Chris@16: //-----------------------------------------------------------------------------
Chris@16: // boost variant/variant_fwd.hpp header file
Chris@16: // See http://www.boost.org for updates, documentation, and revision history.
Chris@16: //-----------------------------------------------------------------------------
Chris@16: //
Chris@101: // Copyright (c) 2003 Eric Friedman, Itay Maman
Chris@101: // Copyright (c) 2013 Antony Polukhin
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_VARIANT_VARIANT_FWD_HPP
Chris@16: #define BOOST_VARIANT_VARIANT_FWD_HPP
Chris@16: 
Chris@16: #include "boost/variant/detail/config.hpp"
Chris@16: 
Chris@16: #include "boost/blank_fwd.hpp"
Chris@16: #include "boost/mpl/arg.hpp"
Chris@16: #include "boost/mpl/limits/arity.hpp"
Chris@16: #include "boost/mpl/aux_/na.hpp"
Chris@16: #include "boost/preprocessor/cat.hpp"
Chris@16: #include "boost/preprocessor/enum.hpp"
Chris@16: #include "boost/preprocessor/enum_params.hpp"
Chris@16: #include "boost/preprocessor/enum_shifted_params.hpp"
Chris@16: #include "boost/preprocessor/repeat.hpp"
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // macro BOOST_VARIANT_NO_REFERENCE_SUPPORT
Chris@16: //
Chris@16: // Defined if variant does not support references as bounded types. 
Chris@16: //
Chris@16: #if defined(BOOST_VARIANT_AUX_BROKEN_CONSTRUCTOR_TEMPLATE_ORDERING) \
Chris@16:  && !defined(BOOST_VARIANT_AUX_HAS_CONSTRUCTOR_TEMPLATE_ORDERING_SFINAE_WKND) \
Chris@16:  && !defined(BOOST_VARIANT_NO_REFERENCE_SUPPORT)
Chris@16: #   define BOOST_VARIANT_NO_REFERENCE_SUPPORT
Chris@16: #endif
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // macro BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT
Chris@16: //
Chris@16: // Defined if variant does not support make_variant_over (see below). 
Chris@16: //
Chris@16: #if defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
Chris@16: #   define BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT
Chris@16: #endif
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // macro BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT
Chris@16: //
Chris@16: // Defined if make_recursive_variant cannot be supported as documented.
Chris@16: //
Chris@16: // Note: Currently, MPL lambda facility is used as workaround if defined, and
Chris@16: // so only types declared w/ MPL lambda workarounds will work.
Chris@16: //
Chris@16: 
Chris@16: #include "boost/variant/detail/substitute_fwd.hpp"
Chris@16: 
Chris@16: #if defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE) \
Chris@101:   && !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT)
Chris@16: #   define BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT
Chris@16: #endif
Chris@16: 
Chris@101: 
Chris@101: ///////////////////////////////////////////////////////////////////////////////
Chris@101: // macro BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES
Chris@101: //
Chris@101: 
Chris@101: /* 
Chris@101:     GCC before 4.0 had no variadic tempaltes; 
Chris@101:     GCC 4.6 has incomplete implementation of variadic templates.
Chris@101: 
Chris@101:     MSVC2013 has variadic templates, but they have issues.
Chris@101: 
Chris@101:     NOTE: Clang compiler defines __GNUC__
Chris@101: */
Chris@101: #if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) \
Chris@101:   || (!defined(__clang__) && defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ < 7)) \
Chris@101:   || (defined(_MSC_VER) && (_MSC_VER <= 1900)) \
Chris@101:   || defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE) \
Chris@101:   || defined (BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
Chris@101: 
Chris@101: #ifndef BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES
Chris@101: #   define BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES
Chris@101: #endif
Chris@101: 
Chris@101: #endif
Chris@101: 
Chris@101: #if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
Chris@101: #include <boost/preprocessor/seq/size.hpp>
Chris@101: 
Chris@101: #define BOOST_VARIANT_CLASS_OR_TYPENAME_TO_SEQ_class class)(
Chris@101: #define BOOST_VARIANT_CLASS_OR_TYPENAME_TO_SEQ_typename typename)(
Chris@101: 
Chris@101: #define BOOST_VARIANT_CLASS_OR_TYPENAME_TO_VARIADIC_class class...
