Contract Source Code:
// SPDX-License-Identifier: AGPL-3.0-or-later
pragma solidity 0.7.5;
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @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) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
/**
* @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 sub(a, b, "SafeMath: subtraction overflow");
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
/**
* @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) {
// 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 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
/**
* @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 div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts 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) {
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @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.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
// babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
function sqrrt(uint256 a) internal pure returns (uint c) {
if (a > 3) {
c = a;
uint b = add( div( a, 2), 1 );
while (b < c) {
c = b;
b = div( add( div( a, b ), b), 2 );
}
} else if (a != 0) {
c = 1;
}
}
/*
* Expects percentage to be trailed by 00,
*/
function percentageAmount( uint256 total_, uint8 percentage_ ) internal pure returns ( uint256 percentAmount_ ) {
return div( mul( total_, percentage_ ), 1000 );
}
/*
* Expects percentage to be trailed by 00,
*/
function substractPercentage( uint256 total_, uint8 percentageToSub_ ) internal pure returns ( uint256 result_ ) {
return sub( total_, div( mul( total_, percentageToSub_ ), 1000 ) );
}
function percentageOfTotal( uint256 part_, uint256 total_ ) internal pure returns ( uint256 percent_ ) {
return div( mul(part_, 100) , total_ );
}
/**
* Taken from Hypersonic https://github.com/M2629/HyperSonic/blob/main/Math.sol
* @dev Returns the average of two numbers. The result is rounded towards
* zero.
*/
function average(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b) / 2 can overflow, so we distribute
return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
}
function quadraticPricing( uint256 payment_, uint256 multiplier_ ) internal pure returns (uint256) {
return sqrrt( mul( multiplier_, payment_ ) );
}
function bondingCurve( uint256 supply_, uint256 multiplier_ ) internal pure returns (uint256) {
return mul( multiplier_, supply_ );
}
}
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies in extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
// solhint-disable-next-line no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain`call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return _functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
// function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
// require(address(this).balance >= value, "Address: insufficient balance for call");
// return _functionCallWithValue(target, data, value, errorMessage);
// }
function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: value }(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.3._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.3._
*/
function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
function addressToString(address _address) internal pure returns(string memory) {
bytes32 _bytes = bytes32(uint256(_address));
bytes memory HEX = "0123456789abcdef";
bytes memory _addr = new bytes(42);
_addr[0] = '0';
_addr[1] = 'x';
for(uint256 i = 0; i < 20; i++) {
_addr[2+i*2] = HEX[uint8(_bytes[i + 12] >> 4)];
_addr[3+i*2] = HEX[uint8(_bytes[i + 12] & 0x0f)];
}
return string(_addr);
}
}
interface IERC20 {
/**
* @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);
}
abstract contract ERC20
is
IERC20
{
using SafeMath for uint256;
// TODO comment actual hash value.
bytes32 constant private ERC20TOKEN_ERC1820_INTERFACE_ID = keccak256( "ERC20Token" );
// Present in ERC777
mapping (address => uint256) internal _balances;
// Present in ERC777
mapping (address => mapping (address => uint256)) internal _allowances;
// Present in ERC777
uint256 internal _totalSupply;
// Present in ERC777
string internal _name;
// Present in ERC777
string internal _symbol;
// Present in ERC777
uint8 internal _decimals;
/**
* @dev Sets the values for {name} and {symbol}, initializes {decimals} with
* a default value of 18.
*
* To select a different value for {decimals}, use {_setupDecimals}.
*
* All three of these values are immutable: they can only be set once during
* construction.
*/
constructor (string memory name_, string memory symbol_, uint8 decimals_) {
_name = name_;
_symbol = symbol_;
_decimals = decimals_;
}
/**
* @dev Returns the name of the token.
*/
// Present in ERC777
function name() public view returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
// Present in ERC777
function symbol() public view 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 {_setupDecimals} is
* called.
*
* 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}.
*/
// Present in ERC777
function decimals() public view returns (uint8) {
return _decimals;
}
/**
* @dev See {IERC20-totalSupply}.
*/
// Present in ERC777
function totalSupply() public view override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
// Present in ERC777
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`.
