unordered_map_index.hpp

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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2008. 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)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////

#ifndef BOOST_INTERPROCESS_UNORDERED_MAP_INDEX_HPP
#define BOOST_INTERPROCESS_UNORDERED_MAP_INDEX_HPP

#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>

#include <functional>
#include <utility>
#include <boost/unordered_map.hpp>
#include <boost/interprocess/detail/utilities.hpp>
#include <boost/interprocess/allocators/private_adaptive_pool.hpp>

//!\file
//!Describes index adaptor of boost::unordered_map container, to use it
//!as name/shared memory index

namespace boost {
namespace interprocess {

///@cond

//!Helper class to define typedefs from
//!IndexTraits
template <class MapConfig>
struct unordered_map_index_aux
{
   typedef typename MapConfig::key_type            key_type;
   typedef typename MapConfig::mapped_type         mapped_type;
   typedef std::equal_to<key_type>                 key_equal;
   typedef std::pair<const key_type, mapped_type>  value_type;
   typedef private_adaptive_pool
            <value_type,
               typename MapConfig::
                  segment_manager_base>      allocator_type;
    struct hasher
      : std::unary_function<key_type, std::size_t>
    {
        std::size_t operator()(const key_type &val) const
        {
            typedef typename key_type::char_type    char_type;
            const char_type *beg = detail::get_pointer(val.mp_str),
                            *end = beg + val.m_len;
            return boost::hash_range(beg, end);
        }
    };
   typedef unordered_map<key_type,  mapped_type, hasher,
                         key_equal, allocator_type>      index_t;
};

///@endcond

//!Index type based in unordered_map. Just derives from unordered_map and
//!defines the interface needed by managed memory segments
template <class MapConfig>
class unordered_map_index
   //Derive class from unordered_map specialization
   : public unordered_map_index_aux<MapConfig>::index_t
{
   /// @cond
   typedef unordered_map_index_aux<MapConfig>   index_aux;
   typedef typename index_aux::index_t          base_type;
   typedef typename 
      MapConfig::segment_manager_base     segment_manager_base;
   /// @endcond

   public:
   //!Constructor. Takes a pointer to the
   //!segment manager. Can throw
   unordered_map_index(segment_manager_base *segment_mngr)
      : base_type(0,
                  typename index_aux::hasher(),
                  typename index_aux::key_equal(),
                  segment_mngr){}

   //!This reserves memory to optimize the insertion of n
   //!elements in the index
   void reserve(std::size_t n)
   {  base_type::rehash(n);  }

   //!This tries to free previously allocate
   //!unused memory.
   void shrink_to_fit()
   {  base_type::rehash(base_type::size()); }
};

/// @cond

//!Trait class to detect if an index is a node
//!index. This allows more efficient operations
//!when deallocating named objects.
template<class MapConfig>
struct is_node_index
   <boost::interprocess::unordered_map_index<MapConfig> >
{
   enum {   value = true };
};
/// @endcond

}}   //namespace boost { namespace interprocess {

#include <boost/interprocess/detail/config_end.hpp>

#endif   //#ifndef BOOST_INTERPROCESS_UNORDERED_MAP_INDEX_HPP