Contract Name:
StakingPoolAirdrop
Contract Source Code:
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "./TokenERC20.sol";
import "./StakingPoolFactory.sol";
import "./RewardManager.sol";
contract StakingPoolAirdrop is Context, Ownable, ReentrancyGuard {
mapping (address => uint256) private stakes;
mapping (address => uint256) private stakeTimes;
uint256 public stakedTotal;
uint256 public maturityDays;
uint256 public launchTime;
uint256 public closingTime;
uint256 public poolSize;
uint256 public poolApy;
uint256 public minStakeAmount;
uint256 public totalSupply;
uint256 public lands_reward;
TokenERC20 public tokenERC20;
StakingPoolFactory public poolFactory;
RewardManager public rewardManager;
uint256 interval = 86400;
event Staked(address indexed _staker, uint256 _requestedAmount, uint256 _stakedAmount);
event PaidOut(address indexed _staker, uint256 _reward);
event Refunded(address indexed _staker, uint256 _amount);
constructor (
TokenERC20 _tokenERC20,
StakingPoolFactory _poolFactory,
RewardManager _rewardManager,
uint256 _maturityDays,
uint256 _launchTime,
uint256 _closingTime,
uint256 _poolSize,
uint256 _poolApy,
uint256 _minStakeAmount,
uint256 _totalSupply,
uint256 _landsReward
) {
tokenERC20 = _tokenERC20;
poolFactory = _poolFactory;
rewardManager = _rewardManager;
require(_maturityDays > 0, "Staking Pool: zero maturity days");
maturityDays = _maturityDays;
require(_launchTime > 0, "Staking Pool: zero staking start time");
if (_launchTime < block.timestamp) {
launchTime = block.timestamp;
} else {
launchTime = _launchTime;
}
require(_closingTime > _launchTime, "Staking Pool: closing time must be after launch time");
closingTime = _closingTime;
require(_poolSize > 0, "Staking Pool: pool size must be positive");
poolSize = _poolSize;
require(_poolApy >= 0, "Staking Pool: pool apy must be positive");
poolApy = _poolApy;
require(_minStakeAmount > 0, "Staking Pool: stake must be positive");
minStakeAmount = _minStakeAmount;
require(_totalSupply > 0, "Staking Pool: amount of supplied NFTs must be positive");
totalSupply = _totalSupply;
require(_landsReward > 0, "Staking Pool: amount of reward must be positive");
lands_reward = _landsReward;
}
function stakeOf(address account) external view returns (uint256) {
return stakes[account];
}
function stakeTimeOf(address account) external view returns (uint256) {
return stakeTimes[account];
}
function getRewards(address account) external view returns (uint256) {
if (block.timestamp > stakeTimes[account] + (maturityDays * interval)) {
return stakes[account] * poolApy * maturityDays / 36000;
}
return 0;
}
function changeMinStakeAmount(uint256 amount) public onlyOwner
{
minStakeAmount = amount;
}
function stake(uint256 amount)
external
_positive(amount)
_realAddress(_msgSender())
_after(launchTime)
_before(closingTime)
_hasAllowance(_msgSender(), amount)
returns (bool)
{
address staker = _msgSender();
uint256 remaining = amount;
if (remaining > (poolSize - stakedTotal)) {
remaining = poolSize - stakedTotal;
}
// These requires are not necessary, because it will never happen, but won't hurt to double check
// this is because stakedTotal is only modified in this method during the staking period
require(amount >= minStakeAmount, "Staking Pool: Staking amount is too low");
require(remaining > 0, "Staking Pool: Pool is filled");
require((remaining + stakedTotal) <= poolSize, "Staking Pool: this will increase staking amount pass the cap");
require((totalSupply - lands_reward) >= 0, "Staking Pool: no more NFTs left");
if (!_payMe(staker, remaining)) {
return false;
}
emit Staked(staker, amount, remaining);
if (remaining < amount) {
// Return the unstaked amount to sender (from allowance)
uint256 refund = amount - remaining;
if (_payTo(staker, staker, refund)) {
emit Refunded(staker, refund);
}
}
// Transfer is completed
stakedTotal = stakedTotal + remaining;
stakes[staker] = stakes[staker] + remaining;
stakeTimes[staker] = block.timestamp;
totalSupply = totalSupply - lands_reward;
return true;
}
function withdraw()
external
nonReentrant
_realAddress(_msgSender())
{
address staker = _msgSender();
require(stakes[staker] > 0, "Zero staked tokens");
uint256 amount = stakes[staker];
require(block.timestamp > stakeTimes[staker] + (maturityDays * interval));
uint256 reward = amount * poolApy * maturityDays / 36000;
_payDirect(staker, amount);
rewardManager.rewardUser(staker, reward);
PaidOut(staker, reward);
stakes[staker] = 0;
}
function _payMe(address payer, uint256 amount)
private
returns (bool)
{
return _payTo(payer, address(this), amount);
}
function _payTo(address allower, address receiver, uint256 amount)
_hasAllowance(allower, amount)
private
returns (bool)
{
// Request to transfer amount from the contract to receiver.
