1 /* Copyright 2006-2014 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)
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 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
26 #include <utility>
27 #endif
28 
29 /* Flyweight factory based on a hashed container implemented
30  * with Boost.MultiIndex.
31  */
32 
33 namespace boost{
34 
35 namespace flyweights{
36 
37 template<
38   typename Entry,typename Key,
39   typename Hash,typename Pred,typename Allocator
40 >
41 class hashed_factory_class:public factory_marker
42 {
43   struct index_list:
44     boost::mpl::vector1<
45       multi_index::hashed_unique<
46         multi_index::identity<Entry>,
47         typename boost::mpl::if_<
48           mpl::is_na<Hash>,
49           hash<Key>,
50           Hash
51         >::type,
52         typename boost::mpl::if_<
53           mpl::is_na<Pred>,
54           std::equal_to<Key>,
55           Pred
56         >::type
57       >
58     >
59   {};
60 
61   typedef multi_index::multi_index_container<
62     Entry,
63     index_list,
64     typename boost::mpl::if_<
65       mpl::is_na<Allocator>,
66       std::allocator<Entry>,
67       Allocator
68     >::type
69   > container_type;
70 
71 public:
72   typedef const Entry* handle_type;
73 
insert(const Entry & x)74   handle_type insert(const Entry& x)
75   {
76     return &*cont.insert(x).first;
77   }
78 
79 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
insert(Entry && x)80   handle_type insert(Entry&& x)
81   {
82     return &*cont.insert(std::move(x)).first;
83   }
84 #endif
85 
erase(handle_type h)86   void erase(handle_type h)
87   {
88     cont.erase(cont.iterator_to(*h));
89   }
90 
entry(handle_type h)91   static const Entry& entry(handle_type h){return *h;}
92 
93 private:
94   container_type cont;
95 
96 public:
97   typedef hashed_factory_class type;
98   BOOST_MPL_AUX_LAMBDA_SUPPORT(
99     5,hashed_factory_class,(Entry,Key,Hash,Pred,Allocator))
100 };
101 
102 /* hashed_factory_class specifier */
103 
104 template<
105   typename Hash,typename Pred,typename Allocator
106   BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION_DEF
107 >
108 struct hashed_factory:factory_marker
109 {
110   template<typename Entry,typename Key>
111   struct apply:
112     mpl::apply2<
113       hashed_factory_class<
114         boost::mpl::_1,boost::mpl::_2,Hash,Pred,Allocator
115       >,
116       Entry,Key
117     >
118   {};
119 };
120 
121 } /* namespace flyweights */
122 
123 } /* namespace boost */
124 
125 #endif
126