sl@0: //-----------------------------------------------------------------------------
sl@0: // boost variant/variant.hpp header file
sl@0: // See http://www.boost.org for updates, documentation, and revision history.
sl@0: //-----------------------------------------------------------------------------
sl@0: //
sl@0: // Copyright (c) 2002-2003
sl@0: // Eric Friedman, Itay Maman
sl@0: //
sl@0: // Distributed under the Boost Software License, Version 1.0. (See
sl@0: // accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: /*
sl@0:  * © Portions copyright (c) 2006-2007 Nokia Corporation.  All rights reserved.
sl@0: */
sl@0: #ifndef BOOST_VARIANT_VARIANT_HPP
sl@0: #define BOOST_VARIANT_VARIANT_HPP
sl@0: 
sl@0: #include <cstddef> // for std::size_t
sl@0: #include <new> // for placement new
sl@0: #ifdef __SYMBIAN32__
sl@0: #include <string>
sl@0: #endif
sl@0: #include <typeinfo> // for typeid, std::type_info
sl@0: 
sl@0: #include "boost/variant/detail/config.hpp"
sl@0: #include "boost/mpl/aux_/config/eti.hpp"
sl@0: #include "boost/mpl/aux_/value_wknd.hpp"
sl@0: 
sl@0: #include "boost/variant/variant_fwd.hpp"
sl@0: #include "boost/variant/detail/backup_holder.hpp"
sl@0: #include "boost/variant/detail/enable_recursive_fwd.hpp"
sl@0: #include "boost/variant/detail/forced_return.hpp"
sl@0: #include "boost/variant/detail/initializer.hpp"
sl@0: #include "boost/variant/detail/make_variant_list.hpp"
sl@0: #include "boost/variant/detail/over_sequence.hpp"
sl@0: #include "boost/variant/detail/visitation_impl.hpp"
sl@0: 
sl@0: #include "boost/variant/detail/generic_result_type.hpp"
sl@0: #include "boost/variant/detail/has_nothrow_move.hpp"
sl@0: #include "boost/variant/detail/move.hpp"
sl@0: 
sl@0: #include "boost/detail/reference_content.hpp"
sl@0: #include "boost/aligned_storage.hpp"
sl@0: #include "boost/blank.hpp"
sl@0: #include "boost/static_assert.hpp"
sl@0: #include "boost/preprocessor/cat.hpp"
sl@0: #include "boost/preprocessor/repeat.hpp"
sl@0: #include "boost/type_traits/alignment_of.hpp"
sl@0: #include "boost/type_traits/add_const.hpp"
sl@0: #include "boost/type_traits/has_nothrow_constructor.hpp"
sl@0: #include "boost/type_traits/has_nothrow_copy.hpp"
sl@0: #include "boost/type_traits/is_const.hpp"
sl@0: #include "boost/type_traits/is_same.hpp"
sl@0: #include "boost/utility/enable_if.hpp"
sl@0: #include "boost/variant/recursive_wrapper_fwd.hpp"
sl@0: #include "boost/variant/static_visitor.hpp"
sl@0: 
sl@0: #include "boost/mpl/eval_if.hpp"
sl@0: #include "boost/mpl/begin_end.hpp"
sl@0: #include "boost/mpl/bool.hpp"
sl@0: #include "boost/mpl/empty.hpp"
sl@0: #include "boost/mpl/find_if.hpp"
sl@0: #include "boost/mpl/front.hpp"
sl@0: #include "boost/mpl/identity.hpp"
sl@0: #include "boost/mpl/if.hpp"
sl@0: #include "boost/mpl/int.hpp"
sl@0: #include "boost/mpl/is_sequence.hpp"
sl@0: #include "boost/mpl/iterator_range.hpp"
sl@0: #include "boost/mpl/iter_fold_if.hpp"
sl@0: #include "boost/mpl/logical.hpp"
sl@0: #include "boost/mpl/max_element.hpp"
sl@0: #include "boost/mpl/next.hpp"
sl@0: #include "boost/mpl/deref.hpp"
sl@0: #include "boost/mpl/pair.hpp"
sl@0: #include "boost/mpl/protect.hpp"
sl@0: #include "boost/mpl/push_front.hpp"
sl@0: #include "boost/mpl/same_as.hpp"
sl@0: #include "boost/mpl/size_t.hpp"
sl@0: #include "boost/mpl/sizeof.hpp"
sl@0: #include "boost/mpl/transform.hpp"
sl@0: #include "boost/mpl/assert.hpp"
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // Implementation Macros:
sl@0: //
sl@0: // BOOST_VARIANT_VISITATION_UNROLLING_LIMIT
sl@0: //   Defined in boost/variant/detail/visitation_impl.hpp.
sl@0: //
sl@0: // BOOST_VARIANT_MINIMIZE_SIZE
sl@0: //   When #defined, implementation employs all known means to minimize the
sl@0: //   size of variant obje   cts. However, often unsuccessful due to alignment
sl@0: //   issues, and potentially harmful to runtime speed, so not enabled by
sl@0: //   default. (TODO: Investigate further.)
sl@0: 
sl@0: #if defined(BOOST_VARIANT_MINIMIZE_SIZE)
sl@0: #   include <climits> // for SCHAR_MAX
sl@0: #   include "boost/mpl/eval_if.hpp"
sl@0: #   include "boost/mpl/equal_to.hpp"
sl@0: #   include "boost/mpl/identity.hpp"
sl@0: #   include "boost/mpl/int.hpp"
sl@0: #   include "boost/mpl/if.hpp"
sl@0: #   include "boost/mpl/less.hpp"
sl@0: #   include "boost/mpl/long.hpp"
sl@0: #   include "boost/mpl/O1_size.hpp"
sl@0: #endif
sl@0: 
sl@0: 
sl@0: namespace boost {
sl@0: 
sl@0: namespace detail { namespace variant {
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) metafunction max_value
sl@0: //
sl@0: // Finds the maximum value of the unary metafunction F over Sequence.
sl@0: //
sl@0: template <typename Sequence, typename F>
sl@0: struct max_value
sl@0: {
sl@0: private: // helpers, for metafunction result (below)
sl@0: 
sl@0:     typedef typename mpl::transform1<Sequence, F>::type transformed_;
sl@0:     typedef typename mpl::max_element<transformed_
sl@0:           
sl@0:         >::type max_it;
sl@0: 
sl@0: public: // metafunction result
sl@0: 
sl@0:     typedef typename mpl::deref<max_it>::type
sl@0:         type;
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) metafunction find_fallback_type
sl@0: //
sl@0: // Provides a fallback (i.e., nothrow default-constructible) type from the
sl@0: // specified sequence, or no_fallback_type if not found.
sl@0: //
sl@0: // This implementation is designed to prefer boost::blank over other potential
sl@0: // fallback types, regardless of its position in the specified sequence.
sl@0: //
sl@0: 
sl@0: class no_fallback_type;
sl@0: 
sl@0: struct find_fallback_type_pred
sl@0: {
sl@0:     template <typename Iterator>
sl@0:     struct apply
sl@0:     {
sl@0:     private:
sl@0:         typedef typename mpl::deref<Iterator>::type t_;
sl@0: 
sl@0:     public:
sl@0:         typedef mpl::not_< has_nothrow_constructor<t_> > type;
sl@0:     };
sl@0: };
sl@0: 
sl@0: template <typename Types>
sl@0: struct find_fallback_type
sl@0: {
sl@0: private: // helpers, for metafunction result (below)
sl@0: 
sl@0:     typedef typename mpl::end<Types>::type end_it;
sl@0: 
sl@0:     // [Find the first suitable fallback type...]
