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suyu/externals/vcpkg/packages/boost-variant_x64-windows/include/boost/variant/variant.hpp
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//-----------------------------------------------------------------------------
// 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
// Copyright (c) 2012-2022 Antony Polukhin
//
// 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)
// Thanks to Adam Romanek for providing patches for exception-disabled env.
#ifndef BOOST_VARIANT_VARIANT_HPP
#define BOOST_VARIANT_VARIANT_HPP
#include <cstddef> // for std::size_t
#include <new> // for placement new
#include <boost/type_index.hpp>
#include <boost/variant/detail/config.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/hash_variant.hpp>
#include <boost/variant/detail/std_hash.hpp>
#include <boost/variant/detail/move.hpp>
#include <boost/detail/reference_content.hpp>
#include <boost/blank.hpp>
#include <boost/integer/common_factor_ct.hpp>
#include <boost/static_assert.hpp>
#include <boost/preprocessor/cat.hpp>
#include <boost/preprocessor/repeat.hpp>
#include <boost/type_traits/aligned_storage.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_nothrow_move_assignable.hpp>
#include <boost/type_traits/is_nothrow_move_constructible.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/type_traits/is_rvalue_reference.hpp>
#include <boost/type_traits/is_constructible.hpp>
#include <boost/type_traits/add_lvalue_reference.hpp>
#include <boost/type_traits/declval.hpp>
#include <boost/core/no_exceptions_support.hpp>
#include <boost/core/enable_if.hpp>
#include <boost/variant/recursive_wrapper_fwd.hpp>
#include <boost/variant/static_visitor.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/mpl/begin_end.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/deref.hpp>
#include <boost/mpl/empty.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/find_if.hpp>
#include <boost/mpl/fold.hpp>
#include <boost/mpl/front.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/insert_range.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/list.hpp>
#include <boost/mpl/logical.hpp>
#include <boost/mpl/max_element.hpp>
#include <boost/mpl/next.hpp>
#include <boost/mpl/not.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>
///////////////////////////////////////////////////////////////////////////////
// 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;
};
struct add_alignment
{
template <typename State, typename Item>
struct apply
: mpl::size_t<
::boost::integer::static_lcm<
BOOST_MPL_AUX_VALUE_WKND(State)::value
, ::boost::alignment_of<Item>::value
>::value
>
{};
};
///////////////////////////////////////////////////////////////////////////////
// (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;
};
#ifndef BOOST_NO_CXX11_NOEXCEPT
///////////////////////////////////////////////////////////////////////////////
// (detail) metafunction is_variant_move_noexcept_constructible
//
// Returns true_type if all the types are nothrow move constructible.
//
template <class Types>
struct is_variant_move_noexcept_constructible {
typedef typename boost::mpl::find_if<
Types, mpl::not_<boost::is_nothrow_move_constructible<boost::mpl::_1> >
>::type iterator_t;
typedef typename boost::mpl::end<Types>::type end_t;
typedef typename boost::is_same<
iterator_t, end_t
>::type type;
};
///////////////////////////////////////////////////////////////////////////////
// (detail) metafunction is_variant_move_noexcept_assignable
//
// Returns true_type if all the types are nothrow move constructible.
//
template <class Types>
struct is_variant_move_noexcept_assignable {
typedef typename boost::mpl::find_if<
Types, mpl::not_<boost::is_nothrow_move_assignable<boost::mpl::_1> >
>::type iterator_t;
typedef typename boost::mpl::end<Types>::type end_t;
typedef typename boost::is_same<
iterator_t, end_t
>::type type;
};
#endif // BOOST_NO_CXX11_NOEXCEPT
///////////////////////////////////////////////////////////////////////////////
// (detail) metafunction is_variant_constructible_from
//
// Derives from true_type if at least one variant's type is constructible from T.
//
template <class T1, class T2>
struct is_constructible_ext:
boost::mpl::or_<
boost::is_constructible<
T1,
T2
>,
boost::is_constructible<
T1,
typename boost::add_lvalue_reference<T2>::type
>
>
{};
template <class T, class Types>
struct is_variant_constructible_from:
boost::mpl::not_< boost::is_same<
typename boost::mpl::find_if<
Types,
is_constructible_ext<boost::mpl::_1, T>
>::type,
typename boost::mpl::end<Types>::type
> >
{};
template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >:
boost::is_same<
typename boost::mpl::find_if<
typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::recursive_enabled_types,
mpl::not_< is_variant_constructible_from< boost::mpl::_1, Types> >
>::type,
typename boost::mpl::end< typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::recursive_enabled_types >::type
>
{};
template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
struct is_variant_constructible_from< const boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& , Types >:
is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
{};
template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& , Types >:
is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
{};
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>&& , Types >:
is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
{};
template <BOOST_VARIANT_ENUM_PARAMS(typename T), class Types>
struct is_variant_constructible_from< boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const && , Types >:
is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>, Types >
{};
#endif // #ifndef BOOST_NO_CXX11_RVALUE_REFERENCE
///////////////////////////////////////////////////////////////////////////////
// (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(BOOST_BORLANDC, BOOST_TESTED_AT(0x0551))
typedef typename mpl::fold<
types
, mpl::size_t<1>
, add_alignment
>::type max_alignment;
#else // borland
// temporary workaround -- use maximal alignment
typedef mpl::size_t< -1 > max_alignment;
#endif // borland workaround
public: // metafunction result
typedef ::boost::aligned_storage<
BOOST_MPL_AUX_VALUE_WKND(max_size)::value
, BOOST_MPL_AUX_VALUE_WKND(max_alignment)::value
> type;
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class destroyer
//
// Internal visitor that destroys the value it visits.
//
struct destroyer
: public static_visitor<>
{
public: // visitor interfaces
template <typename T>
void internal_visit(T& operand, int) const BOOST_NOEXCEPT
{
operand.~T(); // must be noexcept
#if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0551)) || \
BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
(void)operand; // suppresses warnings
#endif
}
};
///////////////////////////////////////////////////////////////////////////////
// (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&>
{
public: // visitor interface
T& operator()(T& operand) const BOOST_NOEXCEPT
{
return operand;
}
template <typename U>
T& operator()(U&) const
{
// logical error to be here: see precondition above
return ::boost::detail::variant::forced_return< T& >();
}
};
///////////////////////////////////////////////////////////////////////////////
// (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) BOOST_NOEXCEPT
: storage_(storage)
{
}
public: // internal visitor interface
template <typename T>
void internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
{
new(storage_) T( operand.get() );
}
template <typename T>
void internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
{
new(storage_) T( operand.get() );
}
template <typename T>
void internal_visit(const T& operand, int) const
{
new(storage_) T(operand);
}
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class move_into
//
// Internal visitor that moves the value it visits into the given buffer.
