{"Address.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/**\r\n * @dev Collection of functions related to the address type\r\n */\r\nlibrary Address {\r\n    /**\r\n     * @dev Returns true if `account` is a contract.\r\n     *\r\n     * This test is non-exhaustive, and there may be false-negatives: during the\r\n     * execution of a contract\u0027s constructor, its address will be reported as\r\n     * not containing a contract.\r\n     *\r\n     * IMPORTANT: It is unsafe to assume that an address for which this\r\n     * function returns false is an externally-owned account (EOA) and not a\r\n     * contract.\r\n     */\r\n    function isContract(address account) internal view returns (bool) {\r\n        // This method relies in extcodesize, which returns 0 for contracts in\r\n        // construction, since the code is only stored at the end of the\r\n        // constructor execution.\r\n\r\n        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts\r\n        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned\r\n        // for accounts without code, i.e. `keccak256(\u0027\u0027)`\r\n        bytes32 codehash;\r\n        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;\r\n        // solhint-disable-next-line no-inline-assembly\r\n        assembly { codehash := extcodehash(account) }\r\n        return (codehash != 0x0 \u0026\u0026 codehash != accountHash);\r\n    }\r\n\r\n        /**\r\n     * @dev Converts an `address` into `address payable`. Note that this is\r\n     * simply a type cast: the actual underlying value is not changed.\r\n     *\r\n     * _Available since v2.4.0._\r\n     */\r\n    function toPayable(address account) internal pure returns (address payable) {\r\n        return address(uint160(account));\r\n    }\r\n}\r\n"},"Context.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/*\r\n * @dev Provides information about the current execution context, including the\r\n * sender of the transaction and its data. While these are generally available\r\n * via msg.sender and msg.data, they should not be accessed in such a direct\r\n * manner, since when dealing with GSN meta-transactions the account sending and\r\n * paying for execution may not be the actual sender (as far as an application\r\n * is concerned).\r\n *\r\n * This contract is only required for intermediate, library-like contracts.\r\n */\r\ncontract Context {\r\n\t// Empty internal constructor, to prevent people from mistakenly deploying\r\n\t// an instance of this contract, which should be used via inheritance.\r\n\tconstructor () internal { }\r\n\t// solhint-disable-previous-line no-empty-blocks\r\n\r\n    /**\r\n     * @dev return msg.sender\r\n     * @return msg.sender\r\n     */\r\n\tfunction _msgSender()\r\n        internal\r\n        view\r\n        returns (address payable)\r\n    {\r\n\t\treturn msg.sender;\r\n\t}\r\n\r\n    /**\r\n     * @dev return msg.value\r\n     * @return msg.value\r\n     */\r\n\tfunction _msgValue()\r\n        internal\r\n        view\r\n        returns (uint)\r\n    {\r\n\t\treturn msg.value;\r\n\t}\r\n\r\n    /**\r\n     * @dev return tx.origin\r\n     * @return tx.origin\r\n     */\r\n\tfunction _txOrigin()\r\n        internal\r\n        view\r\n        returns (address)\r\n    {\r\n\t\treturn tx.origin;\r\n\t}\r\n}"},"ERC777.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\nimport \"./Context.sol\";\r\nimport \"./IERC777.sol\";\r\nimport \"./IERC777Recipient.sol\";\r\nimport \"./IERC777Sender.sol\";\r\nimport \"./IERC20.sol\";\r\nimport \"./SafeMath.sol\";\r\nimport \"./Address.sol\";\r\nimport \"./IERC1820Registry.sol\";\r\n\r\n/**\r\n * @dev Implementation of the {IERC777} interface.\r\n *\r\n * This implementation is agnostic to the way tokens are created. This means\r\n * that a supply mechanism has to be added in a derived contract using {_mint}.\r\n *\r\n * Support for ERC20 is included in this contract, as specified by the EIP: both\r\n * the ERC777 and ERC20 interfaces can be safely used when interacting with it.\r\n * Both {IERC777-Sent} and {IERC20-Transfer} events are emitted on token\r\n * movements.\r\n *\r\n * Additionally, the {IERC777-granularity} value is hard-coded to `1`, meaning that there\r\n * are no special restrictions in the amount of tokens that created, moved, or\r\n * destroyed. This makes integration with ERC20 applications seamless.\r\n */\r\ncontract ERC777 is Context, IERC777, IERC20 {\r\n    using SafeMath for uint256;\r\n    using Address for address;\r\n\r\n    IERC1820Registry constant private ERC1820_REGISTRY = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);\r\n\r\n    mapping(address =\u003e uint256) private _balances;\r\n\r\n    uint256 private _totalSupply;\r\n\r\n    string private _name;\r\n    string private _symbol;\r\n\r\n    // We inline the result of the following hashes because Solidity doesn\u0027t resolve them at compile time.\r\n    // See https://github.com/ethereum/solidity/issues/4024.\r\n\r\n    // keccak256(\"ERC777TokensSender\")\r\n    bytes32 constant private TOKENS_SENDER_INTERFACE_HASH =\r\n        0x29ddb589b1fb5fc7cf394961c1adf5f8c6454761adf795e67fe149f658abe895;\r\n\r\n    // keccak256(\"ERC777TokensRecipient\")\r\n    bytes32 constant private TOKENS_RECIPIENT_INTERFACE_HASH =\r\n        0xb281fc8c12954d22544db45de3159a39272895b169a852b314f9cc762e44c53b;\r\n\r\n    // This isn\u0027t ever read from - it\u0027s only used to respond to the defaultOperators query.\r\n    address[] private _defaultOperatorsArray;\r\n\r\n    // Immutable, but accounts may revoke them (tracked in __revokedDefaultOperators).\r\n    mapping(address =\u003e bool) private _defaultOperators;\r\n\r\n    // For each account, a mapping of its operators and revoked default operators.\r\n    mapping(address =\u003e mapping(address =\u003e bool)) private _operators;\r\n    mapping(address =\u003e mapping(address =\u003e bool)) private _revokedDefaultOperators;\r\n\r\n    // ERC20-allowances\r\n    mapping (address =\u003e mapping (address =\u003e uint256)) private _allowances;\r\n\r\n    /**\r\n     * @dev `defaultOperators` may be an empty array.\r\n     */\r\n    constructor(\r\n        string memory name,\r\n        string memory symbol,\r\n        address[] memory defaultOperators\r\n    ) public {\r\n        _name = name;\r\n        _symbol = symbol;\r\n\r\n        _defaultOperatorsArray = defaultOperators;\r\n        for (uint256 i = 0; i \u003c _defaultOperatorsArray.length; i++) {\r\n            _defaultOperators[_defaultOperatorsArray[i]] = true;\r\n        }\r\n\r\n        // register interfaces\r\n        ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256(\"ERC777Token\"), address(this));\r\n        ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256(\"ERC20Token\"), address(this));\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-name}.\r\n     */\r\n    function name() public view returns (string memory) {\r\n        return _name;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-symbol}.\r\n     */\r\n    function symbol() public view returns (string memory) {\r\n        return _symbol;\r\n    }\r\n\r\n    /**\r\n     * @dev See {ERC20Detailed-decimals}.\r\n     *\r\n     * Always returns 18, as per the\r\n     * [ERC777 EIP](https://eips.ethereum.org/EIPS/eip-777#backward-compatibility).\r\n     */\r\n    function decimals() public pure returns (uint8) {\r\n        return 18;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-granularity}.\r\n     *\r\n     * This implementation always returns `1`.\r\n     */\r\n    function granularity() public view returns (uint256) {\r\n        return 1;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-totalSupply}.\r\n     */\r\n    function totalSupply() public view returns (uint256) {\r\n        return _totalSupply;\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the amount of tokens owned by an account (`tokenHolder`).\r\n     */\r\n    function balanceOf(address tokenHolder) public view returns (uint256) {\r\n        return _balances[tokenHolder];\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-send}.\r\n     *\r\n     * Also emits a {IERC20-Transfer} event for ERC20 compatibility.\r\n     */\r\n    function send(address recipient, uint256 amount, bytes memory data) public {\r\n        _send(_msgSender(), _msgSender(), recipient, amount, data, \"\", true);\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC20-transfer}.\r\n     *\r\n     * Unlike `send`, `recipient` is _not_ required to implement the {IERC777Recipient}\r\n     * interface if it is a contract.\r\n     *\r\n     * Also emits a {Sent} event.\r\n     */\r\n    function transfer(address recipient, uint256 amount) public returns (bool) {\r\n        require(recipient != address(0), \"ERC777: transfer to the zero address\");\r\n\r\n        address from = _msgSender();\r\n\r\n        _callTokensToSend(from, from, recipient, amount, \"\", \"\");\r\n\r\n        _move(from, from, recipient, amount, \"\", \"\");\r\n\r\n        _callTokensReceived(from, from, recipient, amount, \"\", \"\", false);\r\n\r\n        return true;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-burn}.\r\n     *\r\n     * Also emits a {IERC20-Transfer} event for ERC20 compatibility.\r\n     */\r\n    function burn(uint256 amount, bytes memory data) public {\r\n        _burn(_msgSender(), _msgSender(), amount, data, \"\");\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-isOperatorFor}.\r\n     */\r\n    function isOperatorFor(\r\n        address operator,\r\n        address tokenHolder\r\n    ) public view returns (bool) {\r\n        return operator == tokenHolder ||\r\n            (_defaultOperators[operator] \u0026\u0026 !_revokedDefaultOperators[tokenHolder][operator]) ||\r\n            _operators[tokenHolder][operator];\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-authorizeOperator}.\r\n     */\r\n    function authorizeOperator(address operator) public {\r\n        require(_msgSender() != operator, \"ERC777: authorizing self as operator\");\r\n\r\n        if (_defaultOperators[operator]) {\r\n            delete _revokedDefaultOperators[_msgSender()][operator];\r\n        } else {\r\n            _operators[_msgSender()][operator] = true;\r\n        }\r\n\r\n        emit AuthorizedOperator(operator, _msgSender());\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-revokeOperator}.\r\n     */\r\n    function revokeOperator(address operator) public {\r\n        require(operator != _msgSender(), \"ERC777: revoking self as operator\");\r\n\r\n        if (_defaultOperators[operator]) {\r\n            _revokedDefaultOperators[_msgSender()][operator] = true;\r\n        } else {\r\n            delete _operators[_msgSender()][operator];\r\n        }\r\n\r\n        emit RevokedOperator(operator, _msgSender());\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-defaultOperators}.\r\n     */\r\n    function defaultOperators() public view returns (address[] memory) {\r\n        return _defaultOperatorsArray;\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-operatorSend}.