Contract Source Code:
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.6.0;
import '@openzeppelin/contracts/token/ERC20/ERC20.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/math/SafeMath.sol';
contract ATAToken is ERC20, Ownable {
using SafeMath for uint256;
enum VestingCategory {
EARLY_CONTRIBUTORS,
NETWORK_FEES,
PROTOCOL_RESERVE,
PARTNER_ADVISORS,
TEAM,
ECOSYSTEM_COMMUNITY
}
enum VestingType {TIME, BLOCK}
uint256 private constant TOTAL_QUOTA = 100;
uint256 private EARLY_CONTRIBUTORS_QUOTA = 15;
uint256 private NETWORK_FEES_QUOTA = 0;
uint256 private PROTOCOL_RESERVE_QUOTA = 35;
uint256 private PARTNER_ADVISORS_QUOTA = 5;
uint256 private TEAM_QUOTA = 15;
uint256 private ECOSYSTEM_COMMUNITY_QUOTA = 30;
event VestingPlanAdded(uint256 uniqueId);
event VestingPlanRevoked(uint256 uniqueId);
event QuotaAdjusted(
uint256 earlyContributors,
uint256 networkFees,
uint256 protocolReserve,
uint256 parternerAndAdvisor,
uint256 team,
uint256 ecosystemAndCommunity
);
event Withdraw(address beneficiary, uint256 amount);
struct VestingPlan {
uint256 uniqueId; //each vesting plan has a unique id
bool isRevocable; //true if the vesting plan is revocable
bool isRevoked; //true if the vesting plan is revoked
bool accumulateDuringCliff; //true if the token amount is accumulated during cliff
uint256 startTime; //grant start date, in seconds(VestingType.TIME) or block nums(VestingType.BLOCK)
uint256 cliffDuration; //duration of cliff, in seconds(VestingType.TIME) or block nums(VestingType.BLOCK)
uint256 duration; //duration of vesting plan, in seconds(VestingType.TIME) or block nums(VestingType.BLOCK), exclude cliff
uint256 interval; //release interval, in seconds, useless if vestingType is VestingType.BLOCK
uint256 initialAmount; //amount of tokens which will be released at startTime
uint256 totalAmount; //total amount of vesting plan
address beneficiary; //address that benefit from the vesting plan
VestingCategory category; //vesting plan category -e.g. for backers, for team members...
VestingType vestingType; //vesting type, vestingType==VestingType.BLOCK indicates that use block num as timing unit
}
mapping(uint256 => VestingPlan) private _vestingPlans;
mapping(address => uint256[]) private _vestingPlanIds;
mapping(uint256 => uint256) private _released;
mapping(uint32 => uint256) private _categoryVestedAmount;
constructor(uint256 initialSupply) public ERC20('Automata', 'ATA') {
_mint(msg.sender, initialSupply);
}
function addVestingPlan(
address beneficiary,
uint256 totalAmount,
uint256 initialAmount,
uint256 startTime,
uint256 cliffDuration,
uint256 duration,
uint256 interval,
bool accumulateDuringCliff,
bool isRevocable,
VestingCategory category,
VestingType vestingType
) public onlyOwner {
uint256 currentTime = (vestingType == VestingType.TIME ? now : block.number);
//check the startTime
require(startTime > currentTime, 'The start time can not be earlier than the current time');
require(initialAmount <= totalAmount, 'Initial amount can not be greater than the total amount');
//check whether owner's balance is enough
require(balanceOf(owner()) >= totalAmount, "Exceed owner's balance");
//check whether category's balance is enough
require(
(_categoryVestedAmount[uint32(category)] + totalAmount) <=
totalSupply().mul(_getCategoryPercentage(category)).div(TOTAL_QUOTA),
"Exceed category's balance"
);
//generate unique id for vesting plan
uint256 uniqueId = _getUniqueId(beneficiary);
_vestingPlanIds[beneficiary].push(uniqueId);
_vestingPlans[uniqueId] = VestingPlan(
uniqueId,
isRevocable,
false,
accumulateDuringCliff,
startTime,
cliffDuration,
duration,
interval,
initialAmount,
totalAmount,
beneficiary,
category,
vestingType
);
_categoryVestedAmount[uint32(category)] = _categoryVestedAmount[uint32(category)] + totalAmount;
//deposit funds in address(this)
transfer(address(this), totalAmount);
emit VestingPlanAdded(uniqueId);
}
/**
revoke all vesting plan of `beneficiary`
*/
function revokeVestingPlan(uint256 uniqueId) public onlyOwner {
VestingPlan storage plan = _vestingPlans[uniqueId];
require(plan.uniqueId == uniqueId, 'Vesting plan not exist');
require(plan.isRevoked == false, "Vesting plan is already revoked");
require(plan.isRevocable, 'Vesting plan is not revocable');
plan.isRevoked = true;
uint256 unreleasedAmount = _getUnreleasedAmount(uniqueId);
//refund the unreleased tokens to owner
this.transfer(owner(), unreleasedAmount);
emit VestingPlanRevoked(uniqueId);
}
function getVestingPlan(uint256 planUniqueId)
public
view
onlyOwner
returns (
bool isRevocable,
bool isRevoked,
bool accumulateDuringCliff,
uint256 startTime,
uint256 cliffDuration,
uint256 duration,
uint256 interval,
uint256 initialAmount,
uint256 totalAmount,
address beneficiary,
VestingCategory category,
VestingType vestingType
)
// VestingType vestingType
{
VestingPlan memory vestingPlan = _vestingPlans[planUniqueId];
return (
vestingPlan.isRevocable,
vestingPlan.isRevoked,
vestingPlan.accumulateDuringCliff,