//
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
class move_into
: public static_visitor<>
{
private: // representation
void* storage_;
public: // structors
explicit move_into(void* storage) BOOST_NOEXCEPT
: storage_(storage)
{
}
public: // internal visitor interface
template <typename T>
void internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
{
new(storage_) T( ::boost::detail::variant::move(operand.get()) );
}
template <typename T>
void internal_visit(T& operand, int) const BOOST_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(T(boost::declval<T>())))
{
new(storage_) T(::boost::detail::variant::move(operand));
}
};
#endif
///////////////////////////////////////////////////////////////////////////////
// (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) BOOST_NOEXCEPT
: rhs_storage_(rhs_storage)
{
}
public: // internal visitor interfaces
template <typename T>
void internal_visit(backup_holder<T>& lhs_content, long) const
{
lhs_content.get()
= static_cast< const backup_holder<T>* >(rhs_storage_)->get();
}
template <typename T>
void internal_visit(const backup_holder<T>& lhs_content, long) const
{
lhs_content.get()
= static_cast< const backup_holder<T>* >(rhs_storage_)->get();
}
template <typename T>
void 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_);
}
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class move_storage
//
// Internal visitor that moves the given storage (which must be a
// constructed value of the same type) to the value it visits.
//
struct move_storage
: public static_visitor<>
{
private: // representation
void* rhs_storage_;
public: // structors
explicit move_storage(void* rhs_storage) BOOST_NOEXCEPT
: rhs_storage_(rhs_storage)
{
}
public: // internal visitor interfaces
template <typename T>
void internal_visit(backup_holder<T>& lhs_content, long) const
{
lhs_content.get()
= ::boost::detail::variant::move(static_cast<backup_holder<T>* >(rhs_storage_)->get());
}
template <typename T>
void internal_visit(const backup_holder<T>& lhs_content, long) const
{
lhs_content.get()
= ::boost::detail::variant::move(static_cast<backup_holder<T>* >(rhs_storage_)->get());
}
template <typename T>
void 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 = ::boost::detail::variant::move(*static_cast<T* >(rhs_storage_));
}
};
///////////////////////////////////////////////////////////////////////////////
// (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
const T& rhs_;
public: // structors
explicit direct_assigner(const T& rhs) BOOST_NOEXCEPT
: rhs_(rhs)
{
}
public: // visitor interface
bool operator()(T& lhs)
{
lhs = rhs_;
return true;
}
template <typename U>
bool operator()(U&) BOOST_NOEXCEPT
{
return false;
}
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
private:
// silence MSVC warning C4512: assignment operator could not be generated
direct_assigner& operator= (direct_assigner const&);
#endif
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class direct_mover
//
// Generic static visitor that: if and only if the visited value is of the
// specified type, move assigns the given value to the visited value and returns
// true; else returns false.
//
template <typename T>
class direct_mover
: public static_visitor<bool>
{
private: // representation
T& rhs_;
public: // structors
explicit direct_mover(T& rhs) BOOST_NOEXCEPT
: rhs_(rhs)
{
}
public: // visitor interface
bool operator()(T& lhs)
{
lhs = ::boost::detail::variant::move(rhs_);
return true;
}
template <typename U>
bool operator()(U&) BOOST_NOEXCEPT
{
return false;
}
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
private:
// silence MSVC warning C4512: assignment operator could not be generated
direct_mover& operator= (direct_mover const&);
#endif
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class backup_assigner
//
// Internal visitor that "assigns" the given value to the visited value,
// using backup to recover if the destroy-copy sequence fails.
//
// NOTE: This needs to be a friend of variant, as it needs access to
// indicate_which, indicate_backup_which, etc.
//
template <typename Variant>
class backup_assigner
: public static_visitor<>
{
private: // representation
Variant& lhs_;
int rhs_which_;
const void* rhs_content_;
void (*copy_rhs_content_)(void*, const void*);
public: // structors
template<class RhsT>
backup_assigner(Variant& lhs, int rhs_which, const RhsT& rhs_content)
: lhs_(lhs)
, rhs_which_(rhs_which)
, rhs_content_(&rhs_content)
, copy_rhs_content_(&construct_impl<RhsT>)
{
}
private: // helpers, for visitor interface (below)
template<class RhsT>
static void construct_impl(void* addr, const void* obj)
{
new(addr) RhsT(*static_cast<const RhsT*>(obj));
}
template <typename LhsT>
void backup_assign_impl(
backup_holder<LhsT>& lhs_content
, mpl::false_ // is_nothrow_move_constructible
, long
)
{
// Move lhs content to backup...
backup_holder<LhsT> backup_lhs_content(0);
backup_lhs_content.swap(lhs_content); // nothrow
// ...destroy lhs content...
lhs_content.~backup_holder<LhsT>(); // nothrow
BOOST_TRY
{
// ...and attempt to copy rhs content into lhs storage:
copy_rhs_content_(lhs_.storage_.address(), rhs_content_);
}
BOOST_CATCH (...)
{
// In case of failure, copy backup pointer to lhs storage...
new(lhs_.storage_.address())
backup_holder<LhsT>( 0 ); // nothrow
static_cast<backup_holder<LhsT>* >(lhs_.storage_.address())
->swap(backup_lhs_content); // nothrow
// ...and rethrow:
BOOST_RETHROW;
}
BOOST_CATCH_END
// In case of success, indicate new content type:
lhs_.indicate_which(rhs_which_); // nothrow
}
template <typename LhsT>
void backup_assign_impl(
LhsT& lhs_content
, mpl::true_ // is_nothrow_move_constructible
, int
)
{
// Move lhs content to backup...
LhsT backup_lhs_content(
::boost::detail::variant::move(lhs_content)
); // nothrow
// ...destroy lhs content...
lhs_content.~LhsT(); // nothrow
BOOST_TRY
{
// ...and attempt to copy rhs content into lhs storage:
copy_rhs_content_(lhs_.storage_.address(), rhs_content_);
}
BOOST_CATCH (...)