\r\n     *\r\n     * Emits {Sent} and {IERC20-Transfer} events.\r\n     */\r\n    function operatorSend(\r\n        address sender,\r\n        address recipient,\r\n        uint256 amount,\r\n        bytes memory data,\r\n        bytes memory operatorData\r\n    )\r\n    public\r\n    {\r\n        require(isOperatorFor(_msgSender(), sender), \"ERC777: caller is not an operator for holder\");\r\n        _send(_msgSender(), sender, recipient, amount, data, operatorData, true);\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC777-operatorBurn}.\r\n     *\r\n     * Emits {Burned} and {IERC20-Transfer} events.\r\n     */\r\n    function operatorBurn(address account, uint256 amount, bytes memory data, bytes memory operatorData) public {\r\n        require(isOperatorFor(_msgSender(), account), \"ERC777: caller is not an operator for holder\");\r\n        _burn(_msgSender(), account, amount, data, operatorData);\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC20-allowance}.\r\n     *\r\n     * Note that operator and allowance concepts are orthogonal: operators may\r\n     * not have allowance, and accounts with allowance may not be operators\r\n     * themselves.\r\n     */\r\n    function allowance(address holder, address spender) public view returns (uint256) {\r\n        return _allowances[holder][spender];\r\n    }\r\n\r\n    /**\r\n     * @dev See {IERC20-approve}.\r\n     *\r\n     * Note that accounts cannot have allowance issued by their operators.\r\n     */\r\n    function approve(address spender, uint256 value) public returns (bool) {\r\n        address holder = _msgSender();\r\n        _approve(holder, spender, value);\r\n        return true;\r\n    }\r\n\r\n   /**\r\n    * @dev See {IERC20-transferFrom}.\r\n    *\r\n    * Note that operator and allowance concepts are orthogonal: operators cannot\r\n    * call `transferFrom` (unless they have allowance), and accounts with\r\n    * allowance cannot call `operatorSend` (unless they are operators).\r\n    *\r\n    * Emits {Sent}, {IERC20-Transfer} and {IERC20-Approval} events.\r\n    */\r\n    function transferFrom(address holder, address recipient, uint256 amount) public returns (bool) {\r\n        require(recipient != address(0), \"ERC777: transfer to the zero address\");\r\n        require(holder != address(0), \"ERC777: transfer from the zero address\");\r\n\r\n        address spender = _msgSender();\r\n\r\n        _callTokensToSend(spender, holder, recipient, amount, \"\", \"\");\r\n\r\n        _move(spender, holder, recipient, amount, \"\", \"\");\r\n        _approve(holder, spender, _allowances[holder][spender].sub(amount, \"ERC777: transfer amount exceeds allowance\"));\r\n\r\n        _callTokensReceived(spender, holder, recipient, amount, \"\", \"\", false);\r\n\r\n        return true;\r\n    }\r\n\r\n    /**\r\n     * @dev Creates `amount` tokens and assigns them to `account`, increasing\r\n     * the total supply.\r\n     *\r\n     * If a send hook is registered for `account`, the corresponding function\r\n     * will be called with `operator`, `data` and `operatorData`.\r\n     *\r\n     * See {IERC777Sender} and {IERC777Recipient}.\r\n     *\r\n     * Emits {Minted} and {IERC20-Transfer} events.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - `account` cannot be the zero address.\r\n     * - if `account` is a contract, it must implement the {IERC777Recipient}\r\n     * interface.\r\n     */\r\n    function _mint(\r\n        address operator,\r\n        address account,\r\n        uint256 amount,\r\n        bytes memory userData,\r\n        bytes memory operatorData\r\n    )\r\n    internal\r\n    {\r\n        require(account != address(0), \"ERC777: mint to the zero address\");\r\n\r\n        // Update state variables\r\n        _totalSupply = _totalSupply.add(amount);\r\n        _balances[account] = _balances[account].add(amount);\r\n\r\n        _callTokensReceived(operator, address(0), account, amount, userData, operatorData, true);\r\n\r\n        emit Minted(operator, account, amount, userData, operatorData);\r\n        emit Transfer(address(0), account, amount);\r\n    }\r\n\r\n    /**\r\n     * @dev Send tokens\r\n     * @param operator address operator requesting the transfer\r\n     * @param from address token holder address\r\n     * @param to address recipient address\r\n     * @param amount uint256 amount of tokens to transfer\r\n     * @param userData bytes extra information provided by the token holder (if any)\r\n     * @param operatorData bytes extra information provided by the operator (if any)\r\n     * @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient\r\n     */\r\n    function _send(\r\n        address operator,\r\n        address from,\r\n        address to,\r\n        uint256 amount,\r\n        bytes memory userData,\r\n        bytes memory operatorData,\r\n        bool requireReceptionAck\r\n    )\r\n        private\r\n    {\r\n        require(from != address(0), \"ERC777: send from the zero address\");\r\n        require(to != address(0), \"ERC777: send to the zero address\");\r\n\r\n        _callTokensToSend(operator, from, to, amount, userData, operatorData);\r\n\r\n        _move(operator, from, to, amount, userData, operatorData);\r\n\r\n        _callTokensReceived(operator, from, to, amount, userData, operatorData, requireReceptionAck);\r\n    }\r\n\r\n    /**\r\n     * @dev Burn tokens\r\n     * @param operator address operator requesting the operation\r\n     * @param from address token holder address\r\n     * @param amount uint256 amount of tokens to burn\r\n     * @param data bytes extra information provided by the token holder\r\n     * @param operatorData bytes extra information provided by the operator (if any)\r\n     */\r\n    function _burn(\r\n        address operator,\r\n        address from,\r\n        uint256 amount,\r\n        bytes memory data,\r\n        bytes memory operatorData\r\n    )\r\n        internal\r\n    {\r\n        require(from != address(0), \"ERC777: burn from the zero address\");\r\n\r\n        _callTokensToSend(operator, from, address(0), amount, data, operatorData);\r\n\r\n        // Update state variables\r\n        _balances[from] = _balances[from].sub(amount, \"ERC777: burn amount exceeds balance\");\r\n        _totalSupply = _totalSupply.sub(amount);\r\n\r\n        emit Burned(operator, from, amount, data, operatorData);\r\n        emit Transfer(from, address(0), amount);\r\n    }\r\n\r\n    function _move(\r\n        address operator,\r\n        address from,\r\n        address to,\r\n        uint256 amount,\r\n        bytes memory userData,\r\n        bytes memory operatorData\r\n    )\r\n        private\r\n    {\r\n        _balances[from] = _balances[from].sub(amount, \"ERC777: transfer amount exceeds balance\");\r\n        _balances[to] = _balances[to].add(amount);\r\n\r\n        emit Sent(operator, from, to, amount, userData, operatorData);\r\n        emit Transfer(from, to, amount);\r\n    }\r\n\r\n    function _approve(address holder, address spender, uint256 value) private {\r\n        // TODO: restore this require statement if this function becomes internal, or is called at a new callsite. It is\r\n        // currently unnecessary.\r\n        //require(holder != address(0), \"ERC777: approve from the zero address\");\r\n        require(spender != address(0), \"ERC777: approve to the zero address\");\r\n\r\n        _allowances[holder][spender] = value;\r\n        emit Approval(holder, spender, value);\r\n    }\r\n\r\n    /**\r\n     * @dev Call from.tokensToSend() if the interface is registered\r\n     * @param operator address operator requesting the transfer\r\n     * @param from address token holder address\r\n     * @param to address recipient address\r\n     * @param amount uint256 amount of tokens to transfer\r\n     * @param userData bytes extra information provided by the token holder (if any)\r\n     * @param operatorData bytes extra information provided by the operator (if any)\r\n     */\r\n    function _callTokensToSend(\r\n        address operator,\r\n        address from,\r\n        address to,\r\n        uint256 amount,\r\n        bytes memory userData,\r\n        bytes memory operatorData\r\n    )\r\n        private\r\n    {\r\n        address implementer = ERC1820_REGISTRY.getInterfaceImplementer(from, TOKENS_SENDER_INTERFACE_HASH);\r\n        if (implementer != address(0)) {\r\n            IERC777Sender(implementer).tokensToSend(operator, from, to, amount, userData, operatorData);\r\n        }\r\n    }\r\n\r\n    /**\r\n     * @dev Call to.tokensReceived() if the interface is registered. Reverts if the recipient is a contract but\r\n     * tokensReceived() was not registered for the recipient\r\n     * @param operator address operator requesting the transfer\r\n     * @param from address token holder address\r\n     * @param to address recipient address\r\n     * @param amount uint256 amount of tokens to transfer\r\n     * @param userData bytes extra information provided by the token holder (if any)\r\n     * @param operatorData bytes extra information provided by the operator (if any)\r\n     * @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient\r\n     */\r\n    function _callTokensReceived(\r\n        address operator,\r\n        address from,\r\n        address to,\r\n        uint256 amount,\r\n        bytes memory userData,\r\n        bytes memory operatorData,\r\n        bool requireReceptionAck\r\n    )\r\n        private\r\n    {\r\n        address implementer = ERC1820_REGISTRY.getInterfaceImplementer(to, TOKENS_RECIPIENT_INTERFACE_HASH);\r\n        if (implementer != address(0)) {\r\n            IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);\r\n        } else if (requireReceptionAck) {\r\n            require(!to.isContract(), \"ERC777: token recipient contract has no implementer for ERC777TokensRecipient\");\r\n        }\r\n    }\r\n}\r\n"},"ERC777_StandardToken.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\nimport \u0027./SafeMath.sol\u0027;\r\nimport \"./ERC777.sol\";\r\n\r\n\r\n/**\r\n * @dev Optional functions from the ERC777 standard.\r\n */\r\ncontract ERC777_StandardToken is ERC777 {\r\n\r\n    /**\r\n     * @dev `defaultOperators` may be an empty array.\r\n     */\r\n    constructor(\r\n        string memory name,\r\n        string memory symbol,\r\n        address[] memory defaultOperators,\r\n        uint256 claimAmount\r\n    ) ERC777(name, symbol, defaultOperators)\r\n    public\r\n    {\r\n        uint256 mintAmount = claimAmount.mul(10 ** uint256(18));\r\n        _mint(address(0), _msgSender(), mintAmount, \"\", \"\");\r\n    }\r\n\r\n}\r\n"},"IERC1820Registry.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/**\r\n * @dev Interface of the global ERC1820 Registry, as defined in the\r\n * https://eips.ethereum.org/EIPS/eip-1820[EIP]. Accounts may register\r\n * implementers for interfaces in this registry, as well as query support.\r\n *\r\n * Implementers may be shared by multiple accounts, and can also implement more\r\n * than a single interface for each account. Contracts can implement interfaces\r\n * for themselves, but externally-owned accounts (EOA) must delegate this to a\r\n * contract.