snt-gas-relay/test-dapp/contracts/token/MiniMeToken.sol

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pragma solidity ^0.4.23;
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/*
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/>.
*/
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/**
* @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.
*/
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import "../common/Controlled.sol";
import "./TokenController.sol";
import "./ApproveAndCallFallBack.sol";
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import "./MiniMeTokenInterface.sol";
import "./MiniMeTokenFactory.sol";
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/**
* @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"
*/
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contract MiniMeToken is MiniMeTokenInterface, Controlled {
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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
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string public version = "MMT_0.1"; //An arbitrary versioning scheme
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/**
* @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
*/
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struct Checkpoint {
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// `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
////////////////
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/**
* @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
*/
constructor(
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address _tokenFactory,
address _parentToken,
uint _parentSnapShotBlock,
string _tokenName,
uint8 _decimalUnits,
string _tokenSymbol,
bool _transfersEnabled
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)
public
{
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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;
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creationBlock = block.number;
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}
///////////////////
// ERC20 Methods
///////////////////
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/**
* @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
*/
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function transfer(address _to, uint256 _amount) public returns (bool success) {
require(transfersEnabled);
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return doTransfer(msg.sender, _to, _amount);
}
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/**
* @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
*/
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function transferFrom(
address _from,
address _to,
uint256 _amount
)
public
returns (bool success)
{
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// 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) {
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require(transfersEnabled);
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// The standard ERC 20 transferFrom functionality
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if (allowed[_from][msg.sender] < _amount) {
return false;
}
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allowed[_from][msg.sender] -= _amount;
}
return doTransfer(_from, _to, _amount);
}
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/**
* @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
*/
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function doTransfer(
address _from,
address _to,
uint _amount
)
internal
returns(bool)
{
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if (_amount == 0) {
return true;
}
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require(parentSnapShotBlock < block.number);
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// Do not allow transfer to 0x0 or the token contract itself
require((_to != 0) && (_to != address(this)));
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// If the amount being transfered is more than the balance of the
// account the transfer returns false
uint256 previousBalanceFrom = balanceOfAt(_from, block.number);
if (previousBalanceFrom < _amount) {
return false;
}
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// Alerts the token controller of the transfer
if (isContract(controller)) {
require(TokenController(controller).onTransfer(_from, _to, _amount));
}
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// First update the balance array with the new value for the address
// sending the tokens
updateValueAtNow(balances[_from], previousBalanceFrom - _amount);
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// Then update the balance array with the new value for the address
// receiving the tokens
uint256 previousBalanceTo = balanceOfAt(_to, block.number);
require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
updateValueAtNow(balances[_to], previousBalanceTo + _amount);
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// An event to make the transfer easy to find on the blockchain
emit Transfer(_from, _to, _amount);
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return true;
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}
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function doApprove(
address _from,
address _spender,
uint256 _amount
)
internal
returns (bool)
{
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require(transfersEnabled);
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// 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
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require((_amount == 0) || (allowed[_from][_spender] == 0));
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// Alerts the token controller of the approve function call
if (isContract(controller)) {
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require(TokenController(controller).onApprove(_from, _spender, _amount));
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}
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allowed[_from][_spender] = _amount;
emit Approval(_from, _spender, _amount);
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return true;
}
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/**
* @param _owner The address that's balance is being requested
* @return The balance of `_owner` at the current block
*/
function balanceOf(address _owner) external view 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) external returns (bool success) {
doApprove(msg.sender, _spender, _amount);
}
/**
* @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
*/
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function allowance(
address _owner,
address _spender
)
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external
view
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returns (uint256 remaining)
{
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return allowed[_owner][_spender];
}
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/**
* @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
*/
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function approveAndCall(
address _spender,
uint256 _amount,
bytes _extraData
)
public
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returns (bool success)
{
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require(doApprove(msg.sender, _spender, _amount));
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ApproveAndCallFallBack(_spender).receiveApproval(
msg.sender,
_amount,
this,
_extraData
);
return true;
}
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/**
* @dev This function makes it easy to get the total number of tokens
* @return The total number of tokens
*/
function totalSupply() external view returns (uint) {
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return totalSupplyAt(block.number);
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}
////////////////
// Query balance and totalSupply in History
////////////////
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/**
* @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`
*/
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function balanceOfAt(
address _owner,
uint _blockNumber
)
public
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view
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returns (uint)
{
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// 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);
}
}
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/**
* @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 view returns(uint) {
