582 lines
21 KiB
Solidity
582 lines
21 KiB
Solidity
pragma solidity ^0.4.6;
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/*
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Copyright 2016, Jordi Baylina
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/// @title MiniMeToken Contract
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/// @author Jordi Baylina
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/// @dev This token contract's goal is to make it easy for anyone to clone this
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/// token using the token distribution at a given block, this will allow DAO's
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/// and DApps to upgrade their features in a decentralized manner without
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/// affecting the original token
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/// @dev It is ERC20 compliant, but still needs to under go further testing.
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import "../common/Controlled.sol";
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import "./TokenController.sol";
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import "./ApproveAndCallFallBack.sol";
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import "./MiniMeTokenInterface.sol";
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import "./MiniMeTokenFactory.sol";
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/// @dev The actual token contract, the default controller is the msg.sender
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/// that deploys the contract, so usually this token will be deployed by a
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/// 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
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uint8 public decimals; //Number of decimals of the smallest unit
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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
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/// given value, the block number attached is the one that last changed the
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/// value
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struct Checkpoint {
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// `fromBlock` is the block number that the value was generated from
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uint128 fromBlock;
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// `value` is the amount of tokens at a specific block number
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uint128 value;
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}
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// `parentToken` is the Token address that was cloned to produce this token;
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// it will be 0x0 for a token that was not cloned
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MiniMeToken public parentToken;
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// `parentSnapShotBlock` is the block number from the Parent Token that was
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// used to determine the initial distribution of the Clone Token
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uint public parentSnapShotBlock;
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// `creationBlock` is the block number that the Clone Token was created
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uint public creationBlock;
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// `balances` is the map that tracks the balance of each address, in this
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// contract when the balance changes the block number that the change
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// occurred is also included in the map
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mapping (address => Checkpoint[]) balances;
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// `allowed` tracks any extra transfer rights as in all ERC20 tokens
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mapping (address => mapping (address => uint256)) allowed;
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// Tracks the history of the `totalSupply` of the token
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Checkpoint[] totalSupplyHistory;
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// Flag that determines if the token is transferable or not.
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bool public transfersEnabled;
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// The factory used to create new clone tokens
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MiniMeTokenFactory public tokenFactory;
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////////////////
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// Constructor
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////////////////
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/// @notice Constructor to create a MiniMeToken
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/// @param _tokenFactory The address of the MiniMeTokenFactory contract that
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/// will create the Clone token contracts, the token factory needs to be
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/// deployed first
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/// @param _parentToken Address of the parent token, set to 0x0 if it is a
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/// new token
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/// @param _parentSnapShotBlock Block of the parent token that will
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/// determine the initial distribution of the clone token, set to 0 if it
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/// is a new token
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/// @param _tokenName Name of the new token
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/// @param _decimalUnits Number of decimals of the new token
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/// @param _tokenSymbol Token Symbol for the new token
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/// @param _transfersEnabled If true, tokens will be able to be transferred
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function MiniMeToken(
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address _tokenFactory,
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address _parentToken,
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uint _parentSnapShotBlock,
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string _tokenName,
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uint8 _decimalUnits,
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string _tokenSymbol,
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bool _transfersEnabled
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)
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public
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{
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tokenFactory = MiniMeTokenFactory(_tokenFactory);
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name = _tokenName; // Set the name
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decimals = _decimalUnits; // Set the decimals
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symbol = _tokenSymbol; // Set the symbol
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parentToken = MiniMeToken(_parentToken);
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parentSnapShotBlock = _parentSnapShotBlock;
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transfersEnabled = _transfersEnabled;
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creationBlock = block.number;
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}
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///////////////////
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// ERC20 Methods
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///////////////////
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/// @notice Send `_amount` tokens to `_to` from `msg.sender`
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/// @param _to The address of the recipient
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/// @param _amount The amount of tokens to be transferred
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/// @return Whether the transfer was successful or not
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function transfer(address _to, uint256 _amount) public returns (bool success) {
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require(transfersEnabled);
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return doTransfer(msg.sender, _to, _amount);
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}
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/// @notice Send `_amount` tokens to `_to` from `_from` on the condition it
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/// is approved by `_from`
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/// @param _from The address holding the tokens being transferred
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/// @param _to The address of the recipient
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/// @param _amount The amount of tokens to be transferred
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/// @return True if the transfer was successful
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function transferFrom(
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address _from,
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address _to,
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uint256 _amount
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)
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public
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returns (bool success)
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{
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// The controller of this contract can move tokens around at will,
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// this is important to recognize! Confirm that you trust the
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// controller of this contract, which in most situations should be
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// another open source smart contract or 0x0
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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) {
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return false;
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}
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allowed[_from][msg.sender] -= _amount;
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}
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return doTransfer(_from, _to, _amount);
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}
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/// @dev This is the actual transfer function in the token contract, it can
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/// only be called by other functions in this contract.