\r\n *\r\n * {IERC165} interfaces can also be queried via the registry.\r\n *\r\n * For an in-depth explanation and source code analysis, see the EIP text.\r\n */\r\ninterface IERC1820Registry {\r\n    /**\r\n     * @dev Sets `newManager` as the manager for `account`. A manager of an\r\n     * account is able to set interface implementers for it.\r\n     *\r\n     * By default, each account is its own manager. Passing a value of `0x0` in\r\n     * `newManager` will reset the manager to this initial state.\r\n     *\r\n     * Emits a {ManagerChanged} event.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - the caller must be the current manager for `account`.\r\n     */\r\n    function setManager(address account, address newManager) external;\r\n\r\n    /**\r\n     * @dev Returns the manager for `account`.\r\n     *\r\n     * See {setManager}.\r\n     */\r\n    function getManager(address account) external view returns (address);\r\n\r\n    /**\r\n     * @dev Sets the `implementer` contract as `account`\u0027s implementer for\r\n     * `interfaceHash`.\r\n     *\r\n     * `account` being the zero address is an alias for the caller\u0027s address.\r\n     * The zero address can also be used in `implementer` to remove an old one.\r\n     *\r\n     * See {interfaceHash} to learn how these are created.\r\n     *\r\n     * Emits an {InterfaceImplementerSet} event.\r\n     *\r\n     * Requirements:\r\n     *\r\n     * - the caller must be the current manager for `account`.\r\n     * - `interfaceHash` must not be an {IERC165} interface id (i.e. it must not\r\n     * end in 28 zeroes).\r\n     * - `implementer` must implement {IERC1820Implementer} and return true when\r\n     * queried for support, unless `implementer` is the caller. See\r\n     * {IERC1820Implementer-canImplementInterfaceForAddress}.\r\n     */\r\n    function setInterfaceImplementer(address account, bytes32 interfaceHash, address implementer) external;\r\n\r\n    /**\r\n     * @dev Returns the implementer of `interfaceHash` for `account`. If no such\r\n     * implementer is registered, returns the zero address.\r\n     *\r\n     * If `interfaceHash` is an {IERC165} interface id (i.e. it ends with 28\r\n     * zeroes), `account` will be queried for support of it.\r\n     *\r\n     * `account` being the zero address is an alias for the caller\u0027s address.\r\n     */\r\n    function getInterfaceImplementer(address account, bytes32 interfaceHash) external view returns (address);\r\n\r\n    /**\r\n     * @dev Returns the interface hash for an `interfaceName`, as defined in the\r\n     * corresponding\r\n     * https://eips.ethereum.org/EIPS/eip-1820#interface-name[section of the EIP].\r\n     */\r\n    function interfaceHash(string calldata interfaceName) external pure returns (bytes32);\r\n\r\n    /**\r\n     *  @notice Updates the cache with whether the contract implements an ERC165 interface or not.\r\n     *  @param account Address of the contract for which to update the cache.\r\n     *  @param interfaceId ERC165 interface for which to update the cache.\r\n     */\r\n    function updateERC165Cache(address account, bytes4 interfaceId) external;\r\n\r\n    /**\r\n     *  @notice Checks whether a contract implements an ERC165 interface or not.\r\n     *  If the result is not cached a direct lookup on the contract address is performed.\r\n     *  If the result is not cached or the cached value is out-of-date, the cache MUST be updated manually by calling\r\n     *  {updateERC165Cache} with the contract address.\r\n     *  @param account Address of the contract to check.\r\n     *  @param interfaceId ERC165 interface to check.\r\n     *  @return True if `account` implements `interfaceId`, false otherwise.\r\n     */\r\n    function implementsERC165Interface(address account, bytes4 interfaceId) external view returns (bool);\r\n\r\n    /**\r\n     *  @notice Checks whether a contract implements an ERC165 interface or not without using nor updating the cache.\r\n     *  @param account Address of the contract to check.\r\n     *  @param interfaceId ERC165 interface to check.\r\n     *  @return True if `account` implements `interfaceId`, false otherwise.\r\n     */\r\n    function implementsERC165InterfaceNoCache(address account, bytes4 interfaceId) external view returns (bool);\r\n\r\n    event InterfaceImplementerSet(address indexed account, bytes32 indexed interfaceHash, address indexed implementer);\r\n\r\n    event ManagerChanged(address indexed account, address indexed newManager);\r\n}\r\n"},"IERC20.sol":{"content":"pragma solidity \u003e=0.4.22 \u003c 0.6.0;\r\n\r\n/**\r\n * @dev Interface of the ERC20 standard as defined in the EIP. Does not include\r\n * the optional functions; to access them see {ERC20Detailed}.\r\n */\r\ninterface IERC20 {\r\n    /**\r\n     * @dev Returns the amount of tokens in existence.\r\n     */\r\n    function totalSupply() external view returns (uint256);\r\n\r\n    /**\r\n     * @dev Returns the amount of tokens owned by `account`.\r\n     */\r\n    function balanceOf(address account) external view returns (uint256);\r\n\r\n    /**\r\n     * @dev Moves `amount` tokens from the caller\u0027s account to `recipient`.\r\n     *\r\n     * Returns a boolean value indicating whether the operation succeeded.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function transfer(address recipient, uint256 amount) external returns (bool);\r\n\r\n    /**\r\n     * @dev Returns the remaining number of tokens that `spender` will be\r\n     * allowed to spend on behalf of `owner` through {transferFrom}. This is\r\n     * zero by default.\r\n     *\r\n     * This value changes when {approve} or {transferFrom} are called.\r\n     */\r\n    function allowance(address owner, address spender) external view returns (uint256);\r\n\r\n    /**\r\n     * @dev Sets `amount` as the allowance of `spender` over the caller\u0027s tokens.\r\n     *\r\n     * Returns a boolean value indicating whether the operation succeeded.\r\n     *\r\n     * IMPORTANT: Beware that changing an allowance with this method brings the risk\r\n     * that someone may use both the old and the new allowance by unfortunate\r\n     * transaction ordering. One possible solution to mitigate this race\r\n     * condition is to first reduce the spender\u0027s allowance to 0 and set the\r\n     * desired value afterwards:\r\n     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729\r\n     *\r\n     * Emits an {Approval} event.\r\n     */\r\n    function approve(address spender, uint256 amount) external returns (bool);\r\n\r\n    /**\r\n     * @dev Moves `amount` tokens from `sender` to `recipient` using the\r\n     * allowance mechanism. `amount` is then deducted from the caller\u0027s\r\n     * allowance.\r\n     *\r\n     * Returns a boolean value indicating whether the operation succeeded.\r\n     *\r\n     * Emits a {Transfer} event.\r\n     */\r\n    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);\r\n\r\n    /**\r\n     * @dev Emitted when `value` tokens are moved from one account (`from`) to\r\n     * another (`to`).\r\n     *\r\n     * Note that `value` may be zero.\r\n     */\r\n    event Transfer(address indexed from, address indexed to, uint256 value);\r\n\r\n    /**\r\n     * @dev Emitted when the allowance of a `spender` for an `owner` is set by\r\n     * a call to {approve}. `value` is the new allowance.\r\n     */\r\n    event Approval(address indexed owner, address indexed spender, uint256 value);\r\n}\r\n"},"IERC777.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/**\r\n * @dev Interface of the ERC777Token standard as defined in the EIP.\r\n *\r\n * This contract uses the\r\n * https://eips.ethereum.org/EIPS/eip-1820[ERC1820 registry standard] to let\r\n * token holders and recipients react to token movements by using setting implementers\r\n * for the associated interfaces in said registry. See {IERC1820Registry} and\r\n * {ERC1820Implementer}.\r\n */\r\ninterface IERC777 {\r\n    /**\r\n     * @dev Returns the name of the token.\r\n     */\r\n    function name() external view returns (string memory);\r\n\r\n    /**\r\n     * @dev Returns the symbol of the token, usually a shorter version of the\r\n     * name.\r\n     */\r\n    function symbol() external view returns (string memory);\r\n\r\n    /**\r\n     * @dev Returns the smallest part of the token that is not divisible. This\r\n     * means all token operations (creation, movement and destruction) must have\r\n     * amounts that are a multiple of this number.\r\n     *\r\n     * For most token contracts, this value will equal 1.\r\n     */\r\n    function granularity() external view returns (uint256);\r\n\r\n    /**\r\n     * @dev Returns the amount of tokens in existence.\r\n     */\r\n    function totalSupply() external view returns (uint256);\r\n\r\n    /**\r\n     * @dev Returns the amount of tokens owned by an account (`owner`).\r\n     */\r\n    function balanceOf(address owner) external view returns (uint256);\r\n\r\n    /**\r\n     * @dev Moves `amount` tokens from the caller\u0027s account to `recipient`.\r\n     *\r\n     * If send or receive hooks are registered for the caller and `recipient`,\r\n     * the corresponding functions will be called with `data` and empty\r\n     * `operatorData`. See {IERC777Sender} and {IERC777Recipient}.\r\n     *\r\n     * Emits a {Sent} event.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - the caller must have at least `amount` tokens.\r\n     * - `recipient` cannot be the zero address.\r\n     * - if `recipient` is a contract, it must implement the {IERC777Recipient}\r\n     * interface.\r\n     */\r\n    function send(address recipient, uint256 amount, bytes calldata data) external;\r\n\r\n    /**\r\n     * @dev Destroys `amount` tokens from the caller\u0027s account, reducing the\r\n     * total supply.\r\n     *\r\n     * If a send hook is registered for the caller, the corresponding function\r\n     * will be called with `data` and empty `operatorData`. See {IERC777Sender}.\r\n     *\r\n     * Emits a {Burned} event.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - the caller must have at least `amount` tokens.\r\n     */\r\n    function burn(uint256 amount, bytes calldata data) external;\r\n\r\n    /**\r\n     * @dev Returns true if an account is an operator of `tokenHolder`.\r\n     * Operators can send and burn tokens on behalf of their owners. All\r\n     * accounts are their own operator.\r\n     *\r\n     * See {operatorSend} and {operatorBurn}.\r\n     */\r\n    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);\r\n\r\n    /**\r\n     * @dev Make an account an operator of the caller.\r\n     *\r\n     * See {isOperatorFor}.\r\n     *\r\n     * Emits an {AuthorizedOperator} event.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - `operator` cannot be calling address.\r\n     */\r\n    function authorizeOperator(address operator) external;\r\n\r\n    /**\r\n     * @dev Make an account an operator of the caller.