Cryo Explorer Ethereum Mainnet

// SPDX-License-Identifier: MIT

/**
 * @title DEC Token - ERC20 Smart Contract
 * @dev Developed by the DEC Developers team.
 * Special thanks to OpenZeppelin for their reliable ERC20 libraries.
 */

pragma solidity ^0.8.26;

interface IERC20 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );

    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(address to, uint256 value) external returns (bool);

    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);
}

interface IERC20Metadata is IERC20 {
    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

interface IERC20Errors {
    error ERC20InsufficientBalance(
        address sender,
        uint256 balance,
        uint256 needed
    );
    error ERC20InvalidSender(address sender);
    error ERC20InvalidReceiver(address receiver);
    error ERC20InsufficientAllowance(
        address spender,
        uint256 allowance,
        uint256 needed
    );
    error ERC20InvalidApprover(address approver);
    error ERC20InvalidSpender(address spender);
}

abstract contract ERC20 is Context, IERC20, IERC20Metadata, IERC20Errors {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    uint256 private _totalSupply;
    string private _name;
    string private _symbol;

    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    function name() public view virtual returns (string memory) {
        return _name;
    }

    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual returns (uint8) {
        return 18;
    }

    function totalSupply() public view virtual returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual returns (uint256) {
        return _balances[account];
    }

    function transfer(address to, uint256 value) public virtual returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, value);
        return true;
    }

    function allowance(address owner, address spender)
        public
        view
        virtual
        returns (uint256)
    {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 value)
        public
        virtual
        returns (bool)
    {
        address owner = _msgSender();
        _approve(owner, spender, value);
        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) public virtual returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, value);
        _transfer(from, to, value);
        return true;
    }

    function _transfer(
        address from,
        address to,
        uint256 value
    ) internal {
        if (from == address(0)) {
            revert ERC20InvalidSender(address(0));
        }
        if (to == address(0)) {
            revert ERC20InvalidReceiver(address(0));
        }
        _update(from, to, value);
    }

    function _update(
        address from,
        address to,
        uint256 value
    ) internal virtual {
        if (from == address(0)) {
            _totalSupply += value;
        } else {
            uint256 fromBalance = _balances[from];
            if (fromBalance < value) {
                revert ERC20InsufficientBalance(from, fromBalance, value);
            }
            unchecked {
                _balances[from] = fromBalance - value;
            }
        }

        unchecked {
            _balances[to] += value;
        }

        emit Transfer(from, to, value);
    }

    function _approve(
        address owner,
        address spender,
        uint256 value
    ) internal {
        _approve(owner, spender, value, true);
    }

    function _approve(
        address owner,
        address spender,
        uint256 value,
        bool emitEvent
    ) internal virtual {
        if (owner == address(0)) {
            revert ERC20InvalidApprover(address(0));
        }
        if (spender == address(0)) {
            revert ERC20InvalidSpender(address(0));
        }
        _allowances[owner][spender] = value;
        if (emitEvent) {
            emit Approval(owner, spender, value);
        }
    }

    function _spendAllowance(
        address owner,
        address spender,
        uint256 value
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            if (currentAllowance < value) {
                revert ERC20InsufficientAllowance(
                    spender,
                    currentAllowance,
                    value
                );
            }
            unchecked {
                _approve(owner, spender, currentAllowance - value, false);
            }
        }
    }
}

contract DECToken is ERC20 {
    constructor() ERC20("DEC Token", "DECT") {
        _update(address(0), msg.sender, 1000000000 * 10**decimals());
    }
}