lemon/lgf_writer.h
author Alpar Juttner <alpar@cs.elte.hu>
Wed, 09 Jul 2008 07:57:53 +0200
changeset 198 e80e08222fdf
parent 192 7bf5f97d574f
child 201 9757e3d9bfeb
permissions -rw-r--r--
Merge
     1 /* -*- C++ -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     4  *
     5  * Copyright (C) 2003-2008
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 ///\ingroup lemon_io
    20 ///\file
    21 ///\brief \ref lgf-format "Lemon Graph Format" writer.
    22 
    23 
    24 #ifndef LEMON_LGF_WRITER_H
    25 #define LEMON_LGF_WRITER_H
    26 
    27 #include <iostream>
    28 #include <fstream>
    29 #include <sstream>
    30 
    31 #include <algorithm>
    32 
    33 #include <vector>
    34 #include <functional>
    35 
    36 #include <lemon/assert.h>
    37 #include <lemon/graph_utils.h>
    38 
    39 namespace lemon {
    40 
    41   namespace _writer_bits {
    42 
    43     template <typename Value>
    44     struct DefaultConverter {
    45       std::string operator()(const Value& value) {
    46 	std::ostringstream os;
    47 	os << value;
    48 	return os.str();
    49       }
    50     };
    51 
    52     template <typename T>
    53     bool operator<(const T&, const T&) {
    54       throw DataFormatError("Label map is not comparable");
    55     }
    56 
    57     template <typename _Map>
    58     class MapLess {
    59     public:
    60       typedef _Map Map;
    61       typedef typename Map::Key Item;
    62 
    63     private:
    64       const Map& _map;
    65       
    66     public:
    67       MapLess(const Map& map) : _map(map) {}
    68 
    69       bool operator()(const Item& left, const Item& right) {
    70 	return _map[left] < _map[right];
    71       }
    72     };
    73 
    74     template <typename _Graph, bool _dir, typename _Map>
    75     class GraphArcMapLess {
    76     public:
    77       typedef _Map Map;
    78       typedef _Graph Graph;
    79       typedef typename Graph::Edge Item;
    80 
    81     private:
    82       const Graph& _graph;
    83       const Map& _map;
    84       
    85     public:
    86       GraphArcMapLess(const Graph& graph, const Map& map) 
    87 	: _graph(graph), _map(map) {}
    88 
    89       bool operator()(const Item& left, const Item& right) {
    90 	return _map[_graph.direct(left, _dir)] < 
    91 	  _map[_graph.direct(right, _dir)];
    92       }
    93     };
    94 
    95     template <typename _Item>    
    96     class MapStorageBase {
    97     public:
    98       typedef _Item Item;
    99 
   100     public:
   101       MapStorageBase() {}
   102       virtual ~MapStorageBase() {}
   103 
   104       virtual std::string get(const Item& item) = 0;
   105       virtual void sort(std::vector<Item>&) = 0;
   106     };
   107 
   108     template <typename _Item, typename _Map, 
   109 	      typename _Converter = DefaultConverter<typename _Map::Value> >
   110     class MapStorage : public MapStorageBase<_Item> {
   111     public:
   112       typedef _Map Map;
   113       typedef _Converter Converter;
   114       typedef _Item Item;
   115       
   116     private:
   117       const Map& _map;
   118       Converter _converter;
   119 
   120     public:
   121       MapStorage(const Map& map, const Converter& converter = Converter()) 
   122 	: _map(map), _converter(converter) {}
   123       virtual ~MapStorage() {}
   124 
   125       virtual std::string get(const Item& item) {
   126 	return _converter(_map[item]);
   127       }
   128       virtual void sort(std::vector<Item>& items) {
   129 	MapLess<Map> less(_map);
   130 	std::sort(items.begin(), items.end(), less);
   131       }
   132     };
   133 
   134     template <typename _Graph, bool _dir, typename _Map, 
   135 	      typename _Converter = DefaultConverter<typename _Map::Value> >
   136     class GraphArcMapStorage : public MapStorageBase<typename _Graph::Edge> {
   137     public:
   138       typedef _Map Map;
   139       typedef _Converter Converter;
   140       typedef _Graph Graph;
   141       typedef typename Graph::Edge Item;
   142       static const bool dir = _dir;
   143       
   144     private:
   145       const Graph& _graph;
   146       const Map& _map;
   147       Converter _converter;
   148 
   149     public:
   150       GraphArcMapStorage(const Graph& graph, const Map& map,  
   151 			 const Converter& converter = Converter()) 
   152 	: _graph(graph), _map(map), _converter(converter) {}
   153       virtual ~GraphArcMapStorage() {}
   154 
   155       virtual std::string get(const Item& item) {
   156 	return _converter(_map[_graph.direct(item, dir)]);
   157       }
   158       virtual void sort(std::vector<Item>& items) {
   159 	GraphArcMapLess<Graph, dir, Map> less(_graph, _map);
   160 	std::sort(items.begin(), items.end(), less);
   161       }
   162     };
   163 
   164     class ValueStorageBase {
   165     public:
   166       ValueStorageBase() {}
   167       virtual ~ValueStorageBase() {}
   168 
   169       virtual std::string get() = 0;      
   170     };
   171 
   172     template <typename _Value, typename _Converter = DefaultConverter<_Value> >
   173     class ValueStorage : public ValueStorageBase {
   174     public:
   175       typedef _Value Value;
   176       typedef _Converter Converter;
   177 
   178     private:
   179       const Value& _value;
   180       Converter _converter;
   181 
   182     public:
   183       ValueStorage(const Value& value, const Converter& converter = Converter())
   184  	: _value(value), _converter(converter) {}
   185 
   186       virtual std::string get() {
   187 	return _converter(_value);
   188       }
   189     };
   190 
   191     template <typename Value>
   192     struct MapLookUpConverter {
   193       const std::map<Value, std::string>& _map;
   194       
   195       MapLookUpConverter(const std::map<Value, std::string>& map) 
   196 	: _map(map) {}
   197       
   198       std::string operator()(const Value& str) {
   199 	typename std::map<Value, std::string>::const_iterator it = 
   200 	  _map.find(str);
   201 	if (it == _map.end()) {
   202 	  throw DataFormatError("Item not found");
   203 	}
   204 	return it->second;
   205       }
   206     };
   207 
   208     template <typename Graph>
   209     struct GraphArcLookUpConverter {
   210       const Graph& _graph;
   211       const std::map<typename Graph::Edge, std::string>& _map;
   212       
   213       GraphArcLookUpConverter(const Graph& graph, 
   214 			      const std::map<typename Graph::Edge, 
   215 			                     std::string>& map) 
   216 	: _graph(graph), _map(map) {}
   217       
   218       std::string operator()(const typename Graph::Arc& val) {
   219 	typename std::map<typename Graph::Edge, std::string>
   220 	  ::const_iterator it = _map.find(val);
   221 	if (it == _map.end()) {
   222 	  throw DataFormatError("Item not found");
   223 	}
   224 	return (_graph.direction(val) ? '+' : '-') + it->second;