\r\n     *\r\n     * See {isOperatorFor} and {defaultOperators}.\r\n     *\r\n     * Emits a {RevokedOperator} event.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - `operator` cannot be calling address.\r\n     */\r\n    function revokeOperator(address operator) external;\r\n\r\n    /**\r\n     * @dev Returns the list of default operators. These accounts are operators\r\n     * for all token holders, even if {authorizeOperator} was never called on\r\n     * them.\r\n     *\r\n     * This list is immutable, but individual holders may revoke these via\r\n     * {revokeOperator}, in which case {isOperatorFor} will return false.\r\n     */\r\n    function defaultOperators() external view returns (address[] memory);\r\n\r\n    /**\r\n     * @dev Moves `amount` tokens from `sender` to `recipient`. The caller must\r\n     * be an operator of `sender`.\r\n     *\r\n     * If send or receive hooks are registered for `sender` and `recipient`,\r\n     * the corresponding functions will be called with `data` and\r\n     * `operatorData`. See {IERC777Sender} and {IERC777Recipient}.\r\n     *\r\n     * Emits a {Sent} event.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - `sender` cannot be the zero address.\r\n     * - `sender` must have at least `amount` tokens.\r\n     * - the caller must be an operator for `sender`.\r\n     * - `recipient` cannot be the zero address.\r\n     * - if `recipient` is a contract, it must implement the {IERC777Recipient}\r\n     * interface.\r\n     */\r\n    function operatorSend(\r\n        address sender,\r\n        address recipient,\r\n        uint256 amount,\r\n        bytes calldata data,\r\n        bytes calldata operatorData\r\n    ) external;\r\n\r\n    /**\r\n     * @dev Destoys `amount` tokens from `account`, reducing the total supply.\r\n     * The caller must be an operator of `account`.\r\n     *\r\n     * If a send hook is registered for `account`, the corresponding function\r\n     * will be called with `data` and `operatorData`. See {IERC777Sender}.\r\n     *\r\n     * Emits a {Burned} event.\r\n     *\r\n     * Requirements\r\n     *\r\n     * - `account` cannot be the zero address.\r\n     * - `account` must have at least `amount` tokens.\r\n     * - the caller must be an operator for `account`.\r\n     */\r\n    function operatorBurn(\r\n        address account,\r\n        uint256 amount,\r\n        bytes calldata data,\r\n        bytes calldata operatorData\r\n    ) external;\r\n\r\n    event Sent(\r\n        address indexed operator,\r\n        address indexed from,\r\n        address indexed to,\r\n        uint256 amount,\r\n        bytes data,\r\n        bytes operatorData\r\n    );\r\n\r\n    event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);\r\n\r\n    event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);\r\n\r\n    event AuthorizedOperator(address indexed operator, address indexed tokenHolder);\r\n\r\n    event RevokedOperator(address indexed operator, address indexed tokenHolder);\r\n}\r\n"},"IERC777Recipient.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/**\r\n * @dev Interface of the ERC777TokensRecipient standard as defined in the EIP.\r\n *\r\n * Accounts can be notified of {IERC777} tokens being sent to them by having a\r\n * contract implement this interface (contract holders can be their own\r\n * implementer) and registering it on the\r\n * https://eips.ethereum.org/EIPS/eip-1820[ERC1820 global registry].\r\n *\r\n * See {IERC1820Registry} and {ERC1820Implementer}.\r\n */\r\ninterface IERC777Recipient {\r\n    /**\r\n     * @dev Called by an {IERC777} token contract whenever tokens are being\r\n     * moved or created into a registered account (`to`). The type of operation\r\n     * is conveyed by `from` being the zero address or not.\r\n     *\r\n     * This call occurs _after_ the token contract\u0027s state is updated, so\r\n     * {IERC777-balanceOf}, etc., can be used to query the post-operation state.\r\n     *\r\n     * This function may revert to prevent the operation from being executed.\r\n     */\r\n    function tokensReceived(\r\n        address operator,\r\n        address from,\r\n        address to,\r\n        uint256 amount,\r\n        bytes calldata userData,\r\n        bytes calldata operatorData\r\n    ) external;\r\n}\r\n"},"IERC777Sender.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/**\r\n * @dev Interface of the ERC777TokensSender standard as defined in the EIP.\r\n *\r\n * {IERC777} Token holders can be notified of operations performed on their\r\n * tokens by having a contract implement this interface (contract holders can be\r\n *  their own implementer) and registering it on the\r\n * https://eips.ethereum.org/EIPS/eip-1820[ERC1820 global registry].\r\n *\r\n * See {IERC1820Registry} and {ERC1820Implementer}.\r\n */\r\ninterface IERC777Sender {\r\n    /**\r\n     * @dev Called by an {IERC777} token contract whenever a registered holder\u0027s\r\n     * (`from`) tokens are about to be moved or destroyed. The type of operation\r\n     * is conveyed by `to` being the zero address or not.\r\n     *\r\n     * This call occurs _before_ the token contract\u0027s state is updated, so\r\n     * {IERC777-balanceOf}, etc., can be used to query the pre-operation state.\r\n     *\r\n     * This function may revert to prevent the operation from being executed.\r\n     */\r\n    function tokensToSend(\r\n        address operator,\r\n        address from,\r\n        address to,\r\n        uint256 amount,\r\n        bytes calldata userData,\r\n        bytes calldata operatorData\r\n    ) external;\r\n}\r\n"},"SafeMath.sol":{"content":"pragma solidity ^0.5.0;\r\n\r\n/**\r\n * @dev Wrappers over Solidity\u0027s arithmetic operations with added overflow\r\n * checks.\r\n *\r\n * Arithmetic operations in Solidity wrap on overflow. This can easily result\r\n * in bugs, because programmers usually assume that an overflow raises an\r\n * error, which is the standard behavior in high level programming languages.\r\n * `SafeMath` restores this intuition by reverting the transaction when an\r\n * operation overflows.\r\n *\r\n * Using this library instead of the unchecked operations eliminates an entire\r\n * class of bugs, so it\u0027s recommended to use it always.\r\n */\r\nlibrary SafeMath {\r\n    /**\r\n     * @dev Returns the addition of two unsigned integers, reverting on\r\n     * overflow.\r\n     *\r\n     * Counterpart to Solidity\u0027s `+` operator.\r\n     *\r\n     * Requirements:\r\n     * - Addition cannot overflow.\r\n     */\r\n    function add(uint256 a, uint256 b) internal pure returns (uint256) {\r\n        uint256 c = a + b;\r\n        require(c \u003e= a, \"SafeMath: addition overflow\");\r\n\r\n        return c;\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the subtraction of two unsigned integers, reverting on\r\n     * overflow (when the result is negative).\r\n     *\r\n     * Counterpart to Solidity\u0027s `-` operator.\r\n     *\r\n     * Requirements:\r\n     * - Subtraction cannot overflow.\r\n     */\r\n    function sub(uint256 a, uint256 b) internal pure returns (uint256) {\r\n        return sub(a, b, \"SafeMath: subtraction overflow\");\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on\r\n     * overflow (when the result is negative).\r\n     *\r\n     * Counterpart to Solidity\u0027s `-` operator.\r\n     *\r\n     * Requirements:\r\n     * - Subtraction cannot overflow.\r\n     *\r\n     * _Available since v2.4.0._\r\n     */\r\n    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\r\n        require(b \u003c= a, errorMessage);\r\n        uint256 c = a - b;\r\n\r\n        return c;\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the multiplication of two unsigned integers, reverting on\r\n     * overflow.\r\n     *\r\n     * Counterpart to Solidity\u0027s `*` operator.\r\n     *\r\n     * Requirements:\r\n     * - Multiplication cannot overflow.\r\n     */\r\n    function mul(uint256 a, uint256 b) internal pure returns (uint256) {\r\n        // Gas optimization: this is cheaper than requiring \u0027a\u0027 not being zero, but the\r\n        // benefit is lost if \u0027b\u0027 is also tested.\r\n        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522\r\n        if (a == 0) {\r\n            return 0;\r\n        }\r\n\r\n        uint256 c = a * b;\r\n        require(c / a == b, \"SafeMath: multiplication overflow\");\r\n\r\n        return c;\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the integer division of two unsigned integers. Reverts on\r\n     * division by zero. The result is rounded towards zero.\r\n     *\r\n     * Counterpart to Solidity\u0027s `/` operator. Note: this function uses a\r\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\r\n     * uses an invalid opcode to revert (consuming all remaining gas).\r\n     *\r\n     * Requirements:\r\n     * - The divisor cannot be zero.\r\n     */\r\n    function div(uint256 a, uint256 b) internal pure returns (uint256) {\r\n        return div(a, b, \"SafeMath: division by zero\");\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on\r\n     * division by zero. The result is rounded towards zero.\r\n     *\r\n     * Counterpart to Solidity\u0027s `/` operator. Note: this function uses a\r\n     * `revert` opcode (which leaves remaining gas untouched) while Solidity\r\n     * uses an invalid opcode to revert (consuming all remaining gas).\r\n     *\r\n     * Requirements:\r\n     * - The divisor cannot be zero.\r\n     *\r\n     * _Available since v2.4.0._\r\n     */\r\n    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\r\n        // Solidity only automatically asserts when dividing by 0\r\n        require(b \u003e 0, errorMessage);\r\n        uint256 c = a / b;\r\n        // assert(a == b * c + a % b); // There is no case in which this doesn\u0027t hold\r\n\r\n        return c;\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\r\n     * Reverts when dividing by zero.\r\n     *\r\n     * Counterpart to Solidity\u0027s `%` operator. This function uses a `revert`\r\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\r\n     * invalid opcode to revert (consuming all remaining gas).\r\n     *\r\n     * Requirements:\r\n     * - The divisor cannot be zero.\r\n     */\r\n    function mod(uint256 a, uint256 b) internal pure returns (uint256) {\r\n        return mod(a, b, \"SafeMath: modulo by zero\");\r\n    }\r\n\r\n    /**\r\n     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),\r\n     * Reverts with custom message when dividing by zero.\r\n     *\r\n     * Counterpart to Solidity\u0027s `%` operator. This function uses a `revert`\r\n     * opcode (which leaves remaining gas untouched) while Solidity uses an\r\n     * invalid opcode to revert (consuming all remaining gas).\r\n     *\r\n     * Requirements:\r\n     * - The divisor cannot be zero.\r\n     *\r\n     * _Available since v2.4.0._\r\n     */\r\n    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {\r\n        require(b != 0, errorMessage);\r\n        return a % b;\r\n    }\r\n}\r\n"}}

