boost/flyweight/hashed_factory.hpp

   1 /* Copyright 2006-2009 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/flyweight for library home page.
   7  */
   8
   9 #ifndef BOOST_FLYWEIGHT_HASHED_FACTORY_HPP
  10 #define BOOST_FLYWEIGHT_HASHED_FACTORY_HPP
  11
  12 #if defined(_MSC_VER)&&(_MSC_VER>=1200)
  13 #pragma once
  14 #endif
  15
  16 #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
  17 #include <boost/flyweight/factory_tag.hpp>
  18 #include <boost/flyweight/hashed_factory_fwd.hpp>
  19 #include <boost/multi_index_container.hpp>
  20 #include <boost/multi_index/identity.hpp>
  21 #include <boost/multi_index/hashed_index.hpp>
  22 #include <boost/mpl/aux_/lambda_support.hpp>
  23 #include <boost/mpl/if.hpp>
  24
  25 /* Flyweight factory based on a hashed container implemented
  26  * with Boost.MultiIndex.
  27  */
  28
  29 namespace boost{
  30
  31 namespace flyweights{
  32
  33 template<
  34   typename Entry,typename Key,
  35   typename Hash,typename Pred,typename Allocator
  36 >
  37 class hashed_factory_class:public factory_marker
  38 {
  39   struct index_list:
  40     boost::mpl::vector1<
  41       multi_index::hashed_unique<
  42         multi_index::identity<Entry>,
  43         typename boost::mpl::if_<
  44           mpl::is_na<Hash>,
  45           hash<Key>,
  46           Hash
  47         >::type,
  48         typename boost::mpl::if_<
  49           mpl::is_na<Pred>,
  50           std::equal_to<Key>,
  51           Pred
  52         >::type
  53       >
  54     >
  55   {};
  56
  57   typedef multi_index::multi_index_container<
  58     Entry,
  59     index_list,
  60     typename boost::mpl::if_<
  61       mpl::is_na<Allocator>,
  62       std::allocator<Entry>,
  63       Allocator
  64     >::type
  65   > container_type;
  66
  67 public:
  68   typedef const Entry* handle_type;
  69
  70   handle_type insert(const Entry& x)
  71   {
  72     return &*cont.insert(x).first;
  73   }
  74
  75   void erase(handle_type h)
  76   {
  77     cont.erase(cont.iterator_to(*h));
  78   }
  79
  80   static const Entry& entry(handle_type h){return *h;}
  81
  82 private:
  83   container_type cont;
  84
  85 public:
  86   typedef hashed_factory_class type;
  87   BOOST_MPL_AUX_LAMBDA_SUPPORT(
  88     5,hashed_factory_class,(Entry,Key,Hash,Pred,Allocator))
  89 };
  90
  91 /* hashed_factory_class specifier */
  92
  93 template<
  94   typename Hash,typename Pred,typename Allocator
  95   BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION_DEF
  96 >
  97 struct hashed_factory:factory_marker
  98 {
  99   template<typename Entry,typename Key>
 100   struct apply:
 101     mpl::apply2<
 102       hashed_factory_class<
 103         boost::mpl::_1,boost::mpl::_2,Hash,Pred,Allocator
 104       >,
 105       Entry,Key
 106     >
 107   {};
 108 };
 109
 110 } /* namespace flyweights */
 111
 112 } /* namespace boost */
 113
 114 #endif