   225       }
   226     };
   227 
   228     inline bool isWhiteSpace(char c) {
   229       return c == ' ' || c == '\t' || c == '\v' || 
   230         c == '\n' || c == '\r' || c == '\f'; 
   231     }
   232 
   233     inline bool isEscaped(char c) {
   234       return c == '\\' || c == '\"' || c == '\'' || 
   235 	c == '\a' || c == '\b';
   236     }
   237 
   238     inline static void writeEscape(std::ostream& os, char c) {
   239       switch (c) {
   240       case '\\':
   241 	os << "\\\\";
   242 	return;
   243       case '\"':
   244 	os << "\\\"";
   245 	return;
   246       case '\a':
   247 	os << "\\a";
   248 	return;
   249       case '\b':
   250 	os << "\\b";
   251 	return;
   252       case '\f':
   253 	os << "\\f";
   254 	return;
   255       case '\r':
   256 	os << "\\r";
   257 	return;
   258       case '\n':
   259 	os << "\\n";
   260 	return;
   261       case '\t':
   262 	os << "\\t";
   263 	return;
   264       case '\v':
   265 	os << "\\v";
   266 	return;
   267       default:
   268 	if (c < 0x20) {
   269 	  std::ios::fmtflags flags = os.flags();
   270 	  os << '\\' << std::oct << static_cast<int>(c);
   271 	  os.flags(flags);
   272 	} else {
   273 	  os << c;
   274 	}
   275 	return;
   276       }     
   277     }
   278 
   279     inline bool requireEscape(const std::string& str) {
   280       if (str.empty() || str[0] == '@') return true;
   281       std::istringstream is(str);
   282       char c;
   283       while (is.get(c)) {
   284 	if (isWhiteSpace(c) || isEscaped(c)) {
   285 	  return true;
   286 	}
   287       }
   288       return false;
   289     }
   290     
   291     inline std::ostream& writeToken(std::ostream& os, const std::string& str) {
   292 
   293       if (requireEscape(str)) {
   294 	os << '\"';
   295 	for (std::string::const_iterator it = str.begin(); 
   296 	     it != str.end(); ++it) {
   297 	  writeEscape(os, *it);
   298 	}	
   299 	os << '\"';
   300       } else {
   301 	os << str;
   302       }
   303       return os;
   304     }
   305 
   306   }
   307 
   308   template <typename Digraph>
   309   class DigraphWriter;
   310 
   311   template <typename Digraph>
   312   DigraphWriter<Digraph> digraphWriter(std::ostream& os, 
   313 				       const Digraph& digraph);
   314 
   315   template <typename Digraph>
   316   DigraphWriter<Digraph> digraphWriter(const std::string& fn, 
   317 				       const Digraph& digraph);
   318 
   319   template <typename Digraph>
   320   DigraphWriter<Digraph> digraphWriter(const char *fn, 
   321 				       const Digraph& digraph);
   322   
   323   /// \ingroup lemon_io
   324   ///  
   325   /// \brief \ref lgf-format "LGF" writer for directed graphs
   326   ///
   327   /// This utility writes an \ref lgf-format "LGF" file.
   328   ///
   329   /// The writing method does a batch processing. The user creates a
   330   /// writer object, then various writing rules can be added to the
   331   /// writer, and eventually the writing is executed with the \c run()
   332   /// member function. A map writing rule can be added to the writer
   333   /// with the \c nodeMap() or \c arcMap() members. An optional
   334   /// converter parameter can also be added as a standard functor
   335   /// converting from the value type of the map to \c std::string. If it
   336   /// is set, it will determine how the value type of the map is written to
   337   /// the output stream. If the functor is not set, then a default
   338   /// conversion will be used. The \c attribute(), \c node() and \c
   339   /// arc() functions are used to add attribute writing rules.
   340   ///
   341   ///\code
   342   /// DigraphWriter<Digraph>(std::cout, digraph).
   343   ///   nodeMap("coordinates", coord_map).
   344   ///   nodeMap("size", size).
   345   ///   nodeMap("title", title).
   346   ///   arcMap("capacity", cap_map).
   347   ///   node("source", src).
   348   ///   node("target", trg).
   349   ///   attribute("caption", caption).
   350   ///   run();
   351   ///\endcode
   352   ///
   353   ///
   354   /// By default, the writer does not write additional captions to the
   355   /// sections, but they can be give as an optional parameter of
   356   /// the \c nodes(), \c arcs() or \c
   357   /// attributes() functions.
   358   ///
   359   /// The \c skipNodes() and \c skipArcs() functions forbid the
   360   /// writing of the sections. If two arc sections should be written
   361   /// to the output, it can be done in two passes, the first pass
   362   /// writes the node section and the first arc section, then the
   363   /// second pass skips the node section and writes just the arc
   364   /// section to the stream. The output stream can be retrieved with
   365   /// the \c ostream() function, hence the second pass can append its
   366   /// output to the output of the first pass.
   367   template <typename _Digraph>
   368   class DigraphWriter {
   369   public:
   370 
   371     typedef _Digraph Digraph;
   372     TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
   373     
   374   private:
   375 
   376 
   377     std::ostream* _os;
   378     bool local_os;
   379 
   380     const Digraph& _digraph;
   381 
   382     std::string _nodes_caption;
   383     std::string _arcs_caption;
   384     std::string _attributes_caption;
   385     
   386     typedef std::map<Node, std::string> NodeIndex;
   387     NodeIndex _node_index;
   388     typedef std::map<Arc, std::string> ArcIndex;
   389     ArcIndex _arc_index;
   390 
   391     typedef std::vector<std::pair<std::string, 
   392       _writer_bits::MapStorageBase<Node>* > > NodeMaps;    
   393     NodeMaps _node_maps; 
   394 
   395     typedef std::vector<std::pair<std::string, 
   396       _writer_bits::MapStorageBase<Arc>* > >ArcMaps;
   397     ArcMaps _arc_maps;
   398 
   399     typedef std::vector<std::pair<std::string, 
   400       _writer_bits::ValueStorageBase*> > Attributes;
   401     Attributes _attributes;
   402 
   403     bool _skip_nodes;
   404     bool _skip_arcs;
   405 
   406   public:
   407 
   408     /// \brief Constructor
   409     ///
   410     /// Construct a directed graph writer, which writes to the given
   411     /// output stream.
   412     DigraphWriter(std::ostream& is, const Digraph& digraph) 
   413       : _os(&is), local_os(false), _digraph(digraph),
   414 	_skip_nodes(false), _skip_arcs(false) {}
   415 
   416     /// \brief Constructor
   417     ///
   418     /// Construct a directed graph writer, which writes to the given
   419     /// output file.
   420     DigraphWriter(const std::string& fn, const Digraph& digraph) 
   421       : _os(new std::ofstream(fn.c_str())), local_os(true), _digraph(digraph),
   422 	_skip_nodes(false), _skip_arcs(false) {}
   423 
   424     /// \brief Constructor
   425     ///
   426     /// Construct a directed graph writer, which writes to the given
   427     /// output file.
