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- // Copyright [2021] - [2021], [Shaun Reed] and [Karma] contributors
- // SPDX-License-Identifier: MIT
- pragma solidity >= 0.8.0;
- // ----------------------------------------------------------------------------
- // Import ERC Token Standard #20 Interface
- // ETH EIP repo: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
- // ----------------------------------------------------------------------------
- pragma solidity ^0.8.0;
- /**
- * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
- * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
- * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
- * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
- *
- * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
- * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
- *
- * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
- * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
- */
- abstract contract Initializable {
- /**
- * @dev Indicates that the contract has been initialized.
- */
- bool private _initialized;
- /**
- * @dev Indicates that the contract is in the process of being initialized.
- */
- bool private _initializing;
- /**
- * @dev Modifier to protect an initializer function from being invoked twice.
- */
- modifier initializer() {
- require(_initializing || !_initialized, "Initializable: contract is already initialized");
- bool isTopLevelCall = !_initializing;
- if (isTopLevelCall) {
- _initializing = true;
- _initialized = true;
- }
- _;
- if (isTopLevelCall) {
- _initializing = false;
- }
- }
- }
- /**
- * @dev Interface of the ERC20 standard as defined in the EIP.
- */
- interface IERC20Upgradeable {
- /**
- * @dev Returns the amount of tokens in existence.
- */
- function totalSupply() external view returns (uint256);
- /**
- * @dev Returns the amount of tokens owned by `account`.
- */
- function balanceOf(address account) external view returns (uint256);
- /**
- * @dev Moves `amount` tokens from the caller's account to `recipient`.
- *
- * Returns a boolean value indicating whether the operation succeeded.
- *
- * Emits a {Transfer} event.
- */
- function transfer(address recipient, uint256 amount) external returns (bool);
- /**
- * @dev Returns the remaining number of tokens that `spender` will be
- * allowed to spend on behalf of `owner` through {transferFrom}. This is
- * zero by default.
- *
- * This value changes when {approve} or {transferFrom} are called.
- */
- function allowance(address owner, address spender) external view returns (uint256);
- /**
- * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
- *
- * Returns a boolean value indicating whether the operation succeeded.
- *
- * IMPORTANT: Beware that changing an allowance with this method brings the risk
- * that someone may use both the old and the new allowance by unfortunate
- * transaction ordering. One possible solution to mitigate this race
- * condition is to first reduce the spender's allowance to 0 and set the
- * desired value afterwards:
- * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
- *
- * Emits an {Approval} event.
- */
- function approve(address spender, uint256 amount) external returns (bool);
- /**
- * @dev Moves `amount` tokens from `sender` to `recipient` using the
- * allowance mechanism. `amount` is then deducted from the caller's
- * allowance.
- *
- * Returns a boolean value indicating whether the operation succeeded.
- *
- * Emits a {Transfer} event.
- */
- function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
- /**
- * @dev Emitted when `value` tokens are moved from one account (`from`) to
- * another (`to`).
- *
- * Note that `value` may be zero.
- */
- event Transfer(address indexed from, address indexed to, uint256 value);
- /**
- * @dev Emitted when the allowance of a `spender` for an `owner` is set by
- * a call to {approve}. `value` is the new allowance.
- */
- event Approval(address indexed owner, address indexed spender, uint256 value);
- }
- /**
- * @dev Interface for the optional metadata functions from the ERC20 standard.
- *
- * _Available since v4.1._
- */
- interface IERC20MetadataUpgradeable is IERC20Upgradeable {
- /**
- * @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);
- }
- 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 ContextUpgradeable is Initializable {
- function __Context_init() internal initializer {
- __Context_init_unchained();
- }
- function __Context_init_unchained() internal initializer {
- }
- function _msgSender() internal view virtual returns (address) {
- return msg.sender;
- }
- function _msgData() internal view virtual returns (bytes calldata) {
- this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
- return msg.data;
- }
- uint256[50] private __gap;
- }
- pragma solidity ^0.8.0;
- /**
- * @dev Implementation of the {IERC20} interface.
- *
- * This implementation is agnostic to the way tokens are created. This means
- * that a supply mechanism has to be added in a derived contract using {_mint}.
- * For a generic mechanism see {ERC20PresetMinterPauser}.
- *
- * TIP: For a detailed writeup see our guide
- * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
- * to implement supply mechanisms].
- *
- * We have followed general OpenZeppelin guidelines: functions revert instead
- * of returning `false` on failure. This behavior is nonetheless conventional
- * and does not conflict with the expectations of ERC20 applications.
- *
- * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
- * This allows applications to reconstruct the allowance for all accounts just
- * by listening to said events. Other implementations of the EIP may not emit
- * these events, as it isn't required by the specification.
- *
- * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
- * functions have been added to mitigate the well-known issues around setting
- * allowances. See {IERC20-approve}.
- */
- contract ERC20Upgradeable is Initializable, ContextUpgradeable, IERC20Upgradeable, IERC20MetadataUpgradeable {
- 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 defaut 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.
- */
- function __ERC20_init(string memory name_, string memory symbol_) internal initializer {
- __Context_init_unchained();
- __ERC20_init_unchained(name_, symbol_);
- }
- function __ERC20_init_unchained(string memory name_, string memory symbol_) internal initializer {
- _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:
- *
- * - `recipient` cannot be the zero address.
- * - the caller must have a balance of at least `amount`.
