/**
 * This smart contract code is Copyright 2017 TokenMarket Ltd. For more information see https://tokenmarket.net
 *
 * Licensed under the Apache License, version 2.0: https://github.com/TokenMarketNet/ico/blob/master/LICENSE.txt
 */

pragma solidity ^0.4.6;

import "zeppelin/contracts/ownership/Ownable.sol";

/*
 * Haltable
 *
 * Abstract contract that allows children to implement an
 * emergency stop mechanism. Differs from Pausable by causing a throw when in halt mode.
 *
 *
 * Originally envisioned in FirstBlood ICO contract.
 */
contract Haltable is Ownable {
  bool public halted;

  modifier stopInEmergency {
    if (halted) throw;
    _;
  }

  modifier stopNonOwnersInEmergency {
    if (halted && msg.sender != owner) throw;
    _;
  }

  modifier onlyInEmergency {
    if (!halted) throw;
    _;
  }

  // called by the owner on emergency, triggers stopped state
  function halt() external onlyOwner {
    halted = true;
  }

  // called by the owner on end of emergency, returns to normal state
  function unhalt() external onlyOwner onlyInEmergency {
    halted = false;
  }

}