{
// In case of failure, restore backup content to lhs storage...
new(lhs_.storage_.address())
LhsT(
::boost::detail::variant::move(backup_lhs_content)
); // nothrow
// ...and rethrow:
BOOST_RETHROW;
}
BOOST_CATCH_END
// In case of success, indicate new content type:
lhs_.indicate_which(rhs_which_); // nothrow
}
template <typename LhsT>
void backup_assign_impl(
LhsT& lhs_content
, mpl::false_ // is_nothrow_move_constructible
, int
)
{
// Backup lhs content...
LhsT* backup_lhs_ptr = new LhsT(lhs_content);
// ...destroy lhs content...
lhs_content.~LhsT(); // nothrow
BOOST_TRY
{
// ...and attempt to copy rhs content into lhs storage:
copy_rhs_content_(lhs_.storage_.address(), rhs_content_);
}
BOOST_CATCH (...)
{
// In case of failure, copy backup pointer to lhs storage...
new(lhs_.storage_.address())
backup_holder<LhsT>( backup_lhs_ptr ); // nothrow
// ...indicate now using backup...
lhs_.indicate_backup_which( lhs_.which() ); // nothrow
// ...and rethrow:
BOOST_RETHROW;
}
BOOST_CATCH_END
// In case of success, indicate new content type...
lhs_.indicate_which(rhs_which_); // nothrow
// ...and delete backup:
delete backup_lhs_ptr; // nothrow
}
public: // visitor interface
template <typename LhsT>
void internal_visit(LhsT& lhs_content, int)
{
typedef typename is_nothrow_move_constructible<LhsT>::type
nothrow_move;
backup_assign_impl( lhs_content, nothrow_move(), 1L);
}
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
private:
// silence MSVC warning C4512: assignment operator could not be generated
backup_assigner& operator= (backup_assigner const&);
#endif
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class swap_with
//
// Visitor that swaps visited value with content of given variant.
//
// Precondition: Given variant MUST have same logical type as visited value.
//
template <typename Variant>
struct swap_with
: public static_visitor<>
{
private: // representation
Variant& toswap_;
public: // structors
explicit swap_with(Variant& toswap) BOOST_NOEXCEPT
: toswap_(toswap)
{
}
public: // internal visitor interfaces
template <typename T>
void operator()(T& operand) const
{
// Since the precondition ensures types are same, get T...
known_get<T> getter;
T& other = toswap_.apply_visitor(getter);
// ...and swap:
::boost::detail::variant::move_swap( operand, other );
}
private:
swap_with& operator=(const swap_with&);
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class reflect
//
// Generic static visitor that performs a typeid on the value it visits.
//
class reflect
: public static_visitor<const boost::typeindex::type_info&>
{
public: // visitor interfaces
template <typename T>
const boost::typeindex::type_info& operator()(const T&) const BOOST_NOEXCEPT
{
return boost::typeindex::type_id<T>().type_info();
}
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class comparer
//
// Generic static visitor that compares the content of the given lhs variant
// with the visited rhs content using Comp.
//
// Precondition: lhs.which() == rhs.which()
//
template <typename Variant, typename Comp>
class comparer
: public static_visitor<bool>
{
private: // representation
const Variant& lhs_;
public: // structors
explicit comparer(const Variant& lhs) BOOST_NOEXCEPT
: lhs_(lhs)
{
}
public: // visitor interfaces
template <typename T>
bool operator()(T& rhs_content) const
{
// Since the precondition ensures lhs and rhs types are same, get T...
known_get<T> getter;
const T& lhs_content = lhs_.apply_visitor(getter);
// ...and compare lhs and rhs contents:
return Comp()(lhs_content, rhs_content);
}
private:
comparer& operator=(const comparer&);
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class equal_comp
//
// Generic function object compares lhs with rhs using operator==.
//
struct equal_comp
{
template <typename T>
bool operator()(const T& lhs, const T& rhs) const
{
return lhs == rhs;
}
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class less_comp
//
// Generic function object compares lhs with rhs using operator<.
//
struct less_comp
{
template <typename T>
bool operator()(const T& lhs, const T& rhs) const
{
return lhs < rhs;
}
};
///////////////////////////////////////////////////////////////////////////////
// (detail) class template invoke_visitor
//
// Internal visitor that invokes the given visitor using:
// * for wrappers (e.g., recursive_wrapper), the wrapper's held value.
// * for all other values, the value itself.
//
template <typename Visitor, bool MoveSemantics>
class invoke_visitor
{
private: // representation
Visitor& visitor_;
public: // visitor typedefs
typedef typename Visitor::result_type
result_type;
public: // structors
explicit invoke_visitor(Visitor& visitor) BOOST_NOEXCEPT
: visitor_(visitor)
{
}
public: // internal visitor interfaces
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
//using workaround with is_same<T, T> to prenvent compilation error, because we need to use T in enable_if to make SFINAE work
template <typename T>
typename enable_if_c<MoveSemantics && is_same<T, T>::value, result_type>::type internal_visit(T&& operand, int)
{
return visitor_(::boost::move(operand));
}
//using workaround with is_same<T, T> to prenvent compilation error, because we need to use T in enable_if to make SFINAE work
template <typename T>
typename disable_if_c<MoveSemantics && is_same<T, T>::value, result_type>::type internal_visit(T&& operand, int)
{
return visitor_(operand);
}
#else
template <typename T>
result_type internal_visit(T& operand, int)
{
return visitor_(operand);
}
# if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0564))
template <typename T>
result_type internal_visit(const T& operand, int)
{
return visitor_(operand);
}
# endif //BORLAND
#endif //RVALUE REFERENCES
public: // internal visitor interfaces, cont.
template <typename T>
result_type internal_visit(boost::recursive_wrapper<T>& operand, long)
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
result_type internal_visit(const boost::recursive_wrapper<T>& operand, long)
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
result_type internal_visit(boost::detail::reference_content<T>& operand, long)
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
result_type internal_visit(const boost::detail::reference_content<T>& operand, long)
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
result_type internal_visit(boost::detail::variant::backup_holder<T>& operand, long)
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
result_type internal_visit(const boost::detail::variant::backup_holder<T>& operand, long)
{
return internal_visit( operand.get(), 1L );
}
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
private:
// silence MSVC warning C4512: assignment operator could not be generated
invoke_visitor& operator= (invoke_visitor const&);
#endif
};
}} // namespace detail::variant
///////////////////////////////////////////////////////////////////////////////
// class template variant (concept inspired by Andrei Alexandrescu)
//
// See docs and boost/variant/variant_fwd.hpp for more information.