// contract does not own the funds, so the allower must have added allowance to the contract
// Allower is the original owner.
return tokenERC20.transferFrom(allower, receiver, amount);
}
function _payDirect(address to, uint256 amount)
private
_positive(amount)
returns (bool)
{
return tokenERC20.transfer(to, amount);
}
modifier _realAddress(address addr) {
require(addr != address(0), "Staking Pool: zero address");
_;
}
modifier _positive(uint256 amount) {
require(amount >= 0, "Staking Pool: negative amount");
_;
}
modifier _after(uint eventTime) {
require(block.timestamp >= eventTime, "Staking Pool: bad timing for the request");
_;
}
modifier _before(uint eventTime) {
require(block.timestamp < eventTime, "Staking Pool: bad timing for the request");
_;
}
modifier _hasAllowance(address allower, uint256 amount) {
// Make sure the allower has provided the right allowance.
uint256 ourAllowance = tokenERC20.allowance(allower, address(this));
require(amount <= ourAllowance, "Staking Pool: Make sure to add enough allowance");
_;
}
}
// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract TokenERC20 is ERC20('Mars Token', 'Mars') {
constructor () {
_mint(msg.sender, 93777508090614882400000000);
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
import "./TokenERC20.sol";
import "./PoolCreator.sol";
import "./StakingPoolAirdrop.sol";
import "./RewardManager.sol";
contract StakingPoolFactory is PoolCreator {
TokenERC20 public tokenERC20;
RewardManager public rewardManager;
event PoolCreated(
address indexed pool,
uint256 maturityDays,
uint256 launchTime,
uint256 poolSize,
uint256 poolApy
);
constructor(TokenERC20 _tokenERC20, RewardManager _rewardManager) {
tokenERC20 = _tokenERC20;
rewardManager = _rewardManager;
}
function create(
uint256 maturityDays,
uint256 launchTime,
uint256 closingTime,
uint256 poolSize,
uint256 poolApy,
uint256 minStake,
uint256 totalSupply,
uint256 nftRewardUnits
) public onlyPoolCreator returns (address) {
address newPool =
address(
new StakingPoolAirdrop(
tokenERC20,
this,
rewardManager,
maturityDays,
launchTime,
closingTime,
poolSize,
poolApy,
minStake,
totalSupply,
nftRewardUnits
)
);
emit PoolCreated(newPool, maturityDays, launchTime, poolSize, poolApy);
rewardManager.addPool(newPool);
return newPool;
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
/**
* @title Roles
* @dev Library for managing addresses assigned to a Role.
*/
library Roles {
struct Role {
mapping(address => bool) bearer;
}
/**
* @dev Give an account access to this role.
*/
function add(Role storage role, address account) internal {
require(!has(role, account), "Roles: account already has role");
role.bearer[account] = true;
}
/**
* @dev Remove an account's access to this role.
*/
function remove(Role storage role, address account) internal {
require(has(role, account), "Roles: account does not have role");
role.bearer[account] = false;
}
/**
* @dev Check if an account has this role.
* @return bool
*/
function has(Role storage role, address account)
internal
view
returns (bool)
{
require(account != address(0), "Roles: account is the zero address");
return role.bearer[account];
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
import "@openzeppelin/contracts/utils/Context.sol";
import "./Roles.sol";
contract Rewarder is Context {
using Roles for Roles.Role;
event RewarderAdded(address indexed account);
event RewarderRemoved(address indexed account);
Roles.Role private _rewarders;
constructor() {
if (!isRewarder(_msgSender())) {
_addRewarder(_msgSender());
}
}
modifier onlyRewarder() {
require(
isRewarder(_msgSender()),
"RewarderRole: caller does not have the Rewarder role"
);
_;
}
function isRewarder(address account) public view returns (bool) {
return _rewarders.has(account);
}
function addRewarder(address account) public onlyRewarder {
_addRewarder(account);
}
function renounceRewarder() public {
_removeRewarder(_msgSender());
}
function _addRewarder(address account) internal {
_rewarders.add(account);
emit RewarderAdded(account);
}
function _removeRewarder(address account) internal {
_rewarders.remove(account);
emit RewarderRemoved(account);
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "./TokenERC20.sol";
import "./Operator.sol";
import "./Rewarder.sol";
contract RewardManager is Context, Ownable, Operator, Rewarder {
TokenERC20 tokenERC20;
address operator;
constructor(TokenERC20 _tokenERC20) {
tokenERC20 = _tokenERC20;
}
function setOperator(address _newOperator) public onlyOwner {
require(_newOperator != address(0));
addOperator(_newOperator);
}
function addPool(address _poolAddress) public onlyOperator {
require(_poolAddress != address(0));
addRewarder(_poolAddress);
}
function rewardUser(address _user, uint256 _amount) public onlyRewarder {
require(_user != address(0));
tokenERC20.transfer(_user, _amount);
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
import "@openzeppelin/contracts/utils/Context.sol";
import "./Roles.sol";
contract PoolCreator is Context {
using Roles for Roles.Role;
event PoolCreatorAdded(address indexed account);
event PoolCreatorRemoved(address indexed account);
Roles.Role private _poolCreators;
constructor() {
if (!isPoolCreator(_msgSender())) {
_addPoolCreator(_msgSender());
}
}
modifier onlyPoolCreator() {
require(
isPoolCreator(_msgSender()),
"PoolCreatorRole: caller does not have the PoolCreator role"
);
_;
}
function isPoolCreator(address account) public view returns (bool) {
return _poolCreators.has(account);
}
function addPoolCreator(address account) public onlyPoolCreator {
_addPoolCreator(account);
}
function renouncePoolCreator() public {
_removePoolCreator(_msgSender());
}
function _addPoolCreator(address account) internal {
_poolCreators.add(account);
emit PoolCreatorAdded(account);
}
function _removePoolCreator(address account) internal {
_poolCreators.remove(account);
emit PoolCreatorRemoved(account);
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.0;
import "@openzeppelin/contracts/utils/Context.sol";
import "./Roles.sol";
contract Operator is Context {
using Roles for Roles.Role;
event OperatorAdded(address indexed account);
event OperatorRemoved(address indexed account);
Roles.Role private _operators;
constructor() {
if (!isOperator(_msgSender())) {
_addOperator(_msgSender());
}
}
modifier onlyOperator() {
require(
isOperator(_msgSender()),
"OperatorRole: caller does not have the Operator role"
);
_;
}
