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

pragma solidity ^0.4.18;

import "../Crowdsale.sol";
import "../../token/ERC20/MintableToken.sol";


/**
 * @title MintedCrowdsale
 * @dev Extension of Crowdsale contract whose tokens are minted in each purchase.
 * Token ownership should be transferred to MintedCrowdsale for minting. 
 */
contract MintedCrowdsale is Crowdsale {

  /**
  * @dev Overrides delivery by minting tokens upon purchase.
  * @param _beneficiary Token purchaser
  * @param _tokenAmount Number of tokens to be minted
  */
  function _deliverTokens(address _beneficiary, uint256 _tokenAmount) internal {
    require(MintableToken(token).mint(_beneficiary, _tokenAmount));
  }
}