//
template <
typename T0_
, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(typename T)
>
class variant
{
private: // helpers, for typedefs (below)
typedef variant wknd_self_t;
struct is_recursive_
: detail::variant::is_recursive_flag<T0_>
{
};
typedef typename mpl::eval_if<
is_recursive_
, T0_
, mpl::identity< T0_ >
>::type unwrapped_T0_;
struct is_sequence_based_
: detail::variant::is_over_sequence<unwrapped_T0_>
{
};
#if !defined(BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
private: // helpers, for typedefs (below)
typedef typename mpl::eval_if<
is_sequence_based_
, unwrapped_T0_ // over_sequence<...>::type
, detail::variant::make_variant_list<
unwrapped_T0_
, BOOST_VARIANT_ENUM_SHIFTED_PARAMS(T)
>
>::type specified_types;
BOOST_STATIC_ASSERT((
::boost::mpl::not_< mpl::empty<specified_types> >::value
));
public: // public typedefs
typedef typename mpl::eval_if<
is_recursive_
, mpl::transform<
specified_types
, mpl::protect<
detail::variant::quoted_enable_recursive<wknd_self_t>
>
>
, mpl::identity< specified_types >
>::type recursive_enabled_types; // used by is_variant_constructible_from<> trait
typedef typename mpl::transform<
recursive_enabled_types
, unwrap_recursive<mpl::_1>
>::type types;
private: // internal typedefs
typedef typename mpl::transform<
recursive_enabled_types
, mpl::protect< detail::make_reference_content<> >
>::type internal_types;
typedef typename mpl::front<
internal_types
>::type internal_T0;
#else // defined(BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT)
private: // helpers, for typedefs (below)
typedef unwrapped_T0_ T0;
#define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS(z,N,_) \
typedef typename mpl::eval_if< \
is_recursive_ \
, detail::variant::enable_recursive< \
BOOST_PP_CAT(T,N) \
, wknd_self_t \
> \
, mpl::identity< BOOST_PP_CAT(T,N) > \
>::type BOOST_PP_CAT(recursive_enabled_T,N); \
/**/
BOOST_PP_REPEAT(
BOOST_VARIANT_LIMIT_TYPES
, BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
, _
)
#undef BOOST_VARIANT_AUX_ENABLE_RECURSIVE_TYPEDEFS
#define BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS(z,N,_) \
typedef typename unwrap_recursive< \
BOOST_PP_CAT(recursive_enabled_T,N) \
>::type BOOST_PP_CAT(public_T,N); \
/**/
BOOST_PP_REPEAT(
BOOST_VARIANT_LIMIT_TYPES
, BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS
, _
)
#undef BOOST_VARIANT_AUX_UNWRAP_RECURSIVE_TYPEDEFS
public: // public typedefs
typedef typename detail::variant::make_variant_list<
BOOST_VARIANT_ENUM_PARAMS(public_T)
>::type types;
private: // helpers, for internal typedefs (below)
#define BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS(z,N,_) \
typedef detail::make_reference_content< \
BOOST_PP_CAT(recursive_enabled_T,N) \
>::type BOOST_PP_CAT(internal_T,N); \
/**/
BOOST_PP_REPEAT(
BOOST_VARIANT_LIMIT_TYPES
, BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS
, _
)
#undef BOOST_VARIANT_AUX_MAKE_REFERENCE_CONTENT_TYPEDEFS
private: // internal typedefs
typedef typename detail::variant::make_variant_list<
BOOST_VARIANT_ENUM_PARAMS(internal_T)
>::type internal_types;
private: // static precondition assertions
// NOTE TO USER :
// variant< type-sequence > syntax is not supported on this compiler!
//
BOOST_MPL_ASSERT_NOT(( is_sequence_based_ ));
#endif // BOOST_VARIANT_NO_TYPE_SEQUENCE_SUPPORT workaround
private: // helpers, for representation (below)
typedef typename detail::variant::find_fallback_type<
internal_types
>::type fallback_type_result_;
typedef typename fallback_type_result_::first
fallback_type_index_;
typedef typename fallback_type_result_::second
fallback_type_;
struct has_fallback_type_
: mpl::not_<
is_same< fallback_type_, detail::variant::no_fallback_type >
>
{
};
typedef has_fallback_type_
never_uses_backup_flag;
typedef typename detail::variant::make_storage<
internal_types, never_uses_backup_flag
>::type storage_t;
#ifndef BOOST_NO_CXX11_NOEXCEPT
typedef typename detail::variant::is_variant_move_noexcept_constructible<
internal_types
> variant_move_noexcept_constructible;
typedef typename detail::variant::is_variant_move_noexcept_assignable<
internal_types
> variant_move_noexcept_assignable;
#endif
private: // helpers, for representation (below)
// which_ on:
// * [0, size<internal_types>) indicates stack content
// * [-size<internal_types>, 0) indicates pointer to heap backup
// if which_ >= 0:
// * then which() -> which_
// * else which() -> -(which_ + 1)
#if !defined(BOOST_VARIANT_MINIMIZE_SIZE)
typedef int which_t;
#else // defined(BOOST_VARIANT_MINIMIZE_SIZE)
// [if O1_size available, then attempt which_t size optimization...]
