[857] | 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_INDEX_SAVER_HPP
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| 10 | #define BOOST_MULTI_INDEX_DETAIL_INDEX_SAVER_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/multi_index/detail/index_matcher.hpp>
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| 18 | #include <boost/noncopyable.hpp>
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| 19 | #include <boost/serialization/nvp.hpp>
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| 20 | #include <cstddef>
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| 21 |
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| 22 | namespace boost{
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| 23 |
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| 24 | namespace multi_index{
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| 25 |
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| 26 | namespace detail{
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| 27 |
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| 28 | /* index_saver accepts a base sequence of previously saved elements
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| 29 | * and saves a possibly reordered subsequence in an efficient manner,
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| 30 | * serializing only the information needed to rearrange the subsequence
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| 31 | * based on the original order of the base.
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| 32 | * multi_index_container is in charge of supplying the info about the
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| 33 | * base sequence, and each index can subsequently save itself using the
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| 34 | * const interface of index_saver.
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| 35 | */
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| 36 |
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| 37 | template<typename Node,typename Allocator>
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| 38 | class index_saver:private noncopyable
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| 39 | {
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| 40 | public:
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| 41 | index_saver(const Allocator& al,std::size_t size):alg(al,size){}
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| 42 |
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| 43 | template<class Archive>
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| 44 | void add(Node* node,Archive& ar,const unsigned int)
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| 45 | {
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| 46 | ar<<serialization::make_nvp("position",*node);
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| 47 | alg.add(node);
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| 48 | }
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| 49 |
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| 50 | template<class Archive>
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| 51 | void add_track(Node* node,Archive& ar,const unsigned int)
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| 52 | {
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| 53 | ar<<serialization::make_nvp("position",*node);
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| 54 | }
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| 55 |
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| 56 | template<typename IndexIterator,class Archive>
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| 57 | void save(
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| 58 | IndexIterator first,IndexIterator last,Archive& ar,
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| 59 | const unsigned int)const
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| 60 | {
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| 61 | /* calculate ordered positions */
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| 62 |
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| 63 | alg.execute(first,last);
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| 64 |
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| 65 | /* Given a consecutive subsequence of displaced elements
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| 66 | * x1,...,xn, the following information is serialized:
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| 67 | *
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| 68 | * p0,p1,...,pn,0
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| 69 | *
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| 70 | * where pi is a pointer to xi and p0 is a pointer to the element
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| 71 | * preceding x1. Crealy, from this information is possible to
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| 72 | * restore the original order on loading time. If x1 is the first
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| 73 | * element in the sequence, the following is serialized instead:
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| 74 | *
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| 75 | * p1,p1,...,pn,0
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| 76 | *
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| 77 | * For each subsequence of n elements, n+2 pointers are serialized.
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| 78 | * An optimization policy is applied: consider for instance the
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| 79 | * sequence
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| 80 | *
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| 81 | * a,B,c,D
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| 82 | *
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| 83 | * where B and D are displaced, but c is in its correct position.
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| 84 | * Applying the schema described above we would serialize 6 pointers:
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| 85 | *
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| 86 | * p(a),p(B),0
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| 87 | * p(c),p(D),0
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| 88 | *
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| 89 | * but this can be reduced to 5 pointers by treating c as a displaced
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| 90 | * element:
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| 91 | *
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| 92 | * p(a),p(B),p(c),p(D),0
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| 93 | */
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| 94 |
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| 95 | std::size_t last_saved=3; /* distance to last pointer saved */
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| 96 | for(IndexIterator it=first,prev=first;it!=last;prev=it++,++last_saved){
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| 97 | if(!alg.is_ordered(get_node(it))){
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| 98 | if(last_saved>1)save_node(get_node(prev),ar);
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| 99 | save_node(get_node(it),ar);
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| 100 | last_saved=0;
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| 101 | }
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| 102 | else if(last_saved==2)save_node(null_node(),ar);
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| 103 | }
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| 104 | if(last_saved<=2)save_node(null_node(),ar);
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| 105 |
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| 106 | /* marks the end of the serialization info for [first,last) */
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| 107 |
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| 108 | save_node(null_node(),ar);
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| 109 | }
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| 110 |
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| 111 | private:
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| 112 | template<typename IndexIterator>
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| 113 | static Node* get_node(IndexIterator it)
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| 114 | {
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| 115 | return it.get_node();
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| 116 | }
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| 117 |
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| 118 | static Node* null_node(){return 0;}
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| 119 |
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| 120 | template<typename Archive>
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| 121 | static void save_node(Node* node,Archive& ar)
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| 122 | {
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| 123 | ar<<serialization::make_nvp("pointer",node);
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| 124 | }
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| 125 |
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| 126 | index_matcher::algorithm<Node,Allocator> alg;
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| 127 | };
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| 128 |
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| 129 | } /* namespace multi_index::detail */
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| 130 |
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| 131 | } /* namespace multi_index */
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| 132 |
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| 133 | } /* namespace boost */
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| 134 |
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| 135 | #endif
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