Contract Name:
StandardERC20
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "./Vendor.sol";
contract StandardERC20 is ERC20 {
constructor (string memory name, string memory symbol, address to, uint256 totalSupply) public ERC20(name, symbol) {
_mint(to, totalSupply);
}
}
pragma solidity ^0.6.6;
// File: @openzeppelin/contracts/utils/EnumerableSet.sol
/**
* @dev Library for managing
* https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
* types.
*
* Sets have the following properties:
*
* - Elements are added, removed, and checked for existence in constant time
* (O(1)).
* - Elements are enumerated in O(n). No guarantees are made on the ordering.
*
* ```
* contract Example {
* // Add the library methods
* using EnumerableSet for EnumerableSet.AddressSet;
*
* // Declare a set state variable
* EnumerableSet.AddressSet private mySet;
* }
* ```
*
* As of v3.0.0, only sets of type `address` (`AddressSet`) and `uint256`
* (`UintSet`) are supported.
*/
library EnumerableSet {
// To implement this library for multiple types with as little code
// repetition as possible, we write it in terms of a generic Set type with
// bytes32 values.
// The Set implementation uses private functions, and user-facing
// implementations (such as AddressSet) are just wrappers around the
// underlying Set.
// This means that we can only create new EnumerableSets for types that fit
// in bytes32.
struct Set {
// Storage of set values
bytes32[] _values;
// Position of the value in the `values` array, plus 1 because index 0
// means a value is not in the set.
mapping(bytes32 => uint256) _indexes;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function _add(Set storage set, bytes32 value) private returns (bool) {
if (!_contains(set, value)) {
set._values.push(value);
// The value is stored at length-1, but we add 1 to all indexes
// and use 0 as a sentinel value
set._indexes[value] = set._values.length;
return true;
} else {
return false;
}
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function _remove(Set storage set, bytes32 value) private returns (bool) {
// We read and store the value's index to prevent multiple reads from the same storage slot
uint256 valueIndex = set._indexes[value];
if (valueIndex != 0) {// Equivalent to contains(set, value)
// To delete an element from the _values array in O(1), we swap the element to delete with the last one in
// the array, and then remove the last element (sometimes called as 'swap and pop').
// This modifies the order of the array, as noted in {at}.
uint256 toDeleteIndex = valueIndex - 1;
uint256 lastIndex = set._values.length - 1;
// When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
// so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
bytes32 lastvalue = set._values[lastIndex];
// Move the last value to the index where the value to delete is
set._values[toDeleteIndex] = lastvalue;
// Update the index for the moved value
set._indexes[lastvalue] = toDeleteIndex + 1;
// All indexes are 1-based
// Delete the slot where the moved value was stored
set._values.pop();
// Delete the index for the deleted slot
delete set._indexes[value];
return true;
} else {
return false;
}
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function _contains(Set storage set, bytes32 value) private view returns (bool) {
return set._indexes[value] != 0;
}
/**
* @dev Returns the number of values on the set. O(1).
*/
function _length(Set storage set) private view returns (uint256) {
return set._values.length;
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function _at(Set storage set, uint256 index) private view returns (bytes32) {
require(set._values.length > index, "EnumerableSet: index out of bounds");
return set._values[index];
}
// AddressSet
struct AddressSet {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(AddressSet storage set, address value) internal returns (bool) {
return _add(set._inner, bytes32(uint256(value)));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(AddressSet storage set, address value) internal returns (bool) {
return _remove(set._inner, bytes32(uint256(value)));
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(AddressSet storage set, address value) internal view returns (bool) {
return _contains(set._inner, bytes32(uint256(value)));
}
/**
* @dev Returns the number of values in the set. O(1).
*/
function length(AddressSet storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(AddressSet storage set, uint256 index) internal view returns (address) {
return address(uint256(_at(set._inner, index)));
}
// UintSet
struct UintSet {
Set _inner;
}
/**
* @dev Add a value to a set. O(1).
*
* Returns true if the value was added to the set, that is if it was not
* already present.
*/
function add(UintSet storage set, uint256 value) internal returns (bool) {
return _add(set._inner, bytes32(value));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the value was removed from the set, that is if it was
* present.
*/
function remove(UintSet storage set, uint256 value) internal returns (bool) {
return _remove(set._inner, bytes32(value));
}
/**
* @dev Returns true if the value is in the set. O(1).
*/
function contains(UintSet storage set, uint256 value) internal view returns (bool) {
return _contains(set._inner, bytes32(value));
}
/**
* @dev Returns the number of values on the set. O(1).
*/
function length(UintSet storage set) internal view returns (uint256) {
return _length(set._inner);
}
/**
* @dev Returns the value stored at position `index` in the set. O(1).
*
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(UintSet storage set, uint256 index) internal view returns (uint256) {
return uint256(_at(set._inner, index));
}
}
import "./Address.sol";
// File: @openzeppelin/contracts/GSN/Context.sol
/*
* @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;
}
}
// File: @openzeppelin/contracts/access/AccessControl.sol
/**
* @dev Contract module that allows children to implement role-based access
* control mechanisms.
*
* Roles are referred to by their `bytes32` identifier. These should be exposed
* in the external API and be unique. The best way to achieve this is by
* using `public constant` hash digests:
*
* ```
* bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
* ```
*
* Roles can be used to represent a set of permissions. To restrict access to a
* function call, use {hasRole}:
*
* ```
* function foo() public {
* require(hasRole(MY_ROLE, msg.sender));
* ...
