Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity 0.8.14;
import '@openzeppelin/contracts/token/ERC20/ERC20.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/security/ReentrancyGuard.sol';
import '@openzeppelin/contracts/utils/math/SafeMath.sol';
import './utils/Interest.sol';
contract Token is ERC20, Ownable, Interest, ReentrancyGuard {
using SafeMath for uint256;
uint256 public minAmountToStake;
uint256 public totalStaked;
uint256 public numberOfPeopleStaking;
uint256 public startDateSmartContract;
uint256 public ratePerYearInWei;
uint256 public stakingStart;
uint256 public stakingDuration;
uint256 public stakingEndDate;
uint256 public maxAmountManuallyMintable;
uint256 public cap;
mapping(address => Internal) public internalAddresses;
mapping(address => Deposit) public deposits;
struct Internal {
bool isInternal;
}
struct Deposit {
uint256 amount;
uint256 startdate;
}
constructor(
string memory name_,
string memory symbol_,
uint256 cap_,
uint256 ratePerYearInWei_,
uint256 maxAmountManuallyMintable_,
uint256 stakingDuration_,
uint256 minAmountToStake_
) ERC20(name_, symbol_) {
require(
ratePerYearInWei_ >= 100000000000000000 && ratePerYearInWei_ <= 200000000000000000,
'The ratePerYearInWei_ must be between 0.1 and 0.2 ethers'
);
require(
maxAmountManuallyMintable_ >= 400000000 * 1 ether && maxAmountManuallyMintable_ <= 400000002 * 1 ether,
'The maxAmountManuallyMintable_ must be between 400M and 500M ethers'
);
require(
stakingDuration_ >= 1 * 365 days && stakingDuration_ <= 10 * 365 days,
'The stakingDuration_ must be between 1 and 10 years'
);
ratePerYearInWei = ratePerYearInWei_;
cap = cap_;
maxAmountManuallyMintable = maxAmountManuallyMintable_;
stakingStart = block.timestamp;
stakingDuration = stakingDuration_;
stakingEndDate = block.timestamp + stakingDuration;
minAmountToStake = minAmountToStake_;
emit tokenInitialed(address(this), block.timestamp);
}
function mint(address _account, uint256 _amount)
external
onlyOwner
maxAmountManuallyMintableNotReached(_amount)
nonReentrant
{
_mint(_account, _amount);
emit tokenMintedSuccess(_account, _amount, block.timestamp);
}
function burn(address _account, uint256 _amount) external onlyOwner isAnInternalAddress(_account) {
_burn(_account, _amount);
emit tokenBurnedSuccess(_account, _amount, block.timestamp);
}
function stake(uint256 amount_)
external
nonReentrant
isStakingActive
isNotAnInternalAddress(msg.sender)
isNotYetStaking(msg.sender)
hasTheMinAmountToStake(amount_)
{
transferUsersFundsToThisContract(amount_);
createDeposit(amount_);
increaseTheTotalStakedAmount(amount_);
emit stakeSuccess(msg.sender, amount_, block.timestamp);
}
function unstake() external nonReentrant isAlreadyStaking(msg.sender) {
Deposit memory _deposit = deposits[msg.sender];
payUsersProfits(_deposit);
returnUsersFunds(_deposit);
decreaseTheTotalStakedAmount(_deposit);
deleteDeposit();
emit unstakeSuccess(msg.sender, deposits[msg.sender].amount, block.timestamp);
}
function createDeposit(uint256 amount) internal {
deposits[msg.sender] = Deposit(amount, block.timestamp);
}
function deleteDeposit() internal {
delete deposits[msg.sender];
}
function increaseTheTotalStakedAmount(uint256 amount_) internal {
totalStaked = totalStaked.add(amount_);
numberOfPeopleStaking++;
}
function decreaseTheTotalStakedAmount(Deposit memory _deposit) internal {
totalStaked = totalStaked.sub(_deposit.amount);
numberOfPeopleStaking--;
}
function payUsersProfits(Deposit memory _deposit) internal {
uint256 profit = getProfits(_deposit);
if (profit > 0) _mint(msg.sender, profit);
}
function returnUsersFunds(Deposit memory _deposit) internal {
_transfer(address(this), msg.sender, _deposit.amount);
}
function transferUsersFundsToThisContract(uint256 amount_) internal {
_transfer(msg.sender, address(this), amount_);
}
function calculateInterest(Deposit memory deposit) public view returns (uint256) {
uint256 userStakingStartDate = deposit.startdate;
uint256 stakingAge = block.timestamp.sub(userStakingStartDate);
uint256 stakedAmount = deposit.amount;
return accrueYearlyRateInterest(stakedAmount, ratePerYearInWei, stakingAge);
}
function getProfits(Deposit memory deposit) public view returns (uint256) {
if (!isStaking(deposit)) return 0;
uint256 interest = calculateInterest(deposit);
uint256 profit = interest.sub(deposit.amount);
return profit;
}
function setMinAmountToStake(uint256 _minAmountToStake) external onlyOwner {
minAmountToStake = _minAmountToStake;
emit setMinAmountToStakeSuccess(_minAmountToStake);
}
function setStartDateSmartContract() external onlyOwner {
startDateSmartContract = block.timestamp;
emit setStartDateSmartContractSuccess(msg.sender, startDateSmartContract);
}
function setInternalAddress(address _address) external onlyOwner {
require(startDateSmartContract == 0, "You can only add any address to this list before the contract's initialization.");
internalAddresses[_address] = Internal(true);
emit setInternalAddressSuccess(_address);
}
modifier isAnInternalAddress(address _address) {
require(internalAddresses[_address].isInternal, 'It must be an internal address.');
_;
}
modifier isNotAnInternalAddress(address _address) {
require(!internalAddresses[_address].isInternal, 'It must be an external address.');
_;
}
modifier maxAmountManuallyMintableNotReached(uint256 _amountToMint) {
uint256 currentSupplyPlusAmountToMint = this.totalSupply().add(_amountToMint);
require(
currentSupplyPlusAmountToMint <= maxAmountManuallyMintable,
'Total supply will exceed maxAmountManuallyMintable after mint'
);
_;
}
modifier isStakingActive() {
require(
(stakingEndDate > 0 && (stakingEndDate >= block.timestamp)),
'The staking was not yet activated or ended already the period.'
