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- //-----------------------------------------------------------------------------
- // boost variant/static_visitor.hpp header file
- // See http://www.boost.org for updates, documentation, and revision history.
- //-----------------------------------------------------------------------------
- //
- // Copyright (c) 2002-2003
- // Eric Friedman
- //
- // 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_VARIANT_STATIC_VISITOR_HPP
- #define BOOST_VARIANT_STATIC_VISITOR_HPP
- #include <boost/config.hpp>
- #include <boost/detail/workaround.hpp>
- #include <boost/mpl/if.hpp>
- #include <boost/type_traits/is_base_and_derived.hpp>
- #include <boost/type_traits/integral_constant.hpp>
- #include <boost/mpl/aux_/lambda_support.hpp>
- namespace boost {
- //////////////////////////////////////////////////////////////////////////
- // class template static_visitor
- //
- // An empty base class that typedefs the return type of a deriving static
- // visitor. The class is analogous to std::unary_function in this role.
- //
- namespace detail {
- struct is_static_visitor_tag { };
- typedef void static_visitor_default_return;
- } // namespace detail
- template <typename R = ::boost::detail::static_visitor_default_return>
- class static_visitor
- : public detail::is_static_visitor_tag
- {
- public: // typedefs
- typedef R result_type;
- protected: // for use as base class only
- #if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) && !defined(BOOST_NO_CXX11_NON_PUBLIC_DEFAULTED_FUNCTIONS)
- static_visitor() = default;
- #else
- static_visitor() BOOST_NOEXCEPT { }
- #endif
- };
- //////////////////////////////////////////////////////////////////////////
- // metafunction is_static_visitor
- //
- // Value metafunction indicates whether the specified type derives from
- // static_visitor<...>.
- //
- // NOTE #1: This metafunction does NOT check whether the specified type
- // fulfills the requirements of the StaticVisitor concept.
- //
- // NOTE #2: This template never needs to be specialized!
- //
- namespace detail {
- template <typename T>
- struct is_static_visitor_impl
- {
- BOOST_STATIC_CONSTANT(bool, value =
- (::boost::is_base_and_derived<
- detail::is_static_visitor_tag,
- T
- >::value));
- };
- } // namespace detail
- template< typename T > struct is_static_visitor
- : public ::boost::integral_constant<bool,(::boost::detail::is_static_visitor_impl<T>::value)>
- {
- public:
- BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_static_visitor,(T))
- };
- } // namespace boost
- #endif // BOOST_VARIANT_STATIC_VISITOR_HPP
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