/* -*- C++ -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2003-2008

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

///\ingroup lemon_io

///\file

///\brief Lemon Graph Format reader.

#ifndef LEMON_LGF_READER_H

#define LEMON_LGF_READER_H

#include <iostream>

#include <fstream>

#include <sstream>

#include <set>

#include <map>

#include <lemon/assert.h>

#include <lemon/graph_utils.h>

#include <lemon/lgf_writer.h>

#include <lemon/concept_check.h>

#include <lemon/concepts/maps.h>

namespace lemon {

  namespace _reader_bits {

    template <typename Value>

    struct DefaultConverter {

      Value operator()(const std::string& str) {

	std::istringstream is(str);

	Value value;

	is >> value;

	char c;

	if (is >> std::ws >> c) {

	  throw DataFormatError("Remaining characters in token");

	}

	return value;

      }

    };

    template <>

    struct DefaultConverter<std::string> {

      std::string operator()(const std::string& str) {

	return str;

      }

    };

    template <typename _Item>    

    class MapStorageBase {

    public:

      typedef _Item Item;

    public:

      MapStorageBase() {}

      virtual ~MapStorageBase() {}

      virtual void set(const Item& item, const std::string& value) = 0;

    };

    template <typename _Item, typename _Map, 

	      typename _Converter = DefaultConverter<typename _Map::Value> >

    class MapStorage : public MapStorageBase<_Item> {

    public:

      typedef _Map Map;

      typedef _Converter Converter;

      typedef _Item Item;

    private:

      Map& _map;

      Converter _converter;

    public:

      MapStorage(Map& map, const Converter& converter = Converter()) 

	: _map(map), _converter(converter) {}

      virtual ~MapStorage() {}

      virtual void set(const Item& item ,const std::string& value) {

	_map.set(item, _converter(value));

      }

    };

    template <typename _Graph, bool _dir, typename _Map, 

	      typename _Converter = DefaultConverter<typename _Map::Value> >

    class GraphArcMapStorage : public MapStorageBase<typename _Graph::Edge> {

    public:

      typedef _Map Map;

      typedef _Converter Converter;

      typedef _Graph Graph;

      typedef typename Graph::Edge Item;

      static const bool dir = _dir;

    private:

      const Graph& _graph;

      Map& _map;

      Converter _converter;

    public:

      GraphArcMapStorage(const Graph& graph, Map& map, 

			 const Converter& converter = Converter()) 

	: _graph(graph), _map(map), _converter(converter) {}

      virtual ~GraphArcMapStorage() {}

      virtual void set(const Item& item ,const std::string& value) {

	_map.set(_graph.direct(item, dir), _converter(value));

      }

    };

    class ValueStorageBase {

    public:

      ValueStorageBase() {}

      virtual ~ValueStorageBase() {}

      virtual void set(const std::string&) = 0;

    };

    template <typename _Value, typename _Converter = DefaultConverter<_Value> >

    class ValueStorage : public ValueStorageBase {

    public:

      typedef _Value Value;

      typedef _Converter Converter;

    private:

      Value& _value;

      Converter _converter;

    public:

      ValueStorage(Value& value, const Converter& converter = Converter())

 	: _value(value), _converter(converter) {}

      virtual void set(const std::string& value) {

	_value = _converter(value);

      }

    };

    template <typename Value>

    struct MapLookUpConverter {

      const std::map<std::string, Value>& _map;

      MapLookUpConverter(const std::map<std::string, Value>& map)

        : _map(map) {}

      Value operator()(const std::string& str) {

        typename std::map<std::string, Value>::const_iterator it =

          _map.find(str);

        if (it == _map.end()) {

          std::ostringstream msg;

          msg << "Item not found: " << str;

          throw DataFormatError(msg.str().c_str());

        }

        return it->second;

      }

    };

    template <typename Graph>

    struct GraphArcLookUpConverter {

      const Graph& _graph;

      const std::map<std::string, typename Graph::Edge>& _map;

      GraphArcLookUpConverter(const Graph& graph, 

			      const std::map<std::string,

			                     typename Graph::Edge>& map) 

