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/**
/**
*Submitted for verification at snowtrace.io on 2021-11-19
*Submitted for verification at FtmScan.com on 2021-11-22
*/
*/
// SPDX-License-Identifier: MIT
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;
pragma solidity ^0.8.7;
/**
/**
* @dev Provides information about the current execution context, including the
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* 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
* 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
* 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
* paying for execution may not be the actual sender (as far as an application
* is concerned).
* is concerned).
*
*
* This contract is only required for intermediate, library-like contracts.
* This contract is only required for intermediate, library-like contracts.
*/
*/
abstract contract Context {
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
return msg.sender;
}
}
function _msgData() internal view virtual returns (bytes calldata) {
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
return msg.data;
}
}
}
}
/**
/**
* @dev Contract module which provides a basic access control mechanism, where
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
* specific functions.
*
*
* By default, the owner account will be the one that deploys the contract. This
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
* can later be changed with {transferOwnership}.
*
*
* This module is used through inheritance. It will make available the modifier
* 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
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
* the owner.
*/
*/
abstract contract Ownable is Context {
abstract contract Ownable is Context {
address private _owner;
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
/**
* @dev Initializes the contract setting the deployer as the initial owner.
* @dev Initializes the contract setting the deployer as the initial owner.
*/
*/
constructor() {
constructor() {
_transferOwnership(_msgSender());
_transferOwnership(_msgSender());
}
}
/**
/**
* @dev Returns the address of the current owner.
* @dev Returns the address of the current owner.
*/
*/
function owner() public view virtual returns (address) {
function owner() public view virtual returns (address) {
return _owner;
return _owner;
}
}
/**
/**
* @dev Throws if called by any account other than the owner.
* @dev Throws if called by any account other than the owner.
*/
*/
modifier onlyOwner() {
modifier onlyOwner() {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
require(owner() == _msgSender(), "Ownable: caller is not the owner");
_;
_;
}
}
/**
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
* Can only be called by the current owner.
*/
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
require(newOwner != address(0), "Ownable: new owner is the zero address");
_transferOwnership(newOwner);
_transferOwnership(newOwner);
}
}
/**
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Internal function without access restriction.
* Internal function without access restriction.
*/
*/
function _transferOwnership(address newOwner) internal virtual {
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
address oldOwner = _owner;
_owner = newOwner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
emit OwnershipTransferred(oldOwner, newOwner);
}
}
}
}
/**
/**
* @dev Collection of functions related to the address type
* @dev Collection of functions related to the address type
*/
*/
library Address {
library Address {
/**
/**
* @dev Returns true if `account` is a contract.
* @dev Returns true if `account` is a contract.
*
*
* [IMPORTANT]
* [IMPORTANT]
* ====
* ====
* It is unsafe to assume that an address for which this function returns
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
* false is an externally-owned account (EOA) and not a contract.
*
*
* Among others, `isContract` will return false for the following
* Among others, `isContract` will return false for the following
* types of addresses:
* types of addresses:
*
*
* - an externally-owned account
* - an externally-owned account
* - a contract in construction
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* - an address where a contract lived, but was destroyed
* ====
* ====
*/
*/
function isContract(address account) internal view returns (bool) {
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// construction, since the code is only stored at the end of the
// constructor execution.
// constructor execution.
uint256 size;
uint256 size;
assembly {
assembly {
size := extcodesize(account)
size := extcodesize(account)
}
}
return size > 0;
return size > 0;
}
}
/**
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
* `recipient`, forwarding all available gas and reverting on errors.
*
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
* `transfer`. {sendValue} removes this limitation.
*
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
*/
function sendValue(address payable recipient, uint256 amount) internal {
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
require(success, "Address: unable to send value, recipient may have reverted");
}
}
/**
/**
* @dev Performs a Solidity function call using a low level `call`. A
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
* function instead.
*
*
* If `target` reverts with a revert reason, it is bubbled up by this
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
* function (like regular Solidity function calls).
