//-----------------------------------------------------------------------------

// boost variant/variant.hpp header file

// See http://www.boost.org for updates, documentation, and revision history.

//-----------------------------------------------------------------------------

//

// Copyright (c) 2002-2003

// Eric Friedman, Itay Maman

//

// 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)

/*

 * © Portions copyright (c) 2006-2007 Nokia Corporation.  All rights reserved.

*/

#ifndef BOOST_VARIANT_VARIANT_HPP

#define BOOST_VARIANT_VARIANT_HPP

#include <cstddef> // for std::size_t

#include <new> // for placement new

#ifdef __SYMBIAN32__

#include <string>

#endif

#include <typeinfo> // for typeid, std::type_info

#include "boost/variant/detail/config.hpp"

#include "boost/mpl/aux_/config/eti.hpp"

#include "boost/mpl/aux_/value_wknd.hpp"

#include "boost/variant/variant_fwd.hpp"

#include "boost/variant/detail/backup_holder.hpp"

#include "boost/variant/detail/enable_recursive_fwd.hpp"

#include "boost/variant/detail/forced_return.hpp"

#include "boost/variant/detail/initializer.hpp"

#include "boost/variant/detail/make_variant_list.hpp"

#include "boost/variant/detail/over_sequence.hpp"

#include "boost/variant/detail/visitation_impl.hpp"

#include "boost/variant/detail/generic_result_type.hpp"

#include "boost/variant/detail/has_nothrow_move.hpp"

#include "boost/variant/detail/move.hpp"

#include "boost/detail/reference_content.hpp"

#include "boost/aligned_storage.hpp"

#include "boost/blank.hpp"

#include "boost/static_assert.hpp"

#include "boost/preprocessor/cat.hpp"

#include "boost/preprocessor/repeat.hpp"

#include "boost/type_traits/alignment_of.hpp"

#include "boost/type_traits/add_const.hpp"

#include "boost/type_traits/has_nothrow_constructor.hpp"

#include "boost/type_traits/has_nothrow_copy.hpp"

#include "boost/type_traits/is_const.hpp"

#include "boost/type_traits/is_same.hpp"

#include "boost/utility/enable_if.hpp"

#include "boost/variant/recursive_wrapper_fwd.hpp"

#include "boost/variant/static_visitor.hpp"

#include "boost/mpl/eval_if.hpp"

#include "boost/mpl/begin_end.hpp"

#include "boost/mpl/bool.hpp"

#include "boost/mpl/empty.hpp"

#include "boost/mpl/find_if.hpp"

#include "boost/mpl/front.hpp"

#include "boost/mpl/identity.hpp"

#include "boost/mpl/if.hpp"

#include "boost/mpl/int.hpp"

#include "boost/mpl/is_sequence.hpp"

#include "boost/mpl/iterator_range.hpp"

#include "boost/mpl/iter_fold_if.hpp"

#include "boost/mpl/logical.hpp"

#include "boost/mpl/max_element.hpp"

#include "boost/mpl/next.hpp"

#include "boost/mpl/deref.hpp"

#include "boost/mpl/pair.hpp"

#include "boost/mpl/protect.hpp"

#include "boost/mpl/push_front.hpp"

#include "boost/mpl/same_as.hpp"

#include "boost/mpl/size_t.hpp"

#include "boost/mpl/sizeof.hpp"

#include "boost/mpl/transform.hpp"

#include "boost/mpl/assert.hpp"

///////////////////////////////////////////////////////////////////////////////

// Implementation Macros:

//

// BOOST_VARIANT_VISITATION_UNROLLING_LIMIT

//   Defined in boost/variant/detail/visitation_impl.hpp.

//

// BOOST_VARIANT_MINIMIZE_SIZE

//   When #defined, implementation employs all known means to minimize the

//   size of variant obje   cts. However, often unsuccessful due to alignment

//   issues, and potentially harmful to runtime speed, so not enabled by

//   default. (TODO: Investigate further.)

#if defined(BOOST_VARIANT_MINIMIZE_SIZE)

#   include <climits> // for SCHAR_MAX

#   include "boost/mpl/eval_if.hpp"

#   include "boost/mpl/equal_to.hpp"

#   include "boost/mpl/identity.hpp"

#   include "boost/mpl/int.hpp"

#   include "boost/mpl/if.hpp"

#   include "boost/mpl/less.hpp"

#   include "boost/mpl/long.hpp"

#   include "boost/mpl/O1_size.hpp"

#endif

namespace boost {

namespace detail { namespace variant {

///////////////////////////////////////////////////////////////////////////////

// (detail) metafunction max_value

//

// Finds the maximum value of the unary metafunction F over Sequence.