* }
* ```
*
* Roles can be granted and revoked dynamically via the {grantRole} and
* {revokeRole} functions. Each role has an associated admin role, and only
* accounts that have a role's admin role can call {grantRole} and {revokeRole}.
*
* By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
* that only accounts with this role will be able to grant or revoke other
* roles. More complex role relationships can be created by using
* {_setRoleAdmin}.
*
* WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
* grant and revoke this role. Extra precautions should be taken to secure
* accounts that have been granted it.
*/
abstract contract AccessControl is Context {
using EnumerableSet for EnumerableSet.AddressSet;
using Address for address;
struct RoleData {
EnumerableSet.AddressSet members;
bytes32 adminRole;
}
mapping(bytes32 => RoleData) private _roles;
bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
/**
* @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
*
* `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
* {RoleAdminChanged} not being emitted signaling this.
*
* _Available since v3.1._
*/
event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
/**
* @dev Emitted when `account` is granted `role`.
*
* `sender` is the account that originated the contract call, an admin role
* bearer except when using {_setupRole}.
*/
event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
/**
* @dev Emitted when `account` is revoked `role`.
*
* `sender` is the account that originated the contract call:
* - if using `revokeRole`, it is the admin role bearer
* - if using `renounceRole`, it is the role bearer (i.e. `account`)
*/
event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
/**
* @dev Returns `true` if `account` has been granted `role`.
*/
function hasRole(bytes32 role, address account) public view returns (bool) {
return _roles[role].members.contains(account);
}
/**
* @dev Returns the number of accounts that have `role`. Can be used
* together with {getRoleMember} to enumerate all bearers of a role.
*/
function getRoleMemberCount(bytes32 role) public view returns (uint256) {
return _roles[role].members.length();
}
/**
* @dev Returns one of the accounts that have `role`. `index` must be a
* value between 0 and {getRoleMemberCount}, non-inclusive.
*
* Role bearers are not sorted in any particular way, and their ordering may
* change at any point.
*
* WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
* you perform all queries on the same block. See the following
* https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
* for more information.
*/
function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
return _roles[role].members.at(index);
}
/**
* @dev Returns the admin role that controls `role`. See {grantRole} and
* {revokeRole}.
*
* To change a role's admin, use {_setRoleAdmin}.
*/
function getRoleAdmin(bytes32 role) public view returns (bytes32) {
return _roles[role].adminRole;
}
/**
* @dev Grants `role` to `account`.
*
* If `account` had not been already granted `role`, emits a {RoleGranted}
* event.
*
* Requirements:
*
* - the caller must have ``role``'s admin role.
*/
function grantRole(bytes32 role, address account) public virtual {
require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");
_grantRole(role, account);
}
/**
* @dev Revokes `role` from `account`.
*
* If `account` had been granted `role`, emits a {RoleRevoked} event.
*
* Requirements:
*
* - the caller must have ``role``'s admin role.
*/
function revokeRole(bytes32 role, address account) public virtual {
require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");
_revokeRole(role, account);
}
/**
* @dev Revokes `role` from the calling account.
*
* Roles are often managed via {grantRole} and {revokeRole}: this function's
* purpose is to provide a mechanism for accounts to lose their privileges
* if they are compromised (such as when a trusted device is misplaced).
*
* If the calling account had been granted `role`, emits a {RoleRevoked}
* event.
*
* Requirements:
*
* - the caller must be `account`.
*/
function renounceRole(bytes32 role, address account) public virtual {
require(account == _msgSender(), "AccessControl: can only renounce roles for self");
_revokeRole(role, account);
}
/**
* @dev Grants `role` to `account`.
*
* If `account` had not been already granted `role`, emits a {RoleGranted}
* event. Note that unlike {grantRole}, this function doesn't perform any
* checks on the calling account.
*
* [WARNING]
* ====
* This function should only be called from the constructor when setting
* up the initial roles for the system.
*
* Using this function in any other way is effectively circumventing the admin
* system imposed by {AccessControl}.
* ====
*/
function _setupRole(bytes32 role, address account) internal virtual {
_grantRole(role, account);
}
/**
* @dev Sets `adminRole` as ``role``'s admin role.
*
* Emits a {RoleAdminChanged} event.
*/
function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
emit RoleAdminChanged(role, _roles[role].adminRole, adminRole);
_roles[role].adminRole = adminRole;
}
function _grantRole(bytes32 role, address account) private {
if (_roles[role].members.add(account)) {
emit RoleGranted(role, account, _msgSender());
}
}
function _revokeRole(bytes32 role, address account) private {
if (_roles[role].members.remove(account)) {
emit RoleRevoked(role, account, _msgSender());
}
}
}
// File: @openzeppelin/contracts/introspection/IERC165.sol
/**
* @dev Interface of the ERC165 standard, as defined in the
* https://eips.ethereum.org/EIPS/eip-165[EIP].
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({ERC165Checker}).
*
* For an implementation, see {ERC165}.
*/
interface IERC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`. See the corresponding
* https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
* to learn more about how these ids are created.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
// File: @openzeppelin/contracts/token/ERC721/IERC721.sol
/**
* @dev Required interface of an ERC721 compliant contract.
*/
interface IERC721 is IERC165 {
/**
* @dev Emitted when `tokenId` token is transferred from `from` to `to`.
*/
event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
*/
event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
*/
event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
/**
* @dev Returns the number of tokens in ``owner``'s account.
*/
function balanceOf(address owner) external view returns (uint256 balance);
/**
* @dev Returns the owner of the `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function ownerOf(uint256 tokenId) external view returns (address owner);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(address from, address to, uint256 tokenId) external;
/**
* @dev Transfers `tokenId` token from `from` to `to`.
