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pragma solidity ^0.8.0;
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abstract contract Context {
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function _msgSender() internal view virtual returns (address) {
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return msg.sender;
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}
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function _msgData() internal view virtual returns (bytes calldata) {
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return msg.data;
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}
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}
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pragma solidity ^0.8.0;
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interface IERC20 {
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event Transfer(address indexed from, address indexed to, uint256 value);
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event Approval(address indexed owner, address indexed spender, uint256 value);
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function totalSupply() external view returns (uint256);
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function balanceOf(address account) external view returns (uint256);
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function transfer(address to, uint256 amount) external returns (bool);
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function allowance(address owner, address spender) external view returns (uint256);
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function approve(address spender, uint256 amount) external returns (bool);
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function transferFrom(
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address from,
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address to,
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uint256 amount
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) external returns (bool);
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}
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pragma solidity ^0.8.0;
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interface IERC20Metadata is IERC20 {
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function name() external view returns (string memory);
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function symbol() external view returns (string memory);
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function decimals() external view returns (uint8);
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}
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pragma solidity ^0.8.0;
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contract ERC20 is Context, IERC20, IERC20Metadata {
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mapping(address => uint256) private _balances;
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mapping(address => mapping(address => uint256)) private _allowances;
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uint256 private _totalSupply;
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string private _name;
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string private _symbol;
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constructor(string memory name_, string memory symbol_) {
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_name = name_;
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_symbol = symbol_;
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}
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function name() public view virtual override returns (string memory) {
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return _name;
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}
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function symbol() public view virtual override returns (string memory) {
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return _symbol;
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}
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function decimals() public view virtual override returns (uint8) {
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return 18;
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}
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function totalSupply() public view virtual override returns (uint256) {
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return _totalSupply;
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}
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function balanceOf(address account) public view virtual override returns (uint256) {
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return _balances[account];
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}
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function transfer(address to, uint256 amount) public virtual override returns (bool) {
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address owner = _msgSender();
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_transfer(owner, to, amount);
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return true;
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}
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function allowance(address owner, address spender) public view virtual override returns (uint256) {
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return _allowances[owner][spender];
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}
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function approve(address spender, uint256 amount) public virtual override returns (bool) {
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address owner = _msgSender();
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_approve(owner, spender, amount);
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return true;
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}
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function transferFrom(
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address from,
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address to,
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uint256 amount
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) public virtual override returns (bool) {
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address spender = _msgSender();
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_spendAllowance(from, spender, amount);
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_transfer(from, to, amount);
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return true;
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}
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function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
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address owner = _msgSender();
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_approve(owner, spender, allowance(owner, spender) + addedValue);
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return true;
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}
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function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
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address owner = _msgSender();
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uint256 currentAllowance = allowance(owner, spender);
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require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
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unchecked {
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_approve(owner, spender, currentAllowance - subtractedValue);
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}
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return true;
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}
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function _transfer(
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address from,
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address to,
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uint256 amount
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) internal virtual {
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require(from != address(0), "ERC20: transfer from the zero address");
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require(to != address(0), "ERC20: transfer to the zero address");
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_beforeTokenTransfer(from, to, amount);
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uint256 fromBalance = _balances[from];
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require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
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unchecked {
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_balances[from] = fromBalance - amount;
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}
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_balances[to] += amount;
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emit Transfer(from, to, amount);
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_afterTokenTransfer(from, to, amount);
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}
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function _mint(address account, uint256 amount) internal virtual {
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require(account != address(0), "ERC20: mint to the zero address");
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_beforeTokenTransfer(address(0), account, amount);
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_totalSupply += amount;
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_balances[account] += amount;
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emit Transfer(address(0), account, amount);
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_afterTokenTransfer(address(0), account, amount);
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}
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function _burn(address account, uint256 amount) internal virtual {
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require(account != address(0), "ERC20: burn from the zero address");
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_beforeTokenTransfer(account, address(0), amount);
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uint256 accountBalance = _balances[account];
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require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
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unchecked {
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_balances[account] = accountBalance - amount;
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}
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_totalSupply -= amount;
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emit Transfer(account, address(0), amount);
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_afterTokenTransfer(account, address(0), amount);
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}
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function _approve(
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address owner,
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address spender,
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uint256 amount
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) internal virtual {
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require(owner != address(0), "ERC20: approve from the zero address");
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require(spender != address(0), "ERC20: approve to the zero address");
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_allowances[owner][spender] = amount;
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emit Approval(owner, spender, amount);
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}
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function _spendAllowance(
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address owner,
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address spender,
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uint256 amount
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) internal virtual {
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uint256 currentAllowance = allowance(owner, spender);
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if (currentAllowance != type(uint256).max) {
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require(currentAllowance >= amount, "ERC20: insufficient allowance");
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unchecked {
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_approve(owner, spender, currentAllowance - amount);
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}
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}
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}
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function _beforeTokenTransfer(
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address from,
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address to,
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uint256 amount
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) internal virtual {}
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function _afterTokenTransfer(
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address from,
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address to,
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uint256 amount
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) internal virtual {}
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}
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pragma solidity ^0.8.4;
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contract GEMS is ERC20 {
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constructor() ERC20("Teh Treasure Hunter", "GEMS") {
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_mint(msg.sender, 100000000 * 10 ** decimals());
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}
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} |