pragma solidity ^0.4.24;
/*
@title Provides support and utilities for contract ownership
*/
contract Ownable {
address public owner;
address public newOwnerCandidate;
event OwnerUpdate(address prevOwner, address newOwner);
/*
@dev constructor
*/
constructor() public {
owner = msg.sender;
}
/*
@dev allows execution by the owner only
*/
modifier ownerOnly {
require(msg.sender == owner);
_;
}
/*
@dev allows transferring the contract ownership
the new owner still needs to accept the transfer
can only be called by the contract owner
@param _newOwnerCandidate new contract owner
*/
function transferOwnership(address _newOwnerCandidate) public ownerOnly {
require(_newOwnerCandidate != address(0));
require(_newOwnerCandidate != owner);
newOwnerCandidate = _newOwnerCandidate;
}
/*
@dev used by a new owner to accept an ownership transfer
*/
function acceptOwnership() public {
require(msg.sender == newOwnerCandidate);
emit OwnerUpdate(owner, newOwnerCandidate);
owner = newOwnerCandidate;
newOwnerCandidate = address(0);
}
}
/**
* @title SafeMath
* @dev Math operations with safety checks that revert on error
*/
library SafeMath {
/**
* @dev Multiplies two numbers, reverts on overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b);
return c;
}
/**
* @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
require(b > 0); // Solidity only automatically asserts when dividing by 0
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
require(b <= a);
uint256 c = a - b;
return c;
}
/**
* @dev Adds two numbers, reverts on overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a);
return c;
}
/**
* @dev Divides two numbers and returns the remainder (unsigned integer modulo),
* reverts when dividing by zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0);
return a % b;
}
}
/**
* @title ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/20
*/
interface IERC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address who) external view returns (uint256);
function allowance(address owner, address spender)
external view returns (uint256);
function transfer(address to, uint256 value) external returns (bool);
function approve(address spender, uint256 value)
external returns (bool);
function transferFrom(address from, address to, uint256 value)
external returns (bool);
event Transfer(
address indexed from,
address indexed to,
uint256 value
);
event Approval(
address indexed owner,
address indexed spender,
uint256 value
);
}
/**
* @title Standard ERC20 token
*
* @dev Implementation of the basic standard token.
* https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
* Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
*/
contract ERC20 is IERC20 {
using SafeMath for uint256;
mapping (address => uint256) internal _balances;
mapping (address => mapping (address => uint256)) private _allowed;
uint256 internal _totalSupply;
/**
* @dev Total number of tokens in existence
*/
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
/**
* @dev Gets the balance of the specified address.
* @param owner The address to query the balance of.
* @return An uint256 representing the amount owned by the passed address.
*/
function balanceOf(address owner) public view returns (uint256) {
return _balances[owner];
}
/**
* @dev Function to check the amount of tokens that an owner allowed to a spender.
* @param owner address The address which owns the funds.
* @param spender address The address which will spend the funds.
* @return A uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(
address owner,
address spender
)
public
view
returns (uint256)
{
return _allowed[owner][spender];
}
/**
* @dev Transfer token for a specified address
* @param to The address to transfer to.
* @param value The amount to be transferred.
*/
function transfer(address to, uint256 value) public returns (bool) {
_transfer(msg.sender, to, value);
return true;
}
/**
* @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
* Beware that changing an allowance with this method brings the risk that someone may use both the old
* and the new allowance by unfortunate transaction ordering. In order to mitigate this
* race condition is we first check the spender's allowance to 0 and set the desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
* @param spender The address which will spend the funds.
* @param value The amount of tokens to be spent.
*/
function approve(address spender, uint256 value) public returns (bool) {
require(spender != address(0));
// if the allowance isn't 0, it can only be updated to 0 to prevent an allowance change immediately after withdrawal
require(value == 0 || _allowed[msg.sender][spender] == 0);
_allowed[msg.sender][spender] = value;
emit Approval(msg.sender, spender, value);
return true;
}
/**
* @dev Transfer tokens from one address to another
* @param from address The address which you want to send tokens from
* @param to address The address which you want to transfer to
* @param value uint256 the amount of tokens to be transferred
*/
function transferFrom(
address from,
address to,
uint256 value
)
public
returns (bool)
{
_allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
_transfer(from, to, value);
return true;
}
/**
* @dev Increase the amount of tokens that an owner allowed to a spender.
* approve should be called when allowed_[_spender] == 0. To increment
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
* @param spender The address which will spend the funds.
* @param addedValue The amount of tokens to increase the allowance by.
*/
function increaseAllowance(
address spender,
uint256 addedValue
)
public
returns (bool)
{
require(spender != address(0));
_allowed[msg.sender][spender] = (
_allowed[msg.sender][spender].add(addedValue));
emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
return true;
}
/**
* @dev Decrease the amount of tokens that an owner allowed to a spender.
