pragma solidity ^0.4.4; /* Copyright 2016, Jordi Baylina This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . */ /// @title MiniMeToken Contract /// @author Jordi Baylina /// @dev This token contract's goal is to make it easy to clone this token and /// spawn new tokens using the token distribution at a given block. /// @dev It is ERC20 compliant, but still needs to under go further testing. contract Controlled { /// @notice The address of the controller is the only address that can call /// a function with this modifier modifier onlyController { if (msg.sender != controller) throw; _; } address public controller; function Controlled() { controller = msg.sender;} /// @notice Changes the controller of the contract /// @param _newController The new controller of the contract function changeController(address _newController) onlyController { controller = _newController; } } // The controller should implement this interface if wants to receive the ether // sent directly to the token contract. contract Controller { function proxyPayment(address _owner) payable returns(bool); } contract MiniMeToken is Controlled { string public name; //The Token's name: e.g. DigixDAO Tokens uint8 public decimals; //Number of decimals of the smallest unit string public symbol; //An identifier: e.g. REP string public version = 'MMT_0.1'; //An arbitrary versioning scheme /// @dev `Checkpoint` is the structure that attaches a block number to the a /// given value struct Checkpoint { // `fromBlock` is the block number that the value was generated from uint fromBlock; // `value` is the amount of tokens at a specific block number uint value; } // `parentToken` is the Token address that was cloned to produce this token; // it will be 0x0 for a token that was not cloned MiniMeToken public parentToken; // `parentSnapShotBlock` is the Block number from the Parent Token that was // used to determine the initial distribution of the Clone Token uint public parentSnapShotBlock; // `creationBlock` is the block number that the Clone Token was created uint public creationBlock; // `balances` is the map that tracks the balance of each address mapping (address => Checkpoint[]) balances; // `allowed` tracks any extra transfer rights as in all ERC20 tokens mapping (address => mapping (address => uint256)) allowed; // Tracks the history of the `totalSupply` of the token Checkpoint[] totalSupplyHistory; // Flag that determines if the token is transferable or not. bool public transfersEnabled; // The factory used to create new clone tokens MiniMeTokenFactory public tokenFactory; //////////////// // Constructor //////////////// /// @notice Constructor to create a MiniMeToken /// @param _tokenFactory The address of the MiniMeTokenFactory contract that /// will create the Clone token contracts /// @param _parentToken Address of the parent token, set to 0x0 if it is a /// new token /// @param _parentSnapShotBlock Block of the parent token that will /// determine the initial distribution of the clone token, set to 0 if it /// is a new token /// @param _tokenName Name of the new token /// @param _decimalUnits Number of decimals of the new token /// @param _tokenSymbol Token Symbol for the new token /// @param _transfersEnabled If true, tokens will be able to be transferred function MiniMeToken( address _tokenFactory, address _parentToken, uint _parentSnapShotBlock, string _tokenName, uint8 _decimalUnits, string _tokenSymbol, bool _transfersEnabled ) { tokenFactory = MiniMeTokenFactory(_tokenFactory); name = _tokenName; // Set the name decimals = _decimalUnits; // Set the decimals symbol = _tokenSymbol; // Set the symbol parentToken = MiniMeToken(_parentToken); parentSnapShotBlock = _parentSnapShotBlock; transfersEnabled = _transfersEnabled; creationBlock = block.number; } /////////////////// // ERC20 Methods /////////////////// /// @notice Send `_amount` tokens to `_to` from `msg.sender` /// @param _to The address of the recipient /// @param _amount The amount of tokens to be transferred /// @return Whether the transfer was successful or not function transfer(address _to, uint256 _amount) returns (bool success) { if (!transfersEnabled) throw; return doTransfer(msg.sender, _to, _amount); } /// @notice Send `_amount` tokens to `_to` from `_from` on the condition it /// is approved by `_from` /// @param _from The address holding the tokens being transferred /// @param _to The address of the recipient /// @param _amount The amount of tokens to be transferred /// @return True if the transfer was successful function transferFrom(address _from, address _to, uint256 _amount ) returns (bool success) { // The controller of this contract can move tokens around at will, this // is important to recognize! Confirm that you trust the controller of // this contract, which in most situations should be another open // source smart contract or 0x0 if (msg.sender != controller) { if (!transfersEnabled) throw; // The standard ERC 20 transferFrom functionality if (allowed[_from][msg.sender] < _amount) return false; allowed[_from][msg.sender] -= _amount; } return doTransfer(_from, _to, _amount); } function doTransfer(address _from, address _to, uint _amount ) internal returns(bool) { if (_amount == 0) { return true; } // Do not allow transfer to 