	: _graph(graph), _map(map) {}

      typename Graph::Arc operator()(const std::string& str) {

	if (str.empty() || (str[0] != '+' && str[0] != '-')) {

	  throw DataFormatError("Item must start with '+' or '-'");

	}

	typename std::map<std::string, typename Graph::Edge>

	  ::const_iterator it = _map.find(str.substr(1));

	if (it == _map.end()) {

	  throw DataFormatError("Item not found");

	}

	return _graph.direct(it->second, str[0] == '+');

      }

    };

    bool isWhiteSpace(char c) {

      return c == ' ' || c == '\t' || c == '\v' || 

        c == '\n' || c == '\r' || c == '\f'; 

    }

    bool isOct(char c) {

      return '0' <= c && c <='7'; 

    }

    int valueOct(char c) {

      LEMON_ASSERT(isOct(c), "The character is not octal.");

      return c - '0';

    }

    bool isHex(char c) {

      return ('0' <= c && c <= '9') || 

	('a' <= c && c <= 'z') || 

	('A' <= c && c <= 'Z'); 

    }

    int valueHex(char c) {

      LEMON_ASSERT(isHex(c), "The character is not hexadecimal.");

      if ('0' <= c && c <= '9') return c - '0';

      if ('a' <= c && c <= 'z') return c - 'a' + 10;

      return c - 'A' + 10;

    }

    bool isIdentifierFirstChar(char c) {

      return ('a' <= c && c <= 'z') ||

	('A' <= c && c <= 'Z') || c == '_';

    }

    bool isIdentifierChar(char c) {

      return isIdentifierFirstChar(c) ||

	('0' <= c && c <= '9');

    }

    char readEscape(std::istream& is) {

      char c;

      if (!is.get(c))

	throw DataFormatError("Escape format error");

      switch (c) {

      case '\\':

	return '\\';

      case '\"':

	return '\"';

      case '\'':

	return '\'';

      case '\?':

	return '\?';

      case 'a':

	return '\a';

      case 'b':

	return '\b';

      case 'f':

	return '\f';

      case 'n':

	return '\n';

      case 'r':

	return '\r';

      case 't':

	return '\t';

      case 'v':

	return '\v';

      case 'x':

	{

	  int code;

	  if (!is.get(c) || !isHex(c)) 

	    throw DataFormatError("Escape format error");

	  else if (code = valueHex(c), !is.get(c) || !isHex(c)) is.putback(c);

	  else code = code * 16 + valueHex(c);

	  return code;

	}

      default:

	{

	  int code;

	  if (!isOct(c)) 

	    throw DataFormatError("Escape format error");

	  else if (code = valueOct(c), !is.get(c) || !isOct(c)) 

	    is.putback(c);

	  else if (code = code * 8 + valueOct(c), !is.get(c) || !isOct(c)) 

	    is.putback(c);

	  else code = code * 8 + valueOct(c);

	  return code;

	}	      

      } 

    }

    std::istream& readToken(std::istream& is, std::string& str) {

      std::ostringstream os;

      char c;

      is >> std::ws;

      if (!is.get(c)) 

	return is;

      if (c == '\"') {

	while (is.get(c) && c != '\"') {

	  if (c == '\\') 

	    c = readEscape(is);

	  os << c;

	}

	if (!is) 

	  throw DataFormatError("Quoted format error");

      } else {

	is.putback(c);

	while (is.get(c) && !isWhiteSpace(c)) {

	  if (c == '\\') 

	    c = readEscape(is);

	  os << c;

	}

	if (!is) {

	  is.clear();

	} else {

	  is.putback(c);

	}

      }

      str = os.str();

      return is;

    }

    class Section {

    public:

      virtual ~Section() {}

      virtual void process(std::istream& is, int& line_num) = 0;

    };

    template <typename Functor>

    class LineSection : public Section {

    private:

      Functor _functor;

    public:

      LineSection(const Functor& functor) : _functor(functor) {}

      virtual ~LineSection() {}

      virtual void process(std::istream& is, int& line_num) {

	char c;

	std::string line;

	while (is.get(c) && c != '@') {

	  if (c == '\n') {

	    ++line_num;