Chris@101: #define BOOST_VARIANT_CLASS_OR_TYPENAME_TO_VARIADIC_typename typename...
Chris@101: 
Chris@101: #define ARGS_VARIADER_1(x) x ## N...
Chris@101: #define ARGS_VARIADER_2(x) BOOST_VARIANT_CLASS_OR_TYPENAME_TO_VARIADIC_ ## x ## N
Chris@101: 
Chris@101: #define BOOST_VARIANT_MAKE_VARIADIC(sequence, x)        BOOST_VARIANT_MAKE_VARIADIC_I(BOOST_PP_SEQ_SIZE(sequence), x)
Chris@101: #define BOOST_VARIANT_MAKE_VARIADIC_I(argscount, x)     BOOST_VARIANT_MAKE_VARIADIC_II(argscount, x)
Chris@101: #define BOOST_VARIANT_MAKE_VARIADIC_II(argscount, orig) ARGS_VARIADER_ ## argscount(orig)
Chris@101: 
Chris@101: ///////////////////////////////////////////////////////////////////////////////
Chris@101: // BOOST_VARIANT_ENUM_PARAMS and BOOST_VARIANT_ENUM_SHIFTED_PARAMS
Chris@101: //
Chris@101: // Convenience macro for enumeration of variant params.
Chris@101: // When variadic templates are available expands:
Chris@101: //      BOOST_VARIANT_ENUM_PARAMS(class Something)      => class Something0, class... SomethingN
Chris@101: //      BOOST_VARIANT_ENUM_PARAMS(typename Something)   => typename Something0, typename... SomethingN
Chris@101: //      BOOST_VARIANT_ENUM_PARAMS(Something)            => Something0, SomethingN...
Chris@101: //      BOOST_VARIANT_ENUM_PARAMS(Something)            => Something0, SomethingN...
Chris@101: //      BOOST_VARIANT_ENUM_SHIFTED_PARAMS(class Something)      => class... SomethingN
Chris@101: //      BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename Something)   => typename... SomethingN
Chris@101: //      BOOST_VARIANT_ENUM_SHIFTED_PARAMS(Something)            => SomethingN...
Chris@101: //      BOOST_VARIANT_ENUM_SHIFTED_PARAMS(Something)            => SomethingN...
Chris@101: //
Chris@101: // Rationale: Cleaner, simpler code for clients of variant library. Minimal 
Chris@101: // code modifications to move from C++03 to C++11.
Chris@101: //
Chris@101: // With BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES defined
Chris@101: // will be used BOOST_VARIANT_ENUM_PARAMS and BOOST_VARIANT_ENUM_SHIFTED_PARAMS from below `#else`
Chris@101: //
Chris@101: 
Chris@101: #define BOOST_VARIANT_ENUM_PARAMS(x) \
Chris@101:     x ## 0, \
Chris@101:     BOOST_VARIANT_MAKE_VARIADIC( (BOOST_VARIANT_CLASS_OR_TYPENAME_TO_SEQ_ ## x), x) \
Chris@101:     /**/
Chris@101: 
Chris@101: #define BOOST_VARIANT_ENUM_SHIFTED_PARAMS(x) \
Chris@101:     BOOST_VARIANT_MAKE_VARIADIC( (BOOST_VARIANT_CLASS_OR_TYPENAME_TO_SEQ_ ## x), x) \
Chris@101:     /**/
Chris@101: 
Chris@101: #else // defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
Chris@101: 
Chris@101: ///////////////////////////////////////////////////////////////////////////////
Chris@101: // macro BOOST_VARIANT_LIMIT_TYPES
Chris@101: //
Chris@101: // Implementation-defined preprocessor symbol describing the actual
Chris@101: // length of variant's pseudo-variadic template parameter list.
