Contract Source Code:
File 1 of 1 : CrowToken
pragma solidity >=0.6.0 <=0.8.4;
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function transfer(address recipient, uint256 amount) external returns (bool);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(
address sender,
address recipient,
uint256 amount
) external returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
interface IERC20Metadata is IERC20 {
function name() external view returns (string memory);
function symbol() external view returns (string memory);
function decimals() external view returns (uint8);
}
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
contract ERC20 is Context, IERC20, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
function name() public view virtual override returns (string memory) {
return _name;
}
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
function decimals() public view virtual override returns (uint8) {
return 18;
}
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
}
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
function transferFrom(
address sender,
address recipient,
uint256 amount
) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
uint256 currentAllowance = _allowances[sender][_msgSender()];
require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
unchecked {
_approve(sender, _msgSender(), currentAllowance - amount);
}
return true;
}
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
return true;
}
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
uint256 currentAllowance = _allowances[_msgSender()][spender];
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(_msgSender(), spender, currentAllowance - subtractedValue);
}
return true;
}
function _transfer(
address sender,
address recipient,
uint256 amount
) internal virtual {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(sender, recipient, amount);
uint256 senderBalance = _balances[sender];
require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[sender] = senderBalance - amount;
}
_balances[recipient] += amount;
emit Transfer(sender, recipient, amount);
_afterTokenTransfer(sender, recipient, amount);
}
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
_balances[account] += amount;
emit Transfer(address(0), account, amount);
_afterTokenTransfer(address(0), account, amount);
}
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
}
_totalSupply -= amount;
emit Transfer(account, address(0), amount);
_afterTokenTransfer(account, address(0), amount);
}
function _approve(
address owner,
address spender,
uint256 amount
) internal virtual {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
function _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
constructor() {
_transferOwnership(_msgSender());
}
function owner() public view virtual returns (address) {
return _owner;
}
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
}
function renounceOwnership() public virtual onlyOwner {
_transferOwnership(address(0));
}
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_transferOwnership(newOwner);
}
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
library SafeMath {
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
}
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b > a) return (false, 0);
return (true, a - b);
}
}
function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (a == 0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
}
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a / b);
}
}
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a % b);
}
}
function add(uint256 a, uint256 b) internal pure returns (uint256) {
return a + b;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return a - b;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
return a * b;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return a / b;
}
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return a % b;
}
function sub(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b <= a, errorMessage);
return a - b;
}
}
function div(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a / b;
}
}
function mod(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a % b;
}
}
}
contract CrowToken is ERC20('Crow Token', 'CROW'), Ownable {
using SafeMath for uint256;
function mint(address _to, uint256 _amount) public onlyOwner {
_mint(_to, _amount);
_moveDelegates(address(0), _delegates[_to], _amount);
}
mapping (address => address) internal _delegates;
struct Checkpoint {
uint32 fromBlock;
uint256 votes;
}
mapping (address => mapping (uint32 => Checkpoint)) public checkpoints;
mapping (address => uint32) public numCheckpoints;
bytes32 public constant DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)");
bytes32 public constant DELEGATION_TYPEHASH = keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");
mapping (address => uint) public nonces;
event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate);
event DelegateVotesChanged(address indexed delegate, uint previousBalance, uint newBalance);
function delegates(address delegator)
external
view
returns (address)
{
return _delegates[delegator];
}
function delegate(address delegatee) external {
return _delegate(msg.sender, delegatee);
}
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())),
block.chainid,
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), "CROW::delegateBySig: invalid signature");
require(nonce == nonces[signatory]++, "CROW::delegateBySig: invalid nonce");
require(block.timestamp <= expiry, "CROW::delegateBySig: signature expired");
return _delegate(signatory, delegatee);
}
function getCurrentVotes(address account)
external
view
returns (uint256)
{
uint32 nCheckpoints = numCheckpoints[account];
return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
}
function getPriorVotes(address account, uint blockNumber)
external
view
returns (uint256)
{
require(blockNumber < block.number, "CROW::getPriorVotes: not yet determined");
uint32 nCheckpoints = numCheckpoints[account];
if (nCheckpoints == 0) {
return 0;
}
if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
return checkpoints[account][nCheckpoints - 1].votes;
}
if (checkpoints[account][0].fromBlock > blockNumber) {
return 0;
}
uint32 lower = 0;
uint32 upper = nCheckpoints - 1;
while (upper > lower) {
uint32 center = upper - (upper - lower) / 2;
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)) {
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)) {
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, "CROW::_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);
}
}