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250 lines
8.0 KiB
250 lines
8.0 KiB
5 years ago
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//-----------------------------------------------------------------------------
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// boost variant/detail/initializer.hpp header file
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// See http://www.boost.org for updates, documentation, and revision history.
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//-----------------------------------------------------------------------------
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//
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// Copyright (c) 2002-2003
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// Eric Friedman, Itay Maman
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_VARIANT_DETAIL_INITIALIZER_HPP
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#define BOOST_VARIANT_DETAIL_INITIALIZER_HPP
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#include <new> // for placement new
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#include <boost/config.hpp>
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#include <boost/call_traits.hpp>
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#include <boost/detail/reference_content.hpp>
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#include <boost/variant/recursive_wrapper_fwd.hpp>
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#include <boost/variant/detail/move.hpp>
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#if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
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# include <boost/mpl/aux_/value_wknd.hpp>
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# include <boost/mpl/int.hpp>
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# include <boost/mpl/iter_fold.hpp>
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# include <boost/mpl/next.hpp>
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# include <boost/mpl/deref.hpp>
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# include <boost/mpl/pair.hpp>
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# include <boost/mpl/protect.hpp>
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#else
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# include <boost/variant/variant_fwd.hpp>
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# include <boost/preprocessor/cat.hpp>
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# include <boost/preprocessor/enum.hpp>
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# include <boost/preprocessor/repeat.hpp>
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#endif
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namespace boost {
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namespace detail { namespace variant {
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///////////////////////////////////////////////////////////////////////////////
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// (detail) support to simulate standard overload resolution rules
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//
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// The below initializers allows variant to follow standard overload
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// resolution rules over the specified set of bounded types.
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//
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// On compilers where using declarations in class templates can correctly
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// avoid name hiding, use an optimal solution based on the variant's typelist.
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//
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// Otherwise, use a preprocessor workaround based on knowledge of the fixed
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// size of the variant's psuedo-variadic template parameter list.
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//
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#if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
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// (detail) quoted metafunction make_initializer_node
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//
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// Exposes a pair whose first type is a node in the initializer hierarchy.
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//
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struct make_initializer_node
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{
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template <typename BaseIndexPair, typename Iterator>
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struct apply
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{
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private: // helpers, for metafunction result (below)
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typedef typename BaseIndexPair::first
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base;
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typedef typename BaseIndexPair::second
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index;
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class initializer_node
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: public base
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{
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private: // helpers, for static functions (below)
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typedef typename mpl::deref<Iterator>::type
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recursive_enabled_T;
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typedef typename unwrap_recursive<recursive_enabled_T>::type
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public_T;
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#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
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typedef boost::is_reference<public_T>
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is_reference_content_t;
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typedef typename boost::mpl::if_<is_reference_content_t, public_T, const public_T& >::type
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param_T;
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template <class T> struct disable_overload{};
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typedef typename boost::mpl::if_<is_reference_content_t, disable_overload<public_T>, public_T&& >::type
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param2_T;
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#else
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typedef typename call_traits<public_T>::param_type
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param_T;
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#endif
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public: // static functions
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using base::initialize;
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static int initialize(void* dest, param_T operand)
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{
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typedef typename boost::detail::make_reference_content<
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recursive_enabled_T
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>::type internal_T;
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new(dest) internal_T(operand);
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return BOOST_MPL_AUX_VALUE_WKND(index)::value; // which
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}
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#ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
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static int initialize(void* dest, param2_T operand)
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{
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// This assert must newer trigger, because all the reference contents are
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// handled by the initilize(void* dest, param_T operand) function above
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BOOST_ASSERT(!is_reference_content_t::value);
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typedef typename boost::mpl::if_<is_reference_content_t, param2_T, recursive_enabled_T>::type value_T;
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new(dest) value_T( boost::detail::variant::move(operand) );
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return BOOST_MPL_AUX_VALUE_WKND(index)::value; // which
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}
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#endif
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};
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friend class initializer_node;
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public: // metafunction result
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typedef mpl::pair<
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initializer_node
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, typename mpl::next< index >::type
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> type;
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};
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};
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// (detail) class initializer_root
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//
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// Every level of the initializer hierarchy must expose the name
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// "initialize," so initializer_root provides a dummy function:
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//
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class initializer_root
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{
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public: // static functions
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static void initialize();
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};
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#else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
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// Obsolete. Remove.