sl@0: 
sl@0:     typedef typename mpl::iter_fold_if<
sl@0:           Types
sl@0:         , mpl::int_<0>, mpl::protect< mpl::next<> >
sl@0:         , mpl::protect< find_fallback_type_pred >
sl@0:         >::type first_result_;
sl@0: 
sl@0:     typedef typename first_result_::first first_result_index;
sl@0:     typedef typename first_result_::second first_result_it;
sl@0: 
sl@0:     // [...now search the rest of the sequence for boost::blank...]
sl@0: 
sl@0:     typedef typename mpl::iter_fold_if<
sl@0:           mpl::iterator_range< first_result_it,end_it >
sl@0:         , first_result_index, mpl::protect< mpl::next<> >
sl@0:         , mpl::protect< mpl::not_same_as<boost::blank> >
sl@0:         >::type second_result_;
sl@0: 
sl@0:     typedef typename second_result_::second second_result_it;
sl@0: 
sl@0: public: // metafunction result
sl@0: 
sl@0:     // [...and return the results of the search:]
sl@0:     typedef typename mpl::eval_if<
sl@0:           is_same< second_result_it,end_it >
sl@0:         , mpl::if_<
sl@0:               is_same< first_result_it,end_it >
sl@0:             , mpl::pair< no_fallback_type,no_fallback_type >
sl@0:             , first_result_
sl@0:             >
sl@0:         , mpl::identity< second_result_ >
sl@0:         >::type type;
sl@0: 
sl@0: };
sl@0: 
sl@0: #if defined(BOOST_MPL_CFG_MSVC_60_ETI_BUG)
sl@0: 
sl@0: template<>
sl@0: struct find_fallback_type<int>
sl@0: {
sl@0:     typedef mpl::pair< no_fallback_type,no_fallback_type > type;
sl@0: };
sl@0: 
sl@0: #endif // BOOST_MPL_CFG_MSVC_60_ETI_BUG workaround
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) metafunction make_storage
sl@0: //
sl@0: // Provides an aligned storage type capable of holding any of the types
sl@0: // specified in the given type-sequence.
sl@0: //
sl@0: 
sl@0: template <typename Types, typename NeverUsesBackupFlag>
sl@0: struct make_storage
sl@0: {
sl@0: private: // helpers, for metafunction result (below)
sl@0: 
sl@0:     typedef typename mpl::eval_if<
sl@0:           NeverUsesBackupFlag
sl@0:         , mpl::identity< Types >
sl@0:         , mpl::push_front<
sl@0:               Types, backup_holder<void*>
sl@0:             >
sl@0:         >::type types;
sl@0: 
sl@0:     typedef typename max_value<
sl@0:           types, mpl::sizeof_<mpl::_1>
sl@0:         >::type max_size;
sl@0: 
sl@0: #if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0551))
sl@0: 
sl@0:     typedef typename max_value<
sl@0:           types, alignment_of<mpl::_1>
sl@0:         >::type max_alignment;
sl@0: 
sl@0: #else // borland
sl@0: 
sl@0:     // temporary workaround -- use maximal alignment
sl@0:     typedef mpl::size_t< -1 > max_alignment;
sl@0: 
sl@0: #endif // borland workaround
sl@0: 
sl@0: public: // metafunction result
sl@0: 
sl@0: #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
sl@0: 
sl@0:     typedef ::boost::aligned_storage<
sl@0:           BOOST_MPL_AUX_VALUE_WKND(max_size)::value
sl@0:         , BOOST_MPL_AUX_VALUE_WKND(max_alignment)::value
sl@0:         > type;
sl@0: 
sl@0: #else // MSVC7 and below
sl@0: 
sl@0:     BOOST_STATIC_CONSTANT(std::size_t, msvc_max_size_c = max_size::value);
sl@0:     BOOST_STATIC_CONSTANT(std::size_t, msvc_max_alignment_c = max_alignment::value);
sl@0: 
sl@0:     typedef ::boost::aligned_storage<
sl@0:           msvc_max_size_c
sl@0:         , msvc_max_alignment_c
sl@0:         > type;
sl@0: 
sl@0: #endif // MSVC workaround
sl@0: 
sl@0: };
sl@0: 
sl@0: #if defined(BOOST_MPL_CFG_MSVC_60_ETI_BUG)
sl@0: 
sl@0: template<>
sl@0: struct make_storage<int,int>
sl@0: {
sl@0:     typedef int type;
sl@0: };
sl@0: 
sl@0: #endif // BOOST_MPL_CFG_MSVC_60_ETI_BUG workaround
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class destroyer
sl@0: //
sl@0: // Internal visitor that destroys the value it visits.
sl@0: //
sl@0: struct destroyer
sl@0:     : public static_visitor<>
sl@0: {
sl@0: public: // visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(T& operand, int) const
sl@0:     {
sl@0:         operand.~T();
sl@0: 
sl@0: #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0551))
sl@0:         operand; // suppresses warnings
sl@0: #endif
sl@0: 
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class template known_get
sl@0: //
sl@0: // Visitor that returns a reference to content of the specified type.
sl@0: //
sl@0: // Precondition: visited variant MUST contain logical content of type T.
sl@0: //
sl@0: template <typename T>
sl@0: class known_get
sl@0:     : public static_visitor<T&>
sl@0: {
sl@0: 
sl@0: #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
sl@0: 
sl@0: public: // visitor interface
sl@0: 
sl@0:     T& operator()(T& operand) const
sl@0:     {
sl@0:         return operand;
sl@0:     }
sl@0: 
sl@0:     template <typename U>
sl@0:     T& operator()(U&) const
sl@0:     {
sl@0:         // logical error to be here: see precondition above
sl@0:         BOOST_ASSERT(false);
sl@0:         return ::boost::detail::variant::forced_return< T& >();
sl@0:     }
sl@0: 
sl@0: #else // MSVC6
sl@0: 
sl@0: private: // helpers, for visitor interface (below)
sl@0: 
sl@0:     T& execute(T& operand, mpl::true_) const
sl@0:     {
sl@0:         return operand;
sl@0:     }
sl@0: 
sl@0:     template <typename U>
sl@0:     T& execute(U& operand, mpl::false_) const
sl@0:     {
sl@0:         // logical error to be here: see precondition above
sl@0:         BOOST_ASSERT(false);
sl@0:         return ::boost::detail::variant::forced_return< T& >();
sl@0:     }
sl@0: 
sl@0: public: // visitor interface
sl@0: 
sl@0:     template <typename U>
sl@0:     T& operator()(U& operand) const
sl@0:     {
sl@0:         typedef typename is_same< U,T >::type
sl@0:             U_is_T;
sl@0: 
sl@0:         return execute(operand, U_is_T());
sl@0:     }
sl@0: 
sl@0: #endif // MSVC6 workaround
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class copy_into
sl@0: //
sl@0: // Internal visitor that copies the value it visits into the given buffer.
sl@0: //
sl@0: class copy_into
sl@0:     : public static_visitor<>
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     void* storage_;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     explicit copy_into(void* storage)
sl@0:         : storage_(storage)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: public: // internal visitor interface
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
sl@0:     {
sl@0:         new(storage_) T( operand.get() );
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
sl@0:     {
sl@0:         new(storage_) T( operand.get() );
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(const T& operand, int) const
sl@0:     {
sl@0:         new(storage_) T(operand);
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class assign_storage
sl@0: //
sl@0: // Internal visitor that assigns the given storage (which must be a
sl@0: // constructed value of the same type) to the value it visits.
