Contract Name:
CryptoDollarMenu
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
/// @title Crypto Dollar Menu: Great Deals For Tough Times
/// @author cryptodollarmenu.com
/// @notice Claim, contribute and burn $CDM with a maximum of 5_500_000_000.
contract CryptoDollarMenu is ERC20, ERC20Burnable, Ownable {
using SafeMath for uint256;
/// @notice The minted amount of $CDM tokens that are burned.
/// @dev This $CDM is burned using the ERC20 contract method.
uint256 public burnedAmount;
/// @notice A count of the number of $CDM claims made.
/// @dev claimCount will always be below MAX_CLAIMS.
uint256 public claimCount;
/// @notice The minted amount of $CDM tokens allocated for staking rewards.
/// @dev This $CDM is sent directly to the rewards conract.
uint256 public createdStakingRewards;
/// @notice The amount of $CDM tokens created.
/// @dev Includes claimed, contributed and burned $CDM.
uint256 public currentCreated;
/// @notice The claimed amount of $CDM tokens.
/// @dev Includes only minted and claimed $CDM while excluding burned and contibuted.
uint256 public currentClaimed;
/// @notice The IERC721 conctract to which $CDM rewards contributions are sent.
/// @dev Deployed prior to the deployment of this contract so that it can be set permanently.
address public rewardsContract = 0xAFfa8fA8a7D54e4a55fCF8CdaDC2b1113a724a20;
/// @notice The maximum number of $CDM claims available + 1.
uint256 public constant MAX_CLAIMS = 10_001;
/// @notice The maximum amount of $CDM that can be created.
/// @dev This differs from the current totalSupply as it includes all burned tokens.
uint256 public constant MAX_CREATED = 5500000000000000000000000000; // 5_500_000_000 in Ether
/// @notice The claim rewards base value to be used starting at 5_000 claims.
function getClaimRewardBaseHigh(uint256 current) public pure returns (uint256) {
// Define the values that should be assigned to `claimRewardBase`
// Based on which range `current` falls into
uint256 CLAIM_REWARD_BASE_1 = 500000000000000000000000;
uint256 CLAIM_REWARD_BASE_2 = 400000000000000000000000;
uint256 CLAIM_REWARD_BASE_3 = 300000000000000000000000;
uint256 CLAIM_REWARD_BASE_4 = 200000000000000000000000;
uint256 CLAIM_REWARD_BASE_5 = 100000000000000000000000;
uint256 claimRewardBase;
if (current > 4_999 && current < 6_000) {
claimRewardBase = CLAIM_REWARD_BASE_1;
} else if (current > 5_999 && current < 7_000) {
claimRewardBase = CLAIM_REWARD_BASE_2;
} else if (current > 6_999 && current < 8_000) {
claimRewardBase = CLAIM_REWARD_BASE_3;
} else if (current > 7_999 && current < 9_000) {
claimRewardBase = CLAIM_REWARD_BASE_4;
} else if (current > 8_999 && current < 10_001) {
claimRewardBase = CLAIM_REWARD_BASE_5;
}
return claimRewardBase;
}
/// @notice The claim rewards base value to be used below 5_000 claims.
function getClaimRewardBaseLow(uint256 current) public pure returns (uint256) {
// Define the values that should be assigned to `claimRewardBase`
// Based on which range `current` falls into
uint256 CLAIM_REWARD_BASE_1 = 1000000000000000000000000;
uint256 CLAIM_REWARD_BASE_2 = 900000000000000000000000;
uint256 CLAIM_REWARD_BASE_3 = 800000000000000000000000;
uint256 CLAIM_REWARD_BASE_4 = 700000000000000000000000;
uint256 CLAIM_REWARD_BASE_5 = 600000000000000000000000;
uint256 claimRewardBase;
if (current < 1_000) {
claimRewardBase = CLAIM_REWARD_BASE_1;
} else if (current > 999 && current < 2_000) {
claimRewardBase = CLAIM_REWARD_BASE_2;
} else if (current > 1_999 && current < 3_000) {
claimRewardBase = CLAIM_REWARD_BASE_3;
} else if (current > 2_999 && current < 4_000) {
claimRewardBase = CLAIM_REWARD_BASE_4;
} else if (current > 3_999 && current < 5_000) {
claimRewardBase = CLAIM_REWARD_BASE_5;
}
return claimRewardBase;
}
/// @notice A struct indicating that an address has made a claim and their count when they made it.
struct ClaimDetail {
address user;
uint256 count;
}
/// @notice An address is used a key to each struct of information for a given user claim.
