Contract Name:
XplosiveEthereum
Contract Source Code:
// SPDX-License-Identifier: UNLICENSED
/**
*
* ██╗ ██╗███████╗████████╗██╗ ██╗
* ╚██╗██╔╝██╔════╝╚══██╔══╝██║ ██║
* ╚███╔╝ █████╗ ██║ ███████║
* ██╔██╗ ██╔══╝ ██║ ██╔══██║
* ██╔╝ ██╗███████╗ ██║ ██║ ██║
* ╚═╝ ╚═╝╚══════╝ ╚═╝ ╚═╝ ╚═╝
*
* An Ethereum pegged
* base-down, burn-up currency.
*
* https://xEth.finance
*
*
**/
/// SWC-103: Floating Pragma
pragma solidity 0.6.12;
import "./XplosiveSafeMath.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import '@openzeppelin/contracts/utils/Pausable.sol';
import './XplosiveRebaser.sol';
contract XplosiveEthereum is Ownable, Pausable, Rebasable
{
using XplosiveSafeMath for uint256;
event Transfer(address indexed from, address indexed to, uint amount);
event Approval(address indexed owner, address indexed spender, uint amount);
event Rebase(uint256 indexed epoch, uint256 scalingFactor);
event WhitelistFrom(address _addr, bool _whitelisted);
event WhitelistTo(address _addr, bool _whitelisted);
event WhitelistRebase(address _addr, bool _whitelisted);
string public name = "xETH-G";
string public symbol = "xETH-G";
uint8 public decimals = 18;
// address public rebaser;
address public rewardAddress;
/**
* @notice Internal decimals used to handle scaling factor
*/
uint256 public constant internalDecimals = 10**24;
/**
* @notice Used for percentage maths
*/
uint256 public constant BASE = 10**18;
/**
* @notice Scaling factor that adjusts everyone's balances
*/
uint256 public xETHScalingFactor = BASE;
mapping (address => uint256) internal _xETHBalances;
mapping (address => mapping (address => uint256)) internal _allowedFragments;
mapping(address => bool) public whitelistFrom;
mapping(address => bool) public whitelistTo;
mapping(address => bool) public whitelistRebase;
address public noRebaseAddress;
uint256 initSupply = 0;
uint256 _totalSupply = 0;
uint16 public SELL_FEE = 33;
uint16 public TX_FEE = 50;
constructor( uint256 initialSupply, address initialSupplyAddr )
public
Ownable()
Pausable()
Rebasable()
{
_mint(initialSupplyAddr,initialSupply);
}
function totalSupply()
public
view
returns (uint256)
{
return _totalSupply;
}
function getSellBurn(uint256 value)
public
view
whenNotPaused
returns (uint256)
{
uint256 nPercent = value.divRound(SELL_FEE);
return nPercent;
}
function getTxBurn(uint256 value)
public
view
whenNotPaused
returns (uint256)
{
uint256 nPercent = value.divRound(TX_FEE);
return nPercent;
}
function _isWhitelisted(address _from, address _to)
internal
view
returns (bool)
{
return whitelistFrom[_from]||whitelistTo[_to];
}
function _isRebaseWhitelisted(address _addr)
internal
view
returns (bool)
{
return whitelistRebase[_addr];
}
function setWhitelistedTo(address _addr, bool _whitelisted)
external
onlyOwner
{
emit WhitelistTo(_addr, _whitelisted);
whitelistTo[_addr] = _whitelisted;
}
function setTxFee(uint16 fee)
external
onlyRebaser
whenNotPaused
{
TX_FEE = fee;
}
function setSellFee(uint16 fee)
external
onlyRebaser
whenNotPaused
{
SELL_FEE = fee;
}
function setWhitelistedFrom(address _addr, bool _whitelisted)
external
onlyOwner
{
emit WhitelistFrom(_addr, _whitelisted);
whitelistFrom[_addr] = _whitelisted;
}
function setWhitelistedRebase(address _addr, bool _whitelisted)
external
onlyOwner
{
emit WhitelistRebase(_addr, _whitelisted);
whitelistRebase[_addr] = _whitelisted;
}
function setNoRebaseAddress(address _addr)
external
onlyOwner
{
noRebaseAddress = _addr;
}
/**
* @notice Computes the current max scaling factor
*/
function maxScalingFactor()
external
view
whenNotPaused
returns (uint256)
{
return _maxScalingFactor();
}
function _maxScalingFactor()
internal
view
returns (uint256)
{
// scaling factor can only go up to 2**256-1 = initSupply * xETHScalingFactor
// this is used to check if xETHScalingFactor will be too high to compute balances when rebasing.