);
_;
}
modifier hasTheMinAmountToStake(uint256 amount_) {
require(amount_ >= minAmountToStake, 'To stake, you must have the minimum amount of coins required.');
_;
}
modifier isNotYetStaking(address _address) {
require(!isStaking(deposits[_address]), 'Your address is already staking.');
_;
}
modifier isAlreadyStaking(address _address) {
require(isStaking(deposits[_address]), 'You must be staking in order to unstake.');
_;
}
function isStaking(Deposit memory deposit) public pure returns (bool) {
return (deposit.amount > 0 && deposit.startdate > 0);
}
event tokenInitialed(address indexed _who, uint256 timestamp);
event unstakeSuccess(address indexed _who, uint256 _amount, uint256 timestamp);
event stakeSuccess(address indexed _who, uint256 _amount, uint256 timestamp);
event tokenMintedSuccess(address indexed _who, uint256 _amount, uint256 timestamp);
event tokenBurnedSuccess(address indexed _who, uint256 _amount, uint256 timestamp);
event setInternalAddressSuccess(address indexed _address);
event setMinAmountToStakeSuccess(uint256 _amount);
event setStartDateSmartContractSuccess(address indexed _who, uint256 timestamp);
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.14;
import "./DSMath.sol";
// Using DSMath from DappHub https://github.com/dapphub/ds-math
// More info on DSMath and fixed point arithmetic in Solidity:
// https://medium.com/dapphub/introducing-ds-math-an-innovative-safe-math-library-d58bc88313da
/**
* @title Interest
* @author Nick Ward
* @dev Uses DSMath's wad and ray math to implement (approximately)
* continuously compounding interest by calculating discretely compounded
* interest compounded every second.
*/
contract Interest is DSMath {
//// Fixed point scale factors
// wei -> the base unit
// wad -> wei * 10 ** 18. 1 ether = 1 wad, so 0.5 ether can be used
// to represent a decimal wad of 0.5
// ray -> wei * 10 ** 27
// Go from wad (10**18) to ray (10**27)
function wadToRay(uint _wad) internal pure returns (uint) {
return mul(_wad, 10 ** 9);
}
// Go from wei to ray (10**27)
function weiToRay(uint _wei) internal pure returns (uint) {
return mul(_wei, 10 ** 27);
}
/**
* @dev Uses an approximation of continuously compounded interest
* (discretely compounded every second)
* @param _principal The principal to calculate the interest on.
* Accepted in wei.
* @param _rate The interest rate. Accepted as a ray representing
* 1 + the effective interest rate per second, compounded every
* second. As an example:
* I want to accrue interest at a nominal rate (i) of 5.0% per year
* compounded continuously. (Effective Annual Rate of 5.127%).
* This is approximately equal to 5.0% per year compounded every
* second (to 8 decimal places, if max precision is essential,
* calculate nominal interest per year compounded every second from
* your desired effective annual rate). Effective Rate Per Second =
* Nominal Rate Per Second compounded every second = Nominal Rate
* Per Year compounded every second * conversion factor from years
* to seconds
* Effective Rate Per Second = 0.05 / (365 days/yr * 86400 sec/day) = 1.5854895991882 * 10 ** -9
* The value we want to send this function is
* 1 * 10 ** 27 + Effective Rate Per Second * 10 ** 27
* = 1000000001585489599188229325
* This will return 5.1271096334354555 Dai on a 100 Dai principal
* over the course of one year (31536000 seconds)
* @param _age The time period over which to accrue interest. Accepted
* in seconds.