*
*
* Returns the raw returned data. To convert to the expected return value,
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
*
* Requirements:
* Requirements:
*
*
* - `target` must be a contract.
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
* - calling `target` with `data` must not revert.
*
*
* _Available since v3.1._
* _Available since v3.1._
*/
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
return functionCall(target, data, "Address: low-level call failed");
}
}
/**
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
* `errorMessage` as a fallback revert reason when `target` reverts.
*
*
* _Available since v3.1._
* _Available since v3.1._
*/
*/
function functionCall(
function functionCall(
address target,
address target,
bytes memory data,
bytes memory data,
string memory errorMessage
string memory errorMessage
) internal returns (bytes memory) {
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
return functionCallWithValue(target, data, 0, errorMessage);
}
}
/**
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
* but also transferring `value` wei to `target`.
*
*
* Requirements:
* Requirements:
*
*
* - the calling contract must have an ETH balance of at least `value`.
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
* - the called Solidity function must be `payable`.
*
*
* _Available since v3.1._
* _Available since v3.1._
*/
*/
function functionCallWithValue(
function functionCallWithValue(
address target,
address target,
bytes memory data,
bytes memory data,
uint256 value
uint256 value
) internal returns (bytes memory) {
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
}
/**
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
*
* _Available since v3.1._
* _Available since v3.1._
*/
*/
function functionCallWithValue(
function functionCallWithValue(
address target,
address target,
bytes memory data,
bytes memory data,
uint256 value,
uint256 value,
string memory errorMessage
string memory errorMessage
) internal returns (bytes memory) {
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
return verifyCallResult(success, returndata, errorMessage);
}
}
/**
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
* but performing a static call.
*
*
* _Available since v3.3._
* _Available since v3.3._
*/
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
return functionStaticCall(target, data, "Address: low-level static call failed");
}
}
/**
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
* but performing a static call.
*
*
* _Available since v3.3._
* _Available since v3.3._
*/
*/
function functionStaticCall(
function functionStaticCall(
address target,
address target,
bytes memory data,
bytes memory data,
string memory errorMessage
string memory errorMessage
) internal view returns (bytes memory) {
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
return verifyCallResult(success, returndata, errorMessage);
}
}
/**
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
* but performing a delegate call.
*
*
* _Available since v3.4._
* _Available since v3.4._
*/
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
}
/**
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
* but performing a delegate call.
*
*
* _Available since v3.4._
* _Available since v3.4._
*/
*/
function functionDelegateCall(
function functionDelegateCall(
address target,
address target,
bytes memory data,
bytes memory data,
string memory errorMessage
string memory errorMessage
) internal returns (bytes memory) {
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
return verifyCallResult(success, returndata, errorMessage);
}
}
/**
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
* revert reason using the provided one.
*
*
* _Available since v4.3._
* _Available since v4.3._
*/
*/
function verifyCallResult(
function verifyCallResult(
bool success,
bool success,
bytes memory returndata,
bytes memory returndata,
string memory errorMessage
string memory errorMessage
) internal pure returns (bytes memory) {
) internal pure returns (bytes memory) {
if (success) {
if (success) {
return returndata;
return returndata;
} else {
} else {
// Look for revert reason and bubble it up if present
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// The easiest way to bubble the revert reason is using memory via assembly
assembly {
assembly {
let returndata_size := mload(returndata)
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
revert(add(32, returndata), returndata_size)
}
}
} else {
} else {
revert(errorMessage);
revert(errorMessage);
}
}
}
}
}
}
}
}
/**
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
*/
interface IERC20 {
interface IERC20 {
/**
/**
* @dev Returns the amount of tokens in existence.
* @dev Returns the amount of tokens in existence.
*/
*/
function totalSupply() external view returns (uint256);
function totalSupply() external view returns (uint256);
/**
/**
* @dev Returns the amount of tokens owned by `account`.
* @dev Returns the amount of tokens owned by `account`.