   428     DigraphWriter(const char* fn, const Digraph& digraph) 
   429       : _os(new std::ofstream(fn)), local_os(true), _digraph(digraph),
   430 	_skip_nodes(false), _skip_arcs(false) {}
   431 
   432     /// \brief Destructor
   433     ~DigraphWriter() {
   434       for (typename NodeMaps::iterator it = _node_maps.begin(); 
   435 	   it != _node_maps.end(); ++it) {
   436 	delete it->second;
   437       }
   438 
   439       for (typename ArcMaps::iterator it = _arc_maps.begin(); 
   440 	   it != _arc_maps.end(); ++it) {
   441 	delete it->second;
   442       }
   443 
   444       for (typename Attributes::iterator it = _attributes.begin(); 
   445 	   it != _attributes.end(); ++it) {
   446 	delete it->second;
   447       }
   448 
   449       if (local_os) {
   450 	delete _os;
   451       }
   452     }
   453 
   454   private:
   455 
   456     friend DigraphWriter<Digraph> digraphWriter<>(std::ostream& os, 
   457 						  const Digraph& digraph);
   458     friend DigraphWriter<Digraph> digraphWriter<>(const std::string& fn, 
   459 						  const Digraph& digraph);   
   460     friend DigraphWriter<Digraph> digraphWriter<>(const char *fn, 
   461 						  const Digraph& digraph);
   462 
   463     DigraphWriter(DigraphWriter& other) 
   464       : _os(other._os), local_os(other.local_os), _digraph(other._digraph),
   465 	_skip_nodes(other._skip_nodes), _skip_arcs(other._skip_arcs) {
   466 
   467       other._os = 0;
   468       other.local_os = false;
   469 
   470       _node_index.swap(other._node_index);
   471       _arc_index.swap(other._arc_index);
   472 
   473       _node_maps.swap(other._node_maps);
   474       _arc_maps.swap(other._arc_maps);
   475       _attributes.swap(other._attributes);
   476 
   477       _nodes_caption = other._nodes_caption;
   478       _arcs_caption = other._arcs_caption;
   479       _attributes_caption = other._attributes_caption;
   480     }
   481     
   482     DigraphWriter& operator=(const DigraphWriter&);
   483 
   484   public:
   485 
   486     /// \name Writing rules
   487     /// @{
   488     
   489     /// \brief Node map writing rule
   490     ///
   491     /// Add a node map writing rule to the writer.
   492     template <typename Map>
   493     DigraphWriter& nodeMap(const std::string& caption, const Map& map) {
   494       checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();
   495       _writer_bits::MapStorageBase<Node>* storage = 
   496 	new _writer_bits::MapStorage<Node, Map>(map);
   497       _node_maps.push_back(std::make_pair(caption, storage));
   498       return *this;
   499     }
   500 
   501     /// \brief Node map writing rule
   502     ///
   503     /// Add a node map writing rule with specialized converter to the
   504     /// writer.
   505     template <typename Map, typename Converter>
   506     DigraphWriter& nodeMap(const std::string& caption, const Map& map, 
   507 			   const Converter& converter = Converter()) {
   508       checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();
   509       _writer_bits::MapStorageBase<Node>* storage = 
   510 	new _writer_bits::MapStorage<Node, Map, Converter>(map, converter);
   511       _node_maps.push_back(std::make_pair(caption, storage));
   512       return *this;
   513     }
   514 
   515     /// \brief Arc map writing rule
   516     ///
   517     /// Add an arc map writing rule to the writer.
   518     template <typename Map>
   519     DigraphWriter& arcMap(const std::string& caption, const Map& map) {
   520       checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();
   521       _writer_bits::MapStorageBase<Arc>* storage = 
   522 	new _writer_bits::MapStorage<Arc, Map>(map);
   523       _arc_maps.push_back(std::make_pair(caption, storage));
   524       return *this;
   525     }
   526 
   527     /// \brief Arc map writing rule
   528     ///
   529     /// Add an arc map writing rule with specialized converter to the
   530     /// writer.
   531     template <typename Map, typename Converter>
   532     DigraphWriter& arcMap(const std::string& caption, const Map& map, 
   533 			  const Converter& converter = Converter()) {
   534       checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();
   535       _writer_bits::MapStorageBase<Arc>* storage = 
   536 	new _writer_bits::MapStorage<Arc, Map, Converter>(map, converter);
   537       _arc_maps.push_back(std::make_pair(caption, storage));
   538       return *this;
   539     }
   540 
   541     /// \brief Attribute writing rule
   542     ///
   543     /// Add an attribute writing rule to the writer.
   544     template <typename Value>
   545     DigraphWriter& attribute(const std::string& caption, const Value& value) {
   546       _writer_bits::ValueStorageBase* storage = 
   547 	new _writer_bits::ValueStorage<Value>(value);
   548       _attributes.push_back(std::make_pair(caption, storage));
   549       return *this;
   550     }
   551 
   552     /// \brief Attribute writing rule
   553     ///
   554     /// Add an attribute writing rule with specialized converter to the
   555     /// writer.
   556     template <typename Value, typename Converter>
   557     DigraphWriter& attribute(const std::string& caption, const Value& value, 
   558 			     const Converter& converter = Converter()) {
   559       _writer_bits::ValueStorageBase* storage = 
   560 	new _writer_bits::ValueStorage<Value, Converter>(value, converter);
   561       _attributes.push_back(std::make_pair(caption, storage));
   562       return *this;
   563     }
   564 
   565     /// \brief Node writing rule
   566     ///
   567     /// Add a node writing rule to the writer.
   568     DigraphWriter& node(const std::string& caption, const Node& node) {
   569       typedef _writer_bits::MapLookUpConverter<Node> Converter;
   570       Converter converter(_node_index);
   571       _writer_bits::ValueStorageBase* storage = 
   572 	new _writer_bits::ValueStorage<Node, Converter>(node, converter);
   573       _attributes.push_back(std::make_pair(caption, storage));
   574       return *this;
   575     }
   576 
   577     /// \brief Arc writing rule
   578     ///
   579     /// Add an arc writing rule to writer.
   580     DigraphWriter& arc(const std::string& caption, const Arc& arc) {
   581       typedef _writer_bits::MapLookUpConverter<Arc> Converter;
   582       Converter converter(_arc_index);
   583       _writer_bits::ValueStorageBase* storage = 
   584 	new _writer_bits::ValueStorage<Arc, Converter>(arc, converter);
   585       _attributes.push_back(std::make_pair(caption, storage));
   586       return *this;
   587     }
   588 
   589     /// \name Section captions
   590     /// @{
   591 
   592     /// \brief Add an additional caption to the \c \@nodes section
   593     ///
   594     /// Add an additional caption to the \c \@nodes section.
   595     DigraphWriter& nodes(const std::string& caption) {
   596       _nodes_caption = caption;
   597       return *this;
   598     }
   599 
   600     /// \brief Add an additional caption to the \c \@arcs section
   601     ///
   602     /// Add an additional caption to the \c \@arcs section.