	  } else if (c == '#') {

	    getline(is, line);

	    ++line_num;

	  } else if (!isWhiteSpace(c)) {

	    is.putback(c);

	    getline(is, line);

	    _functor(line);

	    ++line_num;

	  }

	}

	if (is) is.putback(c);

	else if (is.eof()) is.clear();

      }

    };

    template <typename Functor>

    class StreamSection : public Section {

    private:

      Functor _functor;

    public:

      StreamSection(const Functor& functor) : _functor(functor) {}

      virtual ~StreamSection() {} 

      virtual void process(std::istream& is, int& line_num) {

	_functor(is, line_num);

	char c;

	std::string line;

	while (is.get(c) && c != '@') {

	  if (c == '\n') {

	    ++line_num;

	  } else if (!isWhiteSpace(c)) {

	    getline(is, line);

	    ++line_num;

	  }

	}

	if (is) is.putback(c);

	else if (is.eof()) is.clear();	

      }

    };

  }

  /// \ingroup lemon_io

  ///  

  /// \brief LGF reader for directed graphs

  ///

  /// This utility reads an \ref lgf-format "LGF" file.

  ///

  /// The reading method does a batch processing. The user creates a

  /// reader object, then various reading rules can be added to the

  /// reader, and eventually the reading is executed with the \c run()

  /// member function. A map reading rule can be added to the reader

  /// with the \c nodeMap() or \c arcMap() members. An optional

  /// converter parameter can also be added as a standard functor

  /// converting from std::string to the value type of the map. If it

  /// is set, it will determine how the tokens in the file should be

  /// is converted to the map's value type. If the functor is not set,

  /// then a default conversion will be used. One map can be read into

  /// multiple map objects at the same time. The \c attribute(), \c

  /// node() and \c arc() functions are used to add attribute reading

  /// rules.

  ///

  ///\code

  ///     DigraphReader<Digraph>(std::cin, digraph).

  ///       nodeMap("coordinates", coord_map).

  ///       arcMap("capacity", cap_map).

  ///       node("source", src).

  ///       node("target", trg).

  ///       attribute("caption", caption).

  ///       run();

  ///\endcode

  ///

  /// By default the reader uses the first section in the file of the

  /// proper type. If a section has an optional name, then it can be

  /// selected for reading by giving an optional name parameter to the

  /// \c nodes(), \c arcs() or \c attributes() functions. The readers

  /// also can load extra sections with the \c sectionLines() and

  /// sectionStream() functions.

  ///

  /// The \c useNodes() and \c useArcs() functions are used to tell the reader

  /// that the nodes or arcs should not be constructed (added to the

  /// graph) during the reading, but instead the label map of the items

  /// are given as a parameter of these functions. An

  /// application of these function is multipass reading, which is

  /// important if two \e \@arcs sections must be read from the

  /// file. In this example the first phase would read the node set and one

  /// of the arc sets, while the second phase would read the second arc

  /// set into an \e ArcSet class (\c SmartArcSet or \c ListArcSet).

  /// The previously read label node map should be passed to the \c

  /// useNodes() functions. Another application of multipass reading when

  /// paths are given as a node map or an arc map. It is impossible read this in

  /// a single pass, because the arcs are not constructed when the node

  /// maps are read.

  template <typename _Digraph>

  class DigraphReader {

  public:

    typedef _Digraph Digraph;

    TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);

  private:

    std::istream* _is;

    bool local_is;

    Digraph& _digraph;

    std::string _nodes_caption;

    std::string _arcs_caption;

    std::string _attributes_caption;

    typedef std::map<std::string, Node> NodeIndex;

    NodeIndex _node_index;

    typedef std::map<std::string, Arc> ArcIndex;

    ArcIndex _arc_index;

    typedef std::vector<std::pair<std::string, 

      _reader_bits::MapStorageBase<Node>*> > NodeMaps;    

    NodeMaps _node_maps; 

    typedef std::vector<std::pair<std::string,

      _reader_bits::MapStorageBase<Arc>*> >ArcMaps;

    ArcMaps _arc_maps;

    typedef std::multimap<std::string, _reader_bits::ValueStorageBase*> 

      Attributes;

    Attributes _attributes;

    typedef std::map<std::string, _reader_bits::Section*> Sections;

    Sections _sections;

    bool _use_nodes;

    bool _use_arcs;

    int line_num;

    std::istringstream line;

  public:

    /// \brief Constructor

    ///

    /// Construct a directed graph reader, which reads from the given

    /// input stream.

