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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_NO_DUPLICATE_TAGS_HPP | |
10 | #define BOOST_MULTI_INDEX_DETAIL_NO_DUPLICATE_TAGS_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/mpl/fold.hpp> | |
18 | #include <boost/mpl/set/set0.hpp> | |
19 | ||
20 | namespace boost{ | |
21 | ||
22 | namespace multi_index{ | |
23 | ||
24 | namespace detail{ | |
25 | ||
26 | /* no_duplicate_tags check at compile-time that a tag list | |
27 | * has no duplicate tags. | |
28 | * The algorithm deserves some explanation: tags | |
29 | * are sequentially inserted into a mpl::set if they were | |
30 | * not already present. Due to the magic of mpl::set | |
31 | * (mpl::has_key is contant time), this operation takes linear | |
32 | * time, and even MSVC++ 6.5 handles it gracefully (other obvious | |
33 | * solutions are quadratic.) | |
34 | */ | |
35 | ||
36 | struct duplicate_tag_mark{}; | |
37 | ||
38 | struct duplicate_tag_marker | |
39 | { | |
40 | template <typename MplSet,typename Tag> | |
41 | struct apply | |
42 | { | |
43 | typedef mpl::s_item< | |
44 | typename mpl::if_<mpl::has_key<MplSet,Tag>,duplicate_tag_mark,Tag>::type, | |
45 | MplSet | |
46 | > type; | |
47 | }; | |
48 | }; | |
49 | ||
50 | template<typename TagList> | |
51 | struct no_duplicate_tags | |
52 | { | |
53 | typedef typename mpl::fold< | |
54 | TagList, | |
55 | mpl::set0<>, | |
56 | duplicate_tag_marker | |
57 | >::type aux; | |
58 | ||
59 | BOOST_STATIC_CONSTANT( | |
60 | bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value)); | |
61 | }; | |
62 | ||
63 | /* Variant for an index list: duplication is checked | |
64 | * across all the indices. | |
65 | */ | |
66 | ||
67 | struct duplicate_tag_list_marker | |
68 | { | |
69 | template <typename MplSet,typename Index> | |
70 | struct apply:mpl::fold< | |
71 | BOOST_DEDUCED_TYPENAME Index::tag_list, | |
72 | MplSet, | |
73 | duplicate_tag_marker> | |
74 | { | |
75 | }; | |
76 | }; | |
77 | ||
78 | template<typename IndexList> | |
79 | struct no_duplicate_tags_in_index_list | |
80 | { | |
81 | typedef typename mpl::fold< | |
82 | IndexList, | |
83 | mpl::set0<>, | |
84 | duplicate_tag_list_marker | |
85 | >::type aux; | |
86 | ||
87 | BOOST_STATIC_CONSTANT( | |
88 | bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value)); | |
89 | }; | |
90 | ||
91 | } /* namespace multi_index::detail */ | |
92 | ||
93 | } /* namespace multi_index */ | |
94 | ||
95 | } /* namespace boost */ | |
96 | ||
97 | #endif |