld, amount, "TOMP::_moveVotes: vote amount underflows");
                    _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
                }
    
                if (dstRep != address(0)) {
                    uint32 dstRepNum = numCheckpoints[dstRep];
                    uint96 dstRepOld = dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0;
                    uint96 dstRepNew = add96(dstRepOld, amount, "TOMP::_moveVotes: vote amount overflows");
                    _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
                }
            }
        }
    
        function _writeCheckpoint(address delegatee, uint32 nCheckpoints, uint96 oldVotes, uint96 newVotes) internal {
          uint32 blockNumber = safe32(block.number, "TOMP::_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 safe96(uint n, string memory errorMessage) internal pure returns (uint96) {
            require(n < 2**96, errorMessage);
            return uint96(n);
        }
    
        function add96(uint96 a, uint96 b, string memory errorMessage) internal pure returns (uint96) {
            uint96 c = a + b;
            require(c >= a, errorMessage);
            return c;
        }
    
        function sub96(uint96 a, uint96 b, string memory errorMessage) internal pure returns (uint96) {
            require(b <= a, errorMessage);
            return a - b;
        }
    
        function getChainId() internal pure returns (uint) {
            uint256 chainId;
            assembly { chainId := chainid() }
            return chainId;
        }
    }