*
* WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
*
* Emits a {Transfer} event.
*/
function transferFrom(address from, address to, uint256 tokenId) external;
/**
* @dev Gives permission to `to` to transfer `tokenId` token to another account.
* The approval is cleared when the token is transferred.
*
* Only a single account can be approved at a time, so approving the zero address clears previous approvals.
*
* Requirements:
*
* - The caller must own the token or be an approved operator.
* - `tokenId` must exist.
*
* Emits an {Approval} event.
*/
function approve(address to, uint256 tokenId) external;
/**
* @dev Returns the account approved for `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function getApproved(uint256 tokenId) external view returns (address operator);
/**
* @dev Approve or remove `operator` as an operator for the caller.
* Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
*
* Requirements:
*
* - The `operator` cannot be the caller.
*
* Emits an {ApprovalForAll} event.
*/
function setApprovalForAll(address operator, bool _approved) external;
/**
* @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
*
* See {setApprovalForAll}
*/
function isApprovedForAll(address owner, address operator) external view returns (bool);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
}
// File: @openzeppelin/contracts/token/ERC721/IERC721Metadata.sol
/**
* @title ERC-721 Non-Fungible Token Standard, optional metadata extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Metadata is IERC721 {
/**
* @dev Returns the token collection name.
*/
function name() external view returns (string memory);
/**
* @dev Returns the token collection symbol.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
*/
function tokenURI(uint256 tokenId) external view returns (string memory);
}
// File: @openzeppelin/contracts/token/ERC721/IERC721Enumerable.sol
/**
* @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Enumerable is IERC721 {
/**
* @dev Returns the total amount of tokens stored by the contract.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns a token ID owned by `owner` at a given `index` of its token list.
* Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
*/
function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);
/**
* @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
* Use along with {totalSupply} to enumerate all tokens.
*/
function tokenByIndex(uint256 index) external view returns (uint256);
}
// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol
/**
* @title ERC721 token receiver interface
* @dev Interface for any contract that wants to support safeTransfers
* from ERC721 asset contracts.
*/
interface IERC721Receiver {
/**
* @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
* by `operator` from `from`, this function is called.
*
* It must return its Solidity selector to confirm the token transfer.
* If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
*
* The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
*/
function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data)
external returns (bytes4);
}
// File: @openzeppelin/contracts/introspection/ERC165.sol
/**
* @dev Implementation of the {IERC165} interface.
*
* Contracts may inherit from this and call {_registerInterface} to declare
* their support of an interface.
*/
contract ERC165 is IERC165 {
/*
* bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
*/
bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
/**
* @dev Mapping of interface ids to whether or not it's supported.
*/
mapping(bytes4 => bool) private _supportedInterfaces;
constructor () internal {
// Derived contracts need only register support for their own interfaces,
// we register support for ERC165 itself here
_registerInterface(_INTERFACE_ID_ERC165);
}
/**
* @dev See {IERC165-supportsInterface}.
*
* Time complexity O(1), guaranteed to always use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) public view override returns (bool) {
return _supportedInterfaces[interfaceId];
}
/**
* @dev Registers the contract as an implementer of the interface defined by
* `interfaceId`. Support of the actual ERC165 interface is automatic and
* registering its interface id is not required.
*
* See {IERC165-supportsInterface}.
*
* Requirements:
*
* - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
*/
function _registerInterface(bytes4 interfaceId) internal virtual {
require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
_supportedInterfaces[interfaceId] = true;
}
}
// File: @openzeppelin/contracts/math/SafeMath.sol
/**
* @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;
}
}
// File: @openzeppelin/contracts/utils/EnumerableMap.sol
/**
* @dev Library for managing an enumerable variant of Solidity's
* https://solidity.readthedocs.io/en/latest/types.html#mapping-types[`mapping`]
* type.
*
* Maps have the following properties:
*
* - Entries are added, removed, and checked for existence in constant time
* (O(1)).
* - Entries are enumerated in O(n). No guarantees are made on the ordering.
*
* ```
* contract Example {
* // Add the library methods
* using EnumerableMap for EnumerableMap.UintToAddressMap;
*
* // Declare a set state variable
* EnumerableMap.UintToAddressMap private myMap;
* }
* ```
*
* As of v3.0.0, only maps of type `uint256 -> address` (`UintToAddressMap`) are
* supported.
*/
library EnumerableMap {
// To implement this library for multiple types with as little code
// repetition as possible, we write it in terms of a generic Map type with
// bytes32 keys and values.
// The Map implementation uses private functions, and user-facing
// implementations (such as Uint256ToAddressMap) are just wrappers around
// the underlying Map.
// This means that we can only create new EnumerableMaps for types that fit
// in bytes32.
struct MapEntry {
bytes32 _key;
bytes32 _value;
}
struct Map {
// Storage of map keys and values
MapEntry[] _entries;
// Position of the entry defined by a key in the `entries` array, plus 1
// because index 0 means a key is not in the map.
mapping(bytes32 => uint256) _indexes;
}
/**
* @dev Adds a key-value pair to a map, or updates the value for an existing
* key. O(1).
*
* Returns true if the key was added to the map, that is if it was not
* already present.
*/
function _set(Map storage map, bytes32 key, bytes32 value) private returns (bool) {
// We read and store the key's index to prevent multiple reads from the same storage slot
uint256 keyIndex = map._indexes[key];
if (keyIndex == 0) {// Equivalent to !contains(map, key)
map._entries.push(MapEntry({_key : key, _value : value}));
// The entry is stored at length-1, but we add 1 to all indexes
// and use 0 as a sentinel value
map._indexes[key] = map._entries.length;
return true;
} else {
map._entries[keyIndex - 1]._value = value;
return false;
}
}
/**
* @dev Removes a key-value pair from a map. O(1).