*/
*/
function balanceOf(address account) external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
/**
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
*
* Returns a boolean value indicating whether the operation succeeded.
* Returns a boolean value indicating whether the operation succeeded.
*
*
* Emits a {Transfer} event.
* Emits a {Transfer} event.
*/
*/
function transfer(address recipient, uint256 amount) external returns (bool);
function transfer(address recipient, uint256 amount) external returns (bool);
/**
/**
* @dev Returns the remaining number of tokens that `spender` will be
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
* zero by default.
*
*
* This value changes when {approve} or {transferFrom} are called.
* This value changes when {approve} or {transferFrom} are called.
*/
*/
function allowance(address owner, address spender) external view returns (uint256);
function allowance(address owner, address spender) external view returns (uint256);
/**
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
*
* Returns a boolean value indicating whether the operation succeeded.
* Returns a boolean value indicating whether the operation succeeded.
*
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* 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
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
*
* Emits an {Approval} event.
* Emits an {Approval} event.
*/
*/
function approve(address spender, uint256 amount) external returns (bool);
function approve(address spender, uint256 amount) external returns (bool);
/**
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
* allowance.
*
*
* Returns a boolean value indicating whether the operation succeeded.
* Returns a boolean value indicating whether the operation succeeded.
*
*
* Emits a {Transfer} event.
* Emits a {Transfer} event.
*/
*/
function transferFrom(
function transferFrom(
address sender,
address sender,
address recipient,
address recipient,
uint256 amount
uint256 amount
) external returns (bool);
) external returns (bool);
/**
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
* another (`to`).
*
*
* Note that `value` may be zero.
* Note that `value` may be zero.
*/
*/
event Transfer(address indexed from, address indexed to, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 value);
/**
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
* a call to {approve}. `value` is the new allowance.
*/
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
}
/**
/**
* @dev Interface for the optional metadata functions from the ERC20 standard.
* @dev Interface for the optional metadata functions from the ERC20 standard.
*
*
* _Available since v4.1._
* _Available since v4.1._
*/
*/
interface IERC20Metadata is IERC20 {
interface IERC20Metadata is IERC20 {
/**
/**
* @dev Returns the name of the token.
* @dev Returns the name of the token.
*/
*/
function name() external view returns (string memory);
function name() external view returns (string memory);
/**
/**
* @dev Returns the symbol of the token.
* @dev Returns the symbol of the token.
*/
*/
function symbol() external view returns (string memory);
function symbol() external view returns (string memory);
/**
/**
* @dev Returns the decimals places of the token.
* @dev Returns the decimals places of the token.
*/
*/
function decimals() external view returns (uint8);
function decimals() external view returns (uint8);
}
}
/**
/**
* @title SafeERC20
* @title SafeERC20
* @dev Wrappers around ERC20 operations that throw on failure (when the token
* @dev Wrappers around ERC20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* successful.
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
*/
library SafeERC20 {
library SafeERC20 {
using Address for address;
using Address for address;
function safeTransfer(
function safeTransfer(
IERC20 token,
IERC20 token,
address to,
address to,
uint256 value
uint256 value
) internal {
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
}
function safeTransferFrom(
function safeTransferFrom(
IERC20 token,
IERC20 token,
address from,
address from,
address to,
address to,
uint256 value
uint256 value
) internal {
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
}
/**
/**
* @dev Deprecated. This function has issues similar to the ones found in
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
* {IERC20-approve}, and its usage is discouraged.
*
*
* Whenever possible, use {safeIncreaseAllowance} and
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
* {safeDecreaseAllowance} instead.
