// SPDX-License-Identifier: MIT
// Factory: CreateMyToken
// Library: OpenZeppelin Contracts
pragma solidity ^0.8.24;
import "./interfaces/IERC20Metadata.sol";
import "./Initializable.sol";
contract ERC20 is Initializable, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
uint256 private _maxSupply;
string private _name;
string private _symbol;
uint8 private _decimals;
function init(
string memory name_,
string memory symbol_,
uint8 decimals_,
uint256 maxSupply_
) internal onlyInitializing {
_name = name_;
_symbol = symbol_;
_decimals = decimals_;
_maxSupply = maxSupply_;
}
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 _decimals;
}
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
function maxSupply() public view virtual returns (uint256) {
return _maxSupply;
}
function balanceOf(address account) public view virtual override returns
(uint256) {
return _balances[account];
}
function transfer(address to, uint256 amount) public virtual override returns
(bool) {
_transfer(msg.sender, to, 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(msg.sender, spender, amount);
return true;
}
function transferFrom(address from, address to, uint256 amount) public virtual
override returns (bool) {
_spendAllowance(from, msg.sender, amount);
_transfer(from, to, amount);
return true;
}
function increaseAllowance(address spender, uint256 addedValue) public virtual
returns (bool) {
address owner = msg.sender;
_approve(owner, spender, allowance(owner, spender) + addedValue);
return true;
}
function decreaseAllowance(address spender, uint256 subtractedValue) public
virtual returns (bool) {
address owner = msg.sender;
uint256 currentAllowance = allowance(owner, spender);
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance
below zero");
unchecked {
_approve(owner, spender, currentAllowance - subtractedValue);
}
return true;
}
function burn(uint256 amount) public virtual {
_burn(msg.sender, amount);
}
function burnFrom(address account, uint256 amount) public virtual {
_spendAllowance(account, msg.sender, amount);
_burn(account, amount);
}
function _transfer(address from, address to, uint256 amount) internal virtual {
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(from, to, amount);
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
// Overflow not possible: the sum of all balances is capped by
totalSupply, and the sum is preserved by
// decrementing then incrementing.
_balances[to] += amount;
}
emit Transfer(from, to, amount);
_afterTokenTransfer(from, to, amount);
}
function _mint(address account, uint256 amount) internal virtual {
require(_totalSupply + amount <= _maxSupply, "ERC20: cap exceeded");
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
unchecked {
// Overflow not possible: balance + amount is at most totalSupply +
amount, which is checked above.
_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;
// Overflow not possible: amount <= accountBalance <= totalSupply.
_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 _spendAllowance(address owner, address spender, uint256 amount)
internal virtual {
uint256 currentAllowance = allowance(owner, spender);
if (currentAllowance != type(uint256).max) {
require(currentAllowance >= amount, "ERC20: insufficient allowance");
unchecked {
_approve(owner, spender, currentAllowance - amount);
}
}
}
function _beforeTokenTransfer(address from, address to, uint256 amount)
internal virtual {}
function _afterTokenTransfer(address from, address to, uint256 amount) internal
virtual {}
}