sl@0: //
sl@0: struct assign_storage
sl@0:     : public static_visitor<>
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     const void* rhs_storage_;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     explicit assign_storage(const void* rhs_storage)
sl@0:         : rhs_storage_(rhs_storage)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: public: // internal visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(backup_holder<T>& lhs_content, long) const
sl@0:     {
sl@0:         lhs_content.get()
sl@0:             = static_cast< const backup_holder<T>* >(rhs_storage_)->get();
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(const backup_holder<T>& lhs_content, long) const
sl@0:     {
sl@0:         lhs_content.get()
sl@0:             = static_cast< const backup_holder<T>* >(rhs_storage_)->get();
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(T& lhs_content, int) const
sl@0:     {
sl@0:         // NOTE TO USER :
sl@0:         // Compile error here indicates one of variant's bounded types does
sl@0:         // not meet the requirements of the Assignable concept. Thus,
sl@0:         // variant is not Assignable.
sl@0:         //
sl@0:         // Hint: Are any of the bounded types const-qualified or references?
sl@0:         //
sl@0:         lhs_content = *static_cast< const T* >(rhs_storage_);
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class direct_assigner
sl@0: //
sl@0: // Generic static visitor that: if and only if the visited value is of the
sl@0: // specified type, assigns the given value to the visited value and returns
sl@0: // true; else returns false.
sl@0: //
sl@0: template <typename T>
sl@0: class direct_assigner
sl@0:     : public static_visitor<bool>
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     T& rhs_;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     explicit direct_assigner(T& rhs)
sl@0:         : rhs_(rhs)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
sl@0: 
sl@0: public: // visitor interface
sl@0: 
sl@0:     bool operator()(T& lhs)
sl@0:     {
sl@0:         lhs = rhs_;
sl@0:         return true;
sl@0:     }
sl@0: 
sl@0:     template <typename U>
sl@0:     bool operator()(U&)
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0: 
sl@0: #else // MSVC6
sl@0: 
sl@0: private: // helpers, for visitor interface (below)
sl@0: 
sl@0:     bool execute(T& lhs, mpl::true_)
sl@0:     {
sl@0:         lhs = rhs_;
sl@0:         return true;
sl@0:     }
sl@0: 
sl@0:     template <typename U>
sl@0:     bool execute(U&, mpl::false_)
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0: 
sl@0: public: // visitor interface
sl@0: 
sl@0:     template <typename U>
sl@0:     bool operator()(U& lhs)
sl@0:     {
sl@0:         typedef typename is_same<U,T>::type U_is_T;
sl@0:         return execute(lhs, U_is_T());
sl@0:     }
sl@0: 
sl@0: #endif // MSVC6 workaround
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class backup_assigner
sl@0: //
sl@0: // Internal visitor that "assigns" the given value to the visited value,
sl@0: // using backup to recover if the destroy-copy sequence fails.
sl@0: //
sl@0: // NOTE: This needs to be a friend of variant, as it needs access to
sl@0: // indicate_which, indicate_backup_which, etc.
sl@0: //
sl@0: template <typename Variant, typename RhsT>
sl@0: class backup_assigner
sl@0:     : public static_visitor<>
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     Variant& lhs_;
sl@0:     int rhs_which_;
sl@0:     const RhsT& rhs_content_;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     backup_assigner(Variant& lhs, int rhs_which, const RhsT& rhs_content)
sl@0:         : lhs_(lhs)
sl@0:         , rhs_which_(rhs_which)
sl@0:         , rhs_content_(rhs_content)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: private: // helpers, for visitor interface (below)
sl@0: 
sl@0:     template <typename LhsT>
sl@0:     void backup_assign_impl(
sl@0:           LhsT& lhs_content
sl@0:         , mpl::true_// has_nothrow_move
sl@0:         )
sl@0:     {
sl@0:         // Move lhs content to backup...
sl@0:         LhsT backup_lhs_content(
sl@0:               ::boost::detail::variant::move(lhs_content)
sl@0:             ); // nothrow
sl@0: 
sl@0:         // ...destroy lhs content...
sl@0:         lhs_content.~LhsT(); // nothrow
sl@0: 
sl@0:         try
sl@0:         {
sl@0:             // ...and attempt to copy rhs content into lhs storage:
sl@0:             new(lhs_.storage_.address()) RhsT(rhs_content_);
sl@0:         }
sl@0:         catch (...)
sl@0:         {
sl@0:             // In case of failure, restore backup content to lhs storage...
sl@0:             new(lhs_.storage_.address())
sl@0:                 LhsT(
sl@0:                       ::boost::detail::variant::move(backup_lhs_content)
sl@0:                     ); // nothrow
sl@0: 
sl@0:             // ...and rethrow:
sl@0:             throw;
sl@0:         }
sl@0: 
sl@0:         // In case of success, indicate new content type:
sl@0:         lhs_.indicate_which(rhs_which_); // nothrow
sl@0:     }
sl@0: 
sl@0:     template <typename LhsT>
sl@0:     void backup_assign_impl(
sl@0:           LhsT& lhs_content
sl@0:         , mpl::false_// has_nothrow_move
sl@0:         )
sl@0:     {
sl@0:         // Backup lhs content...
sl@0:         LhsT* backup_lhs_ptr = new LhsT(lhs_content);
sl@0: 
sl@0:         // ...destroy lhs content...
sl@0:         lhs_content.~LhsT(); // nothrow
sl@0: 
sl@0:         try
sl@0:         {
sl@0:             // ...and attempt to copy rhs content into lhs storage:
sl@0:             new(lhs_.storage_.address()) RhsT(rhs_content_);
sl@0:         }
sl@0:         catch (...)
sl@0:         {
sl@0:             // In case of failure, copy backup pointer to lhs storage...
sl@0:             new(lhs_.storage_.address())
sl@0:                 backup_holder<LhsT>( backup_lhs_ptr ); // nothrow
sl@0: 
sl@0:             // ...indicate now using backup...
sl@0:             lhs_.indicate_backup_which( lhs_.which() ); // nothrow
sl@0: 
sl@0:             // ...and rethrow:
sl@0:             throw;
sl@0:         }
sl@0: 
sl@0:         // In case of success, indicate new content type...
sl@0:         lhs_.indicate_which(rhs_which_); // nothrow
sl@0: 
sl@0:         // ...and delete backup:
sl@0:         delete backup_lhs_ptr; // nothrow
sl@0:     }
sl@0: 
sl@0: public: // visitor interface
sl@0: 
sl@0:     template <typename LhsT>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     internal_visit(LhsT& lhs_content, int)
sl@0:     {
sl@0:         typedef typename has_nothrow_move_constructor<LhsT>::type
sl@0:             nothrow_move;
sl@0: 
sl@0:         backup_assign_impl( lhs_content, nothrow_move() );
sl@0: 
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class swap_with
sl@0: //
sl@0: // Visitor that swaps visited value with content of given variant.
sl@0: //
sl@0: // Precondition: Given variant MUST have same logical type as visited value.
sl@0: //
sl@0: template <typename Variant>
sl@0: struct swap_with
sl@0:     : public static_visitor<>
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     Variant& toswap_;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     explicit swap_with(Variant& toswap)
sl@0:         : toswap_(toswap)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: public: // internal visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:     void operator()(T& operand) const
sl@0:     {
sl@0:         // Since the precondition ensures types are same, get T...
sl@0:         known_get<T> getter;
sl@0:         T& other = toswap_.apply_visitor(getter);
sl@0: 
sl@0:         // ...and swap:
sl@0:         ::boost::detail::variant::move_swap( operand, other );
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class reflect
sl@0: //
sl@0: // Generic static visitor that performs a typeid on the value it visits.
sl@0: //
sl@0: class reflect
sl@0:     : public static_visitor<const std::type_info&>
sl@0: {
sl@0: public: // visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:     const std::type_info& operator()(const T&) const
sl@0:     {
sl@0:         return typeid(T);
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class comparer
sl@0: //
sl@0: // Generic static visitor that compares the content of the given lhs variant
sl@0: // with the visited rhs content using Comp.
