openzeppelin-contracts/contracts/crowdsale/validation/CappedCrowdsale.sol

pragma solidity ^0.4.24;

import "../../math/SafeMath.sol";
import "../Crowdsale.sol";


/**
 * @title CappedCrowdsale
 * @dev Crowdsale with a limit for total contributions.
 */
contract CappedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 private cap_;

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

  /**
   * @return the cap of the crowdsale.
   */
  function cap() public view returns(uint256) {
    return 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_);
  }

}