/** *Submitted for verification at Etherscan.io on 2020-10-22 */ pragma solidity ^0.5.17; /** ******************************************************************** * ******************************************************************** * * ******************************************************************** */ interface IERC20 { function totalSupply() external view returns (uint); function balanceOf(address account) external view returns (uint); function transfer(address recipient, uint amount) external returns (bool); function allowance(address owner, address spender) external view returns (uint); function approve(address spender, uint amount) external returns (bool); function transferFrom(address sender, address recipient, uint amount) external returns (bool); event Transfer(address indexed from, address indexed to, uint value); event Approval(address indexed owner, address indexed spender, uint value); } contract Context { constructor () internal { } // solhint-disable-previous-line no-empty-blocks function _msgSender() internal view returns (address payable) { return msg.sender; } } contract ERC20 is Context, IERC20 { using SafeMath for uint; mapping (address => uint) private _balances; mapping (address => mapping (address => uint)) private _allowances; uint private _totalSupply; function totalSupply() public view returns (uint) { return _totalSupply; } function balanceOf(address account) public view returns (uint) { return _balances[account]; } function transfer(address recipient, uint amount) public returns (bool) { _transfer(_msgSender(), recipient, amount); return true; } function allowance(address owner, address spender) public view returns (uint) { return _allowances[owner][spender]; } function approve(address spender, uint amount) public returns (bool) { _approve(_msgSender(), spender, amount); return true; } function transferFrom(address sender, address recipient, uint amount) public returns (bool) { _transfer(sender, recipient, amount); _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance")); return true; } function increaseAllowance(address spender, uint addedValue) public returns (bool) { _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue)); return true; } function decreaseAllowance(address spender, uint subtractedValue) public returns (bool) { _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero")); return true; } function _transfer(address sender, address recipient, uint amount) internal { require(sender != address(0), "ERC20: transfer from the zero address"); require(recipient != address(0), "ERC20: transfer to the zero address"); _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance"); _balances[recipient] = _balances[recipient].add(amount); emit Transfer(sender, recipient, amount); } function _mint(address account, uint amount) internal { require(account != address(0), "ERC20: mint to the zero address"); _totalSupply = _totalSupply.add(amount); _balances[account] = _balances[account].add(amount); emit Transfer(address(0), account, amount); } function _burn(address account, uint amount) internal { require(account != address(0), "ERC20: burn from the zero address"); _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance"); _totalSupply = _totalSupply.sub(amount); emit Transfer(account, address(0), amount); } function _approve(address owner, address spender, uint amount) internal { 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); } } contract ERC20Detailed is IERC20 { string private _name; string private _symbol; uint8 private _decimals; constructor (string memory name, string memory symbol, uint8 decimals) public { _name = name; _symbol = symbol; _decimals = decimals; } function name() public view returns (string memory) { return _name; } function symbol() public view returns (string memory) { return _symbol; } function decimals() public view returns (uint8) { return _decimals; } } library SafeMath { function add(uint a, uint b) internal pure returns (uint) { uint c = a + b; require(c >= a, "SafeMath: addition overflow"); return c; } function sub(uint a, uint b) internal pure returns (uint) { return sub(a, b, "SafeMath: subtraction overflow"); } function sub(uint a, uint b, string memory errorMessage) internal pure returns (uint) { require(b <= a, errorMessage); uint c = a - b; return c; } function mul(uint a, uint b) internal pure returns (uint) { if (a == 0) { return 0; } uint c = a * b; require(c / a == b, "SafeMath: multiplication overflow"); return c; } function div(uint a, uint b) internal pure returns (uint) { return div(a, b, "SafeMath: division by zero"); } function div(uint a, uint b, string memory errorMessage) internal pure returns (uint) { // Solidity only automatically asserts when dividing by 0 require(b > 0, errorMessage); uint c = a / b; return c; } } library Address { function isContract(address account) internal view returns (bool) { bytes32 codehash; bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470; // solhint-disable-next-line no-inline-assembly assembly { codehash := extcodehash(account) } return (codehash != 0x0 && codehash != accountHash); } } library SafeERC20 { using SafeMath for uint; using Address for address; function safeTransfer(IERC20 token, address to, uint value) internal { callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value)); } function safeTransferFrom(IERC20 token, address from, address to, uint value) internal { callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value)); } function safeApprove(IERC20 token, address spender, uint value) internal { require((value == 0) || (token.allowance(address(this), spender) == 0), "SafeERC20: approve from non-zero to non-zero allowance" ); callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value)); } function callOptionalReturn(IERC20 token, bytes memory data) private { require(address(token).isContract(), "SafeERC20: call to non-contract"); // solhint-disable-next-line avoid-low-level-calls (bool success, bytes memory returndata) = address(token).call(data); require(success, "SafeERC20: low-level call failed"); if (returndata.length > 0) { // Return data is optional // solhint-disable-next-line max-line-length require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed"); } } } contract Xearn is ERC20, ERC20Detailed { using SafeERC20 for IERC20; using Address for address; using SafeMath for uint; address public governance; mapping (address => bool) public minters; constructor () public ERC20Detailed("xEarn Capital", "XRN", 18) { governance = tx.origin; } function mint(address account, uint256 amount) public { require(minters[msg.sender], "!minter"); _mint(account, amount); } function burn(address account, uint256 amount) public { require(minters[msg.sender], "!minter"); _burn(account, amount); } function setGovernance(address _governance) public { require(msg.sender == governance, "!governance"); governance = _governance; } function addMinter(address _minter) public { require(msg.sender == governance, "!governance"); minters[_minter] = true; } function removeMinter(address _minter) public { require(msg.sender == governance, "!governance"); minters[_minter] = false; } }