*
* Returns true if the key was removed from the map, that is if it was present.
*/
function _remove(Map storage map, bytes32 key) private returns (bool) {
// We read and store the key's index to prevent multiple reads from the same storage slot
uint256 keyIndex = map._indexes[key];
if (keyIndex != 0) {// Equivalent to contains(map, key)
// To delete a key-value pair from the _entries array in O(1), we swap the entry to delete with the last one
// in the array, and then remove the last entry (sometimes called as 'swap and pop').
// This modifies the order of the array, as noted in {at}.
uint256 toDeleteIndex = keyIndex - 1;
uint256 lastIndex = map._entries.length - 1;
// When the entry to delete is the last one, the swap operation is unnecessary. However, since this occurs
// so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.
MapEntry storage lastEntry = map._entries[lastIndex];
// Move the last entry to the index where the entry to delete is
map._entries[toDeleteIndex] = lastEntry;
// Update the index for the moved entry
map._indexes[lastEntry._key] = toDeleteIndex + 1;
// All indexes are 1-based
// Delete the slot where the moved entry was stored
map._entries.pop();
// Delete the index for the deleted slot
delete map._indexes[key];
return true;
} else {
return false;
}
}
/**
* @dev Returns true if the key is in the map. O(1).
*/
function _contains(Map storage map, bytes32 key) private view returns (bool) {
return map._indexes[key] != 0;
}
/**
* @dev Returns the number of key-value pairs in the map. O(1).
*/
function _length(Map storage map) private view returns (uint256) {
return map._entries.length;
}
/**
* @dev Returns the key-value pair stored at position `index` in the map. O(1).
*
* Note that there are no guarantees on the ordering of entries inside the
* array, and it may change when more entries are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function _at(Map storage map, uint256 index) private view returns (bytes32, bytes32) {
require(map._entries.length > index, "EnumerableMap: index out of bounds");
MapEntry storage entry = map._entries[index];
return (entry._key, entry._value);
}
/**
* @dev Returns the value associated with `key`. O(1).
*
* Requirements:
*
* - `key` must be in the map.
*/
function _get(Map storage map, bytes32 key) private view returns (bytes32) {
return _get(map, key, "EnumerableMap: nonexistent key");
}
/**
* @dev Same as {_get}, with a custom error message when `key` is not in the map.
*/
function _get(Map storage map, bytes32 key, string memory errorMessage) private view returns (bytes32) {
uint256 keyIndex = map._indexes[key];
require(keyIndex != 0, errorMessage);
// Equivalent to contains(map, key)
return map._entries[keyIndex - 1]._value;
// All indexes are 1-based
}
// UintToAddressMap
struct UintToAddressMap {
Map _inner;
}
/**
* @dev Adds a key-value pair to a map, or updates the value for an existing
* key. O(1).
*
* Returns true if the key was added to the map, that is if it was not
* already present.
*/
function set(UintToAddressMap storage map, uint256 key, address value) internal returns (bool) {
return _set(map._inner, bytes32(key), bytes32(uint256(value)));
}
/**
* @dev Removes a value from a set. O(1).
*
* Returns true if the key was removed from the map, that is if it was present.
*/
function remove(UintToAddressMap storage map, uint256 key) internal returns (bool) {
return _remove(map._inner, bytes32(key));
}
/**
* @dev Returns true if the key is in the map. O(1).
*/
function contains(UintToAddressMap storage map, uint256 key) internal view returns (bool) {
return _contains(map._inner, bytes32(key));
}
/**
* @dev Returns the number of elements in the map. O(1).
*/
function length(UintToAddressMap storage map) internal view returns (uint256) {
return _length(map._inner);
}
/**
* @dev Returns the element stored at position `index` in the set. O(1).
* Note that there are no guarantees on the ordering of values inside the
* array, and it may change when more values are added or removed.
*
* Requirements:
*
* - `index` must be strictly less than {length}.
*/
function at(UintToAddressMap storage map, uint256 index) internal view returns (uint256, address) {
(bytes32 key, bytes32 value) = _at(map._inner, index);
return (uint256(key), address(uint256(value)));
}
/**
* @dev Returns the value associated with `key`. O(1).
*
* Requirements:
*
* - `key` must be in the map.
*/
function get(UintToAddressMap storage map, uint256 key) internal view returns (address) {
return address(uint256(_get(map._inner, bytes32(key))));
}
/**
* @dev Same as {get}, with a custom error message when `key` is not in the map.
*/
function get(UintToAddressMap storage map, uint256 key, string memory errorMessage) internal view returns (address) {
return address(uint256(_get(map._inner, bytes32(key), errorMessage)));
}
}
// File: @openzeppelin/contracts/utils/Strings.sol
/**
* @dev String operations.
*/
library Strings {
/**
* @dev Converts a `uint256` to its ASCII `string` representation.