   603     DigraphWriter& arcs(const std::string& caption) {
   604       _arcs_caption = caption;
   605       return *this;
   606     }
   607 
   608     /// \brief Add an additional caption to the \c \@attributes section
   609     ///
   610     /// Add an additional caption to the \c \@attributes section.
   611     DigraphWriter& attributes(const std::string& caption) {
   612       _attributes_caption = caption;
   613       return *this;
   614     }
   615 
   616     /// \name Skipping section
   617     /// @{
   618 
   619     /// \brief Skip writing the node set
   620     ///
   621     /// The \c \@nodes section will not be written to the stream.
   622     DigraphWriter& skipNodes() {
   623       LEMON_ASSERT(!_skip_nodes, "Multiple usage of skipNodes() member");
   624       _skip_nodes = true;
   625       return *this;
   626     }
   627 
   628     /// \brief Skip writing arc set
   629     ///
   630     /// The \c \@arcs section will not be written to the stream.
   631     DigraphWriter& skipArcs() {
   632       LEMON_ASSERT(!_skip_arcs, "Multiple usage of skipArcs() member");
   633       _skip_arcs = true;
   634       return *this;
   635     }
   636 
   637     /// @}
   638 
   639   private:
   640 
   641     void writeNodes() {
   642       _writer_bits::MapStorageBase<Node>* label = 0;
   643       for (typename NodeMaps::iterator it = _node_maps.begin();
   644 	   it != _node_maps.end(); ++it) {
   645         if (it->first == "label") {
   646 	  label = it->second;
   647 	  break;
   648 	}
   649       }
   650 
   651       *_os << "@nodes";
   652       if (!_nodes_caption.empty()) {
   653 	_writer_bits::writeToken(*_os << ' ', _nodes_caption);
   654       }
   655       *_os << std::endl;
   656 
   657       if (label == 0) {
   658 	*_os << "label" << '\t';
   659       }
   660       for (typename NodeMaps::iterator it = _node_maps.begin();
   661 	   it != _node_maps.end(); ++it) {
   662 	_writer_bits::writeToken(*_os, it->first) << '\t';
   663       }
   664       *_os << std::endl;
   665 
   666       std::vector<Node> nodes;
   667       for (NodeIt n(_digraph); n != INVALID; ++n) {
   668 	nodes.push_back(n);
   669       }
   670       
   671       if (label == 0) {
   672 	IdMap<Digraph, Node> id_map(_digraph);
   673 	_writer_bits::MapLess<IdMap<Digraph, Node> > id_less(id_map);
   674 	std::sort(nodes.begin(), nodes.end(), id_less);
   675       } else {
   676 	label->sort(nodes);
   677       }
   678 
   679       for (int i = 0; i < static_cast<int>(nodes.size()); ++i) {
   680 	Node n = nodes[i];
   681 	if (label == 0) {
   682 	  std::ostringstream os;
   683 	  os << _digraph.id(n);
   684 	  _writer_bits::writeToken(*_os, os.str());
   685 	  *_os << '\t';
   686 	  _node_index.insert(std::make_pair(n, os.str()));
   687 	}
   688 	for (typename NodeMaps::iterator it = _node_maps.begin();
   689 	     it != _node_maps.end(); ++it) {
   690 	  std::string value = it->second->get(n);
   691 	  _writer_bits::writeToken(*_os, value);
   692 	  if (it->first == "label") {
   693 	    _node_index.insert(std::make_pair(n, value));
   694 	  }
   695 	  *_os << '\t';
   696 	}
   697 	*_os << std::endl;
   698       }
   699     }
   700 
   701     void createNodeIndex() {
   702       _writer_bits::MapStorageBase<Node>* label = 0;
   703       for (typename NodeMaps::iterator it = _node_maps.begin();
   704 	   it != _node_maps.end(); ++it) {
   705         if (it->first == "label") {
   706 	  label = it->second;
   707 	  break;
   708 	}
   709       }
   710 
   711       if (label == 0) {
   712 	for (NodeIt n(_digraph); n != INVALID; ++n) {
   713 	  std::ostringstream os;
   714 	  os << _digraph.id(n);
   715 	  _node_index.insert(std::make_pair(n, os.str()));	  
   716 	}	
   717       } else {
   718 	for (NodeIt n(_digraph); n != INVALID; ++n) {
   719 	  std::string value = label->get(n);	  
   720 	  _node_index.insert(std::make_pair(n, value));
   721 	}
   722       }
   723     }
   724 
   725     void writeArcs() {
   726       _writer_bits::MapStorageBase<Arc>* label = 0;
   727       for (typename ArcMaps::iterator it = _arc_maps.begin();
   728 	   it != _arc_maps.end(); ++it) {
   729         if (it->first == "label") {
   730 	  label = it->second;
   731 	  break;
   732 	}
   733       }
   734 
   735       *_os << "@arcs";
   736       if (!_arcs_caption.empty()) {
   737 	_writer_bits::writeToken(*_os << ' ', _arcs_caption);
   738       }
   739       *_os << std::endl;
   740 
   741       *_os << '\t' << '\t';
   742       if (label == 0) {
   743 	*_os << "label" << '\t';
   744       }
   745       for (typename ArcMaps::iterator it = _arc_maps.begin();
   746 	   it != _arc_maps.end(); ++it) {
   747 	_writer_bits::writeToken(*_os, it->first) << '\t';
   748       }
   749       *_os << std::endl;
   750 
   751       std::vector<Arc> arcs;
   752       for (ArcIt n(_digraph); n != INVALID; ++n) {
   753 	arcs.push_back(n);
   754       }
   755       
   756       if (label == 0) {
   757 	IdMap<Digraph, Arc> id_map(_digraph);
   758 	_writer_bits::MapLess<IdMap<Digraph, Arc> > id_less(id_map);
   759 	std::sort(arcs.begin(), arcs.end(), id_less);
   760       } else {
   761 	label->sort(arcs);
   762       }
   763 
   764       for (int i = 0; i < static_cast<int>(arcs.size()); ++i) {
   765 	Arc a = arcs[i];
   766 	_writer_bits::writeToken(*_os, _node_index.
   767 				 find(_digraph.source(a))->second);
   768 	*_os << '\t';
   769 	_writer_bits::writeToken(*_os, _node_index.