    DigraphReader(std::istream& is, Digraph& digraph) 

      : _is(&is), local_is(false), _digraph(digraph),

	_use_nodes(false), _use_arcs(false) {}

    /// \brief Constructor

    ///

    /// Construct a directed graph reader, which reads from the given

    /// file.

    DigraphReader(const std::string& fn, Digraph& digraph) 

      : _is(new std::ifstream(fn.c_str())), local_is(true), _digraph(digraph),

    	_use_nodes(false), _use_arcs(false) {}

    /// \brief Constructor

    ///

    /// Construct a directed graph reader, which reads from the given

    /// file.

    DigraphReader(const char* fn, Digraph& digraph) 

      : _is(new std::ifstream(fn)), local_is(true), _digraph(digraph),

    	_use_nodes(false), _use_arcs(false) {}

    /// \brief Copy constructor

    ///

    /// The copy constructor transfers all data from the other reader,

    /// therefore the copied reader will not be usable more. 

    DigraphReader(DigraphReader& other) 

      : _is(other._is), local_is(other.local_is), _digraph(other._digraph),

	_use_nodes(other._use_nodes), _use_arcs(other._use_arcs) {

      other._is = 0;

      other.local_is = false;

      _node_index.swap(other._node_index);

      _arc_index.swap(other._arc_index);

      _node_maps.swap(other._node_maps);

      _arc_maps.swap(other._arc_maps);

      _attributes.swap(other._attributes);

      _nodes_caption = other._nodes_caption;

      _arcs_caption = other._arcs_caption;

      _attributes_caption = other._attributes_caption;

      _sections.swap(other._sections);

    }

    /// \brief Destructor

    ~DigraphReader() {

      for (typename NodeMaps::iterator it = _node_maps.begin(); 

	   it != _node_maps.end(); ++it) {

	delete it->second;

      }

      for (typename ArcMaps::iterator it = _arc_maps.begin(); 

	   it != _arc_maps.end(); ++it) {

	delete it->second;

      }

      for (typename Attributes::iterator it = _attributes.begin(); 

	   it != _attributes.end(); ++it) {

	delete it->second;

      }

      for (typename Sections::iterator it = _sections.begin(); 

	   it != _sections.end(); ++it) {

	delete it->second;

      }

      if (local_is) {

	delete _is;

      }

    }

  private:

    DigraphReader& operator=(const DigraphReader&);

  public:

    /// \name Reading rules

    /// @{

    /// \brief Node map reading rule

    ///

    /// Add a node map reading rule to the reader.

    template <typename Map>

    DigraphReader& nodeMap(const std::string& caption, Map& map) {

      checkConcept<concepts::WriteMap<Node, typename Map::Value>, Map>();

      _reader_bits::MapStorageBase<Node>* storage = 

	new _reader_bits::MapStorage<Node, Map>(map);

      _node_maps.push_back(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Node map reading rule

    ///

    /// Add a node map reading rule with specialized converter to the

    /// reader.

    template <typename Map, typename Converter>

    DigraphReader& nodeMap(const std::string& caption, Map& map, 

			   const Converter& converter = Converter()) {

      checkConcept<concepts::WriteMap<Node, typename Map::Value>, Map>();

      _reader_bits::MapStorageBase<Node>* storage = 

	new _reader_bits::MapStorage<Node, Map, Converter>(map, converter);

      _node_maps.push_back(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Arc map reading rule

    ///

    /// Add an arc map reading rule to the reader.