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/// @param _from The address holding the tokens being transferred
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/// @param _to The address of the recipient
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/// @param _amount The amount of tokens to be transferred
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/// @return True if the transfer was successful
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function doTransfer(
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address _from,
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address _to,
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uint _amount
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)
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internal
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returns(bool)
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{
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if (_amount == 0) {
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return true;
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}
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require(parentSnapShotBlock < block.number);
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// Do not allow transfer to 0x0 or the token contract itself
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require((_to != 0) && (_to != address(this)));
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// If the amount being transfered is more than the balance of the
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// account the transfer returns false
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var previousBalanceFrom = balanceOfAt(_from, block.number);
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if (previousBalanceFrom < _amount) {
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return false;
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}
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// Alerts the token controller of the transfer
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if (isContract(controller)) {
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require(TokenController(controller).onTransfer(_from, _to, _amount));
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}
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// First update the balance array with the new value for the address
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// sending the tokens
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updateValueAtNow(balances[_from], previousBalanceFrom - _amount);
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// Then update the balance array with the new value for the address
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// receiving the tokens
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var previousBalanceTo = balanceOfAt(_to, block.number);
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require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
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updateValueAtNow(balances[_to], previousBalanceTo + _amount);
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// An event to make the transfer easy to find on the blockchain
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Transfer(_from, _to, _amount);
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return true;
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}
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/// @param _owner The address that's balance is being requested
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/// @return The balance of `_owner` at the current block
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function balanceOf(address _owner) public constant returns (uint256 balance) {
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return balanceOfAt(_owner, block.number);
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}
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/// @notice `msg.sender` approves `_spender` to spend `_amount` tokens on
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/// its behalf. This is a modified version of the ERC20 approve function
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/// to be a little bit safer
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/// @param _spender The address of the account able to transfer the tokens
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/// @param _amount The amount of tokens to be approved for transfer
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/// @return True if the approval was successful
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function approve(address _spender, uint256 _amount) public returns (bool success) {
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require(transfersEnabled);
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// To change the approve amount you first have to reduce the addresses`
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// allowance to zero by calling `approve(_spender,0)` if it is not
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// already 0 to mitigate the race condition described here:
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// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
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require((_amount == 0) || (allowed[msg.sender][_spender] == 0));
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// Alerts the token controller of the approve function call
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if (isContract(controller)) {
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require(TokenController(controller).onApprove(msg.sender, _spender, _amount));
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}
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allowed[msg.sender][_spender] = _amount;
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Approval(msg.sender, _spender, _amount);
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return true;
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}
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/// @dev This function makes it easy to read the `allowed[]` map
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/// @param _owner The address of the account that owns the token
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/// @param _spender The address of the account able to transfer the tokens
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/// @return Amount of remaining tokens of _owner that _spender is allowed
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/// to spend
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function allowance(
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address _owner,
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address _spender
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)
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public
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constant
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returns (uint256 remaining)
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{
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return allowed[_owner][_spender];
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}
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/// @notice `msg.sender` approves `_spender` to send `_amount` tokens on
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/// its behalf, and then a function is triggered in the contract that is
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/// being approved, `_spender`. This allows users to use their tokens to
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/// interact with contracts in one function call instead of two
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/// @param _spender The address of the contract able to transfer the tokens
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/// @param _amount The amount of tokens to be approved for transfer
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/// @return True if the function call was successful
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function approveAndCall(
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address _spender,
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uint256 _amount,
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bytes _extraData
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)
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public
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returns (bool success)
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{
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require(approve(_spender, _amount));
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ApproveAndCallFallBack(_spender).receiveApproval(
