Chris@16: // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
Chris@16: // (C) Copyright 2003-2007 Jonathan Turkanis
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
Chris@16: 
Chris@16: // See http://www.boost.org/libs/iostreams for documentation.
Chris@16: 
Chris@16: // Contains the definition of the class template access_control, which
Chris@16: // allows the type of inheritance from a provided base class to be specified 
Chris@16: // using a template parameter.
Chris@16: 
Chris@16: 
Chris@16: #ifndef BOOST_IOSTREAMS_ACCESS_CONTROL_HPP_INCLUDED
Chris@16: #define BOOST_IOSTREAMS_ACCESS_CONTROL_HPP_INCLUDED
Chris@16: 
Chris@16: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
Chris@16: # pragma once
Chris@16: #endif              
Chris@16: 
Chris@16: #include <boost/iostreams/detail/select.hpp>
Chris@16: #include <boost/mpl/identity.hpp>
Chris@16: #include <boost/type_traits/is_same.hpp>
Chris@16: 
Chris@16: namespace boost { namespace iostreams {
Chris@16: 
Chris@16: struct protected_ { };  // Represents protected inheritance.
Chris@16: struct public_ { };     // Represents public inheritance.
Chris@16: 
Chris@16: 
Chris@16: namespace detail {
Chris@16: 
Chris@16:     // Implements protected inheritance.
Chris@16:     template<typename U>
Chris@16:     struct prot_ : protected U 
Chris@16:     { 
Chris@16:         prot_() { }
Chris@16:         template<typename V> prot_(V v) : U(v) { }
Chris@16:     };
Chris@16: 
Chris@16:     // Implements public inheritance.
Chris@16:     template<typename U> struct pub_ : public U { 
Chris@16:         pub_() { }
Chris@16:         template<typename V> pub_(V v) : U(v) { }
Chris@16:     };
Chris@16: 
Chris@16: //
Chris@16: // Used to deduce the base type for the template access_control.
Chris@16: //
Chris@16: template<typename T, typename Access>
Chris@16: struct access_control_base {
Chris@16:     typedef int                                 bad_access_specifier;
Chris@16:     typedef typename 
Chris@16:             iostreams::select<  // Disambiguation for Tru64
Chris@16:                 ::boost::is_same<
Chris@16:                     Access, protected_
Chris@16:                 >,                              prot_<T>,
Chris@16:                 ::boost::is_same<
Chris@16:                     Access, public_
Chris@16:                 >,                              pub_<T>,
Chris@16:                 else_,                          bad_access_specifier
Chris@16:             >::type                             type;
Chris@16: };
Chris@16: 
Chris@16: } // End namespace detail.
Chris@16: 
Chris@16: //
Chris@16: // Template name: access_control.
Chris@16: // Description: Allows the type of inheritance from a provided base class
Chris@16: //      to be specified using an int template parameter.
Chris@16: // Template parameters:
Chris@16: //      Base - The class from which to inherit (indirectly.)
Chris@16: //      Access - The type of access desired. Must be one of the 
Chris@16: //          values access_base::prot or access_base::pub.
Chris@16: //
Chris@16: template< typename T, typename Access,
Chris@16:           typename Base = // VC6 workaraound (Compiler Error C2516)
Chris@16:               typename detail::access_control_base<T, Access>::type >
Chris@16: struct access_control : public Base { 
Chris@16:     access_control() { }
Chris@16:     template<typename U> explicit access_control(U u) : Base(u) { }
Chris@16: };
Chris@16: 
Chris@16: //----------------------------------------------------------------------------//
Chris@16: 
Chris@16: } } // End namespaces iostreams, boost.
Chris@16: 
Chris@16: #endif // #ifndef BOOST_IOSTREAMS_ACCESS_CONTROL_HPP_INCLUDED