/* ERC1820 Pseudo-introspection Registry Contract
 * This standard defines a universal registry smart contract where any address (contract or regular account) can
 * register which interface it supports and which smart contract is responsible for its implementation.
 *
 * Written in 2019 by Jordi Baylina and Jacques Dafflon
 *
 * To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to
 * this software to the public domain worldwide. This software is distributed without any warranty.
 *
 * You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 *
 *    ███████╗██████╗  ██████╗ ██╗ █████╗ ██████╗  ██████╗
 *    ██╔════╝██╔══██╗██╔════╝███║██╔══██╗╚════██╗██╔═████╗
 *    █████╗  ██████╔╝██║     ╚██║╚█████╔╝ █████╔╝██║██╔██║
 *    ██╔══╝  ██╔══██╗██║      ██║██╔══██╗██╔═══╝ ████╔╝██║
 *    ███████╗██║  ██║╚██████╗ ██║╚█████╔╝███████╗╚██████╔╝
 *    ╚══════╝╚═╝  ╚═╝ ╚═════╝ ╚═╝ ╚════╝ ╚══════╝ ╚═════╝
 *
 *    ██████╗ ███████╗ ██████╗ ██╗███████╗████████╗██████╗ ██╗   ██╗
 *    ██╔══██╗██╔════╝██╔════╝ ██║██╔════╝╚══██╔══╝██╔══██╗╚██╗ ██╔╝
 *    ██████╔╝█████╗  ██║  ███╗██║███████╗   ██║   ██████╔╝ ╚████╔╝
 *    ██╔══██╗██╔══╝  ██║   ██║██║╚════██║   ██║   ██╔══██╗  ╚██╔╝
 *    ██║  ██║███████╗╚██████╔╝██║███████║   ██║   ██║  ██║   ██║
 *    ╚═╝  ╚═╝╚══════╝ ╚═════╝ ╚═╝╚══════╝   ╚═╝   ╚═╝  ╚═╝   ╚═╝
 *
 */
pragma solidity 0.5.3;
// IV is value needed to have a vanity address starting with '0x1820'.
// IV: 53759