- */
- function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
- _transfer(_msgSender(), recipient, amount);
- return true;
- }
- /**
- * @dev See {IERC20-allowance}.
- */
- function allowance(address owner, address spender) public view virtual override returns (uint256) {
- return _allowances[owner][spender];
- }
- /**
- * @dev See {IERC20-approve}.
- *
- * Requirements:
- *
- * - `spender` cannot be the zero address.
- */
- function approve(address spender, uint256 amount) public virtual override returns (bool) {
- _approve(_msgSender(), spender, amount);
- return true;
- }
- /**
- * @dev See {IERC20-transferFrom}.
- *
- * Emits an {Approval} event indicating the updated allowance. This is not
- * required by the EIP. See the note at the beginning of {ERC20}.
- *
- * Requirements:
- *
- * - `sender` and `recipient` cannot be the zero address.
- * - `sender` must have a balance of at least `amount`.
- * - the caller must have allowance for ``sender``'s tokens of at least
- * `amount`.
- */
- function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
- _transfer(sender, recipient, amount);
- uint256 currentAllowance = _allowances[sender][_msgSender()];
- require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
- _approve(sender, _msgSender(), currentAllowance - amount);
- return true;
- }
- /**
- * @dev Atomically increases the allowance granted to `spender` by the caller.
- *
- * This is an alternative to {approve} that can be used as a mitigation for
- * problems described in {IERC20-approve}.
- *
- * Emits an {Approval} event indicating the updated allowance.
- *
- * Requirements:
- *
- * - `spender` cannot be the zero address.
- */
- function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
- _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
- return true;
- }
- /**
- * @dev Atomically decreases the allowance granted to `spender` by the caller.
- *
- * This is an alternative to {approve} that can be used as a mitigation for
- * problems described in {IERC20-approve}.
- *
- * Emits an {Approval} event indicating the updated allowance.
- *
- * Requirements:
- *
- * - `spender` cannot be the zero address.
- * - `spender` must have allowance for the caller of at least
- * `subtractedValue`.
- */
- function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
- uint256 currentAllowance = _allowances[_msgSender()][spender];
- require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
- _approve(_msgSender(), spender, currentAllowance - subtractedValue);
- return true;
- }
- /**
- * @dev Moves tokens `amount` from `sender` to `recipient`.
- *
- * This is internal function is equivalent to {transfer}, and can be used to
- * e.g. implement automatic token fees, slashing mechanisms, etc.
- *
- * Emits a {Transfer} event.
- *
- * Requirements:
- *
- * - `sender` cannot be the zero address.
- * - `recipient` cannot be the zero address.
- * - `sender` must have a balance of at least `amount`.
- */
- function _transfer(address sender, address recipient, uint256 amount) internal virtual {
- require(sender != address(0), "ERC20: transfer from the zero address");
- require(recipient != address(0), "ERC20: transfer to the zero address");
- _beforeTokenTransfer(sender, recipient, amount);
- uint256 senderBalance = _balances[sender];
- require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
- _balances[sender] = senderBalance - amount;
- _balances[recipient] += amount;
- emit Transfer(sender, recipient, amount);
- }
- /** @dev Creates `amount` tokens and assigns them to `account`, increasing
- * the total supply.
- *
- * Emits a {Transfer} event with `from` set to the zero address.
- *
- * Requirements:
- *
- * - `to` cannot be the zero address.
- */
- function _mint(address account, uint256 amount) internal virtual {
- require(account != address(0), "ERC20: mint to the zero address");
- _beforeTokenTransfer(address(0), account, amount);
- _totalSupply += amount;
- _balances[account] += amount;
- emit Transfer(address(0), account, amount);
- }
- /**
- * @dev Destroys `amount` tokens from `account`, reducing the
- * total supply.
- *
- * Emits a {Transfer} event with `to` set to the zero address.
- *
- * Requirements:
- *
- * - `account` cannot be the zero address.
- * - `account` must have at least `amount` tokens.
- */
- function _burn(address account, uint256 amount) internal virtual {
- require(account != address(0), "ERC20: burn from the zero address");
- _beforeTokenTransfer(account, address(0), amount);
- uint256 accountBalance = _balances[account];
- require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
- _balances[account] = accountBalance - amount;
- _totalSupply -= amount;
- emit Transfer(account, address(0), amount);
- }
- /**
- * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
- *
- * This internal function is equivalent to `approve`, and can be used to
- * e.g. set automatic allowances for certain subsystems, etc.
- *
- * Emits an {Approval} event.
- *
- * Requirements:
- *
- * - `owner` cannot be the zero address.
- * - `spender` cannot be the zero address.
- */
- function _approve(address owner, address spender, uint256 amount) internal virtual {
- require(owner != address(0), "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 Hook that is called before any transfer of tokens. This includes
- * minting and burning.
- *
- * Calling conditions:
- *
- * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
- * will be to transferred to `to`.
- * - when `from` is zero, `amount` tokens will be minted for `to`.
- * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
- * - `from` and `to` are never both zero.
- *
- * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
- */
- function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
- uint256[45] private __gap;
- }
- // ----------------------------------------------------------------------------
- // Karma Contract
- // ----------------------------------------------------------------------------
- contract Karma is Initializable, ERC20Upgradeable
- {
- function initialize(string memory name, string memory symbol, uint256 initialSupply) public virtual initializer {
- __ERC20_init(name, symbol);
- _mint(_msgSender(), initialSupply);
- }
- }
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