return uint256(-1) / initSupply;
}
function _mint(address to, uint256 amount)
internal
{
// increase totalSupply
_totalSupply = _totalSupply.add(amount);
// get underlying value
uint256 xETHValue = amount.mul(internalDecimals).div(xETHScalingFactor);
// increase initSupply
initSupply = initSupply.add(xETHValue);
// make sure the mint didnt push maxScalingFactor too low
require(xETHScalingFactor <= _maxScalingFactor(), "max scaling factor too low");
// add balance
_xETHBalances[to] = _xETHBalances[to].add(xETHValue);
emit Transfer(address(0),to,amount);
}
/* - ERC20 functionality - */
/**
* @dev Transfer tokens to a specified address.
* @param to The address to transfer to.
* @param value The amount to be transferred.
* @return True on success, false otherwise.
*/
function transfer(address to, uint256 value)
external
whenNotPaused
returns (bool)
{
// underlying balance is stored in xETH, so divide by current scaling factor
// note, this means as scaling factor grows, dust will be untransferrable.
// minimum transfer value == xETHScalingFactor / 1e24;
// get amount in underlying
//from noRebaseWallet
if(_isRebaseWhitelisted(msg.sender))
{
uint256 noReValue = value.mul(internalDecimals).div(BASE);
uint256 noReNextValue = noReValue.mul(BASE).div(xETHScalingFactor);
_xETHBalances[msg.sender] = _xETHBalances[msg.sender].sub(noReValue); //value==underlying
_xETHBalances[to] = _xETHBalances[to].add(noReNextValue);
emit Transfer(msg.sender, to, value);
}
else if(_isRebaseWhitelisted(to))
{
uint256 fee = getSellBurn(value);
uint256 tokensToBurn = fee/2;
uint256 tokensForRewards = fee-tokensToBurn;
uint256 tokensToTransfer = value-fee;
uint256 xETHValue = value.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueKeep = tokensToTransfer.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueReward = tokensForRewards.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHNextValue = xETHValueKeep.mul(xETHScalingFactor).div(BASE);
_totalSupply = _totalSupply-fee;
_xETHBalances[address(0)] = _xETHBalances[address(0)].add(fee/2);
_xETHBalances[msg.sender] = _xETHBalances[msg.sender].sub(xETHValue);
_xETHBalances[to] = _xETHBalances[to].add(xETHNextValue);
_xETHBalances[rewardAddress] = _xETHBalances[rewardAddress].add(xETHValueReward);
emit Transfer(msg.sender, to, tokensToTransfer);
emit Transfer(msg.sender, address(0), tokensToBurn);
emit Transfer(msg.sender, rewardAddress, tokensForRewards);
}
else
{
if(!_isWhitelisted(msg.sender, to))
{
uint256 fee = getTxBurn(value);
uint256 tokensToBurn = fee/2;
uint256 tokensForRewards = fee-tokensToBurn;
uint256 tokensToTransfer = value-fee;
uint256 xETHValue = value.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueKeep = tokensToTransfer.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueReward = tokensForRewards.mul(internalDecimals).div(xETHScalingFactor);
_totalSupply = _totalSupply-fee;
_xETHBalances[address(0)] = _xETHBalances[address(0)].add(fee/2);
_xETHBalances[msg.sender] = _xETHBalances[msg.sender].sub(xETHValue);
_xETHBalances[to] = _xETHBalances[to].add(xETHValueKeep);
_xETHBalances[rewardAddress] = _xETHBalances[rewardAddress].add(xETHValueReward);
emit Transfer(msg.sender, to, tokensToTransfer);
emit Transfer(msg.sender, address(0), tokensToBurn);
emit Transfer(msg.sender, rewardAddress, tokensForRewards);
}
else
{
uint256 xETHValue = value.mul(internalDecimals).div(xETHScalingFactor);
_xETHBalances[msg.sender] = _xETHBalances[msg.sender].sub(xETHValue);
_xETHBalances[to] = _xETHBalances[to].add(xETHValue);
emit Transfer(msg.sender, to, xETHValue);
}
}
return true;
}
/**
* @dev Transfer tokens from one address to another.