   770 				 find(_digraph.target(a))->second);
   771 	*_os << '\t';
   772 	if (label == 0) {
   773 	  std::ostringstream os;
   774 	  os << _digraph.id(a);
   775 	  _writer_bits::writeToken(*_os, os.str());
   776 	  *_os << '\t';
   777 	  _arc_index.insert(std::make_pair(a, os.str()));
   778 	}
   779 	for (typename ArcMaps::iterator it = _arc_maps.begin();
   780 	     it != _arc_maps.end(); ++it) {
   781 	  std::string value = it->second->get(a);
   782 	  _writer_bits::writeToken(*_os, value);
   783 	  if (it->first == "label") {
   784 	    _arc_index.insert(std::make_pair(a, value));
   785 	  }
   786 	  *_os << '\t';
   787 	}
   788 	*_os << std::endl;
   789       }
   790     }
   791 
   792     void createArcIndex() {
   793       _writer_bits::MapStorageBase<Arc>* label = 0;
   794       for (typename ArcMaps::iterator it = _arc_maps.begin();
   795 	   it != _arc_maps.end(); ++it) {
   796         if (it->first == "label") {
   797 	  label = it->second;
   798 	  break;
   799 	}
   800       }
   801 
   802       if (label == 0) {
   803 	for (ArcIt a(_digraph); a != INVALID; ++a) {
   804 	  std::ostringstream os;
   805 	  os << _digraph.id(a);
   806 	  _arc_index.insert(std::make_pair(a, os.str()));	  
   807 	}	
   808       } else {
   809 	for (ArcIt a(_digraph); a != INVALID; ++a) {
   810 	  std::string value = label->get(a);	  
   811 	  _arc_index.insert(std::make_pair(a, value));
   812 	}
   813       }
   814     }
   815 
   816     void writeAttributes() {
   817       if (_attributes.empty()) return;
   818       *_os << "@attributes";
   819       if (!_attributes_caption.empty()) {
   820 	_writer_bits::writeToken(*_os << ' ', _attributes_caption);
   821       }
   822       *_os << std::endl;
   823       for (typename Attributes::iterator it = _attributes.begin();
   824 	   it != _attributes.end(); ++it) {
   825 	_writer_bits::writeToken(*_os, it->first) << ' ';
   826 	_writer_bits::writeToken(*_os, it->second->get());
   827 	*_os << std::endl;
   828       }
   829     }
   830     
   831   public:
   832     
   833     /// \name Execution of the writer    
   834     /// @{
   835 
   836     /// \brief Start the batch processing
   837     ///
   838     /// This function starts the batch processing.
   839     void run() {
   840       if (!_skip_nodes) {
   841 	writeNodes();
   842       } else {
   843 	createNodeIndex();
   844       }
   845       if (!_skip_arcs) {      
   846 	writeArcs();
   847       } else {
   848 	createArcIndex();
   849       }
   850       writeAttributes();
   851     }
   852 
   853     /// \brief Give back the stream of the writer
   854     ///
   855     /// Give back the stream of the writer.
   856     std::ostream& ostream() {
   857       return *_os;
   858     }
   859 
   860     /// @}
   861   };
   862 
   863   /// \brief Return a \ref DigraphWriter class
   864   /// 
   865   /// This function just returns a \ref DigraphWriter class.
   866   /// \relates DigraphWriter
   867   template <typename Digraph>
   868   DigraphWriter<Digraph> digraphWriter(std::ostream& os, 
   869 				       const Digraph& digraph) {
   870     DigraphWriter<Digraph> tmp(os, digraph);
   871     return tmp;
   872   }
   873 
   874   /// \brief Return a \ref DigraphWriter class
   875   /// 
   876   /// This function just returns a \ref DigraphWriter class.
   877   /// \relates DigraphWriter
   878   template <typename Digraph>
   879   DigraphWriter<Digraph> digraphWriter(const std::string& fn, 
   880 				       const Digraph& digraph) {
   881     DigraphWriter<Digraph> tmp(fn, digraph);
   882     return tmp;
   883   }
   884 
   885   /// \brief Return a \ref DigraphWriter class
   886   /// 
   887   /// This function just returns a \ref DigraphWriter class.
   888   /// \relates DigraphWriter
   889   template <typename Digraph>
   890   DigraphWriter<Digraph> digraphWriter(const char* fn, 
   891 				       const Digraph& digraph) {
   892     DigraphWriter<Digraph> tmp(fn, digraph);
   893     return tmp;
   894   }
   895 
   896   template <typename Graph>
   897   class GraphWriter;
   898 
   899   template <typename Graph>
   900   GraphWriter<Graph> graphWriter(std::ostream& os, const Graph& graph);    
   901 
   902   template <typename Graph>
   903   GraphWriter<Graph> graphWriter(const std::string& fn, const Graph& graph);   
   904 
   905   template <typename Graph>
   906   GraphWriter<Graph> graphWriter(const char *fn, const Graph& graph);    
   907 
   908   /// \ingroup lemon_io
   909   ///  
   910   /// \brief \ref lgf-format "LGF" writer for directed graphs
   911   ///
   912   /// This utility writes an \ref lgf-format "LGF" file.
   913   ///
   914   /// It can be used almost the same way as \c DigraphWriter.
   915   /// The only difference is that this class can handle edges and
   916   /// edge maps as well as arcs and arc maps.
   917   template <typename _Graph>
   918   class GraphWriter {
   919   public:
   920 
   921     typedef _Graph Graph;
   922     TEMPLATE_GRAPH_TYPEDEFS(Graph);
   923     
   924   private:
   925 
   926 
   927     std::ostream* _os;
   928     bool local_os;
   929 
   930     Graph& _graph;
   931 
   932     std::string _nodes_caption;
   933     std::string _edges_caption;
   934     std::string _attributes_caption;
   935     
   936     typedef std::map<Node, std::string> NodeIndex;
   937     NodeIndex _node_index;
   938     typedef std::map<Edge, std::string> EdgeIndex;
   939     EdgeIndex _edge_index;
   940 
   941     typedef std::vector<std::pair<std::string, 
   942       _writer_bits::MapStorageBase<Node>* > > NodeMaps;    
   943     NodeMaps _node_maps; 
   944 
   945     typedef std::vector<std::pair<std::string, 
   946       _writer_bits::MapStorageBase<Edge>* > >EdgeMaps;
   947     EdgeMaps _edge_maps;
   948 
   949     typedef std::vector<std::pair<std::string, 
   950       _writer_bits::ValueStorageBase*> > Attributes;
   951     Attributes _attributes;
   952 
   953     bool _skip_nodes;
   954     bool _skip_edges;
   955 
   956   public:
   957 
   958     /// \brief Constructor
   959     ///
   960     /// Construct a directed graph writer, which writes to the given
   961     /// output stream.
   962     GraphWriter(std::ostream& is, const Graph& graph) 
   963       : _os(&is), local_os(false), _graph(graph),
   964 	_skip_nodes(false), _skip_edges(false) {}
   965 
   966     /// \brief Constructor
   967     ///
   968     /// Construct a directed graph writer, which writes to the given
   969     /// output file.
   970     GraphWriter(const std::string& fn, const Graph& graph) 
   971       : _os(new std::ofstream(fn.c_str())), local_os(true), _graph(graph),
   972 	_skip_nodes(false), _skip_edges(false) {}
   973 
   974     /// \brief Constructor
   975     ///
   976     /// Construct a directed graph writer, which writes to the given
   977     /// output file.