*/
*/
function safeApprove(
function safeApprove(
IERC20 token,
IERC20 token,
address spender,
address spender,
uint256 value
uint256 value
) internal {
) internal {
// safeApprove should only be called when setting an initial allowance,
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
require(
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
"SafeERC20: approve from non-zero to non-zero allowance"
);
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
}
function safeIncreaseAllowance(
function safeIncreaseAllowance(
IERC20 token,
IERC20 token,
address spender,
address spender,
uint256 value
uint256 value
) internal {
) internal {
uint256 newAllowance = token.allowance(address(this), spender) + value;
uint256 newAllowance = token.allowance(address(this), spender) + value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
function safeDecreaseAllowance(
function safeDecreaseAllowance(
IERC20 token,
IERC20 token,
address spender,
address spender,
uint256 value
uint256 value
) internal {
) internal {
unchecked {
unchecked {
uint256 oldAllowance = token.allowance(address(this), spender);
uint256 oldAllowance = token.allowance(address(this), spender);
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
uint256 newAllowance = oldAllowance - value;
uint256 newAllowance = oldAllowance - value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
}
}
/**
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
* @param data The call data (encoded using abi.encode or one of its variants).
*/
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
if (returndata.length > 0) {
// Return data is optional
// Return data is optional
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
}
}
}
/**
/**
* @dev Implementation of the {IERC20} interface.
* @dev Implementation of the {IERC20} interface.
*
*
* This implementation is agnostic to the way tokens are created. This means
* 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}.
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
*
* TIP: For a detailed writeup see our guide
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
* to implement supply mechanisms].
*
*
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* instead returning `false` on failure. This behavior is nonetheless
* instead returning `false` on failure. This behavior is nonetheless
* conventional and does not conflict with the expectations of ERC20
* conventional and does not conflict with the expectations of ERC20
* applications.
* applications.
*
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
* these events, as it isn't required by the specification.
*
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
* allowances. See {IERC20-approve}.
*/
*/
contract ERC20 is Context, Ownable, IERC20, IERC20Metadata {
contract ERC20 is Context, Ownable, IERC20, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
uint256 private _totalSupply;
uint256 private constant MAXSUPPLY = 3000 ether;
uint256 private constant MAXSUPPLY = 3000 ether;
string private _name;
string private _name;
string private _symbol;
string private _symbol;
/**
/**
* @dev Sets the values for {name} and {symbol}.
* @dev Sets the values for {name} and {symbol}.
*
*
* The default value of {decimals} is 18. To select a different value for
* The default value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
* {decimals} you should overload it.
*
*
* All two of these values are immutable: they can only be set once during
* All two of these values are immutable: they can only be set once during
* construction.
* construction.
*/
*/
constructor(string memory name_, string memory symbol_) {
constructor(string memory name_, string memory symbol_) {
_name = name_;
_name = name_;
_symbol = symbol_;
_symbol = symbol_;
}
}
/**
/**
* @dev Returns the name of the token.
* @dev Returns the name of the token.
*/
*/
function name() public view virtual override returns (string memory) {
function name() public view virtual override returns (string memory) {
return _name;
return _name;
}
}
/**
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
* name.
*/
*/
function symbol() public view virtual override returns (string memory) {
function symbol() public view virtual override returns (string memory) {
return _symbol;
return _symbol;
}
}
/**
/**
* @dev Returns the number of decimals used to get its user representation.
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5.05` (`505 / 10 ** 2`).
* be displayed to a user as `5.05` (`505 / 10 ** 2`).
*
*
* Tokens usually opt for a value of 18, imitating the relationship between
* 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
* Ether and Wei. This is the value {ERC20} uses, unless this function is
* overridden;
* overridden;
*
*
* NOTE: This information is only used for _display_ purposes: it in
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
*/
function decimals() public view virtual override returns (uint8) {
function decimals() public view virtual override returns (uint8) {
return 18;
return 18;
}
}
/**
/**
* @dev See {IERC20-totalSupply}.
* @dev See {IERC20-totalSupply}.
*/
*/
function totalSupply() public view virtual override returns (uint256) {
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
return _totalSupply;
}
}
function maxSupply() public pure returns (uint256) {
function maxSupply() public pure returns (uint256) {
return MAXSUPPLY;
return MAXSUPPLY;
}
}
/**
/**
* @dev See {IERC20-balanceOf}.
