Chris@101: /* Copyright 2003-2013 Joaquin M Lopez Munoz.
Chris@16:  * Distributed under the Boost Software License, Version 1.0.
Chris@16:  * (See accompanying file LICENSE_1_0.txt or copy at
Chris@16:  * http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  *
Chris@16:  * See http://www.boost.org/libs/multi_index for library home page.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_MULTI_INDEX_DETAIL_INDEX_SAVER_HPP
Chris@16: #define BOOST_MULTI_INDEX_DETAIL_INDEX_SAVER_HPP
Chris@16: 
Chris@101: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
Chris@16: #include <boost/multi_index/detail/index_matcher.hpp>
Chris@16: #include <boost/noncopyable.hpp>
Chris@16: #include <boost/serialization/nvp.hpp>
Chris@16: #include <cstddef>
Chris@16: 
Chris@16: namespace boost{
Chris@16: 
Chris@16: namespace multi_index{
Chris@16: 
Chris@16: namespace detail{
Chris@16: 
Chris@16: /* index_saver accepts a base sequence of previously saved elements
Chris@16:  * and saves a possibly reordered subsequence in an efficient manner,
Chris@16:  * serializing only the information needed to rearrange the subsequence
Chris@16:  * based on the original order of the base.
Chris@16:  * multi_index_container is in charge of supplying the info about the
Chris@16:  * base sequence, and each index can subsequently save itself using the
Chris@16:  * const interface of index_saver.
Chris@16:  */
Chris@16: 
Chris@16: template<typename Node,typename Allocator>
Chris@16: class index_saver:private noncopyable
Chris@16: {
Chris@16: public:
Chris@16:   index_saver(const Allocator& al,std::size_t size):alg(al,size){}
Chris@16: 
Chris@16:   template<class Archive>
Chris@16:   void add(Node* node,Archive& ar,const unsigned int)
Chris@16:   {
Chris@16:     ar<<serialization::make_nvp("position",*node);
Chris@16:     alg.add(node);
Chris@16:   }
Chris@16: 
Chris@16:   template<class Archive>
Chris@16:   void add_track(Node* node,Archive& ar,const unsigned int)
Chris@16:   {
Chris@16:     ar<<serialization::make_nvp("position",*node);
Chris@16:   }
Chris@16: 
Chris@16:   template<typename IndexIterator,class Archive>
Chris@16:   void save(
Chris@16:     IndexIterator first,IndexIterator last,Archive& ar,
Chris@16:     const unsigned int)const
Chris@16:   {
Chris@16:     /* calculate ordered positions */
Chris@16: 
Chris@16:     alg.execute(first,last);
Chris@16: 
Chris@16:     /* Given a consecutive subsequence of displaced elements
Chris@16:      * x1,...,xn, the following information is serialized:
Chris@16:      *
Chris@16:      *   p0,p1,...,pn,0
Chris@16:      *
Chris@16:      * where pi is a pointer to xi and p0 is a pointer to the element
Chris@16:      * preceding x1. Crealy, from this information is possible to
Chris@16:      * restore the original order on loading time. If x1 is the first
Chris@16:      * element in the sequence, the following is serialized instead:
Chris@16:      *
Chris@16:      *   p1,p1,...,pn,0
Chris@16:      *
Chris@16:      * For each subsequence of n elements, n+2 pointers are serialized.
Chris@16:      * An optimization policy is applied: consider for instance the
Chris@16:      * sequence
Chris@16:      *
Chris@16:      *   a,B,c,D
Chris@16:      * 
Chris@16:      * where B and D are displaced, but c is in its correct position.
Chris@16:      * Applying the schema described above we would serialize 6 pointers:
Chris@16:      *
Chris@16:      *  p(a),p(B),0
Chris@16:      *  p(c),p(D),0
Chris@16:      * 
Chris@16:      * but this can be reduced to 5 pointers by treating c as a displaced
Chris@16:      * element:
Chris@16:      *
Chris@16:      *  p(a),p(B),p(c),p(D),0
Chris@16:      */
Chris@16: 
Chris@16:     std::size_t last_saved=3; /* distance to last pointer saved */
Chris@16:     for(IndexIterator it=first,prev=first;it!=last;prev=it++,++last_saved){
Chris@16:       if(!alg.is_ordered(get_node(it))){
Chris@16:         if(last_saved>1)save_node(get_node(prev),ar);
Chris@16:         save_node(get_node(it),ar);
Chris@16:         last_saved=0;
Chris@16:       }
Chris@16:       else if(last_saved==2)save_node(null_node(),ar);
Chris@16:     }
Chris@16:     if(last_saved<=2)save_node(null_node(),ar);
Chris@16: 
Chris@16:     /* marks the end of the serialization info for [first,last) */
Chris@16: 
Chris@16:     save_node(null_node(),ar);
Chris@16:   }
Chris@16: 
Chris@16: private:
Chris@16:   template<typename IndexIterator>
Chris@16:   static Node* get_node(IndexIterator it)
Chris@16:   {
Chris@16:     return it.get_node();
Chris@16:   }
Chris@16: 
Chris@16:   static Node* null_node(){return 0;}
Chris@16: 
Chris@16:   template<typename Archive>
Chris@16:   static void save_node(Node* node,Archive& ar)
Chris@16:   {
Chris@16:     ar<<serialization::make_nvp("pointer",node);
Chris@16:   }
Chris@16: 
Chris@16:   index_matcher::algorithm<Node,Allocator> alg;
Chris@16: };
Chris@16: 
Chris@16: } /* namespace multi_index::detail */
Chris@16: 
Chris@16: } /* namespace multi_index */
Chris@16: 
Chris@16: } /* namespace boost */
Chris@16: 
Chris@16: #endif