Contract Source Code:
File 1 of 1 : FRToken
// Freedom Reserve is declared as money in the British Isles 05.11.2020
// contracts/FRToken.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;
/*
* @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;
}
}
/**
* @dev Interface of the ERC777Token standard as defined in the EIP.
*
* This contract uses the
* https://eips.ethereum.org/EIPS/eip-1820[ERC1820 registry standard] to let
* token holders and recipients react to token movements by using setting implementers
* for the associated interfaces in said registry. See {IERC1820Registry} and
* {ERC1820Implementer}.
*/
interface IERC777 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the smallest part of the token that is not divisible. This
* means all token operations (creation, movement and destruction) must have
* amounts that are a multiple of this number.
*
* For most token contracts, this value will equal 1.
*/
function granularity() external view returns (uint256);
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by an account (`owner`).
*/
function balanceOf(address owner) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* If send or receive hooks are registered for the caller and `recipient`,
* the corresponding functions will be called with `data` and empty
* `operatorData`. See {IERC777Sender} and {IERC777Recipient}.
*
* Emits a {Sent} event.
*
* Requirements
*
* - the caller must have at least `amount` tokens.
* - `recipient` cannot be the zero address.
* - if `recipient` is a contract, it must implement the {IERC777Recipient}
* interface.
*/
function send(address recipient, uint256 amount, bytes calldata data) external;
/**
* @dev Destroys `amount` tokens from the caller's account, reducing the
* total supply.
*
* If a send hook is registered for the caller, the corresponding function
* will be called with `data` and empty `operatorData`. See {IERC777Sender}.
*
* Emits a {Burned} event.
*
* Requirements
*
* - the caller must have at least `amount` tokens.
*/
function burn(uint256 amount, bytes calldata data) external;
/**
* @dev Returns true if an account is an operator of `tokenHolder`.
* Operators can send and burn tokens on behalf of their owners. All
* accounts are their own operator.
*
* See {operatorSend} and {operatorBurn}.
*/
function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
/**
* @dev Make an account an operator of the caller.
*
* See {isOperatorFor}.
*
* Emits an {AuthorizedOperator} event.
*
* Requirements
*
* - `operator` cannot be calling address.
*/
function authorizeOperator(address operator) external;
/**
* @dev Revoke an account's operator status for the caller.
*
* See {isOperatorFor} and {defaultOperators}.
*
* Emits a {RevokedOperator} event.
*
* Requirements
*
* - `operator` cannot be calling address.
*/
function revokeOperator(address operator) external;
/**
* @dev Returns the list of default operators. These accounts are operators
* for all token holders, even if {authorizeOperator} was never called on
* them.
*
* This list is immutable, but individual holders may revoke these via
* {revokeOperator}, in which case {isOperatorFor} will return false.
*/
function defaultOperators() external view returns (address[] memory);
/**
* @dev Moves `amount` tokens from `sender` to `recipient`. The caller must
* be an operator of `sender`.
*
* If send or receive hooks are registered for `sender` and `recipient`,
* the corresponding functions will be called with `data` and
* `operatorData`. See {IERC777Sender} and {IERC777Recipient}.
*
* Emits a {Sent} event.
*
* Requirements
*
* - `sender` cannot be the zero address.
* - `sender` must have at least `amount` tokens.
* - the caller must be an operator for `sender`.
* - `recipient` cannot be the zero address.
* - if `recipient` is a contract, it must implement the {IERC777Recipient}
* interface.
*/
function operatorSend(
address sender,
address recipient,
uint256 amount,
bytes calldata data,
bytes calldata operatorData
) external;
/**
* @dev Destroys `amount` tokens from `account`, reducing the total supply.
* The caller must be an operator of `account`.
*
* If a send hook is registered for `account`, the corresponding function
* will be called with `data` and `operatorData`. See {IERC777Sender}.
*
* Emits a {Burned} event.
*
* Requirements
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
* - the caller must be an operator for `account`.
*/
function operatorBurn(
address account,
uint256 amount,
bytes calldata data,
bytes calldata operatorData
) external;
event Sent(
address indexed operator,
address indexed from,
address indexed to,
uint256 amount,
bytes data,
bytes operatorData
);
event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);
event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);
event AuthorizedOperator(address indexed operator, address indexed tokenHolder);
event RevokedOperator(address indexed operator, address indexed tokenHolder);
}
/**
* @dev Interface of the ERC777TokensRecipient standard as defined in the EIP.
*
* Accounts can be notified of {IERC777} tokens being sent to them by having a
* contract implement this interface (contract holders can be their own
* implementer) and registering it on the
* https://eips.ethereum.org/EIPS/eip-1820[ERC1820 global registry].