sl@0: //
sl@0: // Precondition: lhs.which() == rhs.which()
sl@0: //
sl@0: template <typename Variant, typename Comp>
sl@0: class comparer
sl@0:     : public static_visitor<bool>
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     const Variant& lhs_;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     explicit comparer(const Variant& lhs)
sl@0:         : lhs_(lhs)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: public: // visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:     bool operator()(const T& rhs_content) const
sl@0:     {
sl@0:         // Since the precondition ensures lhs and rhs types are same, get T...
sl@0:         known_get<const T> getter;
sl@0:         const T& lhs_content = lhs_.apply_visitor(getter);
sl@0: 
sl@0:         // ...and compare lhs and rhs contents:
sl@0:         return Comp()(lhs_content, rhs_content);
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class equal_comp
sl@0: //
sl@0: // Generic function object compares lhs with rhs using operator==.
sl@0: //
sl@0: struct equal_comp
sl@0: {
sl@0:     template <typename T>
sl@0:     bool operator()(const T& lhs, const T& rhs) const
sl@0:     {
sl@0:         return lhs == rhs;
sl@0:     }
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class less_comp
sl@0: //
sl@0: // Generic function object compares lhs with rhs using operator<.
sl@0: //
sl@0: struct less_comp
sl@0: {
sl@0:     template <typename T>
sl@0:     bool operator()(const T& lhs, const T& rhs) const
sl@0:     {
sl@0:         return lhs < rhs;
sl@0:     }
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // (detail) class template invoke_visitor
sl@0: //
sl@0: // Internal visitor that invokes the given visitor using:
sl@0: //  * for wrappers (e.g., recursive_wrapper), the wrapper's held value.
sl@0: //  * for all other values, the value itself.
sl@0: //
sl@0: template <typename Visitor>
sl@0: class invoke_visitor
sl@0: {
sl@0: private: // representation
sl@0: 
sl@0:     Visitor& visitor_;
sl@0: 
sl@0: public: // visitor typedefs
sl@0: 
sl@0:     typedef typename Visitor::result_type
sl@0:         result_type;
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     explicit invoke_visitor(Visitor& visitor)
sl@0:         : visitor_(visitor)
sl@0:     {
sl@0:     }
sl@0: 
sl@0: #if !defined(BOOST_NO_VOID_RETURNS)
sl@0: 
sl@0: public: // internal visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:     result_type internal_visit(T& operand, int)
sl@0:     {
sl@0:         return visitor_(operand);
sl@0:     }
sl@0: 
sl@0: #   if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0564))
sl@0:     template <typename T>
sl@0:     result_type internal_visit(const T& operand, int)
sl@0:     {
sl@0:         return visitor_(operand);
sl@0:     }
sl@0: #   endif
sl@0: 
sl@0: #else // defined(BOOST_NO_VOID_RETURNS)
sl@0: 
sl@0: private: // helpers, for internal visitor interfaces (below)
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     visit_impl(T& operand, mpl::false_)
sl@0:     {
sl@0:         return visitor_(operand);
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:     visit_impl(T& operand, mpl::true_)
sl@0:     {
sl@0:         visitor_(operand);
sl@0:         BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:     }
sl@0: 
sl@0: public: // internal visitor interfaces
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(T& operand, int)
sl@0:     {
sl@0:         typedef typename is_same<result_type, void>::type
sl@0:             has_void_result_type;
sl@0: 
sl@0:         return visit_impl(operand, has_void_result_type());
sl@0:     }
sl@0: 
sl@0: #endif // BOOST_NO_VOID_RETURNS) workaround
sl@0: 
sl@0: public: // internal visitor interfaces, cont.
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(boost::recursive_wrapper<T>& operand, long)
sl@0:     {
sl@0:         return internal_visit( operand.get(), 1L );
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(const boost::recursive_wrapper<T>& operand, long)
sl@0:     {
sl@0:         return internal_visit( operand.get(), 1L );
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(boost::detail::reference_content<T>& operand, long)
sl@0:     {
sl@0:         return internal_visit( operand.get(), 1L );
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(const boost::detail::reference_content<T>& operand, long)
sl@0:     {
sl@0:         return internal_visit( operand.get(), 1L );
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(boost::detail::variant::backup_holder<T>& operand, long)
sl@0:     {
sl@0:         return internal_visit( operand.get(), 1L );
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(result_type)
sl@0:     internal_visit(const boost::detail::variant::backup_holder<T>& operand, long)
sl@0:     {
sl@0:         return internal_visit( operand.get(), 1L );
sl@0:     }
sl@0: 
sl@0: };
sl@0: 
sl@0: }} // namespace detail::variant
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // class template variant (concept inspired by Andrei Alexandrescu)
sl@0: //
sl@0: // See docs and boost/variant/variant_fwd.hpp for more information.
sl@0: //
sl@0: template <
sl@0:       typename T0_
sl@0:     , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename T)
sl@0:     >
sl@0: class variant
sl@0: {
sl@0: private: // helpers, for typedefs (below)
sl@0: 
sl@0:     typedef variant wknd_self_t;
sl@0: 
sl@0:     struct is_recursive_
sl@0:         : detail::variant::is_recursive_flag<T0_>
sl@0:     {
sl@0:     };
sl@0: 
sl@0:     typedef typename mpl::eval_if<
sl@0:           is_recursive_
sl@0:         , T0_
sl@0:         , mpl::identity< T0_ >
sl@0:         >::type unwrapped_T0_;
sl@0: 
sl@0:     struct is_sequence_based_
sl@0:         : detail::variant::is_over_sequence<unwrapped_T0_>
sl@0:     {
sl@0:     };
sl@0: 
sl@0: #if !defined(BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
sl@0: 
sl@0: private: // helpers, for typedefs (below)
sl@0: 
sl@0:     typedef typename mpl::eval_if<
sl@0:           is_sequence_based_
sl@0:         , unwrapped_T0_ // over_sequence<...>::type
sl@0:         , detail::variant::make_variant_list<
sl@0:               unwrapped_T0_
sl@0:             , BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
sl@0:             >
sl@0:         >::type specified_types;
sl@0: 
sl@0:     BOOST_STATIC_ASSERT((
sl@0:           ::boost::mpl::not_< mpl::empty<specified_types> >::value
sl@0:         ));
sl@0: 
sl@0:     typedef typename mpl::eval_if<
sl@0:           is_recursive_
sl@0:         , mpl::transform<
sl@0:               specified_types
sl@0:             , mpl::protect<
sl@0:                   detail::variant::quoted_enable_recursive<wknd_self_t>
sl@0:                 >
sl@0:             >
sl@0:         , mpl::identity< specified_types >
sl@0:         >::type recursive_enabled_types;
sl@0: 
sl@0: public: // public typedefs
sl@0: 
sl@0:     typedef typename mpl::transform<
sl@0:           recursive_enabled_types