*/
// Overrideen in ERC777
// Confirm that this behavior changes
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(msg.sender, recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
// Present in ERC777
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.
*/
// Present in ERC777
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(msg.sender, 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`.
*/
// Present in ERC777
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, msg.sender, _allowances[sender][msg.sender].sub(amount, "ERC20: transfer amount exceeds allowance"));
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(msg.sender, spender, _allowances[msg.sender][spender].add(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) {
_approve(msg.sender, spender, _allowances[msg.sender][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
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);
_balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
_balances[recipient] = _balances[recipient].add(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.
*/
// Present in ERC777
function _mint(address account_, uint256 ammount_) internal virtual {
require(account_ != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address( this ), account_, ammount_);
_totalSupply = _totalSupply.add(ammount_);
_balances[account_] = _balances[account_].add(ammount_);
emit Transfer(address( this ), account_, ammount_);
}
/**
* @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.
*/
// Present in ERC777
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
_balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
_totalSupply = _totalSupply.sub(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.
*/
// Present in ERC777
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 Sets {decimals} to a value other than the default one of 18.
*
* WARNING: This function should only be called from the constructor. Most
* applications that interact with token contracts will not expect
* {decimals} to ever change, and may work incorrectly if it does.
*/
// Considering deprication to reduce size of bytecode as changing _decimals to internal acheived the same functionality.
// function _setupDecimals(uint8 decimals_) internal {
// _decimals = decimals_;
// }
/**
* @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].
*/
// Present in ERC777
function _beforeTokenTransfer( address from_, address to_, uint256 amount_ ) internal virtual { }
}
library Counters {
using SafeMath for uint256;
struct Counter {
// This variable should never be directly accessed by users of the library: interactions must be restricted to
// the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
// this feature: see https://github.com/ethereum/solidity/issues/4637
uint256 _value; // default: 0
}
function current(Counter storage counter) internal view returns (uint256) {
return counter._value;
}
function increment(Counter storage counter) internal {
// The {SafeMath} overflow check can be skipped here, see the comment at the top
counter._value += 1;
}
function decrement(Counter storage counter) internal {
counter._value = counter._value.sub(1);
}
}
interface IERC2612Permit {
/**
* @dev Sets `amount` as the allowance of `spender` over `owner`'s tokens,
* given `owner`'s signed approval.
*
* IMPORTANT: The same issues {IERC20-approve} has related to transaction
* ordering also apply here.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
* - `deadline` must be a timestamp in the future.
* - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
* over the EIP712-formatted function arguments.
* - the signature must use ``owner``'s current nonce (see {nonces}).
*
* For more information on the signature format, see the
* https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
* section].
*/
function permit(
address owner,
address spender,
uint256 amount,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external;
/**
* @dev Returns the current ERC2612 nonce for `owner`. This value must be
* included whenever a signature is generated for {permit}.
*
* Every successful call to {permit} increases ``owner``'s nonce by one. This
* prevents a signature from being used multiple times.
*/
function nonces(address owner) external view returns (uint256);
}
abstract contract ERC20Permit is ERC20, IERC2612Permit {
using Counters for Counters.Counter;
mapping(address => Counters.Counter) private _nonces;
// keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
bytes32 public DOMAIN_SEPARATOR;
constructor() {
uint256 chainID;
assembly {
chainID := chainid()
}
DOMAIN_SEPARATOR = keccak256(abi.encode(
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
keccak256(bytes(name())),
keccak256(bytes("1")), // Version
chainID,
address(this)
));
}
/**
* @dev See {IERC2612Permit-permit}.
*
*/
function permit(
address owner,
address spender,
uint256 amount,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) public virtual override {
require(block.timestamp <= deadline, "Permit: expired deadline");
bytes32 hashStruct =
keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, amount, _nonces[owner].current(), deadline));
bytes32 _hash = keccak256(abi.encodePacked(uint16(0x1901), DOMAIN_SEPARATOR, hashStruct));
address signer = ecrecover(_hash, v, r, s);
require(signer != address(0) && signer == owner, "ZeroSwapPermit: Invalid signature");
_nonces[owner].increment();
_approve(owner, spender, amount);
}
/**
* @dev See {IERC2612Permit-nonces}.