* @param from The address you want to send tokens from.
* @param to The address you want to transfer to.
* @param value The amount of tokens to be transferred.
*/
function transferFrom(address from, address to, uint256 value)
external
whenNotPaused
returns (bool)
{
// decrease allowance
_allowedFragments[from][msg.sender] = _allowedFragments[from][msg.sender].sub(value);
if(_isRebaseWhitelisted(from))
{
uint256 noReValue = value.mul(internalDecimals).div(BASE);
uint256 noReNextValue = noReValue.mul(BASE).div(xETHScalingFactor);
_xETHBalances[from] = _xETHBalances[from].sub(noReValue); //value==underlying
_xETHBalances[to] = _xETHBalances[to].add(noReNextValue);
emit Transfer(from, to, value);
}
else if(_isRebaseWhitelisted(to))
{
uint256 fee = getSellBurn(value);
uint256 tokensForRewards = fee-(fee/2);
uint256 tokensToTransfer = value-fee;
uint256 xETHValue = value.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueKeep = tokensToTransfer.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueReward = tokensForRewards.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHNextValue = xETHValueKeep.mul(xETHScalingFactor).div(BASE);
_totalSupply = _totalSupply-fee;
_xETHBalances[from] = _xETHBalances[from].sub(xETHValue);
_xETHBalances[to] = _xETHBalances[to].add(xETHNextValue);
_xETHBalances[rewardAddress] = _xETHBalances[rewardAddress].add(xETHValueReward);
_xETHBalances[address(0)] = _xETHBalances[address(0)].add(fee/2);
emit Transfer(from, to, tokensToTransfer);
emit Transfer(from, address(0), fee/2);
emit Transfer(from, rewardAddress, tokensForRewards);
}
else
{
if(!_isWhitelisted(from, to))
{
uint256 fee = getTxBurn(value);
uint256 tokensToBurn = fee/2;
uint256 tokensForRewards = fee-tokensToBurn;
uint256 tokensToTransfer = value-fee;
uint256 xETHValue = value.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueKeep = tokensToTransfer.mul(internalDecimals).div(xETHScalingFactor);
uint256 xETHValueReward = tokensForRewards.mul(internalDecimals).div(xETHScalingFactor);
_totalSupply = _totalSupply-fee;
_xETHBalances[address(0)] = _xETHBalances[address(0)].add(fee/2);
_xETHBalances[from] = _xETHBalances[from].sub(xETHValue);
_xETHBalances[to] = _xETHBalances[to].add(xETHValueKeep);
_xETHBalances[rewardAddress] = _xETHBalances[rewardAddress].add(xETHValueReward);
emit Transfer(from, to, tokensToTransfer);
emit Transfer(from, address(0), tokensToBurn);
emit Transfer(from, rewardAddress, tokensForRewards);
}
else
{
uint256 xETHValue = value.mul(internalDecimals).div(xETHScalingFactor);
_xETHBalances[from] = _xETHBalances[from].sub(xETHValue);
_xETHBalances[to] = _xETHBalances[to].add(xETHValue);
emit Transfer(from, to, xETHValue);
}
}
return true;
}
/**
* @param who The address to query.