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// 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
////////////////
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/**
* @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
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* 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
*/
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function createCloneToken(
string _cloneTokenName,
uint8 _cloneDecimalUnits,
string _cloneTokenSymbol,
uint _snapshotBlock,
bool _transfersEnabled
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)
public
returns(address)
{
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uint snapshotBlock = _snapshotBlock;
if (snapshotBlock == 0) {
snapshotBlock = block.number;
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}
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MiniMeToken cloneToken = tokenFactory.createCloneToken(
this,
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snapshotBlock,
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_cloneTokenName,
_cloneDecimalUnits,
_cloneTokenSymbol,
_transfersEnabled
);
cloneToken.changeController(msg.sender);
// An event to make the token easy to find on the blockchain
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emit NewCloneToken(address(cloneToken), snapshotBlock);
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return address(cloneToken);
}
////////////////
// Generate and destroy tokens
////////////////
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/**
* @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
*/
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function generateTokens(
address _owner,
uint _amount
)
public
// onlyController TODO: UNCOMMENT THIS. THIS WAS DISABLED FOR DEMO PURPOSES
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returns (bool)
{
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uint curTotalSupply = totalSupplyAt(block.number);
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require(curTotalSupply + _amount >= curTotalSupply); // Check for overflow
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uint previousBalanceTo = balanceOfAt(_owner, block.number);
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require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
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updateValueAtNow(totalSupplyHistory, curTotalSupply + _amount);
updateValueAtNow(balances[_owner], previousBalanceTo + _amount);
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emit Transfer(0, _owner, _amount);
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return true;
}
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/**
* @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
*/
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function destroyTokens(
address _owner,
uint _amount
)
public
onlyController
returns (bool)
{
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uint curTotalSupply = totalSupplyAt(block.number);
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require(curTotalSupply >= _amount);
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uint previousBalanceFrom = balanceOfAt(_owner, block.number);
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require(previousBalanceFrom >= _amount);
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updateValueAtNow(totalSupplyHistory, curTotalSupply - _amount);
updateValueAtNow(balances[_owner], previousBalanceFrom - _amount);
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emit Transfer(_owner, 0, _amount);
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return true;
}
////////////////
// Enable tokens transfers
////////////////
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/**
* @notice Enables token holders to transfer their tokens freely if true
* @param _transfersEnabled True if transfers are allowed in the clone
*/
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function enableTransfers(bool _transfersEnabled) public onlyController {
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transfersEnabled = _transfersEnabled;
}
////////////////
// Internal helper functions to query and set a value in a snapshot array
////////////////
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/**
* @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
*/
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function getValueAt(
Checkpoint[] storage checkpoints,
uint _block
)
constant
internal
returns (uint)
{
if (checkpoints.length == 0) {
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return 0;
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}
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// Shortcut for the actual value
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if (_block >= checkpoints[checkpoints.length-1].fromBlock) {
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return checkpoints[checkpoints.length-1].value;
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}
if (_block < checkpoints[0].fromBlock) {
return 0;
}
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// Binary search of the value in the array
uint min = 0;
uint max = checkpoints.length-1;
while (max > min) {
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uint mid = (max + min + 1) / 2;
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if (checkpoints[mid].fromBlock<=_block) {
min = mid;
} else {
max = mid-1;
}
}
return checkpoints[min].value;
}
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/**
* @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
*/
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function updateValueAtNow(Checkpoint[] storage checkpoints, uint _value) internal {
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if ((checkpoints.length == 0)
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|| (checkpoints[checkpoints.length -1].fromBlock < block.number)) {
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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);
}
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}
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/**
* @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) internal view returns(bool) {
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uint size;
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if (_addr == 0){
return false;
}
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assembly {
size := extcodesize(_addr)
}
return size>0;
}
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/**
* @dev Helper function to return a min betwen the two uints
*/
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function min(uint a, uint b) internal returns (uint) {
return a < b ? a : b;
}
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/**
* @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
*/
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function () public payable {
require(isContract(controller));
require(TokenController(controller).proxyPayment.value(msg.value)(msg.sender));
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}
//////////
// Safety Methods
//////////
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/**
* @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.
*/
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function claimTokens(address _token) public onlyController {
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if (_token == 0x0) {
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controller.transfer(address(this).balance);
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return;
}
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MiniMeToken token = MiniMeToken(_token);
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uint balance = token.balanceOf(address(this));
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token.transfer(controller, balance);
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emit ClaimedTokens(_token, controller, balance);
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}
////////////////
// Events
////////////////
event ClaimedTokens(address indexed _token, address indexed _controller, uint _amount);
event Transfer(address indexed _from, address indexed _to, uint256 _amount);
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event NewCloneToken(address indexed _cloneToken, uint snapshotBlock);
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event Approval(
address indexed _owner,
address indexed _spender,
uint256 _amount
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);
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}