Chris@101: //
Chris@101: #include "boost/mpl/limits/list.hpp"
Chris@101: #define BOOST_VARIANT_LIMIT_TYPES \
Chris@101:     BOOST_MPL_LIMIT_LIST_SIZE
Chris@101: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // macro BOOST_VARIANT_RECURSIVE_VARIANT_MAX_ARITY
Chris@16: //
Chris@16: // Exposes maximum allowed arity of class templates with recursive_variant
Chris@16: // arguments. That is,
Chris@16: //   make_recursive_variant< ..., T<[1], recursive_variant_, ... [N]> >.
Chris@16: //
Chris@16: #include "boost/mpl/limits/arity.hpp"
Chris@16: #define BOOST_VARIANT_RECURSIVE_VARIANT_MAX_ARITY \
Chris@16:     BOOST_MPL_LIMIT_METAFUNCTION_ARITY
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // macro BOOST_VARIANT_ENUM_PARAMS
Chris@16: //
Chris@16: // Convenience macro for enumeration of BOOST_VARIANT_LIMIT_TYPES params.
Chris@16: //
Chris@16: // Rationale: Cleaner, simpler code for clients of variant library.
Chris@16: //
Chris@16: #define BOOST_VARIANT_ENUM_PARAMS( param )  \
Chris@16:     BOOST_PP_ENUM_PARAMS(BOOST_VARIANT_LIMIT_TYPES, param)
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // macro BOOST_VARIANT_ENUM_SHIFTED_PARAMS
Chris@16: //
Chris@16: // Convenience macro for enumeration of BOOST_VARIANT_LIMIT_TYPES-1 params.
Chris@16: //
Chris@16: #define BOOST_VARIANT_ENUM_SHIFTED_PARAMS( param )  \
Chris@16:     BOOST_PP_ENUM_SHIFTED_PARAMS(BOOST_VARIANT_LIMIT_TYPES, param)
Chris@16: 
Chris@101: #endif // BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES workaround
Chris@101: 
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: namespace detail { namespace variant {
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // (detail) class void_ and class template convert_void
Chris@16: // 
Chris@16: // Provides the mechanism by which void(NN) types are converted to
Chris@16: // mpl::void_ (and thus can be passed to mpl::list).
Chris@16: //
Chris@16: // Rationale: This is particularly needed for the using-declarations
Chris@16: // workaround (below), but also to avoid associating mpl namespace with
Chris@16: // variant in argument dependent lookups (which used to happen because of
Chris@16: // defaulting of template parameters to mpl::void_).
Chris@16: //
Chris@16: 
Chris@16: struct void_;
Chris@16: 
Chris@16: template <typename T>
Chris@16: struct convert_void
Chris@16: {
Chris@16:     typedef T type;
Chris@16: };
Chris@16: 
Chris@16: template <>
Chris@16: struct convert_void< void_ >
Chris@16: {
Chris@16:     typedef mpl::na type;
Chris@16: };
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // (workaround) BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE
Chris@16: //
Chris@16: // Needed to work around compilers that don't support using-declaration
Chris@16: // overloads. (See the variant::initializer workarounds below.)
Chris@16: //
Chris@16: 
Chris@16: #if defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
Chris@16: // (detail) tags voidNN -- NN defined on [0, BOOST_VARIANT_LIMIT_TYPES)
Chris@16: //
Chris@16: // Defines void types that are each unique and specializations of
Chris@16: // convert_void that yields mpl::na for each voidNN type.