    template <typename Map>

    DigraphReader& arcMap(const std::string& caption, Map& map) {

      checkConcept<concepts::WriteMap<Arc, typename Map::Value>, Map>();

      _reader_bits::MapStorageBase<Arc>* storage = 

	new _reader_bits::MapStorage<Arc, Map>(map);

      _arc_maps.push_back(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Arc map reading rule

    ///

    /// Add an arc map reading rule with specialized converter to the

    /// reader.

    template <typename Map, typename Converter>

    DigraphReader& arcMap(const std::string& caption, Map& map, 

			  const Converter& converter = Converter()) {

      checkConcept<concepts::WriteMap<Arc, typename Map::Value>, Map>();

      _reader_bits::MapStorageBase<Arc>* storage = 

	new _reader_bits::MapStorage<Arc, Map, Converter>(map, converter);

      _arc_maps.push_back(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Attribute reading rule

    ///

    /// Add an attribute reading rule to the reader.

    template <typename Value>

    DigraphReader& attribute(const std::string& caption, Value& value) {

      _reader_bits::ValueStorageBase* storage = 

	new _reader_bits::ValueStorage<Value>(value);

      _attributes.insert(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Attribute reading rule

    ///

    /// Add an attribute reading rule with specialized converter to the

    /// reader.

    template <typename Value, typename Converter>

    DigraphReader& attribute(const std::string& caption, Value& value, 

			     const Converter& converter = Converter()) {

      _reader_bits::ValueStorageBase* storage = 

	new _reader_bits::ValueStorage<Value, Converter>(value, converter);

      _attributes.insert(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Node reading rule

    ///

    /// Add a node reading rule to reader.

    DigraphReader& node(const std::string& caption, Node& node) {

      typedef _reader_bits::MapLookUpConverter<Node> Converter;

      Converter converter(_node_index);

      _reader_bits::ValueStorageBase* storage = 

	new _reader_bits::ValueStorage<Node, Converter>(node, converter);

      _attributes.insert(std::make_pair(caption, storage));

      return *this;

    }

    /// \brief Arc reading rule

    ///

    /// Add an arc reading rule to reader.

    DigraphReader& arc(const std::string& caption, Arc& arc) {

      typedef _reader_bits::MapLookUpConverter<Arc> Converter;

      Converter converter(_arc_index);

      _reader_bits::ValueStorageBase* storage = 

	new _reader_bits::ValueStorage<Arc, Converter>(arc, converter);

      _attributes.insert(std::make_pair(caption, storage));

      return *this;

    }

    /// @}

    /// \name Select section by name

    /// @{

    /// \brief Set \c \@nodes section to be read

    ///

    /// Set \c \@nodes section to be read

    DigraphReader& nodes(const std::string& caption) {

      _nodes_caption = caption;

      return *this;

    }

    /// \brief Set \c \@arcs section to be read

    ///

    /// Set \c \@arcs section to be read

    DigraphReader& arcs(const std::string& caption) {

      _arcs_caption = caption;

      return *this;

    }

    /// \brief Set \c \@attributes section to be read

    ///

    /// Set \c \@attributes section to be read

    DigraphReader& attributes(const std::string& caption) {

      _attributes_caption = caption;

      return *this;

    }

    /// @}

    /// \name Section readers

    /// @{

    /// \brief Add a section processor with line oriented reading

    ///

    /// In the \e LGF file extra sections can be placed, which contain

    /// any data in arbitrary format. These sections can be read with

    /// this function line by line. The first parameter is the type

    /// descriptor of the section, the second is a functor, which

    /// takes just one \c std::string parameter. At the reading

    /// process, each line of the section will be given to the functor

    /// object. However, the empty lines and the comment lines are

    /// filtered out, and the leading whitespaces are stipped from

    /// each processed string.

    ///

    /// For example let's see a section, which contain several

    /// integers, which should be inserted into a vector.

