multi_index/detail/any_container_view.hpp

0001 /* Copyright 2003-2021 Joaquin M Lopez Munoz.
0002  * Distributed under the Boost Software License, Version 1.0.
0003  * (See accompanying file LICENSE_1_0.txt or copy at
0004  * http://www.boost.org/LICENSE_1_0.txt)
0005  *
0006  * See http://www.boost.org/libs/multi_index for library home page.
0007  */
0008
0009 #ifndef BOOST_MULTI_INDEX_DETAIL_ANY_CONTAINER_VIEW_HPP
0010 #define BOOST_MULTI_INDEX_DETAIL_ANY_CONTAINER_VIEW_HPP
0011
0012 #if defined(_MSC_VER)
0013 #pragma once
0014 #endif
0015
0016 namespace boost{
0017
0018 namespace multi_index{
0019
0020 namespace detail{
0021
0022 /* type-erased, non-owning view over a ConstIterator-container's range */
0023
0024 template<typename ConstIterator>
0025 class any_container_view
0026 {
0027 public:
0028   template<typename Container>
0029   any_container_view(const Container& x):px(&x),pt(vtable_for<Container>()){}
0030
0031   const void*   container()const{return px;}
0032   ConstIterator begin()const{return pt->begin(px);}
0033   ConstIterator end()const{return pt->end(px);}
0034
0035 private:
0036   struct vtable
0037   {
0038     ConstIterator (*begin)(const void*);
0039     ConstIterator (*end)(const void*);
0040   };
0041
0042   template<typename Container>
0043   static ConstIterator begin_for(const void* px)
0044   {
0045     return static_cast<const Container*>(px)->begin();
0046   }
0047
0048   template<typename Container>
0049   static ConstIterator end_for(const void* px)
0050   {
0051     return static_cast<const Container*>(px)->end();
0052   }
0053
0054   template<typename Container>
0055   vtable* vtable_for()
0056   {
0057     static vtable v=
0058     {
0059       &begin_for<Container>,
0060       &end_for<Container>
0061     };
0062
0063     return &v;
0064   }
0065
0066   const void* px;
0067   vtable*     pt;
0068 };
0069
0070 } /* namespace multi_index::detail */
0071
0072 } /* namespace multi_index */
0073
0074 } /* namespace boost */
0075
0076 #endif