text: //
  // detail/null_signal_blocker.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2015 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // 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)
  //
  
  #ifndef BOOST_ASIO_DETAIL_NULL_SIGNAL_BLOCKER_HPP
  #define BOOST_ASIO_DETAIL_NULL_SIGNAL_BLOCKER_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include <boost/asio/detail/config.hpp>
  
  #if !defined(BOOST_ASIO_HAS_THREADS) \
    || defined(BOOST_ASIO_WINDOWS) \
    || defined(BOOST_ASIO_WINDOWS_RUNTIME) \
    || defined(__CYGWIN__) \
    || defined(__SYMBIAN32__)
  
  #include <boost/asio/detail/noncopyable.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  class null_signal_blocker
    : private noncopyable
  {
  public:
    // Constructor blocks all signals for the calling thread.
    null_signal_blocker()
    {
    }
  
    // Destructor restores the previous signal mask.
    ~null_signal_blocker()
    {
    }
  
    // Block all signals for the calling thread.
    void block()
    {
    }
  
    // Restore the previous signal mask.
    void unblock()
    {
    }
  };
  
  } // namespace detail
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // !defined(BOOST_ASIO_HAS_THREADS)
         // || defined(BOOST_ASIO_WINDOWS)
         // || defined(BOOST_ASIO_WINDOWS_RUNTIME)
         // || defined(__CYGWIN__)
         // || defined(__SYMBIAN32__)
  
  #endif // BOOST_ASIO_DETAIL_NULL_SIGNAL_BLOCKER_HPP
  