// [select signed char if fewer than SCHAR_MAX types, else signed int:]
typedef typename mpl::eval_if<
mpl::equal_to< mpl::O1_size<internal_types>, mpl::long_<-1> >
, mpl::identity< int >
, mpl::if_<
mpl::less< mpl::O1_size<internal_types>, mpl::int_<SCHAR_MAX> >
, signed char
, int
>
>::type which_t;
#endif // BOOST_VARIANT_MINIMIZE_SIZE switch
// representation -- private when possible
#if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
private:
#else
public:
#endif
which_t which_;
storage_t storage_;
void indicate_which(int which_arg) BOOST_NOEXCEPT
{
which_ = static_cast<which_t>( which_arg );
}
void indicate_backup_which(int which_arg) BOOST_NOEXCEPT
{
which_ = static_cast<which_t>( -(which_arg + 1) );
}
private: // helpers, for queries (below)
bool using_backup() const BOOST_NOEXCEPT
{
return which_ < 0;
}
public: // queries
int which() const BOOST_NOEXCEPT
{
// If using heap backup...
if (using_backup())
// ...then return adjusted which_:
return -(which_ + 1);
// Otherwise, return which_ directly:
return which_;
}
private: // helpers, for structors (below)
struct initializer
: BOOST_VARIANT_AUX_INITIALIZER_T(
recursive_enabled_types, recursive_enabled_T
)
{
};
void destroy_content() BOOST_NOEXCEPT
{
detail::variant::destroyer visitor;
this->internal_apply_visitor(visitor);
}
public: // structors
~variant() BOOST_NOEXCEPT
{
destroy_content();
}
variant()
#if !(defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x5130))
BOOST_NOEXCEPT_IF(boost::has_nothrow_constructor<internal_T0>::value)
#endif
{
#ifdef _MSC_VER
#pragma warning( push )
// behavior change: an object of POD type constructed with an initializer of the form () will be default-initialized
#pragma warning( disable : 4345 )
#endif
// NOTE TO USER :
// Compile error from here indicates that the first bound
// type is not default-constructible, and so variant cannot
// support its own default-construction.
//
new( storage_.address() ) internal_T0();
indicate_which(0); // zero is the index of the first bounded type
#ifdef _MSC_VER
#pragma warning( pop )
#endif
}
private: // helpers, for structors, cont. (below)
class convert_copy_into
: public static_visitor<int>
{
private: // representation
void* storage_;
public: // structors
explicit convert_copy_into(void* storage) BOOST_NOEXCEPT
: storage_(storage)
{
}
public: // internal visitor interfaces (below)
template <typename T>
int internal_visit(T& operand, int) const
{
// NOTE TO USER :
// Compile error here indicates one of the source variant's types
// cannot be unambiguously converted to the destination variant's
// types (or that no conversion exists).
//
return initializer::initialize(storage_, operand);
}
# if BOOST_WORKAROUND(BOOST_BORLANDC, BOOST_TESTED_AT(0x0564))
template <typename T>
result_type internal_visit(const T& operand, int) const
{
return initializer::initialize(storage_, operand);
}
# endif
template <typename T>
int internal_visit(boost::detail::reference_content<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(const boost::detail::reference_content<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(boost::recursive_wrapper<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(const boost::recursive_wrapper<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
};
friend class convert_copy_into;
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
class convert_move_into
: public static_visitor<int>
{
private: // representation
void* storage_;
public: // structors
explicit convert_move_into(void* storage) BOOST_NOEXCEPT
: storage_(storage)
{
}
public: // internal visitor interfaces (below)
template <typename T>
int internal_visit(T& operand, int) const
{
// NOTE TO USER :
// Compile error here indicates one of the source variant's types
// cannot be unambiguously converted to the destination variant's
// types (or that no conversion exists).
//
return initializer::initialize(storage_, detail::variant::move(operand) );
}
template <typename T>
int internal_visit(boost::detail::reference_content<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(const boost::detail::reference_content<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(boost::detail::variant::backup_holder<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(const boost::detail::variant::backup_holder<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(boost::recursive_wrapper<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
template <typename T>
int internal_visit(const boost::recursive_wrapper<T>& operand, long) const
{
return internal_visit( operand.get(), 1L );
}
};
friend class convert_move_into;
#endif
private: // helpers, for structors, below
template <typename T>
void convert_construct(
T& operand
, int
, mpl::false_ = mpl::false_() // is_foreign_variant
)
{
// NOTE TO USER :
// Compile error here indicates that the given type is not
// unambiguously convertible to one of the variant's types
// (or that no conversion exists).
//
indicate_which(
initializer::initialize(
storage_.address()
, operand
)
);
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename T>
typename boost::enable_if<boost::is_rvalue_reference<T&&> >::type convert_construct(
T&& operand
, int
, mpl::false_ = mpl::false_() // is_foreign_variant
)
{
// NOTE TO USER :
// Compile error here indicates that the given type is not
// unambiguously convertible to one of the variant's types
// (or that no conversion exists).
//
indicate_which(
initializer::initialize(
storage_.address()
, detail::variant::move(operand)
)
);
}
#endif
template <typename Variant>
void convert_construct(
Variant& operand
, long
, mpl::true_// is_foreign_variant
)
{
convert_copy_into visitor(storage_.address());
indicate_which(
operand.internal_apply_visitor(visitor)
);
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename Variant>
typename boost::enable_if<boost::is_rvalue_reference<Variant&&> >::type convert_construct(
Variant&& operand
, long
, mpl::true_// is_foreign_variant
)
{
convert_move_into visitor(storage_.address());
indicate_which(
operand.internal_apply_visitor(visitor)
);
}
#endif
template <typename Variant>
void convert_construct_variant(Variant& operand)
{
// [Determine if the given variant is itself a bounded type, or if its
// content needs to be converted (i.e., it is a 'foreign' variant):]
//
typedef typename mpl::find_if<
types
, is_same<
add_const<mpl::_1>
, const Variant
>
>::type found_it;
typedef typename mpl::end<types>::type not_found;
typedef typename is_same<
found_it, not_found
>::type is_foreign_variant;
// Convert construct from operand:
convert_construct(
operand, 1L
, is_foreign_variant()
);
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename Variant>
typename boost::enable_if<boost::is_rvalue_reference<Variant&&> >::type convert_construct_variant(Variant&& operand)
{
// [Determine if the given variant is itself a bounded type, or if its
// content needs to be converted (i.e., it is a 'foreign' variant):]
//
typedef typename mpl::find_if<
types
, is_same<
add_const<mpl::_1>
, const Variant
>
>::type found_it;
typedef typename mpl::end<types>::type not_found;
typedef typename is_same<
found_it, not_found
>::type is_foreign_variant;
// Convert move construct from operand:
convert_construct(
detail::variant::move(operand), 1L
, is_foreign_variant()
);
}
#endif
template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
typename boost::enable_if<mpl::or_<
boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>,
boost::detail::variant::is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&, internal_types>
> >::type convert_construct(
boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand
, long
)
{
convert_construct_variant(operand);
}
template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
typename boost::enable_if<mpl::or_<
boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>,
boost::detail::variant::is_variant_constructible_from<const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&, internal_types>
> >::type convert_construct(
const boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>& operand
, long
)
{
convert_construct_variant(operand);
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <BOOST_VARIANT_ENUM_PARAMS(typename U)>
typename boost::enable_if<mpl::or_<
boost::is_same<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>, variant>,
boost::detail::variant::is_variant_constructible_from<boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&&, internal_types>
> >::type convert_construct(
boost::variant<BOOST_VARIANT_ENUM_PARAMS(U)>&& operand
, long
)
{
convert_construct_variant( detail::variant::move(operand) );
}
#endif
public: // structors, cont.
