contract WhitelistedCrowdsale is Crowdsale, Ownable {

  mapping(address => bool) public whitelist;

  /**
   * @dev Reverts if beneficiary is not whitelisted. Can be used when extending this contract.
   */
  modifier isWhitelisted(address _beneficiary) {
    require(whitelist[_beneficiary]);
    _;
  }

  /**
   * @dev Adds single address to whitelist.
   * @param _beneficiary Address to be added to the whitelist
   */
  function addToWhitelist(address _beneficiary) external onlyOwner {
    whitelist[_beneficiary] = true;
  }

  /**
   * @dev Adds list of addresses to whitelist. Not overloaded due to limitations with truffle testing.
   * @param _beneficiaries Addresses to be added to the whitelist
   */
  function addManyToWhitelist(address[] _beneficiaries) external onlyOwner {
    for (uint256 i = 0; i < _beneficiaries.length; i++) {
      whitelist[_beneficiaries[i]] = true;
    }
  }

  /**
   * @dev Removes single address from whitelist.
   * @param _beneficiary Address to be removed to the whitelist
   */
  function removeFromWhitelist(address _beneficiary) external onlyOwner {
    whitelist[_beneficiary] = false;
  }

  /**
   * @dev Extend parent behavior requiring beneficiary to be in whitelist.
   * @param _beneficiary Token beneficiary
   * @param _weiAmount Amount of wei contributed
   */
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal isWhitelisted(_beneficiary) {
    super._preValidatePurchase(_beneficiary, _weiAmount);
  }

}
function removeFromWhitelist(address _beneficiary) external onlyOwner {
  whitelist[_beneficiary] = false;
}

/**
 * @dev Removes single address from whitelist.
 * @param _beneficiary Address to be removed to the whitelist
 */