*/
function nonces(address owner) public view override returns (uint256) {
return _nonces[owner].current();
}
}
interface IOwnable {
function manager() external view returns (address);
function renounceManagement() external;
function pushManagement( address newOwner_ ) external;
function pullManagement() external;
}
contract Ownable is IOwnable {
address internal _owner;
address internal _newOwner;
event OwnershipPushed(address indexed previousOwner, address indexed newOwner);
event OwnershipPulled(address indexed previousOwner, address indexed newOwner);
constructor () {
_owner = msg.sender;
emit OwnershipPushed( address(0), _owner );
}
function manager() public view override returns (address) {
return _owner;
}
modifier onlyManager() {
require( _owner == msg.sender, "Ownable: caller is not the owner" );
_;
}
function renounceManagement() public virtual override onlyManager() {
emit OwnershipPushed( _owner, address(0) );
_owner = address(0);
}
function pushManagement( address newOwner_ ) public virtual override onlyManager() {
require( newOwner_ != address(0), "Ownable: new owner is the zero address");
emit OwnershipPushed( _owner, newOwner_ );
_newOwner = newOwner_;
}
function pullManagement() public virtual override {
require( msg.sender == _newOwner, "Ownable: must be new owner to pull");
emit OwnershipPulled( _owner, _newOwner );
_owner = _newOwner;
}
}
contract sSnoop is ERC20Permit, Ownable {
using SafeMath for uint256;
modifier onlyStakingContract() {
require( msg.sender == stakingContract );
_;
}
address public stakingContract;
address public initializer;
event LogSupply(uint256 indexed epoch, uint256 timestamp, uint256 totalSupply );
event LogRebase( uint256 indexed epoch, uint256 rebase, uint256 index );
event LogStakingContractUpdated( address stakingContract );
struct Rebase {
uint epoch;
uint rebase; // 18 decimals
uint totalStakedBefore;
uint totalStakedAfter;
uint amountRebased;
uint index;
uint blockNumberOccured;
}
Rebase[] public rebases;
uint public INDEX;
uint256 private constant MAX_UINT256 = ~uint256(0);
uint256 private constant INITIAL_FRAGMENTS_SUPPLY = 20000000000 * 10**9; // 20b
// TOTAL_GONS is a multiple of INITIAL_FRAGMENTS_SUPPLY so that _gonsPerFragment is an integer.
// Use the highest value that fits in a uint256 for max granularity.
uint256 private constant TOTAL_GONS = MAX_UINT256 - (MAX_UINT256 % INITIAL_FRAGMENTS_SUPPLY);
// MAX_SUPPLY = maximum integer < (sqrt(4*TOTAL_GONS + 1) - 1) / 2
uint256 private constant MAX_SUPPLY = ~uint128(0); // (2^128) - 1
uint256 private _gonsPerFragment;
mapping(address => uint256) private _gonBalances;
mapping ( address => mapping ( address => uint256 ) ) private _allowedValue;
constructor() ERC20("Staked Snoop", "sSNOOP", 9) ERC20Permit() {
initializer = msg.sender;
_totalSupply = INITIAL_FRAGMENTS_SUPPLY;
_gonsPerFragment = TOTAL_GONS.div(_totalSupply);
}
function initialize( address stakingContract_ ) external returns ( bool ) {
require( msg.sender == initializer );
require( stakingContract_ != address(0) );
stakingContract = stakingContract_;
_gonBalances[ stakingContract ] = TOTAL_GONS;
emit Transfer( address(0x0), stakingContract, _totalSupply );
emit LogStakingContractUpdated( stakingContract_ );
initializer = address(0);
return true;
}
function setIndex( uint _INDEX ) external onlyManager() returns ( bool ) {
require( INDEX == 0 );
INDEX = gonsForBalance( _INDEX );
return true;
}
/**
@notice increases sSNOOP supply to increase staking balances relative to profit_
@param profit_ uint256
@return uint256
*/
function rebase( uint256 profit_, uint epoch_ ) public onlyStakingContract() returns ( uint256 ) {
uint256 rebaseAmount;
uint256 circulatingSupply_ = circulatingSupply();
if ( profit_ == 0 ) {
