data/static/web3-snippets/BEEToken.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
contract BeeToken is IERC20 {
using SafeMath for uint256;
string public constant name = "BeeToken";
string public constant symbol = "BEE";
uint8 public constant decimals = 18;
uint256 private constant _initialSupply = 1000000000 * (10**uint256(decimals));
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
address private _owner;
constructor() {
_owner = msg.sender;
_mint(_owner, _initialSupply);
}
modifier onlyOwner() {
require(msg.sender == _owner, "Only the contract owner can call this function");
_;
}
function totalSupply() external view override returns (uint256) {
return _totalSupply;
}
function balanceOf(address account) external view override returns (uint256) {
return _balances[account];
}
function transfer(address recipient, uint256 amount) external override returns (bool) {
_transfer(msg.sender, recipient, amount);
return true;
}
function allowance(address owner, address spender) external view override returns (uint256) {
return _allowances[owner][spender];
}
function approve(address spender, uint256 amount) external override returns (bool) {
_approve(msg.sender, spender, amount);
return true;
}
function transferFrom(address sender, address recipient, uint256 amount) external override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, msg.sender, _allowances[sender][msg.sender].sub(amount, "ERC20: transfer amount exceeds allowance"));
return true;
}
function increaseAllowance(address spender, uint256 addedValue) external returns (bool) {
_approve(msg.sender, spender, _allowances[msg.sender][spender].add(addedValue));
return true;
}
function mintTokens(address recipient, uint256 amount) external onlyOwner {
_mint(recipient, amount);
}
function decreaseAllowance(address spender, uint256 subtractedValue) external returns (bool) {
_approve(msg.sender, spender, _allowances[msg.sender][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
return true;
}
function _mint(address account, uint256 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, uint256 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, uint256 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);
}
function _transfer(address sender, address recipient, uint256 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);
}
}