sl@0:         , unwrap_recursive<mpl::_1>
sl@0:         >::type types;
sl@0: 
sl@0: private: // internal typedefs
sl@0: 
sl@0:     typedef typename mpl::transform<
sl@0:           recursive_enabled_types
sl@0:         , mpl::protect< detail::make_reference_content<> >
sl@0:         >::type internal_types;
sl@0: 
sl@0:     typedef typename mpl::front<
sl@0:           internal_types
sl@0:         >::type internal_T0;
sl@0: 
sl@0: #else // defined(BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
sl@0: 
sl@0: private: // helpers, for typedefs (below)
sl@0: 
sl@0:     typedef unwrapped_T0_ T0;
sl@0: 
sl@0:     #define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS(z,N,_) \
sl@0:         typedef typename mpl::eval_if< \
sl@0:               is_recursive_ \
sl@0:             , detail::variant::enable_recursive< \
sl@0:                   BOOST_PP_CAT(T,N) \
sl@0:                 , wknd_self_t \
sl@0:                 > \
sl@0:             , mpl::identity< BOOST_PP_CAT(T,N) > \
sl@0:             >::type BOOST_PP_CAT(recursive_enabled_T,N); \
sl@0:         /**/
sl@0: 
sl@0:     BOOST_PP_REPEAT(
sl@0:           BOOST_VARIANT_LIMIT_TYPES
sl@0:         , BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
sl@0:         , _
sl@0:         )
sl@0: 
sl@0:     #undef BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
sl@0: 
sl@0:     #define BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS(z,N,_) \
sl@0:         typedef typename unwrap_recursive< \
sl@0:               BOOST_PP_CAT(recursive_enabled_T,N) \
sl@0:             >::type BOOST_PP_CAT(public_T,N); \
sl@0:         /**/
sl@0: 
sl@0:     BOOST_PP_REPEAT(
sl@0:           BOOST_VARIANT_LIMIT_TYPES
sl@0:         , BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS
sl@0:         , _
sl@0:         )
sl@0: 
sl@0:     #undef BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS
sl@0: 
sl@0: public: // public typedefs
sl@0: 
sl@0:     typedef typename detail::variant::make_variant_list<
sl@0:           BOOST_VARIANT_ENUM_PARAMS(public_T)
sl@0:         >::type types;
sl@0: 
sl@0: private: // helpers, for internal typedefs (below)
sl@0: 
sl@0:     #define BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS(z,N,_) \
sl@0:         typedef detail::make_reference_content< \
sl@0:               BOOST_PP_CAT(recursive_enabled_T,N) \
sl@0:             >::type BOOST_PP_CAT(internal_T,N); \
sl@0:         /**/
sl@0: 
sl@0:     BOOST_PP_REPEAT(
sl@0:           BOOST_VARIANT_LIMIT_TYPES
sl@0:         , BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS
sl@0:         , _
sl@0:         )
sl@0: 
sl@0:     #undef BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS
sl@0: 
sl@0: private: // internal typedefs
sl@0: 
sl@0:     typedef typename detail::variant::make_variant_list<
sl@0:           BOOST_VARIANT_ENUM_PARAMS(internal_T)
sl@0:         >::type internal_types;
sl@0: 
sl@0: private: // static precondition assertions
sl@0: 
sl@0:     // NOTE TO USER :
sl@0:     // variant< type-sequence > syntax is not supported on this compiler!
sl@0:     //
sl@0:     BOOST_MPL_ASSERT_NOT(( is_sequence_based_ ));
sl@0: 
sl@0: #endif // BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT workaround
sl@0: 
sl@0: private: // helpers, for representation (below)
sl@0: 
sl@0:     typedef typename detail::variant::find_fallback_type<
sl@0:           internal_types
sl@0:         >::type fallback_type_result_;
sl@0: 
sl@0:     typedef typename fallback_type_result_::first
sl@0:         fallback_type_index_;
sl@0:     typedef typename fallback_type_result_::second
sl@0:         fallback_type_;
sl@0: 
sl@0:     struct has_fallback_type_
sl@0:         : mpl::not_<
sl@0:               is_same< fallback_type_, detail::variant::no_fallback_type >
sl@0:             >
sl@0:     {
sl@0:     };
sl@0: 
sl@0:     typedef has_fallback_type_
sl@0:         never_uses_backup_flag;
sl@0: 
sl@0:     typedef typename detail::variant::make_storage<
sl@0:           internal_types, never_uses_backup_flag
sl@0:         >::type storage_t;
sl@0: 
sl@0: private: // helpers, for representation (below)
sl@0: 
sl@0:     // which_ on:
sl@0:     // * [0,  size<internal_types>) indicates stack content
sl@0:     // * [-size<internal_types>, 0) indicates pointer to heap backup
sl@0:     // if which_ >= 0:
sl@0:     // * then which() -> which_
sl@0:     // * else which() -> -(which_ + 1)
sl@0: 
sl@0: #if !defined(BOOST_VARIANT_MINIMIZE_SIZE)
sl@0: 
sl@0:     typedef int which_t;
sl@0: 
sl@0: #else // defined(BOOST_VARIANT_MINIMIZE_SIZE)
sl@0: 
sl@0:     // [if O1_size available, then attempt which_t size optimization...]
sl@0:     // [select signed char if fewer than SCHAR_MAX types, else signed int:]
sl@0:     typedef typename mpl::eval_if<
sl@0:           mpl::equal_to< mpl::O1_size<internal_types>, mpl::long_<-1> >
sl@0:         , mpl::identity< int >
sl@0:         , mpl::if_<
sl@0:               mpl::less< mpl::O1_size<internal_types>, mpl::int_<SCHAR_MAX> >
sl@0:             , signed char
sl@0:             , int
sl@0:             >
sl@0:         >::type which_t;
sl@0: 
sl@0: #endif // BOOST_VARIANT_MINIMIZE_SIZE switch
sl@0: 
sl@0: // representation -- private when possible
sl@0: #if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
sl@0:     private:
sl@0: #else
sl@0:     public:
sl@0: #endif
sl@0: 
sl@0:     which_t which_;
sl@0:     storage_t storage_;
sl@0: 
sl@0:     void indicate_which(int which)
sl@0:     {
sl@0:         which_ = static_cast<which_t>( which );
sl@0:     }
sl@0: 
sl@0:     void indicate_backup_which(int which)
sl@0:     {
sl@0:         which_ = static_cast<which_t>( -(which + 1) );
sl@0:     }
sl@0: 
sl@0: private: // helpers, for queries (below)
sl@0: 
sl@0:     bool using_backup() const
sl@0:     {
sl@0:         return which_ < 0;
sl@0:     }
sl@0: 
sl@0: public: // queries
sl@0: 
sl@0:     int which() const
sl@0:     {
sl@0:         // If using heap backup...
sl@0:         if (using_backup())
sl@0:             // ...then return adjusted which_:
sl@0:             return -(which_ + 1);
sl@0: 
sl@0:         // Otherwise, return which_ directly:
sl@0:         return which_;
sl@0:     }
sl@0: 
sl@0: private: // helpers, for structors (below)
sl@0: 
sl@0:     struct initializer
sl@0:         : BOOST_VARIANT_AUX_INITIALIZER_T(
sl@0:               recursive_enabled_types, recursive_enabled_T
sl@0:             )
sl@0:     {
sl@0:     };
sl@0: 
sl@0:     void destroy_content()
sl@0:     {
sl@0:         detail::variant::destroyer visitor;
sl@0:         this->internal_apply_visitor(visitor);
sl@0:     }
sl@0: 
sl@0: public: // structors
sl@0: 
sl@0:     ~variant()
sl@0:     {
sl@0:         destroy_content();
sl@0:     }
sl@0: 
sl@0:     variant()
sl@0:     {
sl@0:         // NOTE TO USER :
sl@0:         // Compile error from here indicates that the first bound
sl@0:         // type is not default-constructible, and so variant cannot
sl@0:         // support its own default-construction.