*
* See {IERC1820Registry} and {ERC1820Implementer}.
*/
interface IERC777Recipient {
/**
* @dev Called by an {IERC777} token contract whenever tokens are being
* moved or created into a registered account (`to`). The type of operation
* is conveyed by `from` being the zero address or not.
*
* This call occurs _after_ the token contract's state is updated, so
* {IERC777-balanceOf}, etc., can be used to query the post-operation state.
*
* This function may revert to prevent the operation from being executed.
*/
function tokensReceived(
address operator,
address from,
address to,
uint256 amount,
bytes calldata userData,
bytes calldata operatorData
) external;
}
/**
* @dev Interface of the ERC777TokensSender standard as defined in the EIP.
*
* {IERC777} Token holders can be notified of operations performed on their
* tokens by having a contract implement this interface (contract holders can be
* their own implementer) and registering it on the
* https://eips.ethereum.org/EIPS/eip-1820[ERC1820 global registry].
*
* See {IERC1820Registry} and {ERC1820Implementer}.
*/
interface IERC777Sender {
/**
* @dev Called by an {IERC777} token contract whenever a registered holder's
* (`from`) tokens are about to be moved or destroyed. The type of operation
* is conveyed by `to` being the zero address or not.
*
* This call occurs _before_ the token contract's state is updated, so
* {IERC777-balanceOf}, etc., can be used to query the pre-operation state.
*
* This function may revert to prevent the operation from being executed.
*/
function tokensToSend(
address operator,
address from,
address to,
uint256 amount,
bytes calldata userData,
bytes calldata operatorData
) external;
}
/**
* @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);
}
/**
* @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;
}
}
/**
* @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 on 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");
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: value }(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.3._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.3._
*/
function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
/**
* @dev Interface of the global ERC1820 Registry, as defined in the
* https://eips.ethereum.org/EIPS/eip-1820[EIP]. Accounts may register
* implementers for interfaces in this registry, as well as query support.
*
* Implementers may be shared by multiple accounts, and can also implement more
* than a single interface for each account. Contracts can implement interfaces
* for themselves, but externally-owned accounts (EOA) must delegate this to a
* contract.
*
* {IERC165} interfaces can also be queried via the registry.
*
* For an in-depth explanation and source code analysis, see the EIP text.
*/
interface IERC1820Registry {
/**
* @dev Sets `newManager` as the manager for `account`. A manager of an
* account is able to set interface implementers for it.
*
* By default, each account is its own manager. Passing a value of `0x0` in
* `newManager` will reset the manager to this initial state.
*
* Emits a {ManagerChanged} event.
*
* Requirements:
*
* - the caller must be the current manager for `account`.
*/
function setManager(address account, address newManager) external;
/**
* @dev Returns the manager for `account`.
*
* See {setManager}.
*/
function getManager(address account) external view returns (address);
/**
* @dev Sets the `implementer` contract as ``account``'s implementer for
* `interfaceHash`.
*
* `account` being the zero address is an alias for the caller's address.
* The zero address can also be used in `implementer` to remove an old one.
*
* See {interfaceHash} to learn how these are created.
*
* Emits an {InterfaceImplementerSet} event.
*
* Requirements:
*
* - the caller must be the current manager for `account`.
* - `interfaceHash` must not be an {IERC165} interface id (i.e. it must not
* end in 28 zeroes).
* - `implementer` must implement {IERC1820Implementer} and return true when
* queried for support, unless `implementer` is the caller. See
* {IERC1820Implementer-canImplementInterfaceForAddress}.
*/
function setInterfaceImplementer(address account, bytes32 interfaceHash, address implementer) external;
/**
* @dev Returns the implementer of `interfaceHash` for `account`. If no such
* implementer is registered, returns the zero address.
*
* If `interfaceHash` is an {IERC165} interface id (i.e. it ends with 28
* zeroes), `account` will be queried for support of it.
*
* `account` being the zero address is an alias for the caller's address.
*/
function getInterfaceImplementer(address account, bytes32 interfaceHash) external view returns (address);
/**
* @dev Returns the interface hash for an `interfaceName`, as defined in the
* corresponding
* https://eips.ethereum.org/EIPS/eip-1820#interface-name[section of the EIP].
*/
function interfaceHash(string calldata interfaceName) external pure returns (bytes32);
/**
* @notice Updates the cache with whether the contract implements an ERC165 interface or not.
* @param account Address of the contract for which to update the cache.
* @param interfaceId ERC165 interface for which to update the cache.
*/
function updateERC165Cache(address account, bytes4 interfaceId) external;
/**
* @notice Checks whether a contract implements an ERC165 interface or not.
