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