sl@0:         //
sl@0:         new( storage_.address() ) internal_T0();
sl@0:         indicate_which(0); // zero is the index of the first bounded type
sl@0:     }
sl@0: 
sl@0: private: // helpers, for structors, cont. (below)
sl@0: 
sl@0:     class convert_copy_into
sl@0:         : public static_visitor<int>
sl@0:     {
sl@0:     private: // representation
sl@0: 
sl@0:         void* storage_;
sl@0: 
sl@0:     public: // structors
sl@0: 
sl@0:         explicit convert_copy_into(void* storage)
sl@0:             : storage_(storage)
sl@0:         {
sl@0:         }
sl@0: 
sl@0:     public: // internal visitor interfaces (below)
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(T& operand, int) const
sl@0:         {
sl@0:             // NOTE TO USER :
sl@0:             // Compile error here indicates one of the source variant's types 
sl@0:             // cannot be unambiguously converted to the destination variant's
sl@0:             // types (or that no conversion exists).
sl@0:             //
sl@0:             return initializer::initialize(storage_, operand);
sl@0:         }
sl@0: 
sl@0: #   if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0564))
sl@0:         template <typename T>
sl@0:         result_type internal_visit(const T& operand, int) const
sl@0:         {
sl@0:             return initializer::initialize(storage_, operand);
sl@0:         }
sl@0: #   endif
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(boost::detail::reference_content<T>& operand, long) const
sl@0:         {
sl@0:             return internal_visit( operand.get(), 1L );
sl@0:         }
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(const boost::detail::reference_content<T>& operand, long) const
sl@0:         {
sl@0:             return internal_visit( operand.get(), 1L );
sl@0:         }
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
sl@0:         {
sl@0:             return internal_visit( operand.get(), 1L );
sl@0:         }
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
sl@0:         {
sl@0:             return internal_visit( operand.get(), 1L );
sl@0:         }
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(boost::recursive_wrapper<T>& operand, long) const
sl@0:         {
sl@0:             return internal_visit( operand.get(), 1L );
sl@0:         }
sl@0: 
sl@0:         template <typename T>
sl@0:         int internal_visit(const boost::recursive_wrapper<T>& operand, long) const
sl@0:         {
sl@0:             return internal_visit( operand.get(), 1L );
sl@0:         }
sl@0: 
sl@0:     };
sl@0: 
sl@0:     friend class convert_copy_into;
sl@0: 
sl@0: private: // helpers, for structors, below 
sl@0: 
sl@0:     template <typename T>
sl@0:     void convert_construct(
sl@0:           T& operand
sl@0:         , int
sl@0:         , mpl::false_ = mpl::false_() // is_foreign_variant
sl@0:         )
sl@0:     {
sl@0:         // NOTE TO USER :
sl@0:         // Compile error here indicates that the given type is not 
sl@0:         // unambiguously convertible to one of the variant's types
sl@0:         // (or that no conversion exists).
sl@0:         //
sl@0:         indicate_which(
sl@0:               initializer::initialize(
sl@0:                   storage_.address()
sl@0:                 , operand
sl@0:                 )
sl@0:             );
sl@0:     }
sl@0: 
sl@0:     template <typename Variant>
sl@0:     void convert_construct(
sl@0:           Variant& operand
sl@0:         , long
sl@0:         , mpl::true_// is_foreign_variant
sl@0:         )
sl@0:     {
sl@0:         convert_copy_into visitor(storage_.address());
sl@0:         indicate_which(
sl@0:               operand.internal_apply_visitor(visitor)
sl@0:             );
sl@0:     }
sl@0: 
sl@0:     template <typename Variant>
sl@0:     void convert_construct_variant(Variant& operand)
sl@0:     {
sl@0:         // [Determine if the given variant is itself a bounded type, or if its
sl@0:         //  content needs to be converted (i.e., it is a 'foreign' variant):]
sl@0:         //
sl@0: 
sl@0:         typedef typename mpl::find_if<
sl@0:               types
sl@0:             , is_same<
sl@0:                   add_const<mpl::_1>
sl@0:                 , const Variant
sl@0:                 >
sl@0:             >::type found_it;
sl@0: 
sl@0:         typedef typename mpl::end<types>::type not_found;
sl@0:         typedef typename is_same<
sl@0:               found_it, not_found
sl@0:             >::type is_foreign_variant;
sl@0: 
sl@0:         // Convert construct from operand:
sl@0:         convert_construct(
sl@0:               operand, 1L
sl@0:             , is_foreign_variant()
sl@0:             );
sl@0:     }
sl@0: 
sl@0:     template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
sl@0:     void convert_construct(
sl@0:           boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand
sl@0:         , long
sl@0:         )
sl@0:     {
sl@0:         convert_construct_variant(operand);
sl@0:     }
sl@0: 
sl@0:     template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
sl@0:     void convert_construct(
sl@0:           const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand
sl@0:         , long
sl@0:         )
sl@0:     {
sl@0:         convert_construct_variant(operand);    
sl@0:     }
sl@0: 
sl@0: public: // structors, cont.
sl@0: 
sl@0: #if !defined(BOOST_VARIANT_AUX_BROKEN_CONSTRUCTOR_TEMPLATE_ORDERING)
sl@0: 
sl@0:     template <typename T>
sl@0:     variant(const T& operand)
sl@0:     {
sl@0:         convert_construct(operand, 1L);
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:     variant(T& operand)
sl@0:     {
sl@0:         convert_construct(operand, 1L);
sl@0:     }
sl@0: 
sl@0: #elif defined(BOOST_VARIANT_AUX_HAS_CONSTRUCTOR_TEMPLATE_ORDERING_SFINAE_WKND)
sl@0: 
sl@0:     // For compilers that cannot distinguish between T& and const T& in
sl@0:     // template constructors, but do fully support SFINAE, we can workaround:
sl@0: 
sl@0:     template <typename T>
sl@0:     variant(const T& operand)
sl@0:     {
sl@0:         convert_construct(operand, 1L);
sl@0:     }
sl@0: 
sl@0:     template <typename T>
sl@0:     variant(
sl@0:           T& operand
sl@0:         , typename enable_if<
sl@0:               mpl::not_< is_const<T> >
sl@0:             , void
sl@0:             >::type* = 0
sl@0:         )
sl@0:     {
sl@0:         convert_construct(operand, 1L);
sl@0:     }
sl@0: 
sl@0: #else // !defined(BOOST_VARIANT_AUX_HAS_CONSTRUCTOR_TEMPLATE_ORDERING_SFINAE_WKND)
sl@0: 
sl@0:     // For compilers that cannot distinguish between T& and const T& in
sl@0:     // template constructors, and do NOT support SFINAE, we can't workaround:
sl@0: 
sl@0:     template <typename T>
sl@0:     variant(const T& operand)
sl@0:     {
sl@0:         convert_construct(operand, 1L);
sl@0:     }
sl@0: 
sl@0: #endif // BOOST_VARIANT_AUX_BROKEN_CONSTRUCTOR_TEMPLATE_ORDERING workarounds
sl@0: 
sl@0: public: // structors, cont.
sl@0: 
sl@0:     // [MSVC6 requires copy constructor appear after template constructors]
sl@0:     variant(const variant& operand)
sl@0:     {
sl@0:         // Copy the value of operand into *this...
sl@0:         detail::variant::copy_into visitor( storage_.address() );
sl@0:         operand.internal_apply_visitor(visitor);
sl@0: 
sl@0:         // ...and activate the *this's primary storage on success:
sl@0:         indicate_which(operand.which());
sl@0:     }
sl@0: 
sl@0: private: // helpers, for modifiers (below)
sl@0: 
sl@0: #   if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
sl@0:     template <typename Variant, typename RhsT>
sl@0:     friend class detail::variant::backup_assigner;
sl@0: #   endif
sl@0: 
sl@0:     // class assigner
sl@0:     //
sl@0:     // Internal visitor that "assigns" the visited value to the given variant
sl@0:     // by appropriate destruction and copy-construction.