* If the result is not cached a direct lookup on the contract address is performed.
* If the result is not cached or the cached value is out-of-date, the cache MUST be updated manually by calling
* {updateERC165Cache} with the contract address.
* @param account Address of the contract to check.
* @param interfaceId ERC165 interface to check.
* @return True if `account` implements `interfaceId`, false otherwise.
*/
function implementsERC165Interface(address account, bytes4 interfaceId) external view returns (bool);
/**
* @notice Checks whether a contract implements an ERC165 interface or not without using nor updating the cache.
* @param account Address of the contract to check.
* @param interfaceId ERC165 interface to check.
* @return True if `account` implements `interfaceId`, false otherwise.
*/
function implementsERC165InterfaceNoCache(address account, bytes4 interfaceId) external view returns (bool);
event InterfaceImplementerSet(address indexed account, bytes32 indexed interfaceHash, address indexed implementer);
event ManagerChanged(address indexed account, address indexed newManager);
}
/**
* @dev Implementation of the {IERC777} 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}.
*
* Support for ERC20 is included in this contract, as specified by the EIP: both
* the ERC777 and ERC20 interfaces can be safely used when interacting with it.
* Both {IERC777-Sent} and {IERC20-Transfer} events are emitted on token
* movements.
*
* Additionally, the {IERC777-granularity} value is hard-coded to `1`, meaning that there
* are no special restrictions in the amount of tokens that created, moved, or
* destroyed. This makes integration with ERC20 applications seamless.
*/
contract ERC777 is Context, IERC777, IERC20 {
using SafeMath for uint256;
using Address for address;
IERC1820Registry constant internal _ERC1820_REGISTRY = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);
mapping(address => uint256) private _balances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
// We inline the result of the following hashes because Solidity doesn't resolve them at compile time.
// See https://github.com/ethereum/solidity/issues/4024.
// keccak256("ERC777TokensSender")
bytes32 constant private _TOKENS_SENDER_INTERFACE_HASH =
0x29ddb589b1fb5fc7cf394961c1adf5f8c6454761adf795e67fe149f658abe895;
// keccak256("ERC777TokensRecipient")
bytes32 constant private _TOKENS_RECIPIENT_INTERFACE_HASH =
0xb281fc8c12954d22544db45de3159a39272895b169a852b314f9cc762e44c53b;
// This isn't ever read from - it's only used to respond to the defaultOperators query.
address[] private _defaultOperatorsArray;
// Immutable, but accounts may revoke them (tracked in __revokedDefaultOperators).
mapping(address => bool) private _defaultOperators;
// For each account, a mapping of its operators and revoked default operators.
mapping(address => mapping(address => bool)) private _operators;
mapping(address => mapping(address => bool)) private _revokedDefaultOperators;
// ERC20-allowances
mapping (address => mapping (address => uint256)) private _allowances;
/**
* @dev `defaultOperators` may be an empty array.
*/
constructor(
string memory name,
string memory symbol,
address[] memory defaultOperators
) public {
_name = name;
_symbol = symbol;
_defaultOperatorsArray = defaultOperators;
for (uint256 i = 0; i < _defaultOperatorsArray.length; i++) {
_defaultOperators[_defaultOperatorsArray[i]] = true;
}
// register interfaces
_ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256("ERC777Token"), address(this));
_ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256("ERC20Token"), address(this));
}
/**
* @dev See {IERC777-name}.
*/
function name() public view override returns (string memory) {
return _name;
}
/**
* @dev See {IERC777-symbol}.
*/
function symbol() public view override returns (string memory) {
return _symbol;
}
/**
* @dev See {ERC20-decimals}.
*
* Always returns 18, as per the
* [ERC777 EIP](https://eips.ethereum.org/EIPS/eip-777#backward-compatibility).
*/
function decimals() public pure returns (uint8) {
return 18;
}
/**
* @dev See {IERC777-granularity}.
*
* This implementation always returns `1`.
*/
function granularity() public view override returns (uint256) {
return 1;
}
/**
* @dev See {IERC777-totalSupply}.
*/
function totalSupply() public view override(IERC20, IERC777) returns (uint256) {
return _totalSupply;
}
/**
* @dev Returns the amount of tokens owned by an account (`tokenHolder`).
*/
function balanceOf(address tokenHolder) public view override(IERC20, IERC777) returns (uint256) {
return _balances[tokenHolder];
}
/**
* @dev See {IERC777-send}.
*
* Also emits a {IERC20-Transfer} event for ERC20 compatibility.