/// @dev Adding an address to user claims restricts multiple claims per wallet.
mapping(address => ClaimDetail) public userClaims;
/// @notice Emitted when a claim is made.
event UserClaim(address indexed user, uint256 count, uint256 claimAmount);
/// @notice Create the $CDM ERC20 contract.
constructor() ERC20("Crypto Dollar Menu", "CDM") {}
/// @notice A random claim of $CDM that sends the remaining base claim amount to staking rewards.
/// @param picked A random uint256 input by a user to give an added degree of randomness.
function claimContribute(uint256 picked) external {
uint256 _claimCount = claimCount;
uint256 _createdStakingRewards = createdStakingRewards;
uint256 _currentCreated = currentCreated;
uint256 _currentClaimed = currentClaimed;
uint256 _claimRewardBase;
_claimRewardBase = (_claimCount < 5_000) ? getClaimRewardBaseLow(_claimCount) : getClaimRewardBaseHigh(_claimCount);
uint256 generatedValue = getGenerated(picked, _claimCount);
uint256 amountRequired = _currentCreated + _claimRewardBase;
uint256 claimAmount = randomClaim(picked, _claimCount, generatedValue, _claimRewardBase);
uint256 unclaimedAmount = _claimRewardBase - claimAmount;
require(amountRequired < MAX_CREATED);
require(_claimCount < MAX_CLAIMS, "Max claims reached");
require(userClaims[_msgSender()].count == 0, "Wallet already claimed");
_mint(_msgSender(), claimAmount);
_mint(rewardsContract, unclaimedAmount);
_claimCount++;
claimCount = _claimCount;
_currentCreated += _claimRewardBase;
currentCreated = _currentCreated;
_currentClaimed += claimAmount;
currentClaimed = _currentClaimed;
_createdStakingRewards += unclaimedAmount;
createdStakingRewards = _createdStakingRewards;
// Create and store new ClaimDetail
ClaimDetail memory claimDetail = ClaimDetail({
user: _msgSender(),
count: _claimCount
});
userClaims[_msgSender()] = claimDetail;
emit UserClaim(_msgSender(), _claimCount, claimAmount);
}
/// @notice A random claim of $CDM that burns the remaining base claim amount.
/// @param picked A random uint256 input by a user to give an added degree of randomness.
/// @dev This is only available at 5_000 claims and above.
function claimBurn(uint256 picked) external {
uint256 _burnedAmount = burnedAmount;
uint256 _claimCount = claimCount;
uint256 _currentCreated = currentCreated;
uint256 _currentClaimed = currentClaimed;
uint256 _claimRewardBase = getClaimRewardBaseHigh(_claimCount);
uint256 amountRequired = _currentCreated + _claimRewardBase;
uint256 generatedValue = getGenerated(picked, _claimCount);
uint256 claimAmount = randomClaim(picked, _claimCount, generatedValue, _claimRewardBase);
uint256 unclaimedAmount = _claimRewardBase - claimAmount;
require(_claimCount > 4_999, "Burn not yet available");
require(_claimCount < MAX_CLAIMS, "Max claims reached");
require(amountRequired < MAX_CREATED);
require(userClaims[_msgSender()].count == 0, "Wallet already claimed");
_mint(_msgSender(), claimAmount);
_mint(_msgSender(), unclaimedAmount);
_burn(_msgSender(), unclaimedAmount);
_claimCount++;
claimCount = _claimCount;
_currentCreated += _claimRewardBase;
currentCreated = _currentCreated;
_currentClaimed += claimAmount;
currentClaimed = _currentClaimed;
_burnedAmount += unclaimedAmount;
burnedAmount = _burnedAmount;
// Create and store new ClaimDetail
ClaimDetail memory claimDetail = ClaimDetail({
user: _msgSender(),
count: _claimCount
});
userClaims[_msgSender()] = claimDetail;
emit UserClaim(_msgSender(), _claimCount, claimAmount);
}
/// @notice Determine if claim and burn is available using a boolean.
/// @return A boolean indicating whether claim and burn is available.
function getBurnAvailable() external view returns (bool) {
uint256 _claimCount = claimCount;
bool status = (_claimCount < 5000) ? false : true;
return status;
}
/// @notice Provides a statement used to display if claim and burn is available.
/// @return A statement indicating the availability of claim and burn.
function getBurnStatement() external view returns (string memory) {
string memory available = "Burn available.";
string memory notAvailable = "Burn not available.";
uint256 _claimCount = claimCount;
string memory status = (_claimCount < 5000) ? notAvailable : available;
return status;
}
/// @notice An explicit function to determine the amount of $CDM contributed for rewards.