function isOperator(address account) public view returns (bool) {
return _operators.has(account);
}
function addOperator(address account) public onlyOperator {
_addOperator(account);
}
function renounceOperator() public {
_removeOperator(_msgSender());
}
function _addOperator(address account) internal {
_operators.add(account);
emit OperatorAdded(account);
}
function _removeOperator(address account) internal {
_operators.remove(account);
emit OperatorRemoved(account);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (utils/Context.sol)
pragma solidity ^0.8.0;
/**
* @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 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) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
function _contextSuffixLength() internal view virtual returns (uint256) {
return 0;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
pragma solidity ^0.8.0;
import "../IERC20.sol";
/**
* @dev Interface for the optional metadata functions from the ERC20 standard.
*
* _Available since v4.1._
*/
interface IERC20Metadata is IERC20 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the decimals places of the token.
*/
function decimals() external view returns (uint8);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @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 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 `to`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address to, 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 `from` to `to` 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 from, address to, uint256 amount) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)
pragma solidity ^0.8.0;
import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";
/**
* @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.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* The default value of {decimals} is 18. To change this, you should override
* this function so it returns a different value.
*
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* instead 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, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
/**
* @dev Sets the values for {name} and {symbol}.
*
* All two of these values are immutable: they can only be set once during
* construction.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev Returns the name of the token.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5.05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the default value returned by this function, unless
* it's overridden.
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view virtual override returns (uint8) {
return 18;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address to, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_transfer(owner, to, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
* `transferFrom`. This is semantically equivalent to an infinite approval.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_approve(owner, 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}.
*
* NOTE: Does not update the allowance if the current allowance
* is the maximum `uint256`.
*
* Requirements:
*
* - `from` and `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
* - the caller must have allowance for ``from``'s tokens of at least
* `amount`.
*/
function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
address spender = _msgSender();
_spendAllowance(from, spender, amount);
_transfer(from, to, 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) {
address owner = _msgSender();
_approve(owner, spender, allowance(owner, 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) {
address owner = _msgSender();
uint256 currentAllowance = allowance(owner, spender);
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(owner, spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `from` to `to`.
*
* This 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:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `from` must have a balance of at least `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);
}
/** @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:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
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);
}
/**
* @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), "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);
}
/**
* @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), "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);
}
/**
* @dev Updates `owner` s allowance for `spender` based on spent `amount`.
*
* Does not update the allowance amount in case of infinite allowance.
* Revert if not enough allowance is available.
*
* Might emit an {Approval} event.
*/
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);
}
}
}
/**
* @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 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 {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (security/ReentrancyGuard.sol)
pragma solidity ^0.8.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor() {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and making it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
_nonReentrantBefore();
_;
_nonReentrantAfter();
}
function _nonReentrantBefore() private {
// On the first call to nonReentrant, _status will be _NOT_ENTERED
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
}
function _nonReentrantAfter() private {
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
/**
* @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
* `nonReentrant` function in the call stack.
*/
function _reentrancyGuardEntered() internal view returns (bool) {
return _status == _ENTERED;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor() {
_transferOwnership(_msgSender());
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
_checkOwner();
_;
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if the sender is not the owner.
*/
function _checkOwner() internal view virtual {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby disabling any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
_transferOwnership(address(0));
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_transferOwnership(newOwner);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Internal function without access restriction.
*/
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
