openzeppelin-contracts/contracts/access/roles/MinterRole.sol

pragma solidity ^0.5.2;

import "@openzeppelin/upgrades/contracts/Initializable.sol";
import "../Roles.sol";


contract MinterRole is Initializable {
    using Roles for Roles.Role;

    event MinterAdded(address indexed account);
    event MinterRemoved(address indexed account);

    Roles.Role private _minters;

    function initialize(address sender) public initializer {
        if (!isMinter(sender)) {
            _addMinter(sender);
        }
    }

    modifier onlyMinter() {
        require(isMinter(msg.sender));
        _;
    }

    function isMinter(address account) public view returns (bool) {
        return _minters.has(account);
    }

    function addMinter(address account) public onlyMinter {
        _addMinter(account);
    }

    function renounceMinter() public {
        _removeMinter(msg.sender);
    }

    function _addMinter(address account) internal {
        _minters.add(account);
        emit MinterAdded(account);
    }

    function _removeMinter(address account) internal {
        _minters.remove(account);
        emit MinterRemoved(account);
    }

    uint256[50] private ______gap;
}