* @return The balance of the specified address.
*/
function balanceOf(address who)
external
view
returns (uint256)
{
if(_isRebaseWhitelisted(who))
{
return _xETHBalances[who].mul(BASE).div(internalDecimals);
}
else
{
return _xETHBalances[who].mul(xETHScalingFactor).div(internalDecimals);
}
}
/** @notice Currently returns the internal storage amount
* @param who The address to query.
* @return The underlying balance of the specified address.
*/
function balanceOfUnderlying(address who)
external
view
returns (uint256)
{
return _xETHBalances[who];
}
/**
* @dev Function to check the amount of tokens that an owner has allowed to a spender.
* @param owner_ The address which owns the funds.
* @param spender The address which will spend the funds.
* @return The number of tokens still available for the spender.
*/
function allowance(address owner_, address spender)
external
view
whenNotPaused
returns (uint256)
{
return _allowedFragments[owner_][spender];
}
/**
* @dev Approve the passed address to spend the specified amount of tokens on behalf of
* msg.sender. This method is included for ERC20 compatibility.
* increaseAllowance and decreaseAllowance should be used instead.
* Changing an allowance with this method brings the risk that someone may transfer both
* the old and the new allowance - if they are both greater than zero - if a transfer
* transaction is mined before the later approve() call is mined.
*
* @param spender The address which will spend the funds.
* @param value The amount of tokens to be spent.
*/
function approve(address spender, uint256 value)
external
whenNotPaused
returns (bool)
{
_allowedFragments[msg.sender][spender] = value;
emit Approval(msg.sender, spender, value);
return true;
}
/**
* @dev Increase the amount of tokens that an owner has allowed to a spender.
* This method should be used instead of approve() to avoid the double approval vulnerability
* described above.
* @param spender The address which will spend the funds.
* @param addedValue The amount of tokens to increase the allowance by.
*/
function increaseAllowance(address spender, uint256 addedValue)
external
whenNotPaused
returns (bool)
{
_allowedFragments[msg.sender][spender] = _allowedFragments[msg.sender][spender].add(addedValue);
emit Approval(msg.sender, spender, _allowedFragments[msg.sender][spender]);
return true;
}
/**
* @dev Decrease the amount of tokens that an owner has allowed to a spender.
*
* @param spender The address which will spend the funds.
* @param subtractedValue The amount of tokens to decrease the allowance by.
*/
function decreaseAllowance(address spender, uint256 subtractedValue)
external
whenNotPaused
returns (bool)
{
uint256 oldValue = _allowedFragments[msg.sender][spender];
if (subtractedValue >= oldValue)
{
_allowedFragments[msg.sender][spender] = 0;
}
else
{
_allowedFragments[msg.sender][spender] = oldValue.sub(subtractedValue);
}
emit Approval(msg.sender, spender, _allowedFragments[msg.sender][spender]);
return true;
}
function _setRewardAddress(address rewards_)
external
onlyOwner
{
rewardAddress = rewards_;
}
/**
* @notice Initiates a new rebase operation, provided the minimum time period has elapsed.
