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

pragma solidity ^0.5.7;
import "../Crowdsale.sol";
import "../../access/roles/WhitelistedRole.sol";


/**
 * @title WhitelistCrowdsale
 * @dev Crowdsale in which only whitelisted users can contribute.
 */
contract WhitelistCrowdsale is WhitelistedRole, Crowdsale {
    /**
     * @dev Extend parent behavior requiring beneficiary to be whitelisted. Note that no
     * restriction is imposed on the account sending the transaction.
     * @param _beneficiary Token beneficiary
     * @param _weiAmount Amount of wei contributed
     */
    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view {
        require(isWhitelisted(_beneficiary));
        super._preValidatePurchase(_beneficiary, _weiAmount);
    }
}