*/
function toString(uint256 value) internal pure returns (string memory) {
// Inspired by OraclizeAPI's implementation - MIT licence
// https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
if (value == 0) {
return "0";
}
uint256 temp = value;
uint256 digits;
while (temp != 0) {
digits++;
temp /= 10;
}
bytes memory buffer = new bytes(digits);
uint256 index = digits - 1;
temp = value;
while (temp != 0) {
buffer[index--] = byte(uint8(48 + temp % 10));
temp /= 10;
}
return string(buffer);
}
}
// File: @openzeppelin/contracts/token/ERC721/ERC721.sol
/**
* @title ERC721 Non-Fungible Token Standard basic implementation
* @dev see https://eips.ethereum.org/EIPS/eip-721
*/
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable {
using SafeMath for uint256;
using Address for address;
using EnumerableSet for EnumerableSet.UintSet;
using EnumerableMap for EnumerableMap.UintToAddressMap;
using Strings for uint256;
// Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
// which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;
// Mapping from holder address to their (enumerable) set of owned tokens
mapping(address => EnumerableSet.UintSet) private _holderTokens;
// Enumerable mapping from token ids to their owners
EnumerableMap.UintToAddressMap private _tokenOwners;
// Mapping from token ID to approved address
mapping(uint256 => address) private _tokenApprovals;
// Mapping from owner to operator approvals
mapping(address => mapping(address => bool)) private _operatorApprovals;
// Token name
string private _name;
// Token symbol
string private _symbol;
// Optional mapping for token URIs
mapping(uint256 => string) private _tokenURIs;
// Base URI
string private _baseURI;
/*
* bytes4(keccak256('balanceOf(address)')) == 0x70a08231
* bytes4(keccak256('ownerOf(uint256)')) == 0x6352211e
* bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
* bytes4(keccak256('getApproved(uint256)')) == 0x081812fc
* bytes4(keccak256('setApprovalForAll(address,bool)')) == 0xa22cb465
* bytes4(keccak256('isApprovedForAll(address,address)')) == 0xe985e9c5
* bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
* bytes4(keccak256('safeTransferFrom(address,address,uint256)')) == 0x42842e0e
* bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)')) == 0xb88d4fde
*
* => 0x70a08231 ^ 0x6352211e ^ 0x095ea7b3 ^ 0x081812fc ^
* 0xa22cb465 ^ 0xe985e9c5 ^ 0x23b872dd ^ 0x42842e0e ^ 0xb88d4fde == 0x80ac58cd
*/
bytes4 private constant _INTERFACE_ID_ERC721 = 0x80ac58cd;
/*
* bytes4(keccak256('name()')) == 0x06fdde03
* bytes4(keccak256('symbol()')) == 0x95d89b41
* bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd
*
* => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f
*/
bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
/*
* bytes4(keccak256('totalSupply()')) == 0x18160ddd
* bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) == 0x2f745c59
* bytes4(keccak256('tokenByIndex(uint256)')) == 0x4f6ccce7
*
* => 0x18160ddd ^ 0x2f745c59 ^ 0x4f6ccce7 == 0x780e9d63
*/
bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
constructor () public {
// register the supported interfaces to conform to ERC721 via ERC165
_registerInterface(_INTERFACE_ID_ERC721);
_registerInterface(_INTERFACE_ID_ERC721_METADATA);
_registerInterface(_INTERFACE_ID_ERC721_ENUMERABLE);
}
/**
* @dev See {IERC721-balanceOf}.
*/
function balanceOf(address owner) public view override returns (uint256) {
require(owner != address(0), "ERC721: balance query for the zero address");
return _holderTokens[owner].length();
}
/**
* @dev See {IERC721-ownerOf}.
*/
function ownerOf(uint256 tokenId) public view override returns (address) {
return _tokenOwners.get(tokenId, "ERC721: owner query for nonexistent token");
}
/**
* @dev See {IERC721Metadata-name}.
*/
function name() public virtual view override returns (string memory) {
return _name;
}
/**
* @dev See {IERC721Metadata-symbol}.
*/
function symbol() public virtual view override returns (string memory) {
return _symbol;
}
/**
* @dev See {IERC721Metadata-tokenURI}.
*/
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
string memory _tokenURI = _tokenURIs[tokenId];
// If there is no base URI, return the token URI.
if (bytes(_baseURI).length == 0) {
return _tokenURI;
}
// If both are set, concatenate the baseURI and tokenURI (via abi.encodePacked).
if (bytes(_tokenURI).length > 0) {
return string(abi.encodePacked(_baseURI, _tokenURI));
}
// If there is a baseURI but no tokenURI, concatenate the tokenID to the baseURI.
return string(abi.encodePacked(_baseURI, tokenId.toString(), ".json"));
}
/**
* @dev Returns the base URI set via {_setBaseURI}. This will be
* automatically added as a prefix in {tokenURI} to each token's URI, or
* to the token ID if no specific URI is set for that token ID.
*/
function baseURI() public view returns (string memory) {
return _baseURI;
}
/**
* @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
*/
function tokenOfOwnerByIndex(address owner, uint256 index) public view override returns (uint256) {
return _holderTokens[owner].at(index);
}
/**
* @dev See {IERC721Enumerable-totalSupply}.
*/
function totalSupply() public view override returns (uint256) {
// _tokenOwners are indexed by tokenIds, so .length() returns the number of tokenIds
return _tokenOwners.length();
}
/**
* @dev See {IERC721Enumerable-tokenByIndex}.
*/
function tokenByIndex(uint256 index) public view override returns (uint256) {
(uint256 tokenId,) = _tokenOwners.at(index);
return tokenId;
}
/**
* @dev See {IERC721-approve}.
*/
function approve(address to, uint256 tokenId) public virtual override {
address owner = ownerOf(tokenId);
require(to != owner, "ERC721: approval to current owner");
require(_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
"ERC721: approve caller is not owner nor approved for all"
);
_approve(to, tokenId);
}
/**
* @dev See {IERC721-getApproved}.