template <typename T>
variant(const T& operand,
typename boost::enable_if<mpl::or_<
mpl::and_<
mpl::not_< boost::is_same<T, variant> >,
boost::detail::variant::is_variant_constructible_from<const T&, internal_types>
>,
boost::is_same<T, boost::recursive_variant_> >,
bool >::type = true)
{
convert_construct(operand, 1L);
}
template <typename T>
variant(
T& operand
, typename boost::enable_if<mpl::or_<
mpl::and_<
mpl::not_< is_const<T> >,
mpl::not_< boost::is_same<T, variant> >,
boost::detail::variant::is_variant_constructible_from<T&, internal_types>
>,
boost::is_same<T, boost::recursive_variant_> >,
bool >::type = true
)
{
convert_construct(operand, 1L);
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <class T>
variant(T&& operand,
typename boost::enable_if<mpl::or_<
mpl::and_<
boost::is_rvalue_reference<T&&>,
mpl::not_< boost::is_const<T> >,
mpl::not_< boost::is_same<T, variant> >,
boost::detail::variant::is_variant_constructible_from<T&&, internal_types>
>,
boost::is_same<T, boost::recursive_variant_> >,
bool >::type = true)
{
convert_construct( detail::variant::move(operand), 1L);
}
#endif
public: // structors, cont.
// [MSVC6 requires copy constructor appear after template constructors]
variant(const variant& operand)
{
// Copy the value of operand into *this...
detail::variant::copy_into visitor( storage_.address() );
operand.internal_apply_visitor(visitor);
// ...and activate the *this's primary storage on success:
indicate_which(operand.which());
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
variant(variant&& operand) BOOST_NOEXCEPT_IF(variant_move_noexcept_constructible::type::value)
{
// Move the value of operand into *this...
detail::variant::move_into visitor( storage_.address() );
operand.internal_apply_visitor(visitor);
// ...and activate the *this's primary storage on success:
indicate_which(operand.which());
}
#endif
private: // helpers, for modifiers (below)
# if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
template <typename Variant>
friend class detail::variant::backup_assigner;
# endif
// class assigner
//
// Internal visitor that "assigns" the visited value to the given variant
// by appropriate destruction and copy-construction.
//
class assigner
: public static_visitor<>
{
protected: // representation
variant& lhs_;
const int rhs_which_;
public: // structors
assigner(variant& lhs, int rhs_which) BOOST_NOEXCEPT
: lhs_(lhs)
, rhs_which_(rhs_which)
{
}
protected: // helpers, for internal visitor interface (below)
template <typename RhsT, typename B1, typename B2>
void assign_impl(
const RhsT& rhs_content
, mpl::true_ // has_nothrow_copy
, B1 // is_nothrow_move_constructible
, B2 // has_fallback_type
) const BOOST_NOEXCEPT
{
// Destroy lhs's content...
lhs_.destroy_content(); // nothrow
// ...copy rhs content into lhs's storage...
new(lhs_.storage_.address())
RhsT( rhs_content ); // nothrow
// ...and indicate new content type:
lhs_.indicate_which(rhs_which_); // nothrow
}
template <typename RhsT, typename B>
void assign_impl(
const RhsT& rhs_content
, mpl::false_ // has_nothrow_copy
, mpl::true_ // is_nothrow_move_constructible
, B // has_fallback_type
) const
{
// Attempt to make a temporary copy (so as to move it below)...
RhsT temp(rhs_content);
// ...and upon success destroy lhs's content...
lhs_.destroy_content(); // nothrow
// ...move the temporary copy into lhs's storage...
new(lhs_.storage_.address())
RhsT( detail::variant::move(temp) ); // nothrow
// ...and indicate new content type:
lhs_.indicate_which(rhs_which_); // nothrow
}
void construct_fallback() const BOOST_NOEXCEPT {
// In case of failure, default-construct fallback type in lhs's storage...
new (lhs_.storage_.address())
fallback_type_; // nothrow
// ...indicate construction of fallback type...
lhs_.indicate_which(
BOOST_MPL_AUX_VALUE_WKND(fallback_type_index_)::value
); // nothrow
}
template <typename RhsT>
void assign_impl(
const RhsT& rhs_content
, mpl::false_ // has_nothrow_copy
, mpl::false_ // is_nothrow_move_constructible
, mpl::true_ // has_fallback_type
) const
{
// Destroy lhs's content...
lhs_.destroy_content(); // nothrow
BOOST_TRY
{
// ...and attempt to copy rhs's content into lhs's storage:
new(lhs_.storage_.address())
RhsT( rhs_content );
}
BOOST_CATCH (...)
{
construct_fallback();
// ...and rethrow:
BOOST_RETHROW;
}
BOOST_CATCH_END
// In the event of success, indicate new content type:
lhs_.indicate_which(rhs_which_); // nothrow
}
template <typename RhsT>
void assign_impl(
const RhsT& rhs_content
, mpl::false_ // has_nothrow_copy
, mpl::false_ // is_nothrow_move_constructible
, mpl::false_ // has_fallback_type
) const
{
detail::variant::backup_assigner<wknd_self_t>
visitor(lhs_, rhs_which_, rhs_content);
lhs_.internal_apply_visitor(visitor);
}
public: // internal visitor interfaces
template <typename RhsT>
void internal_visit(const RhsT& rhs_content, int) const
{
typedef typename has_nothrow_copy<RhsT>::type
nothrow_copy;
typedef typename mpl::or_< // reduces compile-time
nothrow_copy
, is_nothrow_move_constructible<RhsT>
>::type nothrow_move_constructor;
assign_impl(
rhs_content
, nothrow_copy()
, nothrow_move_constructor()
, has_fallback_type_()
);
}
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
private:
// silence MSVC warning C4512: assignment operator could not be generated
assigner& operator= (assigner const&);
#endif
};
friend class assigner;
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
// class move_assigner
//
// Internal visitor that "move assigns" the visited value to the given variant
// by appropriate destruction and move-construction.