* @dev See {IERC20-balanceOf}.
*/
*/
function balanceOf(address account) public view virtual override returns (uint256) {
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
return _balances[account];
}
}
/**
/**
* @dev See {IERC20-transfer}.
* @dev See {IERC20-transfer}.
*
*
* Requirements:
* Requirements:
*
*
* - `recipient` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
* - the caller must have a balance of at least `amount`.
*/
*/
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
_transfer(_msgSender(), recipient, amount);
return true;
return true;
}
}
/**
/**
* @dev See {IERC20-allowance}.
* @dev See {IERC20-allowance}.
*/
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
return _allowances[owner][spender];
}
}
/**
/**
* @dev See {IERC20-approve}.
* @dev See {IERC20-approve}.
*
*
* Requirements:
* Requirements:
*
*
* - `spender` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
_approve(_msgSender(), spender, amount);
return true;
return true;
}
}
/**
/**
* @dev See {IERC20-transferFrom}.
* @dev See {IERC20-transferFrom}.
*
*
* Emits an {Approval} event indicating the updated allowance. This is not
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
* required by the EIP. See the note at the beginning of {ERC20}.
*
*
* Requirements:
* Requirements:
*
*
* - `sender` and `recipient` cannot be the zero address.
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - `sender` must have a balance of at least `amount`.
* - the caller must have allowance for ``sender``'s tokens of at least
* - the caller must have allowance for ``sender``'s tokens of at least
* `amount`.
* `amount`.
*/
*/
function transferFrom(
function transferFrom(
address sender,
address sender,
address recipient,
address recipient,
uint256 amount
uint256 amount
) public virtual override returns (bool) {
) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
_transfer(sender, recipient, amount);
uint256 currentAllowance = _allowances[sender][_msgSender()];
uint256 currentAllowance = _allowances[sender][_msgSender()];
require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
unchecked {
unchecked {
_approve(sender, _msgSender(), currentAllowance - amount);
_approve(sender, _msgSender(), currentAllowance - amount);
}
}
return true;
return true;
}
}
/**
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
* @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
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
* problems described in {IERC20-approve}.
*
*
* Emits an {Approval} event indicating the updated allowance.
* Emits an {Approval} event indicating the updated allowance.
*
*
* Requirements:
* Requirements:
*
*
* - `spender` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
_approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
return true;
return true;
}
}
/**
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
* @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
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
* problems described in {IERC20-approve}.
*
*
* Emits an {Approval} event indicating the updated allowance.
* Emits an {Approval} event indicating the updated allowance.
*
*
* Requirements:
* Requirements:
*
*
* - `spender` cannot be the zero address.
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
* `subtractedValue`.
*/
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
uint256 currentAllowance = _allowances[_msgSender()][spender];
uint256 currentAllowance = _allowances[_msgSender()][spender];
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
unchecked {
_approve(_msgSender(), spender, currentAllowance - subtractedValue);
_approve(_msgSender(), spender, currentAllowance - subtractedValue);
}
}
return true;
return true;
}
}
/**
/**
* @dev Moves `amount` of tokens from `sender` to `recipient`.
* @dev Moves `amount` of tokens from `sender` to `recipient`.
*
*
* This internal function is equivalent to {transfer}, and can be used to
* This internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
*
* Emits a {Transfer} event.
* Emits a {Transfer} event.
*
*
* Requirements:
* Requirements:
*
*
* - `sender` cannot be the zero address.
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - `sender` must have a balance of at least `amount`.
*/
*/
function _transfer(
function _transfer(
address sender,
address sender,
address recipient,
address recipient,
uint256 amount
uint256 amount
) internal virtual {
) internal virtual {
require(sender != address(0), "ERC20: transfer from the zero address");
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero addres
require(recipient != address(0), "ERC20: transfer to the zero address