*/
function getApproved(uint256 tokenId) public view override returns (address) {
require(_exists(tokenId), "ERC721: approved query for nonexistent token");
return _tokenApprovals[tokenId];
}
/**
* @dev See {IERC721-setApprovalForAll}.
*/
function setApprovalForAll(address operator, bool approved) public virtual override {
require(operator != _msgSender(), "ERC721: approve to caller");
_operatorApprovals[_msgSender()][operator] = approved;
emit ApprovalForAll(_msgSender(), operator, approved);
}
/**
* @dev See {IERC721-isApprovedForAll}.
*/
function isApprovedForAll(address owner, address operator) public view override returns (bool) {
return _operatorApprovals[owner][operator];
}
/**
* @dev See {IERC721-transferFrom}.
*/
function transferFrom(address from, address to, uint256 tokenId) public virtual override {
//solhint-disable-next-line max-line-length
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_transfer(from, to, tokenId);
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
safeTransferFrom(from, to, tokenId, "");
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_safeTransfer(from, to, tokenId, _data);
}
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* `_data` is additional data, it has no specified format and it is sent in call to `to`.
*
* This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
* implement alternative mechanisms to perform token transfer, such as signature-based.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {
_transfer(from, to, tokenId);
require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
/**
* @dev Returns whether `tokenId` exists.
*
* Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
*
* Tokens start existing when they are minted (`_mint`),
* and stop existing when they are burned (`_burn`).
*/
function _exists(uint256 tokenId) internal view returns (bool) {
return _tokenOwners.contains(tokenId);
}
/**
* @dev Returns whether `spender` is allowed to manage `tokenId`.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function _isApprovedOrOwner(address spender, uint256 tokenId) internal view returns (bool) {
require(_exists(tokenId), "ERC721: operator query for nonexistent token");
address owner = ownerOf(tokenId);
return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
}
/**
* @dev Safely mints `tokenId` and transfers it to `to`.
*
* Requirements:
d*
* - `tokenId` must not exist.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeMint(address to, uint256 tokenId) internal virtual {
_safeMint(to, tokenId, "");
}
/**
* @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
* forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
*/
function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
_mint(to, tokenId);
require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
/**
* @dev Mints `tokenId` and transfers it to `to`.
*
* WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
*
* Requirements:
*
* - `tokenId` must not exist.
* - `to` cannot be the zero address.
*
* Emits a {Transfer} event.
*/
function _mint(address to, uint256 tokenId) internal virtual {
require(to != address(0), "ERC721: mint to the zero address");
require(!_exists(tokenId), "ERC721: token already minted");
_beforeTokenTransfer(address(0), to, tokenId);
_holderTokens[to].add(tokenId);
_tokenOwners.set(tokenId, to);
emit Transfer(address(0), to, tokenId);
}
/**
* @dev Destroys `tokenId`.
* The approval is cleared when the token is burned.
*
* Requirements:
*
* - `tokenId` must exist.
*
* Emits a {Transfer} event.
*/
function _burn(uint256 tokenId) internal virtual {
address owner = ownerOf(tokenId);
_beforeTokenTransfer(owner, address(0), tokenId);
// Clear approvals
_approve(address(0), tokenId);
// Clear metadata (if any)
if (bytes(_tokenURIs[tokenId]).length != 0) {
delete _tokenURIs[tokenId];
}
_holderTokens[owner].remove(tokenId);
_tokenOwners.remove(tokenId);
emit Transfer(owner, address(0), tokenId);
}
/**
* @dev Transfers `tokenId` from `from` to `to`.
* As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
*
* Emits a {Transfer} event.
*/
function _transfer(address from, address to, uint256 tokenId) internal virtual {
require(ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
require(to != address(0), "ERC721: transfer to the zero address");
_beforeTokenTransfer(from, to, tokenId);
// Clear approvals from the previous owner
_approve(address(0), tokenId);
_holderTokens[from].remove(tokenId);
_holderTokens[to].add(tokenId);
_tokenOwners.set(tokenId, to);
emit Transfer(from, to, tokenId);
}
/**
* @dev Sets `_tokenURI` as the tokenURI of `tokenId`.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function _setTokenURI(uint256 tokenId, string memory _tokenURI) internal virtual {
require(_exists(tokenId), "ERC721Metadata: URI set of nonexistent token");
_tokenURIs[tokenId] = _tokenURI;
}
/**
* @dev Internal function to set the base URI for all token IDs. It is
* automatically added as a prefix to the value returned in {tokenURI},
* or to the token ID if {tokenURI} is empty.
*/
function _setBaseURI(string memory baseURI_) internal virtual {
_baseURI = baseURI_;
}
/**
* @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
* The call is not executed if the target address is not a contract.
*
* @param from address representing the previous owner of the given token ID
* @param to target address that will receive the tokens
* @param tokenId uint256 ID of the token to be transferred
* @param _data bytes optional data to send along with the call
* @return bool whether the call correctly returned the expected magic value
*/
function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
private returns (bool)
{
if (!to.isContract()) {
return true;
}
bytes memory returndata = to.functionCall(abi.encodeWithSelector(
IERC721Receiver(to).onERC721Received.selector,
_msgSender(),
from,
tokenId,
_data
), "ERC721: transfer to non ERC721Receiver implementer");
bytes4 retval = abi.decode(returndata, (bytes4));
return (retval == _ERC721_RECEIVED);
}
function _approve(address to, uint256 tokenId) private {
_tokenApprovals[tokenId] = to;
emit Approval(ownerOf(tokenId), to, tokenId);
}
/**
* @dev Hook that is called before any token transfer. This includes minting
* and burning.