//

template <typename Sequence, typename F>

struct max_value

{

private: // helpers, for metafunction result (below)

    typedef typename mpl::transform1<Sequence, F>::type transformed_;

    typedef typename mpl::max_element<transformed_

        >::type max_it;

public: // metafunction result

    typedef typename mpl::deref<max_it>::type

        type;

};

///////////////////////////////////////////////////////////////////////////////

// (detail) metafunction find_fallback_type

//

// Provides a fallback (i.e., nothrow default-constructible) type from the

// specified sequence, or no_fallback_type if not found.

//

// This implementation is designed to prefer boost::blank over other potential

// fallback types, regardless of its position in the specified sequence.

//

class no_fallback_type;

struct find_fallback_type_pred

{

    template <typename Iterator>

    struct apply

    {

    private:

        typedef typename mpl::deref<Iterator>::type t_;

    public:

        typedef mpl::not_< has_nothrow_constructor<t_> > type;

    };

};

template <typename Types>

struct find_fallback_type

{

private: // helpers, for metafunction result (below)

    typedef typename mpl::end<Types>::type end_it;

    // [Find the first suitable fallback type...]

    typedef typename mpl::iter_fold_if<

          Types

        , mpl::int_<0>, mpl::protect< mpl::next<> >

        , mpl::protect< find_fallback_type_pred >

        >::type first_result_;

    typedef typename first_result_::first first_result_index;

    typedef typename first_result_::second first_result_it;

    // [...now search the rest of the sequence for boost::blank...]

    typedef typename mpl::iter_fold_if<

          mpl::iterator_range< first_result_it,end_it >

        , first_result_index, mpl::protect< mpl::next<> >

        , mpl::protect< mpl::not_same_as<boost::blank> >

        >::type second_result_;

    typedef typename second_result_::second second_result_it;

public: // metafunction result

    // [...and return the results of the search:]

    typedef typename mpl::eval_if<

          is_same< second_result_it,end_it >

        , mpl::if_<

              is_same< first_result_it,end_it >

            , mpl::pair< no_fallback_type,no_fallback_type >

            , first_result_

            >

        , mpl::identity< second_result_ >

        >::type type;

};

#if defined(BOOST_MPL_CFG_MSVC_60_ETI_BUG)

template<>

struct find_fallback_type<int>

{

    typedef mpl::pair< no_fallback_type,no_fallback_type > type;

};

#endif // BOOST_MPL_CFG_MSVC_60_ETI_BUG workaround

///////////////////////////////////////////////////////////////////////////////

// (detail) metafunction make_storage

//

// Provides an aligned storage type capable of holding any of the types

// specified in the given type-sequence.

//

template <typename Types, typename NeverUsesBackupFlag>

struct make_storage

{

private: // helpers, for metafunction result (below)

    typedef typename mpl::eval_if<

          NeverUsesBackupFlag

        , mpl::identity< Types >

        , mpl::push_front<

              Types, backup_holder<void*>

            >

        >::type types;

    typedef typename max_value<

          types, mpl::sizeof_<mpl::_1>

        >::type max_size;

#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0551))

    typedef typename max_value<

          types, alignment_of<mpl::_1>

        >::type max_alignment;

#else // borland

    // temporary workaround -- use maximal alignment

    typedef mpl::size_t< -1 > max_alignment;

#endif // borland workaround

public: // metafunction result

#if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300)

    typedef ::boost::aligned_storage<

          BOOST_MPL_AUX_VALUE_WKND(max_size)::value

        , BOOST_MPL_AUX_VALUE_WKND(max_alignment)::value

        > type;

#else // MSVC7 and below

    BOOST_STATIC_CONSTANT(std::size_t, msvc_max_size_c = max_size::value);

    BOOST_STATIC_CONSTANT(std::size_t, msvc_max_alignment_c = max_alignment::value);

    typedef ::boost::aligned_storage<

          msvc_max_size_c

        , msvc_max_alignment_c

        > type;

#endif // MSVC workaround

};

#if defined(BOOST_MPL_CFG_MSVC_60_ETI_BUG)

template<>

struct make_storage<int,int>

{

    typedef int type;

};

#endif // BOOST_MPL_CFG_MSVC_60_ETI_BUG workaround

///////////////////////////////////////////////////////////////////////////////

// (detail) class destroyer

//

// Internal visitor that destroys the value it visits.