   978     GraphWriter(const char* fn, const Graph& graph) 
   979       : _os(new std::ofstream(fn)), local_os(true), _graph(graph),
   980 	_skip_nodes(false), _skip_edges(false) {}
   981 
   982     /// \brief Destructor
   983     ~GraphWriter() {
   984       for (typename NodeMaps::iterator it = _node_maps.begin(); 
   985 	   it != _node_maps.end(); ++it) {
   986 	delete it->second;
   987       }
   988 
   989       for (typename EdgeMaps::iterator it = _edge_maps.begin(); 
   990 	   it != _edge_maps.end(); ++it) {
   991 	delete it->second;
   992       }
   993 
   994       for (typename Attributes::iterator it = _attributes.begin(); 
   995 	   it != _attributes.end(); ++it) {
   996 	delete it->second;
   997       }
   998 
   999       if (local_os) {
  1000 	delete _os;
  1001       }
  1002     }
  1003     
  1004   private:
  1005 
  1006     friend GraphWriter<Graph> graphWriter<>(std::ostream& os, 
  1007 					    const Graph& graph);    
  1008     friend GraphWriter<Graph> graphWriter<>(const std::string& fn, 
  1009 					    const Graph& graph);   
  1010     friend GraphWriter<Graph> graphWriter<>(const char *fn, 
  1011 					    const Graph& graph);    
  1012 
  1013     GraphWriter(GraphWriter& other) 
  1014       : _os(other._os), local_os(other.local_os), _graph(other._graph),
  1015 	_skip_nodes(other._skip_nodes), _skip_edges(other._skip_edges) {
  1016 
  1017       other._os = 0;
  1018       other.local_os = false;
  1019 
  1020       _node_index.swap(other._node_index);
  1021       _edge_index.swap(other._edge_index);
  1022 
  1023       _node_maps.swap(other._node_maps);
  1024       _edge_maps.swap(other._edge_maps);
  1025       _attributes.swap(other._attributes);
  1026 
  1027       _nodes_caption = other._nodes_caption;
  1028       _edges_caption = other._edges_caption;
  1029       _attributes_caption = other._attributes_caption;
  1030     }
  1031 
  1032     GraphWriter& operator=(const GraphWriter&);
  1033 
  1034   public:
  1035 
  1036     /// \name Writing rules
  1037     /// @{
  1038     
  1039     /// \brief Node map writing rule
  1040     ///
  1041     /// Add a node map writing rule to the writer.
  1042     template <typename Map>
  1043     GraphWriter& nodeMap(const std::string& caption, const Map& map) {
  1044       checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();
  1045       _writer_bits::MapStorageBase<Node>* storage = 
  1046 	new _writer_bits::MapStorage<Node, Map>(map);
  1047       _node_maps.push_back(std::make_pair(caption, storage));
  1048       return *this;
  1049     }
  1050 
  1051     /// \brief Node map writing rule
  1052     ///
  1053     /// Add a node map writing rule with specialized converter to the
  1054     /// writer.
  1055     template <typename Map, typename Converter>
  1056     GraphWriter& nodeMap(const std::string& caption, const Map& map, 
  1057 			   const Converter& converter = Converter()) {
  1058       checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();
  1059       _writer_bits::MapStorageBase<Node>* storage = 
  1060 	new _writer_bits::MapStorage<Node, Map, Converter>(map, converter);
  1061       _node_maps.push_back(std::make_pair(caption, storage));
  1062       return *this;
  1063     }
  1064 
  1065     /// \brief Edge map writing rule
  1066     ///
  1067     /// Add an edge map writing rule to the writer.
  1068     template <typename Map>
  1069     GraphWriter& edgeMap(const std::string& caption, const Map& map) {
  1070       checkConcept<concepts::ReadMap<Edge, typename Map::Value>, Map>();
  1071       _writer_bits::MapStorageBase<Edge>* storage = 
  1072 	new _writer_bits::MapStorage<Edge, Map>(map);
  1073       _edge_maps.push_back(std::make_pair(caption, storage));
  1074       return *this;
  1075     }
  1076 
  1077     /// \brief Edge map writing rule
  1078     ///
  1079     /// Add an edge map writing rule with specialized converter to the
  1080     /// writer.
  1081     template <typename Map, typename Converter>
  1082     GraphWriter& edgeMap(const std::string& caption, const Map& map, 
  1083 			  const Converter& converter = Converter()) {
  1084       checkConcept<concepts::ReadMap<Edge, typename Map::Value>, Map>();
  1085       _writer_bits::MapStorageBase<Edge>* storage = 
  1086 	new _writer_bits::MapStorage<Edge, Map, Converter>(map, converter);
  1087       _edge_maps.push_back(std::make_pair(caption, storage));
  1088       return *this;
  1089     }
  1090 
  1091     /// \brief Arc map writing rule
  1092     ///
  1093     /// Add an arc map writing rule to the writer.
  1094     template <typename Map>
  1095     GraphWriter& arcMap(const std::string& caption, const Map& map) {
  1096       checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();
  1097       _writer_bits::MapStorageBase<Edge>* forward_storage = 
  1098 	new _writer_bits::GraphArcMapStorage<Graph, true, Map>(_graph, map);
  1099       _edge_maps.push_back(std::make_pair('+' + caption, forward_storage));
  1100       _writer_bits::MapStorageBase<Edge>* backward_storage = 
  1101 	new _writer_bits::GraphArcMapStorage<Graph, false, Map>(_graph, map);
  1102       _edge_maps.push_back(std::make_pair('-' + caption, backward_storage));
  1103       return *this;
  1104     }
  1105 
  1106     /// \brief Arc map writing rule
  1107     ///
  1108     /// Add an arc map writing rule with specialized converter to the
  1109     /// writer.
  1110     template <typename Map, typename Converter>
  1111     GraphWriter& arcMap(const std::string& caption, const Map& map, 
  1112 			  const Converter& converter = Converter()) {
  1113       checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();
  1114       _writer_bits::MapStorageBase<Edge>* forward_storage = 
  1115 	new _writer_bits::GraphArcMapStorage<Graph, true, Map, Converter>
  1116 	(_graph, map, converter);
  1117       _edge_maps.push_back(std::make_pair('+' + caption, forward_storage));
  1118       _writer_bits::MapStorageBase<Edge>* backward_storage = 
  1119 	new _writer_bits::GraphArcMapStorage<Graph, false, Map, Converter>
  1120 	(_graph, map, converter);
  1121       _edge_maps.push_back(std::make_pair('-' + caption, backward_storage));
  1122       return *this;
  1123     }
  1124 
  1125     /// \brief Attribute writing rule
  1126     ///
  1127     /// Add an attribute writing rule to the writer.
  1128     template <typename Value>
  1129     GraphWriter& attribute(const std::string& caption, const Value& value) {
  1130       _writer_bits::ValueStorageBase* storage = 
  1131 	new _writer_bits::ValueStorage<Value>(value);
  1132       _attributes.push_back(std::make_pair(caption, storage));
  1133       return *this;
  1134     }
  1135 
  1136     /// \brief Attribute writing rule
  1137     ///
  1138     /// Add an attribute writing rule with specialized converter to the
  1139     /// writer.