*
* Calling conditions:
*
* - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
* transferred to `to`.
* - When `from` is zero, `tokenId` will be minted for `to`.
* - When `to` is zero, ``from``'s `tokenId` will be burned.
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual {}
}
// File: @openzeppelin/contracts/utils/Pausable.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());
}
}
// File: @openzeppelin/contracts/token/ERC721/ERC721Pausable.sol
/**
* @dev ERC721 token with pausable token transfers, minting and burning.
*
* Useful for scenarios such as preventing trades until the end of an evaluation
* period, or having an emergency switch for freezing all token transfers in the
* event of a large bug.
*/
abstract contract ERC721Pausable is ERC721, Pausable {
/**
* @dev See {ERC721-_beforeTokenTransfer}.
*
* Requirements:
*
* - the contract must not be paused.
*/
function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual override {
super._beforeTokenTransfer(from, to, tokenId);
require(!paused(), "ERC721Pausable: token transfer while paused");
}
}
// File: contracts/libraries/TransferHelper.sol
// helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
library TransferHelper {
// function safeApprove(
// address token,
// address to,
// uint256 value
// ) internal {
// // bytes4(keccak256(bytes('approve(address,uint256)')));
// (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
// require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
// }
function safeTransfer(
address token,
address to,
uint256 value
) internal {
// bytes4(keccak256(bytes('transfer(address,uint256)')));
(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
}
function safeTransferFrom(
address token,
address from,
address to,
uint256 value
) internal {
// bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
(bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
}
// function safeTransferETH(address to, uint256 value) internal {
// (bool success,) = to.call{value : value}(new bytes(0));
// require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
// }
}
library LibString {
function replace(
string memory subject,
string memory search,
string memory replacement
) internal pure returns (string memory result) {
assembly {
let subjectLength := mload(subject)
let searchLength := mload(search)
let replacementLength := mload(replacement)
// Store the mask for sub-word comparisons in the scratch space.
mstore(0x00, not(0))
mstore(0x20, 0)
subject := add(subject, 0x20)
search := add(search, 0x20)
replacement := add(replacement, 0x20)
result := add(mload(0x40), 0x20)
let k := 0
let subjectEnd := add(subject, subjectLength)
if iszero(gt(searchLength, subjectLength)) {
let subjectSearchEnd := add(sub(subjectEnd, searchLength), 1)
for {} lt(subject, subjectSearchEnd) {} {
let o := and(searchLength, 31)
// Whether the first `searchLength % 32` bytes of
// `subject` and `search` matches.
let l := iszero(and(xor(mload(subject), mload(search)), mload(sub(0x20, o))))
// Iterate through the rest of `search` and check if any word mismatch.
// If any mismatch is detected, `l` is set to 0.
for {} and(lt(o, searchLength), l) {} {
l := eq(mload(add(subject, o)), mload(add(search, o)))
o := add(o, 0x20)
}
// If `l` is one, there is a match, and we have to copy the `replacement`.
if l {
// Copy the `replacement` one word at a time.
for { o := 0 } lt(o, replacementLength) { o := add(o, 0x20) } {
mstore(add(result, add(k, o)), mload(add(replacement, o)))
}
k := add(k, replacementLength)
subject := add(subject, searchLength)
}
// If `l` or `searchLength` is zero.
if iszero(mul(l, searchLength)) {
mstore(add(result, k), mload(subject))
k := add(k, 1)
subject := add(subject, 1)
}
}
}
let resultRemainder := add(result, k)
k := add(k, sub(subjectEnd, subject))
// Copy the rest of the string one word at a time.
for {} lt(subject, subjectEnd) {} {
mstore(resultRemainder, mload(subject))
resultRemainder := add(resultRemainder, 0x20)
subject := add(subject, 0x20)
}
// Allocate memory for the length and the bytes, rounded up to a multiple of 32.
mstore(0x40, add(result, and(add(k, 64), not(31))))
result := sub(result, 0x20)
mstore(result, k)
}
}
}
contract ERC721Holder is IERC721Receiver {
/**
* @dev See {IERC721Receiver-onERC721Received}.
*
* Always returns `IERC721Receiver.onERC721Received.selector`.
*/
function onERC721Received(address, address, uint256, bytes memory) public virtual override returns (bytes4) {
return this.onERC721Received.selector;
}
}
abstract contract Ownable is Context {
address internal _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;
}
}
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);
}
library SafeERC20 {
using SafeMath for uint256;
using Address for address;
function safeTransfer(IERC20 token, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(IERC20 token, address spender, uint256 value) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
// solhint-disable-next-line max-line-length
require((value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
uint256 newAllowance = token.allowance(address(this), spender).add(value);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) { // Return data is optional
// solhint-disable-next-line max-line-length
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// SPDX-License-Identifier: MIT
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor () internal {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
/**
* @dev These functions deal with verification of Merkle trees (hash trees),
*/
library MerkleProof {
/**
* @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
* defined by `root`. For this, a `proof` must be provided, containing
* sibling hashes on the branch from the leaf to the root of the tree. Each
* pair of leaves and each pair of pre-images are assumed to be sorted.
