1 /* Copyright 2003-2013 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_HASH_INDEX_ARGS_HPP
10 #define BOOST_MULTI_INDEX_DETAIL_HASH_INDEX_ARGS_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/functional/hash.hpp>
18 #include <boost/mpl/aux_/na.hpp>
19 #include <boost/mpl/eval_if.hpp>
20 #include <boost/mpl/identity.hpp>
21 #include <boost/mpl/if.hpp>
22 #include <boost/multi_index/tag.hpp>
23 #include <boost/static_assert.hpp>
24 #include <boost/type_traits/is_same.hpp>
25 #include <functional>
26 
27 namespace boost{
28 
29 namespace multi_index{
30 
31 namespace detail{
32 
33 /* Hashed index specifiers can be instantiated in two forms:
34  *
35  *   (hashed_unique|hashed_non_unique)<
36  *     KeyFromValue,
37  *     Hash=boost::hash<KeyFromValue::result_type>,
38  *     Pred=std::equal_to<KeyFromValue::result_type> >
39  *   (hashed_unique|hashed_non_unique)<
40  *     TagList,
41  *     KeyFromValue,
42  *     Hash=boost::hash<KeyFromValue::result_type>,
43  *     Pred=std::equal_to<KeyFromValue::result_type> >
44  *
45  * hashed_index_args implements the machinery to accept this
46  * argument-dependent polymorphism.
47  */
48 
49 template<typename KeyFromValue>
50 struct index_args_default_hash
51 {
52   typedef ::boost::hash<typename KeyFromValue::result_type> type;
53 };
54 
55 template<typename KeyFromValue>
56 struct index_args_default_pred
57 {
58   typedef std::equal_to<typename KeyFromValue::result_type> type;
59 };
60 
61 template<typename Arg1,typename Arg2,typename Arg3,typename Arg4>
62 struct hashed_index_args
63 {
64   typedef is_tag<Arg1> full_form;
65 
66   typedef typename mpl::if_<
67     full_form,
68     Arg1,
69     tag< > >::type                                   tag_list_type;
70   typedef typename mpl::if_<
71     full_form,
72     Arg2,
73     Arg1>::type                                      key_from_value_type;
74   typedef typename mpl::if_<
75     full_form,
76     Arg3,
77     Arg2>::type                                      supplied_hash_type;
78   typedef typename mpl::eval_if<
79     mpl::is_na<supplied_hash_type>,
80     index_args_default_hash<key_from_value_type>,
81     mpl::identity<supplied_hash_type>
82   >::type                                            hash_type;
83   typedef typename mpl::if_<
84     full_form,
85     Arg4,
86     Arg3>::type                                      supplied_pred_type;
87   typedef typename mpl::eval_if<
88     mpl::is_na<supplied_pred_type>,
89     index_args_default_pred<key_from_value_type>,
90     mpl::identity<supplied_pred_type>
91   >::type                                            pred_type;
92 
93   BOOST_STATIC_ASSERT(is_tag<tag_list_type>::value);
94   BOOST_STATIC_ASSERT(!mpl::is_na<key_from_value_type>::value);
95   BOOST_STATIC_ASSERT(!mpl::is_na<hash_type>::value);
96   BOOST_STATIC_ASSERT(!mpl::is_na<pred_type>::value);
97 };
98 
99 } /* namespace multi_index::detail */
100 
101 } /* namespace multi_index */
102 
103 } /* namespace boost */
104 
105 #endif
106