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openzeppelin-contracts/contracts/crowdsale/distribution/PostDeliveryCrowdsale.sol

65 lines
2.3 KiB

pragma solidity ^0.5.0;
import "../validation/TimedCrowdsale.sol";
import "../../math/SafeMath.sol";
import "../../ownership/Secondary.sol";
import "../../token/ERC20/IERC20.sol";
/**
* @title PostDeliveryCrowdsale
* @dev Crowdsale that locks tokens from withdrawal until it ends.
*/
contract PostDeliveryCrowdsale is TimedCrowdsale {
using SafeMath for uint256;
mapping(address => uint256) private _balances;
__unstable__TokenVault private _vault;
constructor() public {
_vault = new __unstable__TokenVault();
}
/**
* @dev Withdraw tokens only after crowdsale ends.
* @param beneficiary Whose tokens will be withdrawn.
*/
function withdrawTokens(address beneficiary) public {
require(hasClosed(), "PostDeliveryCrowdsale: not closed");
uint256 amount = _balances[beneficiary];
require(amount > 0, "PostDeliveryCrowdsale: beneficiary is not due any tokens");
_balances[beneficiary] = 0;
_vault.transfer(token(), beneficiary, amount);
}
/**
* @return the balance of an account.
*/
function balanceOf(address account) public view returns (uint256) {
return _balances[account];
}
/**
* @dev Overrides parent by storing due balances, and delivering tokens to the vault instead of the end user. This
* ensures that the tokens will be available by the time they are withdrawn (which may not be the case if
* `_deliverTokens` was called later).
* @param beneficiary Token purchaser
* @param tokenAmount Amount of tokens purchased
*/
function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
_balances[beneficiary] = _balances[beneficiary].add(tokenAmount);
_deliverTokens(address(_vault), tokenAmount);
}
}
/**
* @title __unstable__TokenVault
* @dev Similar to an Escrow for tokens, this contract allows its primary account to spend its tokens as it sees fit.
* This contract is an internal helper for PostDeliveryCrowdsale, and should not be used outside of this context.
*/
// solhint-disable-next-line contract-name-camelcase
contract __unstable__TokenVault is Secondary {
function transfer(IERC20 token, address to, uint256 amount) public onlyPrimary {
token.transfer(to, amount);
}
}