*/
function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
bytes32 computedHash = leaf;
for (uint256 i = 0; i < proof.length; i++) {
bytes32 proofElement = proof[i];
if (computedHash <= proofElement) {
// Hash(current computed hash + current element of the proof)
computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
} else {
// Hash(current element of the proof + current computed hash)
computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
}
}
// Check if the computed hash (root) is equal to the provided root
return computedHash == root;
}
}
interface IOperatorFilterRegistry {
function isOperatorAllowed(address registrant, address operator) external view returns (bool);
function register(address registrant) external;
function registerAndSubscribe(address registrant, address subscription) external;
function registerAndCopyEntries(address registrant, address registrantToCopy) external;
function unregister(address addr) external;
function updateOperator(address registrant, address operator, bool filtered) external;
function updateOperators(address registrant, address[] calldata operators, bool filtered) external;
function updateCodeHash(address registrant, bytes32 codehash, bool filtered) external;
function updateCodeHashes(address registrant, bytes32[] calldata codeHashes, bool filtered) external;
function subscribe(address registrant, address registrantToSubscribe) external;
function unsubscribe(address registrant, bool copyExistingEntries) external;
function subscriptionOf(address addr) external returns (address registrant);
function subscribers(address registrant) external returns (address[] memory);
function subscriberAt(address registrant, uint256 index) external returns (address);
function copyEntriesOf(address registrant, address registrantToCopy) external;
function isOperatorFiltered(address registrant, address operator) external returns (bool);
function isCodeHashOfFiltered(address registrant, address operatorWithCode) external returns (bool);
function isCodeHashFiltered(address registrant, bytes32 codeHash) external returns (bool);
function filteredOperators(address addr) external returns (address[] memory);
function filteredCodeHashes(address addr) external returns (bytes32[] memory);
function filteredOperatorAt(address registrant, uint256 index) external returns (address);
function filteredCodeHashAt(address registrant, uint256 index) external returns (bytes32);
function isRegistered(address addr) external returns (bool);
function codeHashOf(address addr) external returns (bytes32);
}
/**
* @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;
using Address for address;
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 returns (string memory) {
return _name;
}
function setname(string memory name_) internal {
_name = name_;
}
function setsymbol(string memory symbol_) internal {
_symbol = symbol_;
}
function setdecimals(uint8 decimals_) internal {
_decimals = decimals_;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
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}.
*/
function decimals() public view returns (uint8) {
return _decimals;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view 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 is 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 {
_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 { }
}
/**
* @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
*
* These functions can be used to verify that a message was signed by the holder
* of the private keys of a given address.
*/
library ECDSA {
enum RecoverError {
NoError,
InvalidSignature,
InvalidSignatureLength,
InvalidSignatureS,
InvalidSignatureV // Deprecated in v4.8
}
function _throwError(RecoverError error) private pure {
if (error == RecoverError.NoError) {
return; // no error: do nothing
} else if (error == RecoverError.InvalidSignature) {
revert("ECDSA: invalid signature");
} else if (error == RecoverError.InvalidSignatureLength) {
revert("ECDSA: invalid signature length");
} else if (error == RecoverError.InvalidSignatureS) {
revert("ECDSA: invalid signature 's' value");
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature` or error string. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*
* Documentation for signature generation:
* - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
* - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
if (signature.length == 65) {
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
/// @solidity memory-safe-assembly
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
return tryRecover(hash, v, r, s);
} else {
return (address(0), RecoverError.InvalidSignatureLength);
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature`. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*/
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, signature);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
*
* See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, bytes32 r, bytes32 vs) internal pure returns (address, RecoverError) {
bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
uint8 v = uint8((uint256(vs) >> 255) + 27);
return tryRecover(hash, v, r, s);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
*
* _Available since v4.2._
*/
function recover(bytes32 hash, bytes32 r, bytes32 vs) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, r, vs);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `v`,
* `r` and `s` signature fields separately.
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address, RecoverError) {
// EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
// unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
// the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
// signatures from current libraries generate a unique signature with an s-value in the lower half order.
//
// If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
// with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
// vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
// these malleable signatures as well.
if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
return (address(0), RecoverError.InvalidSignatureS);
}
// If the signature is valid (and not malleable), return the signer address
address signer = ecrecover(hash, v, r, s);
if (signer == address(0)) {
return (address(0), RecoverError.InvalidSignature);
}
return (signer, RecoverError.NoError);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `v`,
* `r` and `s` signature fields separately.
*/
function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, v, r, s);
_throwError(error);
return recovered;
}
/**
* @dev Returns an Ethereum Signed Message, created from a `hash`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32 message) {
// 32 is the length in bytes of hash,
// enforced by the type signature above
/// @solidity memory-safe-assembly
assembly {
mstore(0x00, "\x19Ethereum Signed Message:\n32")
mstore(0x1c, hash)
message := keccak256(0x00, 0x3c)
}
}
/**
* @dev Returns an Ethereum Signed Message, created from `s`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
}
/**
* @dev Returns an Ethereum Signed Typed Data, created from a
* `domainSeparator` and a `structHash`. This produces hash corresponding
* to the one signed with the
* https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
* JSON-RPC method as part of EIP-712.
*
* See {recover}.
*/
function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32 data) {
/// @solidity memory-safe-assembly
assembly {
let ptr := mload(0x40)
mstore(ptr, "\x19\x01")
mstore(add(ptr, 0x02), domainSeparator)
mstore(add(ptr, 0x22), structHash)
data := keccak256(ptr, 0x42)
}
}
/**
* @dev Returns an Ethereum Signed Data with intended validator, created from a
* `validator` and `data` according to the version 0 of EIP-191.
*
* See {recover}.
*/
function toDataWithIntendedValidatorHash(address validator, bytes memory data) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19\x00", validator, data));
}
}
pragma solidity ^0.6.2;
/**
* @dev Collection of functions related to the address type
*/
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 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);
}
}
}
}