Chris@16: //
Chris@16: 
Chris@16: #define BOOST_VARIANT_DETAIL_DEFINE_VOID_N(z,N,_)          \
Chris@16:     struct BOOST_PP_CAT(void,N);                           \
Chris@16:                                                            \
Chris@16:     template <>                                            \
Chris@16:     struct convert_void< BOOST_PP_CAT(void,N) >            \
Chris@16:     {                                                      \
Chris@16:         typedef mpl::na type;                              \
Chris@16:     };                                                     \
Chris@16:     /**/
Chris@16: 
Chris@16: BOOST_PP_REPEAT(
Chris@16:       BOOST_VARIANT_LIMIT_TYPES
Chris@16:     , BOOST_VARIANT_DETAIL_DEFINE_VOID_N
Chris@16:     , _
Chris@16:     )
Chris@16: 
Chris@16: #undef BOOST_VARIANT_DETAIL_DEFINE_VOID_N
Chris@16: 
Chris@16: #endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround
Chris@16: 
Chris@16: }} // namespace detail::variant
Chris@16: 
Chris@101: #if !defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
Chris@101: #   define BOOST_VARIANT_AUX_DECLARE_PARAMS BOOST_VARIANT_ENUM_PARAMS(typename T)
Chris@101: #else // defined(BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES)
Chris@101: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // (detail) macro BOOST_VARIANT_AUX_DECLARE_PARAM
Chris@16: //
Chris@16: // Template parameter list for variant and recursive_variant declarations.
Chris@16: //
Chris@16: 
Chris@16: #if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
Chris@16: 
Chris@16: #   define BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL(z, N, T) \
Chris@16:     typename BOOST_PP_CAT(T,N) = detail::variant::void_ \
Chris@16:     /**/
Chris@16: 
Chris@16: #else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
Chris@16: 
Chris@16: #   define BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL(z, N, T) \
Chris@16:     typename BOOST_PP_CAT(T,N) = BOOST_PP_CAT(detail::variant::void,N) \
Chris@16:     /**/
Chris@16: 
Chris@16: #endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround
Chris@16: 
Chris@16: #define BOOST_VARIANT_AUX_DECLARE_PARAMS \
Chris@16:     BOOST_PP_ENUM( \
Chris@16:           BOOST_VARIANT_LIMIT_TYPES \
Chris@16:         , BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL \
Chris@16:         , T \
Chris@16:         ) \
Chris@16:     /**/
Chris@16: 
Chris@101: #endif // BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES workaround
Chris@101: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // class template variant (concept inspired by Andrei Alexandrescu)
Chris@16: //
Chris@16: // Efficient, type-safe bounded discriminated union.
Chris@16: //
Chris@16: // Preconditions:
Chris@16: //  - Each type must be unique.
Chris@16: //  - No type may be const-qualified.
Chris@16: //
Chris@16: // Proper declaration form:
Chris@16: //   variant<types>    (where types is a type-sequence)
Chris@16: // or
Chris@16: //   variant<T0,T1,...,Tn>  (where T0 is NOT a type-sequence)
Chris@16: //
Chris@16: template < BOOST_VARIANT_AUX_DECLARE_PARAMS > class variant;
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // metafunction make_recursive_variant
Chris@16: //
Chris@16: // Exposes a boost::variant with recursive_variant_ tags (below) substituted
Chris@16: // with the variant itself (wrapped as needed with boost::recursive_wrapper).
Chris@16: //
Chris@16: template < BOOST_VARIANT_AUX_DECLARE_PARAMS > struct make_recursive_variant;
Chris@16: 
Chris@16: #undef BOOST_VARIANT_AUX_DECLARE_PARAMS_IMPL
Chris@16: #undef BOOST_VARIANT_AUX_DECLARE_PARAMS
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // type recursive_variant_
Chris@16: //
Chris@16: // Tag type indicates where recursive variant substitution should occur.
Chris@16: //
Chris@16: #if !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT)
Chris@16:     struct recursive_variant_ {};
Chris@16: #else
Chris@16:     typedef mpl::arg<1> recursive_variant_;
Chris@16: #endif
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // metafunction make_variant_over
Chris@16: //
Chris@16: // Result is a variant w/ types of the specified type sequence.
Chris@16: //
Chris@16: template <typename Types> struct make_variant_over;
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // metafunction make_recursive_variant_over
Chris@16: //
Chris@16: // Result is a recursive variant w/ types of the specified type sequence.
Chris@16: //
Chris@16: template <typename Types> struct make_recursive_variant_over;
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif // BOOST_VARIANT_VARIANT_FWD_HPP