ceph/src/boost/libs/variant/include/boost/variant/static_visitor.hpp

   1 //-----------------------------------------------------------------------------
   2 // boost variant/static_visitor.hpp header file
   3 // See http://www.boost.org for updates, documentation, and revision history.
   4 //-----------------------------------------------------------------------------
   5 //
   6 // Copyright (c) 2002-2003
   7 // Eric Friedman
   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_STATIC_VISITOR_HPP
  14 #define BOOST_VARIANT_STATIC_VISITOR_HPP
  15
  16 #include <boost/config.hpp>
  17 #include <boost/detail/workaround.hpp>
  18
  19 #include <boost/mpl/if.hpp>
  20 #include <boost/type_traits/is_base_and_derived.hpp>
  21
  22 #include <boost/type_traits/integral_constant.hpp>
  23 #include <boost/mpl/aux_/lambda_support.hpp>
  24
  25 namespace boost {
  26
  27 //////////////////////////////////////////////////////////////////////////
  28 // class template static_visitor
  29 //
  30 // An empty base class that typedefs the return type of a deriving static
  31 // visitor. The class is analogous to std::unary_function in this role.
  32 //
  33
  34 namespace detail {
  35
  36     struct is_static_visitor_tag { };
  37
  38     typedef void static_visitor_default_return;
  39
  40 } // namespace detail
  41
  42 template <typename R = ::boost::detail::static_visitor_default_return>
  43 class static_visitor
  44     : public detail::is_static_visitor_tag
  45 {
  46 public: // typedefs
  47
  48     typedef R result_type;
  49
  50 protected: // for use as base class only
  51 #if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) && !defined(BOOST_NO_CXX11_NON_PUBLIC_DEFAULTED_FUNCTIONS)
  52     static_visitor() = default;
  53     ~static_visitor() = default;
  54 #else
  55     static_visitor()  BOOST_NOEXCEPT { }
  56     ~static_visitor()  BOOST_NOEXCEPT { }
  57 #endif
  58 };
  59
  60 //////////////////////////////////////////////////////////////////////////
  61 // metafunction is_static_visitor
  62 //
  63 // Value metafunction indicates whether the specified type derives from
  64 // static_visitor<...>.
  65 //
  66 // NOTE #1: This metafunction does NOT check whether the specified type
  67 //  fulfills the requirements of the StaticVisitor concept.
  68 //
  69 // NOTE #2: This template never needs to be specialized!
  70 //
  71
  72 namespace detail {
  73
  74 template <typename T>
  75 struct is_static_visitor_impl
  76 {
  77     BOOST_STATIC_CONSTANT(bool, value =
  78         (::boost::is_base_and_derived<
  79             detail::is_static_visitor_tag,
  80             T
  81         >::value));
  82 };
  83
  84 } // namespace detail
  85
  86 template< typename T > struct is_static_visitor
  87         : public ::boost::integral_constant<bool,(::boost::detail::is_static_visitor_impl<T>::value)>
  88 {
  89 public:
  90     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_static_visitor,(T))
  91 };
  92
  93 } // namespace boost
  94
  95 #endif // BOOST_VARIANT_STATIC_VISITOR_HPP