sl@0:     //
sl@0: 
sl@0:     class assigner
sl@0:         : public static_visitor<>
sl@0:     {
sl@0:     private: // representation
sl@0: 
sl@0:         variant& lhs_;
sl@0:         int rhs_which_;
sl@0: 
sl@0:     public: // structors
sl@0: 
sl@0:         assigner(variant& lhs, int rhs_which)
sl@0:             : lhs_(lhs)
sl@0:             , rhs_which_(rhs_which)
sl@0:         {
sl@0:         }
sl@0: 
sl@0:     private: // helpers, for internal visitor interface (below)
sl@0: 
sl@0:         template <typename RhsT, typename B1, typename B2>
sl@0:         void assign_impl(
sl@0:               const RhsT& rhs_content
sl@0:             , mpl::true_// has_nothrow_copy
sl@0:             , B1// has_nothrow_move_constructor
sl@0:             , B2// has_fallback_type
sl@0:             )
sl@0:         {
sl@0:             // Destroy lhs's content...
sl@0:             lhs_.destroy_content(); // nothrow
sl@0: 
sl@0:             // ...copy rhs content into lhs's storage...
sl@0:             new(lhs_.storage_.address())
sl@0:                 RhsT( rhs_content ); // nothrow
sl@0: 
sl@0:             // ...and indicate new content type:
sl@0:             lhs_.indicate_which(rhs_which_); // nothrow
sl@0:         }
sl@0: 
sl@0:         template <typename RhsT, typename B>
sl@0:         void assign_impl(
sl@0:               const RhsT& rhs_content
sl@0:             , mpl::false_// has_nothrow_copy
sl@0:             , mpl::true_// has_nothrow_move_constructor
sl@0:             , B// has_fallback_type
sl@0:             )
sl@0:         {
sl@0:             // Attempt to make a temporary copy (so as to move it below)...
sl@0:             RhsT temp(rhs_content);
sl@0: 
sl@0:             // ...and upon success destroy lhs's content...
sl@0:             lhs_.destroy_content(); // nothrow
sl@0: 
sl@0:             // ...move the temporary copy into lhs's storage...
sl@0:             new(lhs_.storage_.address())
sl@0:                 RhsT( detail::variant::move(temp) ); // nothrow
sl@0: 
sl@0:             // ...and indicate new content type:
sl@0:             lhs_.indicate_which(rhs_which_); // nothrow
sl@0:         }
sl@0: 
sl@0:         template <typename RhsT>
sl@0:         void assign_impl(
sl@0:               const RhsT& rhs_content
sl@0:             , mpl::false_// has_nothrow_copy
sl@0:             , mpl::false_// has_nothrow_move_constructor
sl@0:             , mpl::true_// has_fallback_type
sl@0:             )
sl@0:         {
sl@0:             // Destroy lhs's content...
sl@0:             lhs_.destroy_content(); // nothrow
sl@0: 
sl@0:             try
sl@0:             {
sl@0:                 // ...and attempt to copy rhs's content into lhs's storage:
sl@0:                 new(lhs_.storage_.address())
sl@0:                     RhsT( rhs_content );
sl@0:             }
sl@0:             catch (...)
sl@0:             {
sl@0:                 // In case of failure, default-construct fallback type in lhs's storage...
sl@0:                 new (lhs_.storage_.address())
sl@0:                     fallback_type_; // nothrow
sl@0: 
sl@0:                 // ...indicate construction of fallback type...
sl@0:                 lhs_.indicate_which(
sl@0:                       BOOST_MPL_AUX_VALUE_WKND(fallback_type_index_)::value
sl@0:                     ); // nothrow
sl@0: 
sl@0:                 // ...and rethrow:
sl@0:                 throw;
sl@0:             }
sl@0: 
sl@0:             // In the event of success, indicate new content type:
sl@0:             lhs_.indicate_which(rhs_which_); // nothrow
sl@0:         }
sl@0: 
sl@0:         template <typename RhsT>
sl@0:         void assign_impl(
sl@0:               const RhsT& rhs_content
sl@0:             , mpl::false_// has_nothrow_copy
sl@0:             , mpl::false_// has_nothrow_move_constructor
sl@0:             , mpl::false_// has_fallback_type
sl@0:             )
sl@0:         {
sl@0:             detail::variant::backup_assigner<wknd_self_t, RhsT>
sl@0:                 visitor(lhs_, rhs_which_, rhs_content);
sl@0:             lhs_.internal_apply_visitor(visitor);
sl@0:         }
sl@0: 
sl@0:     public: // internal visitor interfaces
sl@0: 
sl@0:         template <typename RhsT>
sl@0:             BOOST_VARIANT_AUX_RETURN_VOID_TYPE
sl@0:         internal_visit(const RhsT& rhs_content, int)
sl@0:         {
sl@0:             typedef typename has_nothrow_copy<RhsT>::type
sl@0:                 nothrow_copy;
sl@0:             typedef typename mpl::or_< // reduces compile-time
sl@0:                   nothrow_copy
sl@0:                 , detail::variant::has_nothrow_move_constructor<RhsT>
sl@0:                 >::type nothrow_move_constructor;
sl@0: 
sl@0:             assign_impl(
sl@0:                   rhs_content
sl@0:                 , nothrow_copy()
sl@0:                 , nothrow_move_constructor()
sl@0:                 , has_fallback_type_()
sl@0:                 );
sl@0: 
sl@0:             BOOST_VARIANT_AUX_RETURN_VOID;
sl@0:         }
sl@0: 
sl@0:     };
sl@0: 
sl@0:     friend class assigner;
sl@0: 
sl@0:     void variant_assign(const variant& rhs)
sl@0:     {
sl@0:         // If the contained types are EXACTLY the same...
sl@0:         if (which_ == rhs.which_)
sl@0:         {
sl@0:             // ...then assign rhs's storage to lhs's content:
sl@0:             detail::variant::assign_storage visitor(rhs.storage_.address());
sl@0:             this->internal_apply_visitor(visitor);
sl@0:         }
sl@0:         else
sl@0:         {
sl@0:             // Otherwise, perform general (copy-based) variant assignment:
sl@0:             assigner visitor(*this, rhs.which());
sl@0:             rhs.internal_apply_visitor(visitor); 
sl@0:         }
sl@0:     }
sl@0: 
sl@0: private: // helpers, for modifiers (below)
sl@0: 
sl@0:     template <typename T>
sl@0:     void assign(const T& rhs)
sl@0:     {
sl@0:         // If direct T-to-T assignment is not possible...
sl@0:         detail::variant::direct_assigner<const T> direct_assign(rhs);
sl@0:         if (this->apply_visitor(direct_assign) == false)
sl@0:         {
sl@0:             // ...then convert rhs to variant and assign:
sl@0:             //
sl@0:             // While potentially inefficient, the following construction of a
sl@0:             // variant allows T as any type convertible to one of the bounded
sl@0:             // types without excessive code redundancy.
sl@0:             //
sl@0:             variant temp(rhs);
sl@0:             variant_assign( detail::variant::move(temp) );
sl@0:         }
sl@0:     }
sl@0: 
sl@0: public: // modifiers
sl@0: 
sl@0:     template <typename T>
sl@0:     variant& operator=(const T& rhs)
sl@0:     {
sl@0:         assign(rhs);
sl@0:         return *this;
sl@0:     }
sl@0: 
sl@0:     // [MSVC6 requires copy assign appear after templated operator=]
sl@0:     variant& operator=(const variant& rhs)
sl@0:     {
sl@0:         variant_assign(rhs);
sl@0:         return *this;
sl@0:     }
sl@0: 
sl@0:     void swap(variant& rhs)
sl@0:     {
sl@0:         // If the contained types are the same...
