1 | /* Copyright 2003-2005 Joaquín M López Muñoz.
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2 | * Distributed under the Boost Software License, Version 1.0.
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3 | * (See accompanying file LICENSE_1_0.txt or copy at
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4 | * http://www.boost.org/LICENSE_1_0.txt)
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5 | *
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6 | * See http://www.boost.org/libs/multi_index for library home page.
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7 | */
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8 |
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9 | #ifndef BOOST_MULTI_INDEX_DETAIL_NO_DUPLICATE_TAGS_HPP
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10 | #define BOOST_MULTI_INDEX_DETAIL_NO_DUPLICATE_TAGS_HPP
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11 |
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12 | #if defined(_MSC_VER)&&(_MSC_VER>=1200)
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13 | #pragma once
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14 | #endif
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15 |
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16 | #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
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17 | #include <boost/mpl/fold.hpp>
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18 | #include <boost/mpl/set/set0.hpp>
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19 |
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20 | namespace boost{
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21 |
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22 | namespace multi_index{
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23 |
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24 | namespace detail{
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25 |
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26 | /* no_duplicate_tags check at compile-time that a tag list
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27 | * has no duplicate tags.
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28 | * The algorithm deserves some explanation: tags
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29 | * are sequentially inserted into a mpl::set if they were
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30 | * not already present. Due to the magic of mpl::set
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31 | * (mpl::has_key is contant time), this operation takes linear
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32 | * time, and even MSVC++ 6.5 handles it gracefully (other obvious
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33 | * solutions are quadratic.)
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34 | */
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35 |
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36 | struct duplicate_tag_mark{};
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37 |
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38 | struct duplicate_tag_marker
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39 | {
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40 | template <typename MplSet,typename Tag>
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41 | struct apply
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42 | {
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43 | typedef mpl::s_item<
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44 | typename mpl::if_<mpl::has_key<MplSet,Tag>,duplicate_tag_mark,Tag>::type,
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45 | MplSet
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46 | > type;
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47 | };
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48 | };
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49 |
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50 | template<typename TagList>
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51 | struct no_duplicate_tags
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52 | {
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53 | typedef typename mpl::fold<
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54 | TagList,
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55 | mpl::set0<>,
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56 | duplicate_tag_marker
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57 | >::type aux;
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58 |
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59 | BOOST_STATIC_CONSTANT(
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60 | bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value));
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61 | };
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62 |
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63 | /* Variant for an index list: duplication is checked
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64 | * across all the indices.
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65 | */
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66 |
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67 | struct duplicate_tag_list_marker
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68 | {
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69 | template <typename MplSet,typename Index>
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70 | struct apply:mpl::fold<
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71 | BOOST_DEDUCED_TYPENAME Index::tag_list,
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72 | MplSet,
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73 | duplicate_tag_marker>
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74 | {
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75 | };
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76 | };
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77 |
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78 | template<typename IndexList>
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79 | struct no_duplicate_tags_in_index_list
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80 | {
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81 | typedef typename mpl::fold<
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82 | IndexList,
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83 | mpl::set0<>,
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84 | duplicate_tag_list_marker
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85 | >::type aux;
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86 |
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87 | BOOST_STATIC_CONSTANT(
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88 | bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value));
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89 | };
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90 |
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91 | } /* namespace multi_index::detail */
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92 |
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93 | } /* namespace multi_index */
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94 |
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95 | } /* namespace boost */
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96 |
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97 | #endif
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