//

struct destroyer

    : public static_visitor<>

{

public: // visitor interfaces

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(T& operand, int) const

    {

        operand.~T();

#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x0551))

        operand; // suppresses warnings

#endif

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

};

///////////////////////////////////////////////////////////////////////////////

// (detail) class template known_get

//

// Visitor that returns a reference to content of the specified type.

//

// Precondition: visited variant MUST contain logical content of type T.

//

template <typename T>

class known_get

    : public static_visitor<T&>

{

#if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)

public: // visitor interface

    T& operator()(T& operand) const

    {

        return operand;

    }

    template <typename U>

    T& operator()(U&) const

    {

        // logical error to be here: see precondition above

        BOOST_ASSERT(false);

        return ::boost::detail::variant::forced_return< T& >();

    }

#else // MSVC6

private: // helpers, for visitor interface (below)

    T& execute(T& operand, mpl::true_) const

    {

        return operand;

    }

    template <typename U>

    T& execute(U& operand, mpl::false_) const

    {

        // logical error to be here: see precondition above

        BOOST_ASSERT(false);

        return ::boost::detail::variant::forced_return< T& >();

    }

public: // visitor interface

    template <typename U>

    T& operator()(U& operand) const

    {

        typedef typename is_same< U,T >::type

            U_is_T;

        return execute(operand, U_is_T());

    }

#endif // MSVC6 workaround

};

///////////////////////////////////////////////////////////////////////////////

// (detail) class copy_into

//

// Internal visitor that copies the value it visits into the given buffer.

//

class copy_into

    : public static_visitor<>

{

private: // representation

    void* storage_;

public: // structors

    explicit copy_into(void* storage)

        : storage_(storage)

    {

    }

public: // internal visitor interface

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const

    {

        new(storage_) T( operand.get() );

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const

    {

        new(storage_) T( operand.get() );

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(const T& operand, int) const

    {

        new(storage_) T(operand);

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

};

///////////////////////////////////////////////////////////////////////////////

// (detail) class assign_storage

//

// Internal visitor that assigns the given storage (which must be a

// constructed value of the same type) to the value it visits.

//

struct assign_storage

    : public static_visitor<>

{

private: // representation

    const void* rhs_storage_;

public: // structors

    explicit assign_storage(const void* rhs_storage)

        : rhs_storage_(rhs_storage)

    {

    }

public: // internal visitor interfaces

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(backup_holder<T>& lhs_content, long) const

    {

        lhs_content.get()

            = static_cast< const backup_holder<T>* >(rhs_storage_)->get();

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(const backup_holder<T>& lhs_content, long) const

    {

        lhs_content.get()

            = static_cast< const backup_holder<T>* >(rhs_storage_)->get();

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

    template <typename T>

        BOOST_VARIANT_AUX_RETURN_VOID_TYPE

    internal_visit(T& lhs_content, int) const

    {

        // NOTE TO USER :

        // Compile error here indicates one of variant's bounded types does

        // not meet the requirements of the Assignable concept. Thus,

        // variant is not Assignable.

        //

        // Hint: Are any of the bounded types const-qualified or references?

        //

        lhs_content = *static_cast< const T* >(rhs_storage_);

        BOOST_VARIANT_AUX_RETURN_VOID;

    }

};

///////////////////////////////////////////////////////////////////////////////

// (detail) class direct_assigner

//

// Generic static visitor that: if and only if the visited value is of the

// specified type, assigns the given value to the visited value and returns

// true; else returns false.

//

template <typename T>

class direct_assigner

    : public static_visitor<bool>

{

private: // representation

    T& rhs_;

public: // structors

    explicit direct_assigner(T& rhs)

        : rhs_(rhs)

    {

    }

#if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)

public: // visitor interface

    bool operator()(T& lhs)

    {

        lhs = rhs_;

        return true;

    }

    template <typename U>

    bool operator()(U&)

    {

        return false;

    }

#else // MSVC6

private: // helpers, for visitor interface (below)

    bool execute(T& lhs, mpl::true_)

    {

        lhs = rhs_;

        return true;

    }

    template <typename U>

    bool execute(U&, mpl::false_)

    {

        return false;

    }

public: // visitor interface

    template <typename U>