*/
function send(address recipient, uint256 amount, bytes memory data) public override {
_send(_msgSender(), recipient, amount, data, "", true);
}
/**
* @dev See {IERC20-transfer}.
*
* Unlike `send`, `recipient` is _not_ required to implement the {IERC777Recipient}
* interface if it is a contract.
*
* Also emits a {Sent} event.
*/
function transfer(address recipient, uint256 amount) public override returns (bool) {
require(recipient != address(0), "ERC777: transfer to the zero address");
address from = _msgSender();
_callTokensToSend(from, from, recipient, amount, "", "");
_move(from, from, recipient, amount, "", "");
_callTokensReceived(from, from, recipient, amount, "", "", false);
return true;
}
/**
* @dev See {IERC777-burn}.
*
* Also emits a {IERC20-Transfer} event for ERC20 compatibility.
*/
function burn(uint256 amount, bytes memory data) public override {
_burn(_msgSender(), amount, data, "");
}
/**
* @dev See {IERC777-isOperatorFor}.
*/
function isOperatorFor(
address operator,
address tokenHolder
) public view override returns (bool) {
return operator == tokenHolder ||
(_defaultOperators[operator] && !_revokedDefaultOperators[tokenHolder][operator]) ||
_operators[tokenHolder][operator];
}
/**
* @dev See {IERC777-authorizeOperator}.
*/
function authorizeOperator(address operator) public override {
require(_msgSender() != operator, "ERC777: authorizing self as operator");
if (_defaultOperators[operator]) {
delete _revokedDefaultOperators[_msgSender()][operator];
} else {
_operators[_msgSender()][operator] = true;
}
emit AuthorizedOperator(operator, _msgSender());
}
/**
* @dev See {IERC777-revokeOperator}.
*/
function revokeOperator(address operator) public override {
require(operator != _msgSender(), "ERC777: revoking self as operator");
if (_defaultOperators[operator]) {
_revokedDefaultOperators[_msgSender()][operator] = true;
} else {
delete _operators[_msgSender()][operator];
}
emit RevokedOperator(operator, _msgSender());
}
/**
* @dev See {IERC777-defaultOperators}.
*/
function defaultOperators() public view override returns (address[] memory) {
return _defaultOperatorsArray;
}
/**
* @dev See {IERC777-operatorSend}.
*
* Emits {Sent} and {IERC20-Transfer} events.
*/
function operatorSend(
address sender,
address recipient,
uint256 amount,
bytes memory data,
bytes memory operatorData
)
public override
{
require(isOperatorFor(_msgSender(), sender), "ERC777: caller is not an operator for holder");
_send(sender, recipient, amount, data, operatorData, true);
}
/**
* @dev See {IERC777-operatorBurn}.
*
* Emits {Burned} and {IERC20-Transfer} events.
*/
function operatorBurn(address account, uint256 amount, bytes memory data, bytes memory operatorData) public override {
require(isOperatorFor(_msgSender(), account), "ERC777: caller is not an operator for holder");
_burn(account, amount, data, operatorData);
}
/**
* @dev See {IERC20-allowance}.
*
* Note that operator and allowance concepts are orthogonal: operators may
* not have allowance, and accounts with allowance may not be operators
* themselves.
*/
function allowance(address holder, address spender) public view override returns (uint256) {
return _allowances[holder][spender];
}
/**
* @dev See {IERC20-approve}.
*
* Note that accounts cannot have allowance issued by their operators.
*/
function approve(address spender, uint256 value) public override returns (bool) {
address holder = _msgSender();
_approve(holder, spender, value);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Note that operator and allowance concepts are orthogonal: operators cannot
* call `transferFrom` (unless they have allowance), and accounts with
* allowance cannot call `operatorSend` (unless they are operators).
*
* Emits {Sent}, {IERC20-Transfer} and {IERC20-Approval} events.
*/
function transferFrom(address holder, address recipient, uint256 amount) public override returns (bool) {
require(recipient != address(0), "ERC777: transfer to the zero address");
require(holder != address(0), "ERC777: transfer from the zero address");
address spender = _msgSender();
_callTokensToSend(spender, holder, recipient, amount, "", "");
_move(spender, holder, recipient, amount, "", "");
_approve(holder, spender, _allowances[holder][spender].sub(amount, "ERC777: transfer amount exceeds allowance"));
_callTokensReceived(spender, holder, recipient, amount, "", "", false);
return true;
}
/**
* @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* If a send hook is registered for `account`, the corresponding function
* will be called with `operator`, `data` and `operatorData`.
*
* See {IERC777Sender} and {IERC777Recipient}.
*
* Emits {Minted} and {IERC20-Transfer} events.
*
* Requirements
*
* - `account` cannot be the zero address.