  1140     template <typename Value, typename Converter>
  1141     GraphWriter& attribute(const std::string& caption, const Value& value, 
  1142 			     const Converter& converter = Converter()) {
  1143       _writer_bits::ValueStorageBase* storage = 
  1144 	new _writer_bits::ValueStorage<Value, Converter>(value, converter);
  1145       _attributes.push_back(std::make_pair(caption, storage));
  1146       return *this;
  1147     }
  1148 
  1149     /// \brief Node writing rule
  1150     ///
  1151     /// Add a node writing rule to the writer.
  1152     GraphWriter& node(const std::string& caption, const Node& node) {
  1153       typedef _writer_bits::MapLookUpConverter<Node> Converter;
  1154       Converter converter(_node_index);
  1155       _writer_bits::ValueStorageBase* storage = 
  1156 	new _writer_bits::ValueStorage<Node, Converter>(node, converter);
  1157       _attributes.push_back(std::make_pair(caption, storage));
  1158       return *this;
  1159     }
  1160 
  1161     /// \brief Edge writing rule
  1162     ///
  1163     /// Add an edge writing rule to writer.
  1164     GraphWriter& edge(const std::string& caption, const Edge& edge) {
  1165       typedef _writer_bits::MapLookUpConverter<Edge> Converter;
  1166       Converter converter(_edge_index);
  1167       _writer_bits::ValueStorageBase* storage = 
  1168 	new _writer_bits::ValueStorage<Edge, Converter>(edge, converter);
  1169       _attributes.push_back(std::make_pair(caption, storage));
  1170       return *this;
  1171     }
  1172 
  1173     /// \brief Arc writing rule
  1174     ///
  1175     /// Add an arc writing rule to writer.
  1176     GraphWriter& arc(const std::string& caption, const Arc& arc) {
  1177       typedef _writer_bits::GraphArcLookUpConverter<Graph> Converter;
  1178       Converter converter(_graph, _edge_index);
  1179       _writer_bits::ValueStorageBase* storage = 
  1180 	new _writer_bits::ValueStorage<Arc, Converter>(arc, converter);
  1181       _attributes.push_back(std::make_pair(caption, storage));
  1182       return *this;
  1183     }
  1184 
  1185     /// \name Section captions
  1186     /// @{
  1187 
  1188     /// \brief Add an additional caption to the \c \@nodes section
  1189     ///
  1190     /// Add an additional caption to the \c \@nodes section.
  1191     GraphWriter& nodes(const std::string& caption) {
  1192       _nodes_caption = caption;
  1193       return *this;
  1194     }
  1195 
  1196     /// \brief Add an additional caption to the \c \@arcs section
  1197     ///
  1198     /// Add an additional caption to the \c \@arcs section.
  1199     GraphWriter& edges(const std::string& caption) {
  1200       _edges_caption = caption;
  1201       return *this;
  1202     }
  1203 
  1204     /// \brief Add an additional caption to the \c \@attributes section
  1205     ///
  1206     /// Add an additional caption to the \c \@attributes section.
  1207     GraphWriter& attributes(const std::string& caption) {
  1208       _attributes_caption = caption;
  1209       return *this;
  1210     }
  1211 
  1212     /// \name Skipping section
  1213     /// @{
  1214 
  1215     /// \brief Skip writing the node set
  1216     ///
  1217     /// The \c \@nodes section will not be written to the stream.
  1218     GraphWriter& skipNodes() {
  1219       LEMON_ASSERT(!_skip_nodes, "Multiple usage of skipNodes() member");
  1220       _skip_nodes = true;
  1221       return *this;
  1222     }
  1223 
  1224     /// \brief Skip writing edge set
  1225     ///
  1226     /// The \c \@edges section will not be written to the stream.
  1227     GraphWriter& skipEdges() {
  1228       LEMON_ASSERT(!_skip_edges, "Multiple usage of skipEdges() member");
  1229       _skip_edges = true;
  1230       return *this;
  1231     }
  1232 
  1233     /// @}
  1234 
  1235   private:
  1236 
  1237     void writeNodes() {
  1238       _writer_bits::MapStorageBase<Node>* label = 0;
  1239       for (typename NodeMaps::iterator it = _node_maps.begin();
  1240 	   it != _node_maps.end(); ++it) {
  1241         if (it->first == "label") {
  1242 	  label = it->second;
  1243 	  break;
  1244 	}
  1245       }
  1246 
  1247       *_os << "@nodes";
  1248       if (!_nodes_caption.empty()) {
  1249 	_writer_bits::writeToken(*_os << ' ', _nodes_caption);
  1250       }
  1251       *_os << std::endl;
  1252 
  1253       if (label == 0) {
  1254 	*_os << "label" << '\t';
  1255       }
  1256       for (typename NodeMaps::iterator it = _node_maps.begin();
  1257 	   it != _node_maps.end(); ++it) {
  1258 	_writer_bits::writeToken(*_os, it->first) << '\t';
  1259       }
  1260       *_os << std::endl;
  1261 
  1262       std::vector<Node> nodes;
  1263       for (NodeIt n(_graph); n != INVALID; ++n) {
  1264 	nodes.push_back(n);
  1265       }
  1266       
  1267       if (label == 0) {
  1268 	IdMap<Graph, Node> id_map(_graph);
  1269 	_writer_bits::MapLess<IdMap<Graph, Node> > id_less(id_map);
  1270 	std::sort(nodes.begin(), nodes.end(), id_less);
  1271       } else {
  1272 	label->sort(nodes);
  1273       }
  1274 
  1275       for (int i = 0; i < static_cast<int>(nodes.size()); ++i) {
  1276 	Node n = nodes[i];
  1277 	if (label == 0) {
  1278 	  std::ostringstream os;
  1279 	  os << _graph.id(n);
  1280 	  _writer_bits::writeToken(*_os, os.str());
  1281 	  *_os << '\t';
  1282 	  _node_index.insert(std::make_pair(n, os.str()));
  1283 	}
  1284 	for (typename NodeMaps::iterator it = _node_maps.begin();
  1285 	     it != _node_maps.end(); ++it) {
  1286 	  std::string value = it->second->get(n);
  1287 	  _writer_bits::writeToken(*_os, value);
  1288 	  if (it->first == "label") {
  1289 	    _node_index.insert(std::make_pair(n, value));
  1290 	  }
  1291 	  *_os << '\t';
  1292 	}
  1293 	*_os << std::endl;
  1294       }
  1295     }
  1296 
  1297     void createNodeIndex() {
  1298       _writer_bits::MapStorageBase<Node>* label = 0;
  1299       for (typename NodeMaps::iterator it = _node_maps.begin();
  1300 	   it != _node_maps.end(); ++it) {