/// @dev The interface a contract MUST implement if it is the implementer of
/// some (other) interface for any address other than itself.
interface ERC1820ImplementerInterface {
    /// @notice Indicates whether the contract implements the interface 'interfaceHash' for the address 'addr' or not.
    /// @param interfaceHash keccak256 hash of the name of the interface
    /// @param addr Address for which the contract will implement the interface
    /// @return ERC1820_ACCEPT_MAGIC only if the contract implements 'interfaceHash' for the address 'addr'.
    function canImplementInterfaceForAddress(bytes32 interfaceHash, address addr) external view returns(bytes32);
}


/// @title ERC1820 Pseudo-introspection Registry Contract
/// @author Jordi Baylina and Jacques Dafflon
/// @notice This contract is the official implementation of the ERC1820 Registry.
/// @notice For more details, see https://eips.ethereum.org/EIPS/eip-1820
contract ERC1820Registry {
    /// @notice ERC165 Invalid ID.
    bytes4 constant internal INVALID_ID = 0xffffffff;
    /// @notice Method ID for the ERC165 supportsInterface method (= `bytes4(keccak256('supportsInterface(bytes4)'))`).
    bytes4 constant internal ERC165ID = 0x01ffc9a7;
    /// @notice Magic value which is returned if a contract implements an interface on behalf of some other address.
    bytes32 constant internal ERC1820_ACCEPT_MAGIC = keccak256(abi.encodePacked("ERC1820_ACCEPT_MAGIC"));

