Contract Name:
BurnableMintableCappedERC20
Contract Source Code:
File 1 of 1 : BurnableMintableCappedERC20
// SPDX-License-Identifier: MIT
pragma solidity >=0.8.0 <0.9.0;
abstract contract Ownable {
address public owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
constructor() {
owner = msg.sender;
emit OwnershipTransferred(address(0), msg.sender);
}
modifier onlyOwner() {
require(owner == msg.sender, 'NOT_OWNER');
_;
}
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), 'ZERO_ADDR');
emit OwnershipTransferred(owner, newOwner);
owner = newOwner;
}
}
/**
* @title EternalStorage
* @dev This contract holds all the necessary state variables to carry out the storage of any contract.
*/
contract EternalStorage {
mapping(bytes32 => uint256) private _uintStorage;
mapping(bytes32 => string) private _stringStorage;
mapping(bytes32 => address) private _addressStorage;
mapping(bytes32 => bytes) private _bytesStorage;
mapping(bytes32 => bool) private _boolStorage;
mapping(bytes32 => int256) private _intStorage;
// *** Getter Methods ***
function getUint(bytes32 key) public view returns (uint256) {
return _uintStorage[key];
}
function getString(bytes32 key) public view returns (string memory) {
return _stringStorage[key];
}
function getAddress(bytes32 key) public view returns (address) {
return _addressStorage[key];
}
function getBytes(bytes32 key) public view returns (bytes memory) {
return _bytesStorage[key];
}
function getBool(bytes32 key) public view returns (bool) {
return _boolStorage[key];
}
function getInt(bytes32 key) public view returns (int256) {
return _intStorage[key];
}
// *** Setter Methods ***
function _setUint(bytes32 key, uint256 value) internal {
_uintStorage[key] = value;
}
function _setString(bytes32 key, string memory value) internal {
_stringStorage[key] = value;
}
function _setAddress(bytes32 key, address value) internal {
_addressStorage[key] = value;
}
function _setBytes(bytes32 key, bytes memory value) internal {
_bytesStorage[key] = value;
}
function _setBool(bytes32 key, bool value) internal {
_boolStorage[key] = value;
}
function _setInt(bytes32 key, int256 value) internal {
_intStorage[key] = value;
}
// *** Delete Methods ***
function _deleteUint(bytes32 key) internal {
delete _uintStorage[key];
}
function _deleteString(bytes32 key) internal {
delete _stringStorage[key];
}
function _deleteAddress(bytes32 key) internal {
delete _addressStorage[key];
}
function _deleteBytes(bytes32 key) internal {
delete _bytesStorage[key];
}
function _deleteBool(bytes32 key) internal {
delete _boolStorage[key];
}
function _deleteInt(bytes32 key) internal {
delete _intStorage[key];
}
}
contract Burner {
constructor(address tokenAddress, bytes32 salt) {
BurnableMintableCappedERC20(tokenAddress).burn(salt);
selfdestruct(payable(address(0)));
}
}
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with GSN meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address payable) {
return payable(msg.sender);
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
/**
* @dev Implementation of the {IERC20} interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* We have followed general OpenZeppelin guidelines: functions revert instead
* of returning `false` on failure. This behavior is nonetheless conventional
* and does not conflict with the expectations of ERC20 applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract ERC20 is Context, IERC20 {
mapping(address => uint256) public override balanceOf;
mapping(address => mapping(address => uint256)) public override allowance;
uint256 public override totalSupply;
string public name;
string public symbol;
uint8 public immutable decimals;
/**
* @dev Sets the values for {name}, {symbol}, and {decimals}.
*
* All three of these values are immutable: they can only be set once during
* construction.
*/
constructor(
string memory name_,
string memory symbol_,
uint8 decimals_
) {
name = name_;
symbol = symbol_;
decimals = decimals_;
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
*
* Requirements:
*
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - the caller must have allowance for ``sender``'s tokens of at least
* `amount`.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), allowance[sender][_msgSender()] - amount);
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, allowance[_msgSender()][spender] + addedValue);
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, allowance[_msgSender()][spender] - subtractedValue);
return true;
}
/**
* @dev Moves tokens `amount` from `sender` to `recipient`.
*
* This is internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
*/
function _transfer(
address sender,
address recipient,
uint256 amount
) internal virtual {
require(sender != address(0), 'ZERO_ADDR');
require(recipient != address(0), 'ZERO_ADDR');
_beforeTokenTransfer(sender, recipient, amount);
balanceOf[sender] -= amount;
balanceOf[recipient] += amount;
emit Transfer(sender, recipient, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `to` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), 'ZERO_ADDR');
_beforeTokenTransfer(address(0), account, amount);
totalSupply += amount;
balanceOf[account] += amount;
emit Transfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), 'ZERO_ADDR');
_beforeTokenTransfer(account, address(0), amount);
balanceOf[account] -= amount;
totalSupply -= amount;
emit Transfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
*
* This internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(
address owner,
address spender,
uint256 amount
) internal virtual {
require(owner != address(0), 'ZERO_ADDR');
require(spender != address(0), 'ZERO_ADDR');
allowance[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be to transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}
contract BurnableMintableCappedERC20 is ERC20, Ownable {
uint256 public cap;
bytes32 private constant PREFIX_TOKEN_FROZEN = keccak256('token-frozen');
bytes32 private constant KEY_ALL_TOKENS_FROZEN = keccak256('all-tokens-frozen');
event Frozen(address indexed owner);
event Unfrozen(address indexed owner);
constructor(
string memory name,
string memory symbol,
uint8 decimals,
uint256 capacity
) ERC20(name, symbol, decimals) Ownable() {
cap = capacity;
}
function depositAddress(bytes32 salt) public view returns (address) {
// This would be easier, cheaper, simpler, and result in globally consistent deposit addresses for any salt (all chains, all tokens).
// return address(uint160(uint256(keccak256(abi.encodePacked(bytes32(0x000000000000000000000000000000000000000000000000000000000000dead), salt)))));
/* Convert a hash which is bytes32 to an address which is 20-byte long
according to https://docs.soliditylang.org/en/v0.8.1/control-structures.html?highlight=create2#salted-contract-creations-create2 */
return
address(
uint160(
uint256(
keccak256(
abi.encodePacked(
bytes1(0xff),
owner,
salt,
keccak256(abi.encodePacked(type(Burner).creationCode, abi.encode(address(this)), salt))
)
)
)
)
);
}
function mint(address account, uint256 amount) public onlyOwner {
uint256 capacity = cap;
require(capacity == 0 || totalSupply + amount <= capacity, 'CAP_EXCEEDED');
_mint(account, amount);
}
function burn(bytes32 salt) public onlyOwner {
address account = depositAddress(salt);
_burn(account, balanceOf[account]);
}
function _beforeTokenTransfer(
address,
address,
uint256
) internal view override {
require(!EternalStorage(owner).getBool(KEY_ALL_TOKENS_FROZEN), 'IS_FROZEN');
require(!EternalStorage(owner).getBool(keccak256(abi.encodePacked(PREFIX_TOKEN_FROZEN, symbol))), 'IS_FROZEN');
}
}