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pragma solidity ^0.4.18;
/*
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 <http://www.gnu.org/licenses/>.
*/
/// @title MiniMeToken Contract
/// @author Jordi Baylina
/// @dev This token contract's goal is to make it easy for anyone to clone this
/// token using the token distribution at a given block, this will allow DAO's
/// and DApps to upgrade their features in a decentralized manner without
/// affecting the original token
/// @dev It is ERC20 compliant, but still needs to under go further testing.
import "./Controlled.sol";
import "./TokenController.sol";
contract ApproveAndCallFallBack {
function receiveApproval(address from, uint256 _amount, address _token, bytes _data) public;
}
/// @dev The actual token contract, the default controller is the msg.sender
/// that deploys the contract, so usually this token will be deployed by a
/// token controller contract, which Giveth will call a "Campaign"
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_0.2'; //An arbitrary versioning scheme
/// @dev `Checkpoint` is the structure that attaches a block number to a
/// given value, the block number attached is the one that last changed the
/// value
struct Checkpoint {
// `fromBlock` is the block number that the value was generated from
uint128 fromBlock;
// `value` is the amount of tokens at a specific block number
uint128 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, in this
// contract when the balance changes the block number that the change
// occurred is also included in the map
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, the token factory needs to be
/// deployed first
/// @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
) public {
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) public returns (bool success) {
require(transfersEnabled);
doTransfer(msg.sender, _to, _amount);
return true;
}
/// @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
) public 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) {
require(transfersEnabled);
// The standard ERC 20 transferFrom functionality
require(allowed[_from][msg.sender] >= _amount);
allowed[_from][msg.sender] -= _amount;
}
doTransfer(_from, _to, _amount);
return true;
}
/// @dev This is the actual transfer function in the token contract, it can
/// only be called by other functions in this contract.
/// @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 doTransfer(address _from, address _to, uint _amount
) internal {
if (_amount == 0) {
Transfer(_from, _to, _amount); // Follow the spec to louch the event when transfer 0
return;
}
require(parentSnapShotBlock < block.number);
// Do not allow transfer to 0x0 or the token contract itself
require((_to != 0) && (_to != address(this)));
// If the amount being transfered is more than the balance of the
// account the transfer throws
var previousBalanceFrom = balanceOfAt(_from, block.number);
require(previousBalanceFrom >= _amount);
// Alerts the token controller of the transfer
if (isContract(controller)) {
require(TokenController(controller).onTransfer(_from, _to, _amount));
}
// 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);
require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
updateValueAtNow(balances[_to], previousBalanceTo + _amount);
// An event to make the transfer easy to find on the blockchain
Transfer(_from, _to, _amount);
}
/// @param _owner The address that's balance is being requested
/// @return The balance of `_owner` at the current block
function balanceOf(address _owner) public constant returns (uint256 balance) {
return balanceOfAt(_owner, block.number);
}
/// @notice `msg.sender` approves `_spender` to spend `_amount` tokens on
/// its behalf. This is a modified version of the ERC20 approve function
/// to be a little bit safer
/// @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) public returns (bool success) {
require(transfersEnabled);
// To change the approve amount you first have to reduce the addresses`
// allowance to zero by calling `approve(_spender,0)` if it is not
// already 0 to mitigate the race condition described here:
// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
require((_amount == 0) || (allowed[msg.sender][_spender] == 0));
// Alerts the token controller of the approve function call
if (isContract(controller)) {
require(TokenController(controller).onApprove(msg.sender, _spender, _amount));
}
allowed[msg.sender][_spender] = _amount;
Approval(msg.sender, _spender, _amount);
return true;
}
/// @dev This function makes it easy to read the `allowed[]` map
/// @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
) public 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`. This allows users to use their tokens to
/// interact with contracts in one function call instead of two
/// @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
) public returns (bool success) {
require(approve(_spender, _amount));
ApproveAndCallFallBack(_spender).receiveApproval(
msg.sender,
_amount,
this,
_extraData
);
return true;
}
/// @dev This function makes it easy to get the total number of tokens
/// @return The total number of tokens
function totalSupply() public constant returns (uint) {
return totalSupplyAt(block.number);
}
////////////////
// Query balance and totalSupply in History
////////////////
/// @dev 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) public constant
returns (uint) {
// 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
if ((balances[_owner].length == 0)
|| (balances[_owner][0].fromBlock > _blockNumber)) {
if (address(parentToken) != 0) {
return parentToken.balanceOfAt(_owner, min(_blockNumber, 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) public constant returns(uint) {
// 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.