    /// @notice mapping from addresses and interface hashes to their implementers.
    mapping(address => mapping(bytes32 => address)) internal interfaces;
    /// @notice mapping from addresses to their manager.
    mapping(address => address) internal managers;
    /// @notice flag for each address and erc165 interface to indicate if it is cached.
    mapping(address => mapping(bytes4 => bool)) internal erc165Cached;

    /// @notice Indicates a contract is the 'implementer' of 'interfaceHash' for 'addr'.
    event InterfaceImplementerSet(address indexed addr, bytes32 indexed interfaceHash, address indexed implementer);
    /// @notice Indicates 'newManager' is the address of the new manager for 'addr'.
    event ManagerChanged(address indexed addr, address indexed newManager);

    /// @notice Query if an address implements an interface and through which contract.
    /// @param _addr Address being queried for the implementer of an interface.
    /// (If '_addr' is the zero address then 'msg.sender' is assumed.)
    /// @param _interfaceHash Keccak256 hash of the name of the interface as a string.
    /// E.g., 'web3.utils.keccak256("ERC777TokensRecipient")' for the 'ERC777TokensRecipient' interface.
    /// @return The address of the contract which implements the interface '_interfaceHash' for '_addr'
    /// or '0' if '_addr' did not register an implementer for this interface.
    function getInterfaceImplementer(address _addr, bytes32 _interfaceHash) external view returns (address) {
        address addr = _addr == address(0) ? msg.sender : _addr;
        if (isERC165Interface(_interfaceHash)) {
            bytes4 erc165InterfaceHash = bytes4(_interfaceHash);
            return implementsERC165Interface(addr, erc165InterfaceHash) ? addr : address(0);
        }
        return interfaces[addr][_interfaceHash];
    }