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msg.sender,
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_amount,
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this,
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_extraData
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);
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return true;
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}
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/// @dev This function makes it easy to get the total number of tokens
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/// @return The total number of tokens
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function totalSupply() public constant returns (uint) {
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return totalSupplyAt(block.number);
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}
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////////////////
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// Query balance and totalSupply in History
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////////////////
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/// @dev Queries the balance of `_owner` at a specific `_blockNumber`
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/// @param _owner The address from which the balance will be retrieved
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/// @param _blockNumber The block number when the balance is queried
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/// @return The balance at `_blockNumber`
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function balanceOfAt(
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address _owner,
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uint _blockNumber
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)
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public
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constant
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returns (uint)
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{
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// These next few lines are used when the balance of the token is
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// requested before a check point was ever created for this token, it
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// requires that the `parentToken.balanceOfAt` be queried at the
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// genesis block for that token as this contains initial balance of
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// this token
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if ((balances[_owner].length == 0)
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|| (balances[_owner][0].fromBlock > _blockNumber)) {
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if (address(parentToken) != 0) {
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return parentToken.balanceOfAt(_owner, min(_blockNumber, parentSnapShotBlock));
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} else {
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// Has no parent
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return 0;
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}
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// This will return the expected balance during normal situations
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} else {
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return getValueAt(balances[_owner], _blockNumber);
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}
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}
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/// @notice Total amount of tokens at a specific `_blockNumber`.
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/// @param _blockNumber The block number when the totalSupply is queried
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/// @return The total amount of tokens at `_blockNumber`
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function totalSupplyAt(uint _blockNumber) public constant returns(uint) {
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// These next few lines are used when the totalSupply of the token is
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// requested before a check point was ever created for this token, it
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// requires that the `parentToken.totalSupplyAt` be queried at the
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// genesis block for this token as that contains totalSupply of this
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// token at this block number.
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if ((totalSupplyHistory.length == 0)
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|| (totalSupplyHistory[0].fromBlock > _blockNumber)) {
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if (address(parentToken) != 0) {
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return parentToken.totalSupplyAt(min(_blockNumber, parentSnapShotBlock));
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} else {
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return 0;
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}
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// This will return the expected totalSupply during normal situations
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} else {
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return getValueAt(totalSupplyHistory, _blockNumber);
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}
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}
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////////////////
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// Clone Token Method
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////////////////
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/// @notice Creates a new clone token with the initial distribution being
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/// this token at `_snapshotBlock`
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/// @param _cloneTokenName Name of the clone token
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/// @param _cloneDecimalUnits Number of decimals of the smallest unit
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/// @param _cloneTokenSymbol Symbol of the clone token
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/// @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;
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/// if the block is zero than the actual block, the current block is used
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/// @param _transfersEnabled True if transfers are allowed in the clone
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/// @return The address of the new MiniMeToken Contract
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function createCloneToken(
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string _cloneTokenName,
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uint8 _cloneDecimalUnits,
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string _cloneTokenSymbol,
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uint _snapshotBlock,
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bool _transfersEnabled
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)
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public
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returns(address)
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{
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if (_snapshotBlock == 0) {
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_snapshotBlock = block.number;
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}
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MiniMeToken cloneToken = tokenFactory.createCloneToken(
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this,
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_snapshotBlock,
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_cloneTokenName,
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_cloneDecimalUnits,
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_cloneTokenSymbol,
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_transfersEnabled
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);
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cloneToken.changeController(msg.sender);
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// An event to make the token easy to find on the blockchain
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NewCloneToken(address(cloneToken), _snapshotBlock);
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return address(cloneToken);
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}
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////////////////