//
class move_assigner
: public assigner
{
public: // structors
move_assigner(variant& lhs, int rhs_which) BOOST_NOEXCEPT
: assigner(lhs, rhs_which)
{
}
private: // helpers, for internal visitor interface (below)
template <typename RhsT, typename B2>
void assign_impl(
RhsT& rhs_content
, mpl::true_ // has_nothrow_copy
, mpl::false_ // is_nothrow_move_constructible
, B2 // has_fallback_type
) const BOOST_NOEXCEPT
{
assigner::assign_impl(rhs_content, mpl::true_(), mpl::false_(), B2());
}
template <typename RhsT, typename B, typename B2>
void assign_impl(
RhsT& rhs_content
, B // has_nothrow_copy
, mpl::true_ // is_nothrow_move_constructible
, B2 // has_fallback_type
) const BOOST_NOEXCEPT
{
// ...destroy lhs's content...
assigner::lhs_.destroy_content(); // nothrow
// ...move the rhs_content into lhs's storage...
new(assigner::lhs_.storage_.address())
RhsT( detail::variant::move(rhs_content) ); // nothrow
// ...and indicate new content type:
assigner::lhs_.indicate_which(assigner::rhs_which_); // nothrow
}
template <typename RhsT>
void assign_impl(
RhsT& rhs_content
, mpl::false_ // has_nothrow_copy
, mpl::false_ // is_nothrow_move_constructible
, mpl::true_ // has_fallback_type
) const
{
// Destroy lhs's content...
assigner::lhs_.destroy_content(); // nothrow
BOOST_TRY
{
// ...and attempt to copy rhs's content into lhs's storage:
new(assigner::lhs_.storage_.address())
RhsT( detail::variant::move(rhs_content) );
}
BOOST_CATCH (...)
{
assigner::construct_fallback();
// ...and rethrow:
BOOST_RETHROW;
}
BOOST_CATCH_END
// In the event of success, indicate new content type:
assigner::lhs_.indicate_which(assigner::rhs_which_); // nothrow
}
template <typename RhsT>
void assign_impl(
RhsT& rhs_content
, mpl::false_ // has_nothrow_copy
, mpl::false_ // is_nothrow_move_constructible
, mpl::false_ // has_fallback_type
) const
{
assigner::assign_impl(rhs_content, mpl::false_(), mpl::false_(), mpl::false_());
}
public: // internal visitor interfaces
template <typename RhsT>
void internal_visit(RhsT& rhs_content, int) const
{
typedef typename is_nothrow_move_constructible<RhsT>::type
nothrow_move_constructor;
typedef typename mpl::or_< // reduces compile-time
nothrow_move_constructor
, has_nothrow_copy<RhsT>
>::type nothrow_copy;
assign_impl(
rhs_content
, nothrow_copy()
, nothrow_move_constructor()
, has_fallback_type_()
);
}
#if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1600))
private:
// silence MSVC warning C4512: assignment operator could not be generated
move_assigner& operator= (move_assigner const&);
#endif
};
friend class move_assigner;
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
void variant_assign(const variant& rhs)
{
// If the contained types are EXACTLY the same...
if (which_ == rhs.which_)
{
// ...then assign rhs's storage to lhs's content:
detail::variant::assign_storage visitor(rhs.storage_.address());
this->internal_apply_visitor(visitor);
}
else
{
// Otherwise, perform general (copy-based) variant assignment:
assigner visitor(*this, rhs.which());
rhs.internal_apply_visitor(visitor);
}
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
void variant_assign(variant&& rhs)
{
// If the contained types are EXACTLY the same...
if (which_ == rhs.which_)
{
// ...then move rhs's storage to lhs's content:
detail::variant::move_storage visitor(rhs.storage_.address());
this->internal_apply_visitor(visitor);
}
else
{
// Otherwise, perform general (move-based) variant assignment:
move_assigner visitor(*this, rhs.which());
rhs.internal_apply_visitor(visitor);
}
}
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
private: // helpers, for modifiers (below)
template <typename T>
void assign(const T& rhs)
{
// If direct T-to-T assignment is not possible...
detail::variant::direct_assigner<T> direct_assign(rhs);
if (this->apply_visitor(direct_assign) == false)
{
// ...then convert rhs to variant and assign:
//
// While potentially inefficient, the following construction of a
// variant allows T as any type convertible to one of the bounded
// types without excessive code redundancy.
//
variant temp(rhs);
variant_assign( detail::variant::move(temp) );
}
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename T>
void move_assign(T&& rhs)
{
// If direct T-to-T move assignment is not possible...
detail::variant::direct_mover<T> direct_move(rhs);
if (this->apply_visitor(direct_move) == false)
{
// ...then convert rhs to variant and assign:
//
// While potentially inefficient, the following construction of a
// variant allows T as any type convertible to one of the bounded
// types without excessive code redundancy.
//
variant temp( detail::variant::move(rhs) );
variant_assign( detail::variant::move(temp) );
}
}
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
public: // modifiers
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
template <class T>
typename boost::enable_if<
boost::mpl::and_<
boost::is_rvalue_reference<T&&>,
mpl::not_< boost::is_const<T> >,
boost::detail::variant::is_variant_constructible_from<T&&, internal_types>
>,
variant&
>::type operator=(T&& rhs)
{
move_assign( detail::variant::move(rhs) );
return *this;
}
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
template <typename T>
typename boost::enable_if<
mpl::or_<
boost::is_same<T, variant>,
boost::detail::variant::is_variant_constructible_from<const T&, internal_types>
>,
variant&
>::type operator=(const T& rhs)
{
assign(rhs);
return *this;
}
// [MSVC6 requires copy assign appear after templated operator=]
variant& operator=(const variant& rhs)
{
variant_assign(rhs);
return *this;
}
#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
variant& operator=(variant&& rhs)
#if !defined(__GNUC__) || (__GNUC__ != 4) || (__GNUC_MINOR__ > 6) || defined(__clang__)
BOOST_NOEXCEPT_IF(variant_move_noexcept_constructible::type::value && variant_move_noexcept_assignable::type::value)
#endif
{
variant_assign( detail::variant::move(rhs) );
return *this;
}
#endif // BOOST_NO_CXX11_RVALUE_REFERENCES
void swap(variant& rhs)
{
// If the contained types are the same...
if (which() == rhs.which())
{
// ...then swap the values directly:
detail::variant::swap_with<variant> visitor(rhs);
this->apply_visitor(visitor);
}
else
{
// ...otherwise, perform general variant swap:
variant tmp( detail::variant::move(rhs) );
rhs = detail::variant::move(*this);
*this = detail::variant::move(tmp);
}
}
public: // queries
//
// NOTE: member which() defined above.
