ceph/src/boost/boost/multi_index/detail/header_holder.hpp

   1 /* Copyright 2003-2008 Joaquin M Lopez Munoz.
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * See http://www.boost.org/libs/multi_index for library home page.
   7  */
   8
   9 #ifndef BOOST_MULTI_INDEX_DETAIL_HEADER_HOLDER_HPP
  10 #define BOOST_MULTI_INDEX_DETAIL_HEADER_HOLDER_HPP
  11
  12 #if defined(_MSC_VER)
  13 #pragma once
  14 #endif
  15
  16 #include <boost/noncopyable.hpp>
  17
  18 namespace boost{
  19
  20 namespace multi_index{
  21
  22 namespace detail{
  23
  24 /* A utility class used to hold a pointer to the header node.
  25  * The base from member idiom is used because index classes, which are
  26  * superclasses of multi_index_container, need this header in construction
  27  * time. The allocation is made by the allocator of the multi_index_container
  28  * class --hence, this allocator needs also be stored resorting
  29  * to the base from member trick.
  30  */
  31
  32 template<typename NodeTypePtr,typename Final>
  33 struct header_holder:private noncopyable
  34 {
  35   header_holder():member(final().allocate_node()){}
  36   ~header_holder(){final().deallocate_node(&*member);}
  37
  38   NodeTypePtr member;
  39
  40 private:
  41   Final& final(){return *static_cast<Final*>(this);}
  42 };
  43
  44 } /* namespace multi_index::detail */
  45
  46 } /* namespace multi_index */
  47
  48 } /* namespace boost */
  49
  50 #endif