emit LogSupply( epoch_, block.timestamp, _totalSupply );
emit LogRebase( epoch_, 0, index() );
return _totalSupply;
} else if ( circulatingSupply_ > 0 ){
rebaseAmount = profit_.mul( _totalSupply ).div( circulatingSupply_ );
} else {
rebaseAmount = profit_;
}
_totalSupply = _totalSupply.add( rebaseAmount );
if ( _totalSupply > MAX_SUPPLY ) {
_totalSupply = MAX_SUPPLY;
}
_gonsPerFragment = TOTAL_GONS.div( _totalSupply );
_storeRebase( circulatingSupply_, profit_, epoch_ );
return _totalSupply;
}
/**
@notice emits event with data about rebase
@param previousCirculating_ uint
@param profit_ uint
@param epoch_ uint
@return bool
*/
function _storeRebase( uint previousCirculating_, uint profit_, uint epoch_ ) internal returns ( bool ) {
uint rebasePercent = profit_.mul( 1e18 ).div( previousCirculating_ );
rebases.push( Rebase ( {
epoch: epoch_,
rebase: rebasePercent, // 18 decimals
totalStakedBefore: previousCirculating_,
totalStakedAfter: circulatingSupply(),
amountRebased: profit_,
index: index(),
blockNumberOccured: block.number
}));
emit LogSupply( epoch_, block.timestamp, _totalSupply );
emit LogRebase( epoch_, rebasePercent, index() );
return true;
}
function balanceOf( address who ) public view override returns ( uint256 ) {
return _gonBalances[ who ].div( _gonsPerFragment );
}
function gonsForBalance( uint amount ) public view returns ( uint ) {
return amount.mul( _gonsPerFragment );
}
function balanceForGons( uint gons ) public view returns ( uint ) {
return gons.div( _gonsPerFragment );
}
// Staking contract holds excess sSNOOP
function circulatingSupply() public view returns ( uint ) {
return _totalSupply.sub( balanceOf( stakingContract ) );
}
function index() public view returns ( uint ) {
return balanceForGons( INDEX );
}
function transfer( address to, uint256 value ) public override returns (bool) {
uint256 gonValue = value.mul( _gonsPerFragment );
_gonBalances[ msg.sender ] = _gonBalances[ msg.sender ].sub( gonValue );
_gonBalances[ to ] = _gonBalances[ to ].add( gonValue );
emit Transfer( msg.sender, to, value );
return true;
}
function allowance( address owner_, address spender ) public view override returns ( uint256 ) {
return _allowedValue[ owner_ ][ spender ];
}
function transferFrom( address from, address to, uint256 value ) public override returns ( bool ) {
_allowedValue[ from ][ msg.sender ] = _allowedValue[ from ][ msg.sender ].sub( value );
emit Approval( from, msg.sender, _allowedValue[ from ][ msg.sender ] );
uint256 gonValue = gonsForBalance( value );
_gonBalances[ from ] = _gonBalances[from].sub( gonValue );
_gonBalances[ to ] = _gonBalances[to].add( gonValue );
emit Transfer( from, to, value );
return true;
}
function approve( address spender, uint256 value ) public override returns (bool) {
_allowedValue[ msg.sender ][ spender ] = value;
emit Approval( msg.sender, spender, value );
return true;
}
// What gets called in a permit
function _approve( address owner, address spender, uint256 value ) internal override virtual {
_allowedValue[owner][spender] = value;
emit Approval( owner, spender, value );
}
function increaseAllowance( address spender, uint256 addedValue ) public override returns (bool) {
_allowedValue[ msg.sender ][ spender ] = _allowedValue[ msg.sender ][ spender ].add( addedValue );
emit Approval( msg.sender, spender, _allowedValue[ msg.sender ][ spender ] );
return true;
}
function decreaseAllowance( address spender, uint256 subtractedValue ) public override returns (bool) {
uint256 oldValue = _allowedValue[ msg.sender ][ spender ];
if (subtractedValue >= oldValue) {
_allowedValue[ msg.sender ][ spender ] = 0;
} else {
_allowedValue[ msg.sender ][ spender ] = oldValue.sub( subtractedValue );
}
emit Approval( msg.sender, spender, _allowedValue[ msg.sender ][ spender ] );
return true;
}
}