ceph/src/boost/boost/variant/detail/make_variant_list.hpp

   1 //-----------------------------------------------------------------------------
   2 // boost variant/detail/make_variant_list.hpp header file
   3 // See http://www.boost.org for updates, documentation, and revision history.
   4 //-----------------------------------------------------------------------------
   5 //
   6 // Copyright (c) 2002-2003 Eric Friedman, Itay Maman
   7 // Copyright (c) 2013 Antony Polukhin
   8 //
   9 // Distributed under the Boost Software License, Version 1.0. (See
  10 // accompanying file LICENSE_1_0.txt or copy at
  11 // http://www.boost.org/LICENSE_1_0.txt)
  12
  13 #ifndef BOOST_VARIANT_DETAIL_MAKE_VARIANT_LIST_HPP
  14 #define BOOST_VARIANT_DETAIL_MAKE_VARIANT_LIST_HPP
  15
  16 #include <boost/variant/variant_fwd.hpp>
  17
  18 #include <boost/mpl/list.hpp>
  19 #include <boost/preprocessor/cat.hpp>
  20 #include <boost/preprocessor/enum.hpp>
  21
  22 namespace boost {
  23 namespace detail { namespace variant {
  24
  25 ///////////////////////////////////////////////////////////////////////////////
  26 // (detail) metafunction make_variant_list
  27 //
  28 // Provides a MPL-compatible sequence with the specified non-void types
  29 // as arguments.
  30 //
  31 // Rationale: see class template convert_void (variant_fwd.hpp) and using-
  32 // declaration workaround (below).
  33 //
  34
  35 #if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
  36
  37 template < typename... T >
  38 struct make_variant_list
  39 {
  40     typedef typename mpl::list< T... >::type type;
  41 };
  42
  43 #else // defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
  44
  45 template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
  46 struct make_variant_list
  47 {
  48 public: // metafunction result
  49
  50     // [Define a macro to convert any void(NN) tags to mpl::void...]
  51 #   define BOOST_VARIANT_AUX_CONVERT_VOID(z, N,_)  \
  52         typename convert_void< BOOST_PP_CAT(T,N) >::type
  53
  54     // [...so that the specified types can be passed to mpl::list...]
  55     typedef typename mpl::list<
  56           BOOST_PP_ENUM(
  57               BOOST_VARIANT_LIMIT_TYPES
  58             , BOOST_VARIANT_AUX_CONVERT_VOID
  59             , _
  60             )
  61         >::type type;
  62
  63     // [...and, finally, the conversion macro can be undefined:]
  64 #   undef BOOST_VARIANT_AUX_CONVERT_VOID
  65
  66 };
  67
  68 #endif // BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES workaround
  69
  70 }} // namespace detail::variant
  71 } // namespace boost
  72
  73 #endif // BOOST_VARIANT_DETAIL_MAKE_VARIANT_LIST_HPP