* @return The new principal as a wad. Equal to original principal +
* interest accrued
*/
function accrueInterest(uint _principal, uint _rate, uint _age) public pure returns (uint) {
return rmul(_principal, rpow(_rate, _age));
}
//1000000000000000000000000,500000000000000000,10368000
// Eu somente precisoo enviar o balance do usuario no principal.
// Por exemplo. Se ele tem 1 moeda, então é o balance que ele iniciou o staking
// 1 ether = 1 * 10**18 => 1 + 18 ZEROS => 1 000 000 000 000 000 000 => 1
// o rate é =POW(10,18)*0.5
// Nunca posso enviar em decimal então eu multiplico 0.5 * 10 elevado 18 potência (10ˆ18) ou (10**10)
// Isso dá 500000000000000000
// o _age é o tempo em staking
// block.timestamp (AGORA) - a data que ele fez o stacking
// Tudo em epoch. Segundos.
function accrueYearlyRateInterest(uint _principal, uint _rate, uint _age) public pure returns (uint) {
return rmul(_principal, rpow(yearlyRateToRay(_rate), _age));
}
/**
* @dev Takes in the desired nominal interest rate per year, compounded
* every second (this is approximately equal to nominal interest rate
* per year compounded continuously). Returns the ray value expected
* by the accrueInterest function
* @param _rateWad A wad of the desired nominal interest rate per year,
* compounded continuously. Converting from ether to wei will effectively
* convert from a decimal value to a wad. So 5% rate = 0.05
* should be input as yearlyRateToRay( 0.05 ether )
* @return 1 * 10 ** 27 + Effective Interest Rate Per Second * 10 ** 27
*/
function yearlyRateToRay(uint _rateWad) public pure returns (uint) {
return add(wadToRay(1 ether), rdiv(wadToRay(_rateWad), weiToRay(365*86400)));
}
}
// DSMath from DappHub -> https://github.com/dapphub/ds-math/blob/784079b72c4d782b022b3e893a7c5659aa35971a/src/math.sol
/// math.sol -- mixin for inline numerical wizardry
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
contract DSMath {
function add(uint x, uint y) internal pure returns (uint z) {
require((z = x + y) >= x, "ds-math-add-overflow");
}
function sub(uint x, uint y) internal pure returns (uint z) {
require((z = x - y) <= x, "ds-math-sub-underflow");
}
function mul(uint x, uint y) internal pure returns (uint z) {
require(y == 0 || (z = x * y) / y == x, "ds-math-mul-overflow");
}
function min(uint x, uint y) internal pure returns (uint z) {
return x <= y ? x : y;
}
function max(uint x, uint y) internal pure returns (uint z) {
return x >= y ? x : y;
}
function imin(int x, int y) internal pure returns (int z) {
return x <= y ? x : y;
}
function imax(int x, int y) internal pure returns (int z) {
return x >= y ? x : y;
}
uint constant WAD = 10 ** 18;
uint constant RAY = 10 ** 27;
function wmul(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, y), WAD / 2) / WAD;
}
function rmul(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, y), RAY / 2) / RAY;
}
function wdiv(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, WAD), y / 2) / y;
}
function rdiv(uint x, uint y) internal pure returns (uint z) {
z = add(mul(x, RAY), y / 2) / y;
}
// This famous algorithm is called "exponentiation by squaring"
// and calculates x^n with x as fixed-point and n as regular unsigned.
//
// It's O(log n), instead of O(n) for naive repeated multiplication.
//
// These facts are why it works:
//
// If n is even, then x^n = (x^2)^(n/2).
// If n is odd, then x^n = x * x^(n-1),
// and applying the equation for even x gives
// x^n = x * (x^2)^((n-1) / 2).
//
// Also, EVM division is flooring and
// floor[(n-1) / 2] = floor[n / 2].
//
function rpow(uint x, uint n) internal pure returns (uint z) {
z = n % 2 != 0 ? x : RAY;
for (n /= 2; n != 0; n /= 2) {
x = rmul(x, x);
if (n % 2 != 0) {
z = rmul(z, x);
}
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)
pragma solidity ^0.8.0;
// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.
/**
* @dev Wrappers over Solidity's arithmetic operations.
*
* NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
* now has built in overflow checking.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the subtraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b > a) return (false, 0);
return (true, a - b);
}
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a / b);
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
unchecked {
if (b == 0) return (false, 0);
return (true, a % b);
}
}
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
*
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
return a + b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return a - b;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
*
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
return a * b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator.
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b <= a, errorMessage);
return a - b;
}
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a / b;
}
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
unchecked {
require(b > 0, errorMessage);
return a % b;
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (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;
}
}
// 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 v4.6.0) (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 v4.7.0) (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.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* 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}.
*
* The default value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
*
* 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 value {ERC20} uses, unless this function is
* 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;
}
_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;
_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;
}
_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 v4.4.1 (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() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (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 anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing 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);
}
}