    /// @notice Sets the contract which implements a specific interface for an address.
    /// Only the manager defined for that address can set it.
    /// (Each address is the manager for itself until it sets a new manager.)
    /// @param _addr Address for which to set the interface.
    /// (If '_addr' is the zero address then 'msg.sender' is assumed.)
    /// @param _interfaceHash Keccak256 hash of the name of the interface as a string.
    /// E.g., 'web3.utils.keccak256("ERC777TokensRecipient")' for the 'ERC777TokensRecipient' interface.
    /// @param _implementer Contract address implementing '_interfaceHash' for '_addr'.
    function setInterfaceImplementer(address _addr, bytes32 _interfaceHash, address _implementer) external {
        address addr = _addr == address(0) ? msg.sender : _addr;
        require(getManager(addr) == msg.sender, "Not the manager");

        require(!isERC165Interface(_interfaceHash), "Must not be an ERC165 hash");
        if (_implementer != address(0) && _implementer != msg.sender) {
            require(
                ERC1820ImplementerInterface(_implementer)
                    .canImplementInterfaceForAddress(_interfaceHash, addr) == ERC1820_ACCEPT_MAGIC,
                "Does not implement the interface"
            );
        }
        interfaces[addr][_interfaceHash] = _implementer;
        emit InterfaceImplementerSet(addr, _interfaceHash, _implementer);
    }

    /// @notice Sets '_newManager' as manager for '_addr'.
    /// The new manager will be able to call 'setInterfaceImplementer' for '_addr'.
    /// @param _addr Address for which to set the new manager.
    /// @param _newManager Address of the new manager for 'addr'. (Pass '0x0' to reset the manager to '_addr'.)
    function setManager(address _addr, address _newManager) external {
        require(getManager(_addr) == msg.sender, "Not the manager");
        managers[_addr] = _newManager == _addr ? address(0) : _newManager;
        emit ManagerChanged(_addr, _newManager);
    }

    /// @notice Get the manager of an address.
    /// @param _addr Address for which to return the manager.
    /// @return Address of the manager for a given address.
    function getManager(address _addr) public view returns(address) {
        // By default the manager of an address is the same address
        if (managers[_addr] == address(0)) {
            return _addr;
        } else {
            return managers[_addr];
        }
    }

    /// @notice Compute the keccak256 hash of an interface given its name.
    /// @param _interfaceName Name of the interface.
    /// @return The keccak256 hash of an interface name.
    function interfaceHash(string calldata _interfaceName) external pure returns(bytes32) {
        return keccak256(abi.encodePacked(_interfaceName));
    }

    /* --- ERC165 Related Functions --- */
    /* --- Developed in collaboration with William Entriken. --- */

    /// @notice Updates the cache with whether the contract implements an ERC165 interface or not.
    /// @param _contract Address of the contract for which to update the cache.
    /// @param _interfaceId ERC165 interface for which to update the cache.
    function updateERC165Cache(address _contract, bytes4 _interfaceId) external {
        interfaces[_contract][_interfaceId] = implementsERC165InterfaceNoCache(
            _contract, _interfaceId) ? _contract : address(0);
        erc165Cached[_contract][_interfaceId] = true;
    }

    /// @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 _contract Address of the contract to check.
    /// @param _interfaceId ERC165 interface to check.
    /// @return True if '_contract' implements '_interfaceId', false otherwise.
    function implementsERC165Interface(address _contract, bytes4 _interfaceId) public view returns (bool) {
        if (!erc165Cached[_contract][_interfaceId]) {
            return implementsERC165InterfaceNoCache(_contract, _interfaceId);
        }
        return interfaces[_contract][_interfaceId] == _contract;
    }

    /// @notice Checks whether a contract implements an ERC165 interface or not without using nor updating the cache.
    /// @param _contract Address of the contract to check.
    /// @param _interfaceId ERC165 interface to check.
    /// @return True if '_contract' implements '_interfaceId', false otherwise.
    function implementsERC165InterfaceNoCache(address _contract, bytes4 _interfaceId) public view returns (bool) {
        uint256 success;
        uint256 result;

        (success, result) = noThrowCall(_contract, ERC165ID);
        if (success == 0 || result == 0) {
            return false;
        }

        (success, result) = noThrowCall(_contract, INVALID_ID);
        if (success == 0 || result != 0) {
            return false;
        }

        (success, result) = noThrowCall(_contract, _interfaceId);
        if (success == 1 && result == 1) {
            return true;
        }
        return false;
    }

    /// @notice Checks whether the hash is a ERC165 interface (ending with 28 zeroes) or not.
    /// @param _interfaceHash The hash to check.
    /// @return True if '_interfaceHash' is an ERC165 interface (ending with 28 zeroes), false otherwise.
    function isERC165Interface(bytes32 _interfaceHash) internal pure returns (bool) {
        return _interfaceHash & 0x00000000FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF == 0;
    }

    /// @dev Make a call on a contract without throwing if the function does not exist.
    function noThrowCall(address _contract, bytes4 _interfaceId)
        internal view returns (uint256 success, uint256 result)
    {
        bytes4 erc165ID = ERC165ID;

        assembly {
            let x := mload(0x40)               // Find empty storage location using "free memory pointer"
            mstore(x, erc165ID)                // Place signature at beginning of empty storage
            mstore(add(x, 0x04), _interfaceId) // Place first argument directly next to signature

            success := staticcall(
                30000,                         // 30k gas
                _contract,                     // To addr
                x,                             // Inputs are stored at location x
                0x24,                          // Inputs are 36 (4 + 32) bytes long
                x,                             // Store output over input (saves space)
                0x20                           // Outputs are 32 bytes long
            )

            result := mload(x)                 // Load the result
        }
    }
}