* approve should be called when allowed_[_spender] == 0. To decrement
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
* @param spender The address which will spend the funds.
* @param subtractedValue The amount of tokens to decrease the allowance by.
*/
function decreaseAllowance(
address spender,
uint256 subtractedValue
)
public
returns (bool)
{
require(spender != address(0));
_allowed[msg.sender][spender] = (
_allowed[msg.sender][spender].sub(subtractedValue));
emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
return true;
}
/**
* @dev Transfer token for a specified addresses
* @param from The address to transfer from.
* @param to The address to transfer to.
* @param value The amount to be transferred.
*/
function _transfer(address from, address to, uint256 value) internal {
require(to != address(0));
_balances[from] = _balances[from].sub(value);
_balances[to] = _balances[to].add(value);
emit Transfer(from, to, value);
}
}
/**
* @title Mintable token
* @dev Simple ERC20 Token example, with mintable token creation
* @dev Issue: * https://github.com/OpenZeppelin/zeppelin-solidity/issues/120
* Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol
*/
contract MintableToken is ERC20, Ownable {
event Mint(address indexed to, uint256 amount);
event MintFinished();
event Burn(address indexed from, uint256 amount);
bool public mintingFinished = false;
modifier canMint() {
require(!mintingFinished);
_;
}
/**
* @dev Function to mint tokens
* @param to The address that will receive the minted tokens.
* @param amount The amount of tokens to mint.
* @return A boolean that indicates if the operation was successful.
*/
function mint(address to, uint256 amount) public ownerOnly canMint returns (bool) {
require(to != address(0));
_totalSupply = _totalSupply.add(amount);
_balances[to] = _balances[to].add(amount);
emit Mint(to, amount);
emit Transfer(address(0), to, amount);
return true;
}
/**
* @dev Function to burn tokens
* @param from The address whose tokens will be burnt.
* @param amount The amount of tokens to burn.
* @return A boolean that indicates if the operation was successful.
*/
function burn(address from, uint256 amount) public ownerOnly canMint returns (bool) {
require(from != address(0));
_totalSupply = _totalSupply.sub(amount);
_balances[from] = _balances[from].sub(amount);
emit Burn(from, amount);
emit Transfer(from, address(0), amount);
}
/**
* @dev Function to stop minting new tokens.
* @return True if the operation was successful.
*/
function finishMinting() public ownerOnly canMint returns (bool) {
mintingFinished = true;
emit MintFinished();
return true;
}
}
/**
* @title FreezableToken
* @dev LimitedTransferToken transfers start as disabled untill enabled by the contract owner
*/
contract FreezableToken is ERC20, Ownable {
event TransfersEnabled();
bool public allowTransfers = false;
/**
* @dev Checks whether it can transfer or otherwise throws.
*/
modifier canTransfer() {
require(allowTransfers || msg.sender == owner);
_;
}
/**
* @dev Checks modifier and allows transfer if tokens are not locked.
*/
function enableTransfers() public ownerOnly {
allowTransfers = true;
emit TransfersEnabled();
}
/**
* @dev Checks modifier and allows transfer if tokens are not locked.
* @param to The address that will receive the tokens.
* @param value The amount of tokens to be transferred.
*/
function transfer(address to, uint256 value) public canTransfer returns (bool) {
return super.transfer(to, value);
}
/**
* @dev Checks modifier and allows transfer if tokens are not locked.
* @param from The address that will send the tokens.
* @param to The address that will receive the tokens.
* @param value The amount of tokens to be transferred.
*/
function transferFrom(address from, address to, uint256 value) public canTransfer returns (bool) {
return super.transferFrom(from, to, value);
}
}
/**
* @title Capped token
* @dev Mintable token with a token cap.
*/
contract CappedToken is MintableToken {
uint256 public constant cap = 1000000000000000000000000000;
/**
* @dev Function to mint tokens
* @param to The address that will receive the minted tokens.
* @param amount The amount of tokens to mint.
* @return A boolean that indicates if the operation was successful.
*/
function mint(
address to,
uint256 amount
)
public
returns (bool)
{
require(_totalSupply.add(amount) <= cap);
return super.mint(to, amount);
}
}
/**
* @title VeganCoin
* @dev Based on openzeppelin ERC20 token
*/
contract VeganCoin is CappedToken, FreezableToken {
string public name = "VeganCoin";
string public symbol = "VCN";
uint8 public decimals = 18;
}
/// @title Vesting contract
contract VestingTrustee is Ownable {
using SafeMath for uint256;
// The address of the VCN ERC20 token.