  1301         if (it->first == "label") {
  1302 	  label = it->second;
  1303 	  break;
  1304 	}
  1305       }
  1306 
  1307       if (label == 0) {
  1308 	for (NodeIt n(_graph); n != INVALID; ++n) {
  1309 	  std::ostringstream os;
  1310 	  os << _graph.id(n);
  1311 	  _node_index.insert(std::make_pair(n, os.str()));	  
  1312 	}	
  1313       } else {
  1314 	for (NodeIt n(_graph); n != INVALID; ++n) {
  1315 	  std::string value = label->get(n);	  
  1316 	  _node_index.insert(std::make_pair(n, value));
  1317 	}
  1318       }
  1319     }
  1320 
  1321     void writeEdges() {
  1322       _writer_bits::MapStorageBase<Edge>* label = 0;
  1323       for (typename EdgeMaps::iterator it = _edge_maps.begin();
  1324 	   it != _edge_maps.end(); ++it) {
  1325         if (it->first == "label") {
  1326 	  label = it->second;
  1327 	  break;
  1328 	}
  1329       }
  1330 
  1331       *_os << "@edges";
  1332       if (!_edges_caption.empty()) {
  1333 	_writer_bits::writeToken(*_os << ' ', _edges_caption);
  1334       }
  1335       *_os << std::endl;
  1336 
  1337       *_os << '\t' << '\t';
  1338       if (label == 0) {
  1339 	*_os << "label" << '\t';
  1340       }
  1341       for (typename EdgeMaps::iterator it = _edge_maps.begin();
  1342 	   it != _edge_maps.end(); ++it) {
  1343 	_writer_bits::writeToken(*_os, it->first) << '\t';
  1344       }
  1345       *_os << std::endl;
  1346 
  1347       std::vector<Edge> edges;
  1348       for (EdgeIt n(_graph); n != INVALID; ++n) {
  1349 	edges.push_back(n);
  1350       }
  1351       
  1352       if (label == 0) {
  1353 	IdMap<Graph, Edge> id_map(_graph);
  1354 	_writer_bits::MapLess<IdMap<Graph, Edge> > id_less(id_map);
  1355 	std::sort(edges.begin(), edges.end(), id_less);
  1356       } else {
  1357 	label->sort(edges);
  1358       }
  1359 
  1360       for (int i = 0; i < static_cast<int>(edges.size()); ++i) {
  1361 	Edge e = edges[i];
  1362 	_writer_bits::writeToken(*_os, _node_index.
  1363 				 find(_graph.u(e))->second);
  1364 	*_os << '\t';
  1365 	_writer_bits::writeToken(*_os, _node_index.
  1366 				 find(_graph.v(e))->second);
  1367 	*_os << '\t';
  1368 	if (label == 0) {
  1369 	  std::ostringstream os;
  1370 	  os << _graph.id(e);
  1371 	  _writer_bits::writeToken(*_os, os.str());
  1372 	  *_os << '\t';
  1373 	  _edge_index.insert(std::make_pair(e, os.str()));
  1374 	}
  1375 	for (typename EdgeMaps::iterator it = _edge_maps.begin();
  1376 	     it != _edge_maps.end(); ++it) {
  1377 	  std::string value = it->second->get(e);
  1378 	  _writer_bits::writeToken(*_os, value);
  1379 	  if (it->first == "label") {
  1380 	    _edge_index.insert(std::make_pair(e, value));
  1381 	  }
  1382 	  *_os << '\t';
  1383 	}
  1384 	*_os << std::endl;
  1385       }
  1386     }
  1387 
  1388     void createEdgeIndex() {
  1389       _writer_bits::MapStorageBase<Edge>* label = 0;
  1390       for (typename EdgeMaps::iterator it = _edge_maps.begin();
  1391 	   it != _edge_maps.end(); ++it) {
  1392         if (it->first == "label") {
  1393 	  label = it->second;
  1394 	  break;
  1395 	}
  1396       }
  1397 
  1398       if (label == 0) {
  1399 	for (EdgeIt e(_graph); e != INVALID; ++e) {
  1400 	  std::ostringstream os;
  1401 	  os << _graph.id(e);
  1402 	  _edge_index.insert(std::make_pair(e, os.str()));	  
  1403 	}	
  1404       } else {
  1405 	for (EdgeIt e(_graph); e != INVALID; ++e) {
  1406 	  std::string value = label->get(e);	  
  1407 	  _edge_index.insert(std::make_pair(e, value));
  1408 	}
  1409       }
  1410     }
  1411 
  1412     void writeAttributes() {
  1413       if (_attributes.empty()) return;
  1414       *_os << "@attributes";
  1415       if (!_attributes_caption.empty()) {
  1416 	_writer_bits::writeToken(*_os << ' ', _attributes_caption);
  1417       }
  1418       *_os << std::endl;
  1419       for (typename Attributes::iterator it = _attributes.begin();
  1420 	   it != _attributes.end(); ++it) {
  1421 	_writer_bits::writeToken(*_os, it->first) << ' ';
  1422 	_writer_bits::writeToken(*_os, it->second->get());
  1423 	*_os << std::endl;
  1424       }
  1425     }
  1426     
  1427   public:
  1428     
  1429     /// \name Execution of the writer    
  1430     /// @{
  1431 
  1432     /// \brief Start the batch processing
  1433     ///
  1434     /// This function starts the batch processing.
  1435     void run() {
  1436       if (!_skip_nodes) {
  1437 	writeNodes();
  1438       } else {
  1439 	createNodeIndex();
  1440       }
  1441       if (!_skip_edges) {      
  1442 	writeEdges();
  1443       } else {
  1444 	createEdgeIndex();
  1445       }
  1446       writeAttributes();
  1447     }
  1448 
  1449     /// \brief Give back the stream of the writer
  1450     ///
  1451     /// Give back the stream of the writer
  1452     std::ostream& ostream() {
  1453       return *_os;
  1454     }
  1455 
  1456     /// @}
  1457   };
  1458 
  1459   /// \brief Return a \ref GraphWriter class
  1460   /// 
  1461   /// This function just returns a \ref GraphWriter class.
  1462   /// \relates GraphWriter
  1463   template <typename Graph>
  1464   GraphWriter<Graph> graphWriter(std::ostream& os, const Graph& graph) {
  1465     GraphWriter<Graph> tmp(os, graph);
  1466     return tmp;
  1467   }
  1468 
  1469   /// \brief Return a \ref GraphWriter class
  1470   /// 
  1471   /// This function just returns a \ref GraphWriter class.
  1472   /// \relates GraphWriter
  1473   template <typename Graph>
  1474   GraphWriter<Graph> graphWriter(const std::string& fn, const Graph& graph) {
  1475     GraphWriter<Graph> tmp(fn, graph);
  1476     return tmp;
  1477   }
  1478 
  1479   /// \brief Return a \ref GraphWriter class
  1480   /// 
  1481   /// This function just returns a \ref GraphWriter class.
  1482   /// \relates GraphWriter
  1483   template <typename Graph>
  1484   GraphWriter<Graph> graphWriter(const char* fn, const Graph& graph) {
  1485     GraphWriter<Graph> tmp(fn, graph);
  1486     return tmp;
  1487   }
  1488 }
  1489 
  1490 #endif