//
bool empty() const BOOST_NOEXCEPT
{
return false;
}
const boost::typeindex::type_info& type() const
{
detail::variant::reflect visitor;
return this->apply_visitor(visitor);
}
public: // prevent comparison with foreign types
template <typename U>
void operator==(const U&) const
{
BOOST_STATIC_ASSERT( false && sizeof(U) );
}
template <typename U>
void operator<(const U&) const
{
BOOST_STATIC_ASSERT( false && sizeof(U) );
}
template <typename U>
void operator!=(const U&) const
{
BOOST_STATIC_ASSERT( false && sizeof(U) );
}
template <typename U>
void operator>(const U&) const
{
BOOST_STATIC_ASSERT( false && sizeof(U) );
}
template <typename U>
void operator<=(const U&) const
{
BOOST_STATIC_ASSERT( false && sizeof(U) );
}
template <typename U>
void operator>=(const U&) const
{
BOOST_STATIC_ASSERT( false && sizeof(U) );
}
public: // comparison operators
// [MSVC6 requires these operators appear after template operators]
bool operator==(const variant& rhs) const
{
if (this->which() != rhs.which())
return false;
detail::variant::comparer<
variant, detail::variant::equal_comp
> visitor(*this);
return rhs.apply_visitor(visitor);
}
bool operator<(const variant& rhs) const
{
//
// Dirk Schreib suggested this collating order.
//
if (this->which() != rhs.which())
return this->which() < rhs.which();
detail::variant::comparer<
variant, detail::variant::less_comp
> visitor(*this);
return rhs.apply_visitor(visitor);
}
///////////////////////////////////////////////////////////////////////////////
// comparison operators != > <= >=
inline bool operator!=(const variant& rhs) const
{
return !(*this == rhs);
}
inline bool operator>(const variant& rhs) const
{
return rhs < *this;
}
inline bool operator<=(const variant& rhs) const
{
return !(*this > rhs);
}
inline bool operator>=(const variant& rhs) const
{
return !(*this < rhs);
}
// helpers, for visitation support (below) -- private when possible
#if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
template < BOOST_VARIANT_ENUM_PARAMS(typename U) >
friend class variant;
private:
#else// defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
public:
#endif// !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
template <typename Visitor, typename VoidPtrCV>
BOOST_FORCEINLINE static typename Visitor::result_type
internal_apply_visitor_impl(
int internal_which
, int logical_which
, Visitor& visitor
, VoidPtrCV storage
)
{
typedef mpl::int_<0> first_which;
typedef typename mpl::begin<internal_types>::type first_it;
typedef typename mpl::end<internal_types>::type last_it;
typedef detail::variant::visitation_impl_step<
first_it, last_it
> first_step;
return detail::variant::visitation_impl(
internal_which, logical_which
, visitor, storage, mpl::false_()
, never_uses_backup_flag()
, static_cast<first_which*>(0), static_cast<first_step*>(0)
);
}
template <typename Visitor>
BOOST_FORCEINLINE typename Visitor::result_type
internal_apply_visitor(Visitor& visitor)
{
return internal_apply_visitor_impl(
which_, which(), visitor, storage_.address()
);
}
template <typename Visitor>
BOOST_FORCEINLINE typename Visitor::result_type
internal_apply_visitor(Visitor& visitor) const
{
return internal_apply_visitor_impl(
which_, which(), visitor, storage_.address()
);
}
public: // visitation support
#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
template <typename Visitor>
typename Visitor::result_type
apply_visitor(Visitor& visitor) &&
{
detail::variant::invoke_visitor<Visitor, true> invoker(visitor);
return this->internal_apply_visitor(invoker);
}
template <typename Visitor>
typename Visitor::result_type
apply_visitor(Visitor& visitor) const&&
{
detail::variant::invoke_visitor<Visitor, true> invoker(visitor);
return this->internal_apply_visitor(invoker);
}
#endif
template <typename Visitor>
typename Visitor::result_type
apply_visitor(Visitor& visitor)
#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
&
#endif
{
detail::variant::invoke_visitor<Visitor, false> invoker(visitor);
return this->internal_apply_visitor(invoker);
}
template <typename Visitor>
typename Visitor::result_type
apply_visitor(Visitor& visitor) const
#ifndef BOOST_NO_CXX11_REF_QUALIFIERS
&
#endif
{
detail::variant::invoke_visitor<Visitor, false> invoker(visitor);
return this->internal_apply_visitor(invoker);
}
}; // class variant
///////////////////////////////////////////////////////////////////////////////
// metafunction make_variant_over
//
// See docs and boost/variant/variant_fwd.hpp for more information.
//
template <typename Types>
struct make_variant_over
{
private: // precondition assertions
BOOST_STATIC_ASSERT(( ::boost::mpl::is_sequence<Types>::value ));
typedef typename boost::mpl::insert_range<
boost::mpl::list<>
, boost::mpl::end< boost::mpl::list<> >::type
, Types
>::type copied_sequence_t;
public: // metafunction result
typedef variant<
detail::variant::over_sequence<copied_sequence_t>
> type;
};
///////////////////////////////////////////////////////////////////////////////
// function template swap
//
// Swaps two variants of the same type (i.e., identical specification).
//
template < BOOST_VARIANT_ENUM_PARAMS(typename T) >
inline void swap(
variant< BOOST_VARIANT_ENUM_PARAMS(T) >& lhs
, variant< BOOST_VARIANT_ENUM_PARAMS(T) >& rhs
)
{
lhs.swap(rhs);
}
} // namespace boost
// implementation additions
#if !defined(BOOST_NO_IOSTREAM)
#include <boost/variant/detail/variant_io.hpp>
#endif // BOOST_NO_IOSTREAM
#endif // BOOST_VARIANT_VARIANT_HPP
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