VeganCoin public veganCoin;
struct Grant {
uint256 value;
uint256 start;
uint256 cliff;
uint256 end;
uint256 transferred;
bool revokable;
}
// Grants holder.
mapping (address => Grant) public grants;
// Total tokens available for vesting.
uint256 public totalVesting;
event NewGrant(address indexed _from, address indexed _to, uint256 _value);
event UnlockGrant(address indexed _holder, uint256 _value);
event RevokeGrant(address indexed _holder, uint256 _refund);
/// @dev Constructor that initializes the address of the VeganCoin contract.
/// @param _veganCoin The address of the previously deployed VeganCoin smart contract.
constructor(VeganCoin _veganCoin) public {
require(_veganCoin != address(0));
veganCoin = _veganCoin;
}
/// @dev Grant tokens to a specified address.
/// @param _to address The address to grant tokens to.
/// @param _value uint256 The amount of tokens to be granted.
/// @param _start uint256 The beginning of the vesting period.
/// @param _cliff uint256 Duration of the cliff period.
/// @param _end uint256 The end of the vesting period.
/// @param _revokable bool Whether the grant is revokable or not.
function grant(address _to, uint256 _value, uint256 _start, uint256 _cliff, uint256 _end, bool _revokable)
public ownerOnly {
require(_to != address(0));
require(_value > 0);
// Make sure that a single address can be granted tokens only once.
require(grants[_to].value == 0);
// Check for date inconsistencies that may cause unexpected behavior.
require(_start <= _cliff && _cliff <= _end);
// Check that this grant doesn't exceed the total amount of tokens currently available for vesting.
require(totalVesting.add(_value) <= veganCoin.balanceOf(address(this)));
// Assign a new grant.
grants[_to] = Grant({
value: _value,
start: _start,
cliff: _cliff,
end: _end,
transferred: 0,
revokable: _revokable
});
// Tokens granted, reduce the total amount available for vesting.
totalVesting = totalVesting.add(_value);
emit NewGrant(msg.sender, _to, _value);
}
/// @dev Revoke the grant of tokens of a specifed address.
/// @param _holder The address which will have its tokens revoked.
function revoke(address _holder) public ownerOnly {
Grant storage grant = grants[_holder];
require(grant.revokable);
// Revoke the remaining VCN.
uint256 refund = grant.value.sub(grant.transferred);
// Remove the grant.
delete grants[_holder];
totalVesting = totalVesting.sub(refund);
emit RevokeGrant(_holder, refund);
}
/// @dev Calculate the total amount of vested tokens of a holder at a given time.
/// @param _holder address The address of the holder.
/// @param _time uint256 The specific time.
/// @return a uint256 representing a holder's total amount of vested tokens.
function vestedTokens(address _holder, uint256 _time) public constant returns (uint256) {
Grant storage grant = grants[_holder];
if (grant.value == 0) {
return 0;
}
return calculateVestedTokens(grant, _time);
}
/// @dev Calculate amount of vested tokens at a specifc time.
/// @param _grant Grant The vesting grant.
/// @param _time uint256 The time to be checked
/// @return An uint256 representing the amount of vested tokens of a specific grant.
/// | _/-------- vestedTokens rect
/// | _/
/// | _/
/// | _/
/// | _/
/// | /
/// | .|
/// | . |
/// | . |
/// | . |
/// | . |
/// | . |
/// +===+===========+---------+----------> time
/// Start Cliff End
function calculateVestedTokens(Grant _grant, uint256 _time) private pure returns (uint256) {
// If we're before the cliff, then nothing is vested.
if (_time < _grant.cliff) {
return 0;
}
// If we're after the end of the vesting period - everything is vested;
if (_time >= _grant.end) {
return _grant.value;
}
// Interpolate all vested tokens: vestedTokens = tokens/// (time - start) / (end - start)
return _grant.value.mul(_time.sub(_grant.start)).div(_grant.end.sub(_grant.start));
}
/// @dev Unlock vested tokens and transfer them to their holder.
/// @return a uint256 representing the amount of vested tokens transferred to their holder.
function unlockVestedTokens() public {
Grant storage grant = grants[msg.sender];
require(grant.value != 0);
// Get the total amount of vested tokens, acccording to grant.
uint256 vested = calculateVestedTokens(grant, now);
if (vested == 0) {
return;
}
// Make sure the holder doesn't transfer more than what he already has.
uint256 transferable = vested.sub(grant.transferred);
if (transferable == 0) {
return;
}
grant.transferred = grant.transferred.add(transferable);
totalVesting = totalVesting.sub(transferable);
veganCoin.transfer(msg.sender, transferable);
emit UnlockGrant(msg.sender, transferable);
}
}
{
"compilationTarget": {
"VeganCoin.sol": "VeganCoin"
},
"evmVersion": "byzantium",
"libraries": {},
"optimizer": {
"enabled": true,
"runs": 200
},
"remappings": []
}
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