vestingPlan.startTime,
vestingPlan.cliffDuration,
vestingPlan.duration,
vestingPlan.interval,
vestingPlan.initialAmount,
vestingPlan.totalAmount,
vestingPlan.beneficiary,
vestingPlan.category,
vestingPlan.vestingType
);
}
function adjustQuota(
uint256 earlyContributors,
uint256 networkFees,
uint256 protocolReserve,
uint256 parternerAndAdvisor,
uint256 team,
uint256 ecosystemAndCommunity
) public onlyOwner {
require(
earlyContributors + networkFees + protocolReserve + parternerAndAdvisor + team + ecosystemAndCommunity ==
100,
'Invalid quota'
);
uint256 totalSupply = totalSupply();
require(
_categoryVestedAmount[uint32(VestingCategory.EARLY_CONTRIBUTORS)] <=
totalSupply.mul(earlyContributors).div(TOTAL_QUOTA),
'Exceed allocated quota, EARLY_CONTRIBUTORS'
);
require(
_categoryVestedAmount[uint32(VestingCategory.NETWORK_FEES)] <=
totalSupply.mul(networkFees).div(TOTAL_QUOTA),
'Exceed allocated quota, NETWORK_FEES'
);
require(
_categoryVestedAmount[uint32(VestingCategory.PROTOCOL_RESERVE)] <=
totalSupply.mul(protocolReserve).div(TOTAL_QUOTA),
'Exceed allocated quota, PROTOCOL_RESERVE'
);
require(
_categoryVestedAmount[uint32(VestingCategory.PARTNER_ADVISORS)] <=
totalSupply.mul(parternerAndAdvisor).div(TOTAL_QUOTA),
'Exceed allocated quota, PARTNER_ADVISORS'
);
require(
_categoryVestedAmount[uint32(VestingCategory.TEAM)] <= totalSupply.mul(team).div(TOTAL_QUOTA),
'Exceed allocated quota, TEAM'
);
require(
_categoryVestedAmount[uint32(VestingCategory.ECOSYSTEM_COMMUNITY)] <=
totalSupply.mul(ecosystemAndCommunity).div(TOTAL_QUOTA),
'Exceed allocated quota, ECOSYSTEM_COMMUNITY'
);
EARLY_CONTRIBUTORS_QUOTA = earlyContributors;
NETWORK_FEES_QUOTA = networkFees;
PROTOCOL_RESERVE_QUOTA = protocolReserve;
PARTNER_ADVISORS_QUOTA = parternerAndAdvisor;
TEAM_QUOTA = team;
ECOSYSTEM_COMMUNITY_QUOTA = ecosystemAndCommunity;
emit QuotaAdjusted(
earlyContributors,
networkFees,
protocolReserve,
parternerAndAdvisor,
team,
ecosystemAndCommunity
);
}
/**
withdraw releaseable tokens
*/
function withdraw() public {
uint256[] memory vestingPlanIds = _vestingPlanIds[msg.sender];
require(vestingPlanIds.length != 0, 'No vesting plans exist');
uint256 totalWithdrawableAmount = 0;
for (uint32 i = 0; i < vestingPlanIds.length; i++) {
uint256 vestingPlanId = vestingPlanIds[i];
uint256 planWithdrawableAmount = _calculateWithdrawableAmount(_vestingPlans[vestingPlanId]);
_released[vestingPlanId] = _released[vestingPlanId] + planWithdrawableAmount;
totalWithdrawableAmount += planWithdrawableAmount;
}
//transfer withdrawable tokens to beneficiary
this.transfer(msg.sender, totalWithdrawableAmount);
emit Withdraw(msg.sender, totalWithdrawableAmount);
}
function getTotalVestedAmount() public view returns (uint256) {
uint256[] memory vestingPlanIds = _vestingPlanIds[msg.sender];
require(vestingPlanIds.length != 0, 'No vesting plans exist');
uint256 totalVestedAmount = 0;
for (uint32 i = 0; i < vestingPlanIds.length; i++) {
VestingPlan memory vestingPlan = _vestingPlans[vestingPlanIds[i]];
if (!vestingPlan.isRevoked) {
totalVestedAmount += vestingPlan.totalAmount;
}
}
return totalVestedAmount;
}
function getWithdrawableAmount() public view returns (uint256) {
uint256[] memory vestingPlanIds = _vestingPlanIds[msg.sender];
require(vestingPlanIds.length != 0, 'No vesting plans exist');
uint256 totalWithdrawableAmount = 0;
for (uint32 i = 0; i < vestingPlanIds.length; i++) {
uint256 planWithdrawableAmount = _calculateWithdrawableAmount(_vestingPlans[vestingPlanIds[i]]);
totalWithdrawableAmount += planWithdrawableAmount;
}
return totalWithdrawableAmount;
}
function _getCategoryPercentage(VestingCategory category) private view returns (uint256) {
if (category == VestingCategory.EARLY_CONTRIBUTORS) {
return EARLY_CONTRIBUTORS_QUOTA;
} else if (category == VestingCategory.NETWORK_FEES) {
return NETWORK_FEES_QUOTA;
} else if (category == VestingCategory.PROTOCOL_RESERVE) {
return PROTOCOL_RESERVE_QUOTA;
} else if (category == VestingCategory.PARTNER_ADVISORS) {
return PARTNER_ADVISORS_QUOTA;
} else if (category == VestingCategory.TEAM) {
return TEAM_QUOTA;
} else if (category == VestingCategory.ECOSYSTEM_COMMUNITY) {
return ECOSYSTEM_COMMUNITY_QUOTA;
} else {
revert('Invalid vesting category');
}
}
function _getUniqueId(address beneficiary) private view returns (uint256) {
uint256 uniqueId =
uint256(
keccak256(
abi.encodePacked(string(abi.encodePacked(beneficiary)), block.number, now)
)
);
return uniqueId;
}
function _getUnreleasedAmount(uint256 uniqueId) private view returns (uint256) {
VestingPlan memory plan = _vestingPlans[uniqueId];
uint256 unreleasedAmount = plan.totalAmount - _released[uniqueId];
return unreleasedAmount;
}
function _calculateWithdrawableAmount(VestingPlan memory plan) private view returns (uint256) {
//revoked vesting plan
if (plan.isRevoked) {
return uint256(0);
}
uint256 currentTime = (plan.vestingType == VestingType.TIME ? now : block.number);
if (currentTime < plan.startTime) {
return uint256(0);