if ((totalSupplyHistory.length == 0)
|| (totalSupplyHistory[0].fromBlock > _blockNumber)) {
if (address(parentToken) != 0) {
return parentToken.totalSupplyAt(min(_blockNumber, 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 Number of decimals of the smallest unit
/// @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 zero 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
) public returns(address) {
if (_snapshotBlock == 0) _snapshotBlock = block.number;
MiniMeToken cloneToken = tokenFactory.createCloneToken(
this,
_snapshotBlock,
_cloneTokenName,
_cloneDecimalUnits,
_cloneTokenSymbol,
_transfersEnabled
);
cloneToken.changeController(msg.sender);
// 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
) public onlyController returns (bool) {
uint curTotalSupply = totalSupply();
require(curTotalSupply + _amount >= curTotalSupply); // Check for overflow
uint previousBalanceTo = balanceOf(_owner);
require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
updateValueAtNow(totalSupplyHistory, curTotalSupply + _amount);
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 public returns (bool) {
uint curTotalSupply = totalSupply();
require(curTotalSupply >= _amount);
uint previousBalanceFrom = balanceOf(_owner);
require(previousBalanceFrom >= _amount);
updateValueAtNow(totalSupplyHistory, curTotalSupply - _amount);
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) public onlyController {
transfersEnabled = _transfersEnabled;
}
////////////////
// Internal helper functions to query and set a value in a snapshot array
////////////////
/// @dev `getValueAt` retrieves the number of tokens at a given block number
/// @param checkpoints The history of values being queried
/// @param _block The block number to retrieve the value at
/// @return The number of tokens being queried
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;
}
/// @dev `updateValueAtNow` used to update the `balances` map and the
/// `totalSupplyHistory`
/// @param checkpoints The history of data being updated
/// @param _value The new number of tokens
function updateValueAtNow(Checkpoint[] storage checkpoints, uint _value
) internal {
if ((checkpoints.length == 0)
|| (checkpoints[checkpoints.length -1].fromBlock < block.number)) {
Checkpoint storage newCheckPoint = checkpoints[ checkpoints.length++ ];
newCheckPoint.fromBlock = uint128(block.number);
newCheckPoint.value = uint128(_value);
} else {
Checkpoint storage oldCheckPoint = checkpoints[checkpoints.length-1];
oldCheckPoint.value = uint128(_value);
}
}
/// @dev Internal function to determine if an address is a contract
/// @param _addr The address being queried
/// @return True if `_addr` is a contract
function isContract(address _addr) constant internal returns(bool) {
uint size;
if (_addr == 0) return false;
assembly {
size := extcodesize(_addr)
}
return size>0;
}
/// @dev Helper function to return a min betwen the two uints
function min(uint a, uint b) pure internal returns (uint) {
return a < b ? a : b;
}
/// @notice The fallback function: If the contract's controller has not been
/// set to 0, then the `proxyPayment` method is called which relays the
/// ether and creates tokens as described in the token controller contract
function () public payable {
require(isContract(controller));
require(TokenController(controller).proxyPayment.value(msg.value)(msg.sender));
}
//////////
// Safety Methods
//////////
/// @notice This method can be used by the controller to extract mistakenly
/// sent tokens to this contract.
/// @param _token The address of the token contract that you want to recover
/// set to 0 in case you want to extract ether.
function claimTokens(address _token) public onlyController {
if (_token == 0x0) {
controller.transfer(this.balance);
return;
}
MiniMeToken token = MiniMeToken(_token);
uint balance = token.balanceOf(this);
token.transfer(controller, balance);
ClaimedTokens(_token, controller, balance);
}
////////////////
// Events
////////////////
event ClaimedTokens(address indexed _token, address indexed _controller, uint _amount);
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
////////////////
/// @dev 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 {
/// @notice Update the DApp by creating a new token with new functionalities
/// the msg.sender becomes the controller of this clone token
/// @param _parentToken Address of the token being cloned
/// @param _snapshotBlock Block of the parent token that will
/// determine the initial distribution of the clone 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
/// @return The address of the new token contract
function createCloneToken(
address _parentToken,
uint _snapshotBlock,
string _tokenName,
uint8 _decimalUnits,
string _tokenSymbol,
bool _transfersEnabled
) public returns (MiniMeToken) {
MiniMeToken newToken = new MiniMeToken(
this,
_parentToken,
_snapshotBlock,
_tokenName,
_decimalUnits,
_tokenSymbol,
_transfersEnabled
);
newToken.changeController(msg.sender);
return newToken;
}
}