0x0 or the token contract itself if ((_to == 0) || (_to == address(this))) throw; // If the amount being transfered is more than the balance of the // account the transfer returns false var previousBalanceFrom = balanceOfAt(_from, block.number); if (previousBalanceFrom < _amount) { return false; } // First update the balance array with the new value for the address // sending the tokens updateValueAtNow(balances[_from], previousBalanceFrom - _amount); // Then update the balance array with the new value for the address // receiving the tokens var previousBalanceTo = balanceOfAt(_to, block.number); updateValueAtNow(balances[_to], previousBalanceTo + _amount); // An event to make the transfer easy to find on the blockchain Transfer(_from, _to, _amount); return true; } /// @param _owner The address that's balance is being requested /// @return The balance of `_owner` at the current block function balanceOf(address _owner) constant returns (uint256 balance) { return balanceOfAt(_owner, block.number); } /// @notice `msg.sender` approves `_spender` to spend `_amount` tokens on /// its behalf /// @param _spender The address of the account able to transfer the tokens /// @param _amount The amount of tokens to be approved for transfer /// @return True if the approval was successful function approve(address _spender, uint256 _amount) returns (bool success) { if (!transfersEnabled) throw; allowed[msg.sender][_spender] = _amount; Approval(msg.sender, _spender, _amount); return true; } /// @param _owner The address of the account that owns the token /// @param _spender The address of the account able to transfer the tokens /// @return Amount of remaining tokens of _owner that _spender is allowed /// to spend function allowance(address _owner, address _spender ) constant returns (uint256 remaining) { return allowed[_owner][_spender]; } /// @notice `msg.sender` approves `_spender` to send `_amount` tokens on /// its behalf, and then a function is triggered in the contract that is /// being approved, `_spender` /// @param _spender The address of the contract able to transfer the tokens /// @param _amount The amount of tokens to be approved for transfer /// @return True if the function call was successful function approveAndCall(address _spender, uint256 _amount, bytes _extraData ) returns (bool success) { allowed[msg.sender][_spender] = _amount; Approval(msg.sender, _spender, _amount); // This portion is copied from ConsenSys's Standard Token Contract. It // calls the receiveApproval function that is part of the contract that // is being approved (`_spender`). The function should look like: // `receiveApproval(address _from, uint256 _amount, address // _tokenContract, bytes _extraData)` It is assumed that the call // *should* succeed, otherwise one would use vanilla approve instead. if(!_spender.call( bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _amount, this, _extraData )) { throw; } return true; } /// @return The total amount of tokens function totalSupply() constant returns (uint) { return totalSupplyAt(block.number); } //////////////// // Query balance and totalSupply in History //////////////// /// @notice Queries the balance of `_owner` at a specific `_blockNumber` /// @param _owner The address from which the balance will be retrieved /// @param _blockNumber The block number when the balance is queried /// @return The balance at `_blockNumber` function balanceOfAt(address _owner, uint _blockNumber) constant returns (uint) { // If the `_blockNumber` requested is before the genesis block for the // the token being queried, the value returned is 0 if (_blockNumber < creationBlock) { return 0; // These next few lines are used when the balance of the token is // requested before a check point was ever created for this token, it // requires that the `parentToken.balanceOfAt` be queried at the // genesis block for that token as this contains initial balance of // this token } else if ((balances[_owner].length == 0) || (balances[_owner][0].fromBlock > _blockNumber)) { if (address(parentToken) != 0) { return parentToken.balanceOfAt(_owner, parentSnapShotBlock); } else { // Has no parent return 0; } // This will return the expected balance during normal situations } else { return getValueAt( balances[_owner], _blockNumber); } } /// @notice Total amount of tokens at a specific `_blockNumber`. /// @param _blockNumber The block number when the totalSupply is queried /// @return The total amount of tokens at `_blockNumber` function totalSupplyAt(uint _blockNumber) constant returns(uint) { // If the `_blockNumber` requested is before the genesis block for the // the token being queried, the value returned is 0 if (_blockNumber < creationBlock) { return 0; // These next few lines are used when the totalSupply of the token is // requested before a check point was ever created for this token, it // requires that the `parentToken.totalSupplyAt` be queried at the // genesis block for this token as that contains totalSupply of this // token at this block number. } else if ((totalSupplyHistory.length == 0) || (totalSupplyHistory[0].fromBlock > _blockNumber)) { if (address(parentToken) != 0) { return parentToken.totalSupplyAt(parentSnapShotBlock); } else { return 0; } // This will return the expected