sl@0:         if (which() == rhs.which())
sl@0:         {
sl@0:             // ...then swap the values directly:
sl@0:             detail::variant::swap_with<variant> visitor(rhs);
sl@0:             this->apply_visitor(visitor);
sl@0:         }
sl@0:         else
sl@0:         {
sl@0:             // ...otherwise, perform general variant swap:
sl@0:             variant tmp( detail::variant::move(rhs) );
sl@0:             rhs = detail::variant::move(*this);
sl@0:             *this = detail::variant::move(tmp);
sl@0:         }
sl@0:     }
sl@0: 
sl@0: public: // queries
sl@0: 
sl@0:     //
sl@0:     // NOTE: member which() defined above.
sl@0:     //
sl@0: 
sl@0:     bool empty() const
sl@0:     {
sl@0:         return false;
sl@0:     }
sl@0: 
sl@0:     const std::type_info& type() const
sl@0:     {
sl@0:         detail::variant::reflect visitor;
sl@0:         return this->apply_visitor(visitor);
sl@0:     }
sl@0: 
sl@0: public: // prevent comparison with foreign types
sl@0: 
sl@0: #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
sl@0: 
sl@0: #   define BOOST_VARIANT_AUX_FAIL_COMPARISON_RETURN_TYPE \
sl@0:     void
sl@0: 
sl@0: #else // MSVC7
sl@0: 
sl@0:     //
sl@0:     // MSVC7 gives error about return types for above being different than
sl@0:     // the true comparison operator overloads:
sl@0:     //
sl@0: 
sl@0: #   define BOOST_VARIANT_AUX_FAIL_COMPARISON_RETURN_TYPE \
sl@0:     bool
sl@0: 
sl@0: #endif // MSVC7 workaround
sl@0: 
sl@0:     template <typename U>
sl@0:         BOOST_VARIANT_AUX_FAIL_COMPARISON_RETURN_TYPE
sl@0:     operator==(const U&) const
sl@0:     {
sl@0:         BOOST_STATIC_ASSERT( false && sizeof(U) );
sl@0:     }
sl@0: 
sl@0:     template <typename U>
sl@0:         BOOST_VARIANT_AUX_FAIL_COMPARISON_RETURN_TYPE
sl@0:     operator<(const U&) const
sl@0:     {
sl@0:         BOOST_STATIC_ASSERT( false && sizeof(U) );
sl@0:     }
sl@0: 
sl@0: public: // comparison operators
sl@0: 
sl@0:     // [MSVC6 requires these operators appear after template operators]
sl@0: 
sl@0:     bool operator==(const variant& rhs) const
sl@0:     {
sl@0:         if (this->which() != rhs.which())
sl@0:             return false;
sl@0: 
sl@0:         detail::variant::comparer<
sl@0:               variant, detail::variant::equal_comp
sl@0:             > visitor(*this);
sl@0:         return rhs.apply_visitor(visitor);
sl@0:     }
sl@0: 
sl@0:     bool operator<(const variant& rhs) const
sl@0:     {
sl@0:         //
sl@0:         // Dirk Schreib suggested this collating order.
sl@0:         //
sl@0: 
sl@0:         if (this->which() != rhs.which())
sl@0:             return this->which() < rhs.which();
sl@0: 
sl@0:         detail::variant::comparer<
sl@0:               variant, detail::variant::less_comp
sl@0:             > visitor(*this);
sl@0:         return rhs.apply_visitor(visitor);
sl@0:     }
sl@0: 
sl@0: // helpers, for visitation support (below) -- private when possible
sl@0: #if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
sl@0: 
sl@0:     template < BOOST_VARIANT_ENUM_PARAMS(typename U) >
sl@0:     friend class variant;
sl@0: 
sl@0: private:
sl@0: 
sl@0: #else// defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
sl@0: 
sl@0: public:
sl@0: 
sl@0: #endif// !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
sl@0: 
sl@0:     template <typename Visitor, typename VoidPtrCV>
sl@0:     static
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(
sl@0:               typename Visitor::result_type
sl@0:             )
sl@0:     internal_apply_visitor_impl(
sl@0:           int internal_which
sl@0:         , int logical_which
sl@0:         , Visitor& visitor
sl@0:         , VoidPtrCV storage
sl@0:         )
sl@0:     {
sl@0:         typedef mpl::int_<0> first_which;
sl@0:         typedef typename mpl::begin<internal_types>::type first_it;
sl@0:         typedef typename mpl::end<internal_types>::type last_it;
sl@0: 
sl@0:         typedef detail::variant::visitation_impl_step<
sl@0:               first_it, last_it
sl@0:             > first_step;
sl@0: 
sl@0:         return detail::variant::visitation_impl(
sl@0:               internal_which, logical_which
sl@0:             , visitor, storage, mpl::false_()
sl@0:             , never_uses_backup_flag()
sl@0:             , static_cast<first_which*>(0), static_cast<first_step*>(0)
sl@0:             );
sl@0:     }
sl@0: 
sl@0:     template <typename Visitor>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(
sl@0:               typename Visitor::result_type
sl@0:             )
sl@0:     internal_apply_visitor(Visitor& visitor)
sl@0:     {
sl@0:         return internal_apply_visitor_impl(
sl@0:               which_, which(), visitor, storage_.address()
sl@0:             );
sl@0:     }
sl@0: 
sl@0:     template <typename Visitor>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(
sl@0:               typename Visitor::result_type
sl@0:             )
sl@0:     internal_apply_visitor(Visitor& visitor) const
sl@0:     {
sl@0:         return internal_apply_visitor_impl(
sl@0:               which_, which(), visitor, storage_.address()
sl@0:             );
sl@0:     }
sl@0: 
sl@0: public: // visitation support
sl@0: 
sl@0:     template <typename Visitor>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(
sl@0:               typename Visitor::result_type
sl@0:             )
sl@0:     apply_visitor(Visitor& visitor)
sl@0:     {
sl@0:         detail::variant::invoke_visitor<Visitor> invoker(visitor);
sl@0:         return this->internal_apply_visitor(invoker);
sl@0:     }
sl@0: 
sl@0:     template <typename Visitor>
sl@0:         BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(
sl@0:               typename Visitor::result_type
sl@0:             )
sl@0:     apply_visitor(Visitor& visitor) const
sl@0:     {
sl@0:         detail::variant::invoke_visitor<Visitor> invoker(visitor);
sl@0:         return this->internal_apply_visitor(invoker);
sl@0:     }
sl@0: 
sl@0: }; // class variant
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // metafunction make_variant_over
sl@0: //
sl@0: // See docs and boost/variant/variant_fwd.hpp for more information.
sl@0: //
sl@0: template <typename Types>
sl@0: struct make_variant_over
sl@0: {
sl@0: private: // precondition assertions
sl@0: 
sl@0: #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
sl@0:     BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value ));
sl@0: #endif
sl@0: 
sl@0: public: // metafunction result
sl@0: 
sl@0:     typedef variant<
sl@0:           detail::variant::over_sequence< Types >
sl@0:         > type;
sl@0: 
sl@0: };
sl@0: 
sl@0: ///////////////////////////////////////////////////////////////////////////////
sl@0: // function template swap
sl@0: //
sl@0: // Swaps two variants of the same type (i.e., identical specification).
sl@0: //
sl@0: template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
sl@0: inline void swap(
sl@0:       variant< BOOST_VARIANT_ENUM_PARAMS(T) >& lhs
sl@0:     , variant< BOOST_VARIANT_ENUM_PARAMS(T) >& rhs
sl@0:     )
sl@0: {
sl@0:     lhs.swap(rhs);
sl@0: }
sl@0: 
sl@0: } // namespace boost
sl@0: 
sl@0: // implementation additions
sl@0: #include "boost/variant/detail/variant_io.hpp"
sl@0: 
sl@0: #endif // BOOST_VARIANT_VARIANT_HPP