Squashed 'third_party/boostorg/multi_index/' content from commit d95a949
Change-Id: Ie67c2d797c11dc122c7f11e767e81691bf2191a4
git-subtree-dir: third_party/boostorg/multi_index
git-subtree-split: d95a94942b918140e565feb99ed36ea97c30084e
diff --git a/example/serialization.cpp b/example/serialization.cpp
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+/* Boost.MultiIndex example of serialization of a MRU list.
+ *
+ * Copyright 2003-2008 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.
+ */
+
+#if !defined(NDEBUG)
+#define BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING
+#define BOOST_MULTI_INDEX_ENABLE_SAFE_MODE
+#endif
+
+#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
+#include <algorithm>
+#include <boost/archive/text_oarchive.hpp>
+#include <boost/archive/text_iarchive.hpp>
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/hashed_index.hpp>
+#include <boost/multi_index/identity.hpp>
+#include <boost/multi_index/sequenced_index.hpp>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <sstream>
+#include <string>
+
+using namespace boost::multi_index;
+
+/* An MRU (most recently used) list keeps record of the last n
+ * inserted items, listing first the newer ones. Care has to be
+ * taken when a duplicate item is inserted: instead of letting it
+ * appear twice, the MRU list relocates it to the first position.
+ */
+
+template <typename Item>
+class mru_list
+{
+ typedef multi_index_container<
+ Item,
+ indexed_by<
+ sequenced<>,
+ hashed_unique<identity<Item> >
+ >
+ > item_list;
+
+public:
+ typedef Item item_type;
+ typedef typename item_list::iterator iterator;
+
+ mru_list(std::size_t max_num_items_):max_num_items(max_num_items_){}
+
+ void insert(const item_type& item)
+ {
+ std::pair<iterator,bool> p=il.push_front(item);
+
+ if(!p.second){ /* duplicate item */
+ il.relocate(il.begin(),p.first); /* put in front */
+ }
+ else if(il.size()>max_num_items){ /* keep the length <= max_num_items */
+ il.pop_back();
+ }
+ }
+
+ iterator begin(){return il.begin();}
+ iterator end(){return il.end();}
+
+ /* Utilities to save and load the MRU list, internally
+ * based on Boost.Serialization.
+ */
+
+ void save_to_file(const char* file_name)const
+ {
+ std::ofstream ofs(file_name);
+ boost::archive::text_oarchive oa(ofs);
+ oa<<boost::serialization::make_nvp("mru",*this);
+ }
+
+ void load_from_file(const char* file_name)
+ {
+ std::ifstream ifs(file_name);
+ if(ifs){
+ boost::archive::text_iarchive ia(ifs);
+ ia>>boost::serialization::make_nvp("mru",*this);
+ }
+ }
+
+private:
+ item_list il;
+ std::size_t max_num_items;
+
+ /* serialization support */
+
+ friend class boost::serialization::access;
+
+ template<class Archive>
+ void serialize(Archive& ar,const unsigned int)
+ {
+ ar&BOOST_SERIALIZATION_NVP(il);
+ ar&BOOST_SERIALIZATION_NVP(max_num_items);
+ }
+};
+
+int main()
+{
+ const char* mru_store="mru_store";
+
+ /* Construct a MRU limited to 10 items and retrieve its
+ * previous contents.
+ */
+
+ mru_list<std::string> mru(10);
+ mru.load_from_file(mru_store);
+
+ /* main loop */
+
+ for(;;){
+ std::cout<<"enter a term: ";
+
+ std::string line;
+ std::getline(std::cin,line);
+ if(line.empty())break;
+
+ std::string term;
+ std::istringstream iss(line);
+ iss>>term;
+ if(term.empty())break;
+
+ mru.insert(term);
+
+ std::cout<<"most recently entered terms:"<<std::endl;
+ std::copy(
+ mru.begin(),mru.end(),
+ std::ostream_iterator<std::string>(std::cout,"\n"));
+ }
+
+ /* persist the MRU list */
+
+ mru.save_to_file(mru_store);
+
+ return 0;
+}