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109 lines
3.1 KiB
109 lines
3.1 KiB
pragma solidity ^0.4.11;
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import './ERC20Basic.sol';
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import '../ownership/Ownable.sol';
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import '../math/Math.sol';
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import '../math/SafeMath.sol';
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/**
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* @title TokenVesting
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* @dev A token holder contract that can release its token balance gradually like a
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* typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
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* owner.
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*/
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contract TokenVesting is Ownable {
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using SafeMath for uint256;
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event Released(uint256 amount);
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event Revoked();
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// beneficiary of tokens after they are released
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address beneficiary;
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uint256 cliff;
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uint256 start;
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uint256 duration;
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bool revocable;
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mapping (address => uint256) released;
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mapping (address => bool) revoked;
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/**
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* @dev Creates a vesting contract that vests its balance of any ERC20 token to the
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* _beneficiary, gradually in a linear fashion until _start + _duration. By then all
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* of the balance will have vested.
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* @param _beneficiary address of the beneficiary to whom vested tokens are transferred
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* @param _cliff duration in seconds of the cliff in which tokens will begin to vest
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* @param _duration duration in seconds of the period in which the tokens will vest
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* @param _revocable whether the vesting is revocable or not
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*/
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function TokenVesting(address _beneficiary, uint256 _start, uint256 _cliff, uint256 _duration, bool _revocable) {
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require(_beneficiary != 0x0);
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require(_cliff <= _duration);
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beneficiary = _beneficiary;
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revocable = _revocable;
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duration = _duration;
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cliff = _start + _cliff;
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start = _start;
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}
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/**
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* @notice Transfers vested tokens to beneficiary.
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* @param token ERC20 token which is being vested
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*/
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function release(ERC20Basic token) {
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uint256 vested = vestedAmount(token);
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require(vested > 0);
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token.transfer(beneficiary, vested);
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released[token] = released[token].add(vested);
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Released(vested);
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}
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/**
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* @notice Allows the owner to revoke the vesting. Tokens already vested
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* remain in the contract, the rest are returned to the owner.
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* @param token ERC20 token which is being vested
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*/
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function revoke(ERC20Basic token) onlyOwner {
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require(revocable);
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require(!revoked[token]);
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uint256 balance = token.balanceOf(this);
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uint256 vested = vestedAmount(token);
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uint256 vesting = balance - vested;
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revoked[token] = true;
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token.transfer(owner, vesting);
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Revoked();
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}
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/**
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* @dev Calculates the amount that has already vested but hasn't been released yet.
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* @param token ERC20 token which is being vested
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*/
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function vestedAmount(ERC20Basic token) constant returns (uint256) {
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if (now < cliff) {
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return 0;
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} else if (now >= start + duration || revoked[token]) {
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return token.balanceOf(this);
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} else {
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uint256 currentBalance = token.balanceOf(this);
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uint256 totalBalance = currentBalance.add(released[token]);
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uint256 vested = totalBalance.mul(now - start).div(duration);
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uint256 unreleased = vested.sub(released[token]);
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// currentBalance can be 0 in case of vesting being revoked earlier.
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return Math.min256(currentBalance, unreleased);
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}
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}
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}
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