contract CappedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 public cap;

  /**
   * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
   * @param _cap Max amount of wei to be contributed
   */
  function CappedCrowdsale(uint256 _cap) public {
    require(_cap > 0);
    cap = _cap;
  }

  /**
   * @dev Checks whether the cap has been reached. 
   * @return Whether the cap was reached
   */
  function capReached() public view returns (bool) {
    return weiRaised >= cap;
  }

  /**
   * @dev Extend parent behavior requiring purchase to respect the funding cap.
   * @param _beneficiary Token purchaser
   * @param _weiAmount Amount of wei contributed
   */
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
    super._preValidatePurchase(_beneficiary, _weiAmount);
    require(weiRaised.add(_weiAmount) <= cap);
  }

}
function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
    super._preValidatePurchase(_beneficiary, _weiAmount);
    require(weiRaised.add(_weiAmount) <= cap);
  }
/**
 * @dev Extend parent behavior requiring purchase to respect the funding cap.
 * @param _beneficiary Token purchaser
 * @param _weiAmount Amount of wei contributed
 */