text: //===----------------------------------------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is dual licensed under the MIT and the University of Illinois Open
  // Source Licenses. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  // Copyright (C) 2011 Vicente J. Botet Escriba
  //
  //  Distributed under the Boost Software License, Version 1.0. (See accompanying
  //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  
  // <boost/thread/locks.hpp>
  
  // template <class Mutex> class shared_lock;
  
  // explicit operator bool() const;
  
  #include <boost/thread/locks.hpp>
  #include <boost/thread/shared_mutex.hpp>
  #include <boost/detail/lightweight_test.hpp>
  
  boost::shared_mutex m;
  
  int main()
  {
    boost::shared_lock < boost::shared_mutex > lk0;
    BOOST_TEST(bool(lk0) == false);
    boost::shared_lock < boost::shared_mutex > lk1(m);
    BOOST_TEST(bool(lk1) == true);
    lk1.unlock();
    BOOST_TEST(bool(lk1) == false);
  
    return boost::report_errors();
  }
  
  