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#define BOOST_VARIANT_AUX_PP_INITIALIZER_TEMPLATE_PARAMS \
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BOOST_VARIANT_ENUM_PARAMS(typename recursive_enabled_T) \
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/**/
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// Obsolete. Remove.
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#define BOOST_VARIANT_AUX_PP_INITIALIZER_DEFINE_PARAM_T(N) \
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typedef typename unwrap_recursive< \
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BOOST_PP_CAT(recursive_enabled_T,N) \
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>::type BOOST_PP_CAT(public_T,N); \
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typedef typename call_traits< \
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BOOST_PP_CAT(public_T,N) \
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>::param_type BOOST_PP_CAT(param_T,N); \
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/**/
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template < BOOST_VARIANT_ENUM_PARAMS(typename recursive_enabled_T) >
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struct preprocessor_list_initializer
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{
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public: // static functions
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#define BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION(z,N,_) \
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typedef typename unwrap_recursive< \
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BOOST_PP_CAT(recursive_enabled_T,N) \
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>::type BOOST_PP_CAT(public_T,N); \
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typedef typename call_traits< \
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BOOST_PP_CAT(public_T,N) \
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>::param_type BOOST_PP_CAT(param_T,N); \
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static int initialize( \
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void* dest \
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, BOOST_PP_CAT(param_T,N) operand \
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) \
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{ \
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typedef typename boost::detail::make_reference_content< \
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BOOST_PP_CAT(recursive_enabled_T,N) \
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>::type internal_T; \
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\
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new(dest) internal_T(operand); \
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return (N); /*which*/ \
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} \
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/**/
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BOOST_PP_REPEAT(
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BOOST_VARIANT_LIMIT_TYPES
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, BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION
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, _
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)
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#undef BOOST_VARIANT_AUX_PP_INITIALIZE_FUNCTION
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};
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#endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround
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}} // namespace detail::variant
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} // namespace boost
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///////////////////////////////////////////////////////////////////////////////
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// macro BOOST_VARIANT_AUX_INITIALIZER_T
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//
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// Given both the variant's typelist and a basename for forming the list of
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// bounded types (i.e., T becomes T1, T2, etc.), exposes the initializer
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// most appropriate to the current compiler.
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//
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#if !defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
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#define BOOST_VARIANT_AUX_INITIALIZER_T( mpl_seq, typename_base ) \
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::boost::mpl::iter_fold< \
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mpl_seq \
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, ::boost::mpl::pair< \
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::boost::detail::variant::initializer_root \
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, ::boost::mpl::int_<0> \
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> \
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, ::boost::mpl::protect< \
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::boost::detail::variant::make_initializer_node \
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> \
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>::type::first \
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/**/
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#else // defined(BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE)
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// Obsolete. Remove.
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#define BOOST_VARIANT_AUX_PP_INITIALIZER_TEMPLATE_ARGS(typename_base) \
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BOOST_VARIANT_ENUM_PARAMS(typename_base) \
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/**/
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#define BOOST_VARIANT_AUX_INITIALIZER_T( mpl_seq, typename_base ) \
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::boost::detail::variant::preprocessor_list_initializer< \
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BOOST_VARIANT_ENUM_PARAMS(typename_base) \
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> \
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/**/
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#endif // BOOST_NO_USING_DECLARATION_OVERLOADS_FROM_TYPENAME_BASE workaround
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#endif // BOOST_VARIANT_DETAIL_INITIALIZER_HPP
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