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// Generate and destroy tokens
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////////////////
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/// @notice Generates `_amount` tokens that are assigned to `_owner`
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/// @param _owner The address that will be assigned the new tokens
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/// @param _amount The quantity of tokens generated
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/// @return True if the tokens are generated correctly
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function generateTokens(
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address _owner,
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uint _amount
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)
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public
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onlyController
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returns (bool)
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{
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uint curTotalSupply = totalSupply();
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require(curTotalSupply + _amount >= curTotalSupply); // Check for overflow
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uint previousBalanceTo = balanceOf(_owner);
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require(previousBalanceTo + _amount >= previousBalanceTo); // Check for overflow
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updateValueAtNow(totalSupplyHistory, curTotalSupply + _amount);
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updateValueAtNow(balances[_owner], previousBalanceTo + _amount);
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Transfer(0, _owner, _amount);
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return true;
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}
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/// @notice Burns `_amount` tokens from `_owner`
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/// @param _owner The address that will lose the tokens
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/// @param _amount The quantity of tokens to burn
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/// @return True if the tokens are burned correctly
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function destroyTokens(
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address _owner,
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uint _amount
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)
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public
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onlyController
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returns (bool)
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{
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uint curTotalSupply = totalSupply();
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require(curTotalSupply >= _amount);
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uint previousBalanceFrom = balanceOf(_owner);
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require(previousBalanceFrom >= _amount);
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updateValueAtNow(totalSupplyHistory, curTotalSupply - _amount);
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updateValueAtNow(balances[_owner], previousBalanceFrom - _amount);
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Transfer(_owner, 0, _amount);
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return true;
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}
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////////////////
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// Enable tokens transfers
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////////////////
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/// @notice Enables token holders to transfer their tokens freely if true
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/// @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;
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}
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////////////////
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// Internal helper functions to query and set a value in a snapshot array
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////////////////
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/// @dev `getValueAt` retrieves the number of tokens at a given block number
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/// @param checkpoints The history of values being queried
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/// @param _block The block number to retrieve the value at
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/// @return The number of tokens being queried
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function getValueAt(
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Checkpoint[] storage checkpoints,
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uint _block
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)
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constant
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internal
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returns (uint)
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{
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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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}
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if (_block < checkpoints[0].fromBlock) {
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return 0;
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}
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// Binary search of the value in the array
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uint min = 0;
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uint max = checkpoints.length-1;
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while (max > min) {
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uint mid = (max + min + 1) / 2;
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if (checkpoints[mid].fromBlock<=_block) {
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min = mid;
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} else {
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max = mid-1;
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}
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}
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return checkpoints[min].value;
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}
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/// @dev `updateValueAtNow` used to update the `balances` map and the
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/// `totalSupplyHistory`
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/// @param checkpoints The history of data being updated
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/// @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++ ];
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newCheckPoint.fromBlock = uint128(block.number);
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newCheckPoint.value = uint128(_value);
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} else {
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Checkpoint storage oldCheckPoint = checkpoints[checkpoints.length-1];
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oldCheckPoint.value = uint128(_value);
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}
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}
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/// @dev Internal function to determine if an address is a contract
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/// @param _addr The address being queried
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/// @return True if `_addr` is a contract
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function isContract(address _addr) constant internal returns(bool) {
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uint size;
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if (_addr == 0){
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return false;
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}
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assembly {
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size := extcodesize(_addr)
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}
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return size>0;
|
|
}
|
|
|
|
/// @dev Helper function to return a min betwen the two uints
|
|
function min(uint a, uint b) 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
|
|
);
|
|
|
|
} |