/// @return The amount of $CDM currently contributed as rewards expressed in Wei.
function getCreatedStakingRewards() external view returns (uint256) {
return createdStakingRewards;
}
/// @notice An explicit function to determine the amount of $CDM created.
/// @dev Includes claimed, contributed and burned tokens.
/// @return The amount of currently created $CDM tokens expressed in Wei.
function getCurrentCreated() external view returns (uint256) {
return currentCreated;
}
/// @notice An explicit function to determine the amount of $CDM claimed.
/// @dev Excludes contributed and burned $CDM.
/// @return The amount of currently claimed $CDM tokens expressed in Wei.
function getCurrentClaimed() external view returns (uint256) {
return currentClaimed;
}
/// @notice An explicit function to determine the current max claim.
/// @return The maximum amount of $CDM that can currently be claimed.
function getCurrentMaxClaim() external view returns (uint256) {
uint256 _claimCount = claimCount;
uint256 _claimRewardBase;
_claimRewardBase = (_claimCount < 5_000) ? getClaimRewardBaseLow(_claimCount) : getClaimRewardBaseHigh(_claimCount);
return _claimRewardBase;
}
/// @notice Get struct providing the information for a speciic user claim.
/// @return The claim detail for a specific address.
function getUserClaim(address user) external view returns (ClaimDetail memory) {
return userClaims[user];
}
/// @notice An explicit function to return the maximum about of $CDM that can be created.
/// @return The maximum amount of $CDM that can be created expressed in Wei.
function getMaximumCreated() external pure returns (uint256) {
return MAX_CREATED;
}
/// @notice An explicit function to provide the current total supply of $CDM.
/// @dev This does not include burned $CDM.
/// @return Retuns the current total supply of $CDM.
function getTotalSupply() public view returns (uint256) {
return totalSupply();
}
/// @notice A function to generate a random uint256 value using two uint256 inputs.
function getGenerated(uint256 a, uint256 b) private view returns (uint256) {
uint256 generated = random(string(abi.encodePacked("9b96e70d-c72a-47de-b5ed-6e325b14a60c", block.timestamp, _msgSender(), toString(a), toString(b))));
return generated;
}
/// @notice Create a random claim amount between 0 and the claim reward base amount.
/// @param a A variable input to create randomness.
/// @param b A variable input to create randomness.
/// @param c A variable input to create randomness.
/// @param reward The claim reward base value.
/// @return A random claim value.
function randomClaim(uint256 a, uint256 b, uint256 c, uint256 reward) private view returns (uint256) {
uint256 v = uint(keccak256(abi.encodePacked("459ead19-8da5-40a6-b958-4ae8f04786c7", block.timestamp, toString(a), toString(b), toString(c)))) % reward;
return v;
}
/// @notice A general random function to be used to shuffle and generate values.
/// @param input Any string value to be randomized.
/// @return The output of a random hash using keccak256.
function random(string memory input) private pure returns (uint256) {
return uint256(keccak256(abi.encodePacked(input)));
}
/// @notice Returns an uint256 value as a string.
/// @param value The uint256 value to have a type change.
/// @return A string of the inputted uint256 value.
function toString(uint256 value) private pure returns (string memory) {
if (value == 0) {
return "0";
}
uint256 temp = value;
uint256 digits;
while (temp != 0) {
digits++;
temp /= 10;
}
bytes memory buffer = new bytes(digits);
while (value != 0) {
digits -= 1;
buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
value /= 10;
}
return string(buffer);
}
}
// 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 (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);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/extensions/ERC20Burnable.sol)
pragma solidity ^0.8.0;
import "../ERC20.sol";
import "../../../utils/Context.sol";
/**
* @dev Extension of {ERC20} that allows token holders to destroy both their own
* tokens and those that they have an allowance for, in a way that can be
* recognized off-chain (via event analysis).
*/
abstract contract ERC20Burnable is Context, ERC20 {
/**
* @dev Destroys `amount` tokens from the caller.
*
* See {ERC20-_burn}.
*/
function burn(uint256 amount) public virtual {
_burn(_msgSender(), amount);
}
/**
* @dev Destroys `amount` tokens from `account`, deducting from the caller's
* allowance.
*
* See {ERC20-_burn} and {ERC20-allowance}.
*
* Requirements:
*
* - the caller must have allowance for ``accounts``'s tokens of at least
* `amount`.
*/
function burnFrom(address account, uint256 amount) public virtual {
_spendAllowance(account, _msgSender(), amount);
_burn(account, amount);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (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].
*
* 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;
// 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 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);
}