}
//during cliff
uint256 releasedAmount = _released[plan.uniqueId];
if (currentTime <= plan.startTime.add(plan.cliffDuration)) {
if (plan.initialAmount > releasedAmount) {
return plan.initialAmount.sub(releasedAmount);
} else {
return uint256(0);
}
//vesting finished
} else if (currentTime > plan.startTime.add(plan.cliffDuration).add(plan.duration)) {
if (plan.totalAmount > releasedAmount) {
return plan.totalAmount.sub(releasedAmount);
} else {
return uint256(0);
}
// during the vesting duration, exclude cliff
} else {
uint256 accumulatstartTime =
(plan.accumulateDuringCliff ? plan.startTime : plan.startTime + plan.cliffDuration);
uint256 totalDuration =
(plan.accumulateDuringCliff ? plan.duration.add(plan.cliffDuration) : plan.duration);
uint256 intervalCounts;
if (plan.vestingType == VestingType.TIME) {
intervalCounts = (
totalDuration.mod(plan.interval) == 0
? totalDuration.div(plan.interval)
: totalDuration.div(plan.interval).add(1)
);
} else {
intervalCounts = totalDuration;
}
uint256 planInterval = (plan.vestingType == VestingType.TIME ? plan.interval : 1);
uint256 accumulatedAmount =
plan.totalAmount.sub(plan.initialAmount).mul(currentTime.sub(accumulatstartTime).div(planInterval)).div(
intervalCounts
);
return accumulatedAmount.add(plan.initialAmount).sub(releasedAmount);
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../../utils/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.sol";
/**
* @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}.
*/
contract ERC20 is Context, IERC20 {
using SafeMath for uint256;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
uint8 private _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_) public {
_name = name_;
_symbol = symbol_;
_decimals = 18;
}
/**
* @dev Returns the name of the token.
*/
function name() public view virtual returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view virtual 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}.
*/
function decimals() public view virtual returns (uint8) {
return _decimals;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
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`.
*/
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
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.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), 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`.
*/
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].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(_msgSender(), spender, _allowances[_msgSender()][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(_msgSender(), spender, _allowances[_msgSender()][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.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
emit Transfer(address(0), account, amount);
}
/**
* @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.
*/
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.
*/
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.
*/
function _setupDecimals(uint8 decimals_) internal virtual {
_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].
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "../utils/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.
*/
abstract 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 virtual 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 <0.8.0;
/**
* @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 SafeMath {
/**
* @dev Returns the addition of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
/**
* @dev Returns the substraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b > a) return (false, 0);
return (true, a - b);
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, 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 (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a / b);
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a % b);
}
/**
* @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) {
require(b <= a, "SafeMath: subtraction overflow");
return a - b;
}
/**
* @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) {
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, reverting 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) {
require(b > 0, "SafeMath: division by zero");
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting 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) {
require(b > 0, "SafeMath: modulo by zero");
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* 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);
return a - b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryDiv}.
*
* 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);
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* 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;
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/*
* @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 <0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
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);
}