totalSupply during normal situations } else { return getValueAt( totalSupplyHistory, _blockNumber); } } //////////////// // Clone Token Method //////////////// /// @notice Creates a new clone token with the initial distribution being /// this token at `_snapshotBlock` /// @param _cloneTokenName Name of the clone token /// @param _cloneDecimalUnits Units of the clone token /// @param _cloneTokenSymbol Symbol of the clone token /// @param _snapshotBlock Block when the distribution of the parent token is /// copied to set the initial distribution of the new clone token; /// if the block is higher than the actual block, the current block is used /// @param _transfersEnabled True if transfers are allowed in the clone /// @return The address of the new MiniMeToken Contract function createCloneToken( string _cloneTokenName, uint8 _cloneDecimalUnits, string _cloneTokenSymbol, uint _snapshotBlock, bool _transfersEnabled ) returns(address) { if (_snapshotBlock > block.number) _snapshotBlock = block.number; MiniMeToken cloneToken = tokenFactory.createCloneToken( this, _snapshotBlock, _cloneTokenName, _cloneDecimalUnits, _cloneTokenSymbol, _transfersEnabled ); // An event to make the token easy to find on the blockchain NewCloneToken(address(cloneToken), _snapshotBlock); return address(cloneToken); } //////////////// // Generate and destroy tokens //////////////// /// @notice Generates `_amount` tokens that are assigned to `_owner` /// @param _owner The address that will be assigned the new tokens /// @param _amount The quantity of tokens generated /// @return True if the tokens are generated correctly function generateTokens(address _owner, uint _amount ) onlyController returns (bool) { uint curTotalSupply = getValueAt(totalSupplyHistory, block.number); updateValueAtNow(totalSupplyHistory, curTotalSupply + _amount); var previousBalanceTo = balanceOf(_owner); updateValueAtNow(balances[_owner], previousBalanceTo + _amount); Transfer(0, _owner, _amount); return true; } /// @notice Burns `_amount` tokens from `_owner` /// @param _owner The address that will lose the tokens /// @param _amount The quantity of tokens to burn /// @return True if the tokens are burned correctly function destroyTokens(address _owner, uint _amount ) onlyController returns (bool) { uint curTotalSupply = getValueAt(totalSupplyHistory, block.number); if (curTotalSupply < _amount) throw; updateValueAtNow(totalSupplyHistory, curTotalSupply - _amount); var previousBalanceFrom = balanceOf(_owner); if (previousBalanceFrom < _amount) throw; updateValueAtNow(balances[_owner], previousBalanceFrom - _amount); Transfer(_owner, 0, _amount); return true; } //////////////// // Enable tokens transfers //////////////// /// @notice Enables token holders to transfer their tokens freely if true /// @param _transfersEnabled True if transfers are allowed in the clone function enableTransfers(bool _transfersEnabled) onlyController { transfersEnabled = _transfersEnabled; } //////////////// // Internal helper functions to query and set a value in a snapshot array //////////////// function getValueAt(Checkpoint[] storage checkpoints, uint _block ) constant internal returns (uint) { if (checkpoints.length == 0) return 0; // Shortcut for the actual value if (_block >= checkpoints[checkpoints.length-1].fromBlock) return checkpoints[checkpoints.length-1].value; if (_block < checkpoints[0].fromBlock) return 0; // Binary search of the value in the array uint min = 0; uint max = checkpoints.length-1; while (max > min) { uint mid = (max + min + 1)/ 2; if (checkpoints[mid].fromBlock<=_block) { min = mid; } else { max = mid-1; } } return checkpoints[min].value; } function updateValueAtNow(Checkpoint[] storage checkpoints, uint _value ) internal { if ((checkpoints.length == 0) || (checkpoints[checkpoints.length -1].fromBlock < block.number)) { Checkpoint newCheckPoint = checkpoints[ checkpoints.length++ ]; newCheckPoint.fromBlock = block.number; newCheckPoint.value = _value; } else { Checkpoint oldCheckPoint = checkpoints[checkpoints.length-1]; oldCheckPoint.value = _value; } } /// @notice The fallback function: If the contract's controller has not been /// set to 0, the ether is sent to the controller (normally the token /// creation contract) using the `proxyPayment` method. function () payable { if (controller == 0) throw; if (! Controller(controller).proxyPayment.value(msg.value)(msg.sender)) { throw; } } //////////////// // Events //////////////// event Transfer(address indexed _from, address indexed _to, uint256 _amount); event NewCloneToken(address indexed _cloneToken, uint _snapshotBlock); event Approval( address indexed _owner, address indexed _spender, uint256 _amount ); } //////////////// // MiniMeTokenFactory //////////////// // This contract is used to generate clone contracts from a contract. // In solidity this is the way to create a contract from a contract of the same // class contract MiniMeTokenFactory { function createCloneToken( address _parentToken, uint _snapshotBlock, string _tokenName, uint8 _decimalUnits, string _tokenSymbol, bool _transfersEnabled ) returns (MiniMeToken) { MiniMeToken newToken = new MiniMeToken( this, _parentToken, _snapshotBlock, _tokenName, _decimalUnits, _tokenSymbol, _transfersEnabled ); return newToken; } }