263 lines
6.6 KiB
C++
263 lines
6.6 KiB
C++
/* Copyright 2003-2015 Joaquin M Lopez Munoz.
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* Distributed under the Boost Software License, Version 1.0.
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* (See 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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*
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* See http://www.boost.org/libs/multi_index for library home page.
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*/
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#ifndef BOOST_MULTI_INDEX_MEMBER_HPP
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#define BOOST_MULTI_INDEX_MEMBER_HPP
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
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#include <boost/mpl/if.hpp>
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#include <boost/type_traits/is_const.hpp>
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#include <boost/utility/enable_if.hpp>
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#include <cstddef>
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#if !defined(BOOST_NO_SFINAE)
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#include <boost/type_traits/is_convertible.hpp>
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#endif
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namespace boost{
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template<class T> class reference_wrapper; /* fwd decl. */
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namespace multi_index{
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namespace detail{
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/* member is a read/write key extractor for accessing a given
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* member of a class.
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* Additionally, member is overloaded to support referece_wrappers
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* of T and "chained pointers" to T's. By chained pointer to T we mean
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* a type P such that, given a p of Type P
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* *...n...*x is convertible to T&, for some n>=1.
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* Examples of chained pointers are raw and smart pointers, iterators and
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* arbitrary combinations of these (vg. T** or unique_ptr<T*>.)
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*/
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template<class Class,typename Type,Type Class::*PtrToMember>
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struct const_member_base
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{
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typedef Type result_type;
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template<typename ChainedPtr>
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#if !defined(BOOST_NO_SFINAE)
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typename disable_if<
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is_convertible<const ChainedPtr&,const Class&>,Type&>::type
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#else
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Type&
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#endif
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operator()(const ChainedPtr& x)const
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{
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return operator()(*x);
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}
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Type& operator()(const Class& x)const
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{
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return x.*PtrToMember;
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}
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Type& operator()(const reference_wrapper<const Class>& x)const
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{
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return operator()(x.get());
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}
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Type& operator()(const reference_wrapper<Class>& x)const
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{
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return operator()(x.get());
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}
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};
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template<class Class,typename Type,Type Class::*PtrToMember>
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struct non_const_member_base
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{
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typedef Type result_type;
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template<typename ChainedPtr>
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#if !defined(BOOST_NO_SFINAE)
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typename disable_if<
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is_convertible<const ChainedPtr&,const Class&>,Type&>::type
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#else
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Type&
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#endif
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operator()(const ChainedPtr& x)const
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{
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return operator()(*x);
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}
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const Type& operator()(const Class& x)const
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{
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return x.*PtrToMember;
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}
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Type& operator()(Class& x)const
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{
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return x.*PtrToMember;
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}
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const Type& operator()(const reference_wrapper<const Class>& x)const
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{
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return operator()(x.get());
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}
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Type& operator()(const reference_wrapper<Class>& x)const
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{
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return operator()(x.get());
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}
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};
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} /* namespace multi_index::detail */
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template<class Class,typename Type,Type Class::*PtrToMember>
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struct member:
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mpl::if_c<
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is_const<Type>::value,
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detail::const_member_base<Class,Type,PtrToMember>,
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detail::non_const_member_base<Class,Type,PtrToMember>
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>::type
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{
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};
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namespace detail{
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/* MSVC++ 6.0 does not support properly pointers to members as
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* non-type template arguments, as reported in
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* http://support.microsoft.com/default.aspx?scid=kb;EN-US;249045
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* A similar problem (though not identical) is shown by MSVC++ 7.0.
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* We provide an alternative to member<> accepting offsets instead
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* of pointers to members. This happens to work even for non-POD
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* types (although the standard forbids use of offsetof on these),
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* so it serves as a workaround in this compiler for all practical
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* purposes.
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* Surprisingly enough, other compilers, like Intel C++ 7.0/7.1 and
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* Visual Age 6.0, have similar bugs. This replacement of member<>
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* can be used for them too.
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*
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* Support for such old compilers is dropped and
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* [non_]const_member_offset_base is deprecated.
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*/
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template<class Class,typename Type,std::size_t OffsetOfMember>
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struct const_member_offset_base
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{
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typedef Type result_type;
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template<typename ChainedPtr>
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#if !defined(BOOST_NO_SFINAE)
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typename disable_if<
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is_convertible<const ChainedPtr&,const Class&>,Type&>::type
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#else
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Type&
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#endif
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operator()(const ChainedPtr& x)const
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{
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return operator()(*x);
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}
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Type& operator()(const Class& x)const
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{
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return *static_cast<const Type*>(
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static_cast<const void*>(
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static_cast<const char*>(
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static_cast<const void *>(&x))+OffsetOfMember));
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}
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Type& operator()(const reference_wrapper<const Class>& x)const
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{
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return operator()(x.get());
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}
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Type& operator()(const reference_wrapper<Class>& x)const
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{
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return operator()(x.get());
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}
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};
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template<class Class,typename Type,std::size_t OffsetOfMember>
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struct non_const_member_offset_base
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{
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typedef Type result_type;
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template<typename ChainedPtr>
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#if !defined(BOOST_NO_SFINAE)
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typename disable_if<
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is_convertible<const ChainedPtr&,const Class&>,Type&>::type
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#else
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Type&
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#endif
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operator()(const ChainedPtr& x)const
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{
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return operator()(*x);
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}
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const Type& operator()(const Class& x)const
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{
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return *static_cast<const Type*>(
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static_cast<const void*>(
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static_cast<const char*>(
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static_cast<const void *>(&x))+OffsetOfMember));
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}
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Type& operator()(Class& x)const
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{
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return *static_cast<Type*>(
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static_cast<void*>(
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static_cast<char*>(static_cast<void *>(&x))+OffsetOfMember));
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}
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const Type& operator()(const reference_wrapper<const Class>& x)const
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{
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return operator()(x.get());
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}
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Type& operator()(const reference_wrapper<Class>& x)const
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{
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return operator()(x.get());
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}
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};
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} /* namespace multi_index::detail */
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template<class Class,typename Type,std::size_t OffsetOfMember>
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struct member_offset:
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mpl::if_c<
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is_const<Type>::value,
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detail::const_member_offset_base<Class,Type,OffsetOfMember>,
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detail::non_const_member_offset_base<Class,Type,OffsetOfMember>
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>::type
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{
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};
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/* BOOST_MULTI_INDEX_MEMBER resolves to member in the normal cases,
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* and to member_offset as a workaround in those defective compilers for
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* which BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS is defined.
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*/
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#if defined(BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS)
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#define BOOST_MULTI_INDEX_MEMBER(Class,Type,MemberName) \
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::boost::multi_index::member_offset< Class,Type,offsetof(Class,MemberName) >
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#else
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#define BOOST_MULTI_INDEX_MEMBER(Class,Type,MemberName) \
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::boost::multi_index::member< Class,Type,&Class::MemberName >
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#endif
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} /* namespace multi_index */
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} /* namespace boost */
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#endif
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