* - if `account` is a contract, it must implement the {IERC777Recipient}
* interface.
*/
function _mint(
address account,
uint256 amount,
bytes memory userData,
bytes memory operatorData
)
internal virtual
{
require(account != address(0), "ERC777: mint to the zero address");
address operator = _msgSender();
_beforeTokenTransfer(operator, address(0), account, amount);
// Update state variables
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
_callTokensReceived(operator, address(0), account, amount, userData, operatorData, true);
emit Minted(operator, account, amount, userData, operatorData);
emit Transfer(address(0), account, amount);
}
/**
* @dev Send tokens
* @param from address token holder address
* @param to address recipient address
* @param amount uint256 amount of tokens to transfer
* @param userData bytes extra information provided by the token holder (if any)
* @param operatorData bytes extra information provided by the operator (if any)
* @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
*/
function _send(
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData,
bool requireReceptionAck
)
internal
{
require(from != address(0), "ERC777: send from the zero address");
require(to != address(0), "ERC777: send to the zero address");
address operator = _msgSender();
_callTokensToSend(operator, from, to, amount, userData, operatorData);
_move(operator, from, to, amount, userData, operatorData);
_callTokensReceived(operator, from, to, amount, userData, operatorData, requireReceptionAck);
}
/**
* @dev Burn tokens
* @param from address token holder address
* @param amount uint256 amount of tokens to burn
* @param data bytes extra information provided by the token holder
* @param operatorData bytes extra information provided by the operator (if any)
*/
function _burn(
address from,
uint256 amount,
bytes memory data,
bytes memory operatorData
)
internal virtual
{
require(from != address(0), "ERC777: burn from the zero address");
address operator = _msgSender();
_beforeTokenTransfer(operator, from, address(0), amount);
_callTokensToSend(operator, from, address(0), amount, data, operatorData);
// Update state variables
_balances[from] = _balances[from].sub(amount, "ERC777: burn amount exceeds balance");
_totalSupply = _totalSupply.sub(amount);
emit Burned(operator, from, amount, data, operatorData);
emit Transfer(from, address(0), amount);
}
function _move(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData
)
private
{
_beforeTokenTransfer(operator, from, to, amount);
_balances[from] = _balances[from].sub(amount, "ERC777: transfer amount exceeds balance");
_balances[to] = _balances[to].add(amount);
emit Sent(operator, from, to, amount, userData, operatorData);
emit Transfer(from, to, amount);
}
/**
* @dev See {ERC20-_approve}.
*
* Note that accounts cannot have allowance issued by their operators.
*/
function _approve(address holder, address spender, uint256 value) internal {
require(holder != address(0), "ERC777: approve from the zero address");
require(spender != address(0), "ERC777: approve to the zero address");
_allowances[holder][spender] = value;
emit Approval(holder, spender, value);
}
/**
* @dev Call from.tokensToSend() if the interface is registered
* @param operator address operator requesting the transfer
* @param from address token holder address
* @param to address recipient address
* @param amount uint256 amount of tokens to transfer
* @param userData bytes extra information provided by the token holder (if any)
* @param operatorData bytes extra information provided by the operator (if any)
*/
function _callTokensToSend(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData
)
private
{
address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(from, _TOKENS_SENDER_INTERFACE_HASH);
if (implementer != address(0)) {
IERC777Sender(implementer).tokensToSend(operator, from, to, amount, userData, operatorData);
}
}
/**
* @dev Call to.tokensReceived() if the interface is registered. Reverts if the recipient is a contract but
* tokensReceived() was not registered for the recipient
* @param operator address operator requesting the transfer
* @param from address token holder address
* @param to address recipient address
* @param amount uint256 amount of tokens to transfer
* @param userData bytes extra information provided by the token holder (if any)
* @param operatorData bytes extra information provided by the operator (if any)
* @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
*/
function _callTokensReceived(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData,
bool requireReceptionAck
)
private
{
address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(to, _TOKENS_RECIPIENT_INTERFACE_HASH);
if (implementer != address(0)) {
IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);
} else if (requireReceptionAck) {
require(!to.isContract(), "ERC777: token recipient contract has no implementer for ERC777TokensRecipient");
}
}
/**
* @dev Hook that is called before any token transfer. This includes
* calls to {send}, {transfer}, {operatorSend}, 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 operator, address from, address to, uint256 amount) internal virtual { }
}
contract FRToken is ERC777 {
constructor(uint256 initialSupply, address[] memory defaultOperators)
ERC777("Freedom Reserve", "FR", defaultOperators)
public
{
_mint(msg.sender, initialSupply, "", "");
}
}