*
* @dev The supply adjustment equals (totalSupply * DeviationFromTargetRate) / rebaseLag
* Where DeviationFromTargetRate is (MarketOracleRate - targetRate) / targetRate
* and targetRate is CpiOracleRate / baseCpi
*/
function rebase(uint256 epoch, uint256 indexDelta, bool positive)
external
onlyRebaser
whenNotPaused
returns (uint256)
{
if (indexDelta == 0 || !positive)
{
emit Rebase(epoch, xETHScalingFactor);
return _totalSupply;
}
uint256 newScalingFactor = xETHScalingFactor.mul(BASE.add(indexDelta)).div(BASE);
if (newScalingFactor < _maxScalingFactor())
{
xETHScalingFactor = newScalingFactor;
}
else
{
xETHScalingFactor = _maxScalingFactor();
}
_totalSupply = ((initSupply.sub(_xETHBalances[address(0)]).sub(_xETHBalances[noRebaseAddress]))
.mul(xETHScalingFactor).div(internalDecimals))
.add(_xETHBalances[noRebaseAddress].mul(BASE).div(internalDecimals));
emit Rebase(epoch, xETHScalingFactor);
return _totalSupply;
}
}
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.12;
import "@openzeppelin/contracts/access/Ownable.sol";
contract Rebasable is Ownable {
address private _rebaser;
event TransferredRebasership(address indexed previousRebaser, address indexed newRebaser);
constructor() internal {
address msgSender = _msgSender();
_rebaser = msgSender;
emit TransferredRebasership(address(0), msgSender);
}
function Rebaser() public view returns(address) {
return _rebaser;
}
modifier onlyRebaser() {
require(_rebaser == _msgSender(), "caller is not rebaser");
_;
}
function transferRebasership(address newRebaser) public virtual onlyOwner {
require(newRebaser != address(0), "new rebaser is address zero");
emit TransferredRebasership(_rebaser, newRebaser);
_rebaser = newRebaser;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @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 XplosiveSafeMath {
/**
* @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;
}
function ceil(uint256 a, uint256 m) internal pure returns (uint256)
{
uint256 c = add(a,m);
uint256 d = sub(c,1);
return mul(div(d,m),m);
}
function divRound(uint256 x, uint256 y) internal pure returns (uint256) {
require(y != 0, "Div by zero");
uint256 r = x / y;
if (x % y != 0) {
r = r + 1;
}
return r;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/*
* @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 GSN 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 Context {
function _msgSender() internal view virtual returns (address payable) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../GSN/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor () internal {
address msgSender = _msgSender();
_owner = msgSender;
emit OwnershipTransferred(address(0), msgSender);
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(_owner == _msgSender(), "Ownable: caller is not the owner");
_;
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions anymore. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby removing any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
emit OwnershipTransferred(_owner, address(0));
_owner = address(0);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
emit OwnershipTransferred(_owner, newOwner);
_owner = newOwner;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../GSN/Context.sol";
/**
* @dev Contract module which allows children to implement an emergency stop
* mechanism that can be triggered by an authorized account.
*
* This module is used through inheritance. It will make available the
* modifiers `whenNotPaused` and `whenPaused`, which can be applied to
* the functions of your contract. Note that they will not be pausable by
* simply including this module, only once the modifiers are put in place.
*/
contract Pausable is Context {
/**
* @dev Emitted when the pause is triggered by `account`.
*/
event Paused(address account);
/**
* @dev Emitted when the pause is lifted by `account`.
*/
event Unpaused(address account);
bool private _paused;
/**
* @dev Initializes the contract in unpaused state.
*/
constructor () internal {
_paused = false;
}
/**
* @dev Returns true if the contract is paused, and false otherwise.
*/
function paused() public view returns (bool) {
return _paused;
}
/**
* @dev Modifier to make a function callable only when the contract is not paused.
*
* Requirements:
*
* - The contract must not be paused.
*/
modifier whenNotPaused() {
require(!_paused, "Pausable: paused");
_;
}
/**
* @dev Modifier to make a function callable only when the contract is paused.
*
* Requirements:
*
* - The contract must be paused.
*/
modifier whenPaused() {
require(_paused, "Pausable: not paused");
_;
}
/**
* @dev Triggers stopped state.
*
* Requirements:
*
* - The contract must not be paused.
*/
function _pause() internal virtual whenNotPaused {
_paused = true;
emit Paused(_msgSender());
}
/**
* @dev Returns to normal state.
*
* Requirements:
*
* - The contract must be paused.
*/
function _unpause() internal virtual whenPaused {
_paused = false;
emit Unpaused(_msgSender());
}
}