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openzeppelin-contracts/contracts/crowdsale/emission/AllowanceCrowdsale.sol

51 lines
1.6 KiB

pragma solidity ^0.5.2;
import "../Crowdsale.sol";
import "../../token/ERC20/IERC20.sol";
import "../../token/ERC20/SafeERC20.sol";
import "../../math/SafeMath.sol";
import "../../math/Math.sol";
/**
* @title AllowanceCrowdsale
* @dev Extension of Crowdsale where tokens are held by a wallet, which approves an allowance to the crowdsale.
*/
contract AllowanceCrowdsale is Crowdsale {
using SafeMath for uint256;
using SafeERC20 for IERC20;
address private _tokenWallet;
/**
* @dev Constructor, takes token wallet address.
* @param tokenWallet Address holding the tokens, which has approved allowance to the crowdsale
*/
constructor (address tokenWallet) public {
require(tokenWallet != address(0));
_tokenWallet = tokenWallet;
}
/**
* @return the address of the wallet that will hold the tokens.
*/
function tokenWallet() public view returns (address) {
return _tokenWallet;
}
/**
* @dev Checks the amount of tokens left in the allowance.
* @return Amount of tokens left in the allowance
*/
function remainingTokens() public view returns (uint256) {
return Math.min(token().balanceOf(_tokenWallet), token().allowance(_tokenWallet, address(this)));
}
/**
* @dev Overrides parent behavior by transferring tokens from wallet.
* @param beneficiary Token purchaser
* @param tokenAmount Amount of tokens purchased
*/
function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
token().safeTransferFrom(_tokenWallet, beneficiary, tokenAmount);
}
}