    ///\code

    ///  @numbers

    ///  12 45 23

    ///  4

    ///  23 6

    ///\endcode

    ///

    /// The functor is implemented as an struct:

    ///\code

    ///  struct NumberSection {

    ///    std::vector<int>& _data;

    ///    NumberSection(std::vector<int>& data) : _data(data) {}

    ///    void operator()(const std::string& line) {

    ///      std::istringstream ls(line);

    ///      int value;

    ///      while (ls >> value) _data.push_back(value);

    ///    }

    ///  };

    ///

    ///  // ...

    ///

    ///  reader.sectionLines("numbers", NumberSection(vec));  

    ///\endcode

    template <typename Functor>

    DigraphReader& sectionLines(const std::string& type, Functor functor) {

      LEMON_ASSERT(!type.empty(), "Type is not empty.");

      LEMON_ASSERT(_sections.find(type) == _sections.end(), 

		   "Multiple reading of section.");

      LEMON_ASSERT(type != "nodes" && type != "arcs" && type != "edges" &&

		   type != "attributes", "Multiple reading of section.");

      _sections.insert(std::make_pair(type, 

        new _reader_bits::LineSection<Functor>(functor)));

      return *this;

    }

    /// \brief Add a section processor with stream oriented reading

    ///

    /// In the \e LGF file extra sections can be placed, which contain

    /// any data in arbitrary format. These sections can be read

    /// directly with this function. The first parameter is the type

    /// of the section, the second is a functor, which takes an \c

    /// std::istream& and an int& parameter, the latter regard to the

    /// line number of stream. The functor can read the input while

    /// the section go on, and the line number should be modified

    /// accordingly.

    template <typename Functor>

    DigraphReader& sectionStream(const std::string& type, Functor functor) {

      LEMON_ASSERT(!type.empty(), "Type is not empty.");

      LEMON_ASSERT(_sections.find(type) == _sections.end(), 

		   "Multiple reading of section.");

      LEMON_ASSERT(type != "nodes" && type != "arcs" && type != "edges" &&

		   type != "attributes", "Multiple reading of section.");

      _sections.insert(std::make_pair(type, 

	 new _reader_bits::StreamSection<Functor>(functor)));

      return *this;

    }    

    /// @}

    /// \name Using previously constructed node or arc set

    /// @{

    /// \brief Use previously constructed node set

    ///

    /// Use previously constructed node set, and specify the node

    /// label map.

    template <typename Map>

    DigraphReader& useNodes(const Map& map) {

      checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();

      LEMON_ASSERT(!_use_nodes, "Multiple usage of useNodes() member"); 

      _use_nodes = true;

      _writer_bits::DefaultConverter<typename Map::Value> converter;

      for (NodeIt n(_digraph); n != INVALID; ++n) {

	_node_index.insert(std::make_pair(converter(map[n]), n));

      }

      return *this;

    }

    /// \brief Use previously constructed node set

    ///

    /// Use previously constructed node set, and specify the node

    /// label map and a functor which converts the label map values to

    /// std::string.

    template <typename Map, typename Converter>

    DigraphReader& useNodes(const Map& map, 

			    const Converter& converter = Converter()) {

      checkConcept<concepts::ReadMap<Node, typename Map::Value>, Map>();

      LEMON_ASSERT(!_use_nodes, "Multiple usage of useNodes() member"); 

      _use_nodes = true;

      for (NodeIt n(_digraph); n != INVALID; ++n) {

	_node_index.insert(std::make_pair(converter(map[n]), n));

      }

      return *this;

    }

    /// \brief Use previously constructed arc set

    ///

    /// Use previously constructed arc set, and specify the arc

    /// label map.

    template <typename Map>

    DigraphReader& useArcs(const Map& map) {

      checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();

      LEMON_ASSERT(!_use_arcs, "Multiple usage of useArcs() member");

      _use_arcs = true;

      _writer_bits::DefaultConverter<typename Map::Value> converter;

      for (ArcIt a(_digraph); a != INVALID; ++a) {

	_arc_index.insert(std::make_pair(converter(map[a]), a));

      }

      return *this;

    }

    /// \brief Use previously constructed arc set

    ///

    /// Use previously constructed arc set, and specify the arc

    /// label map and a functor which converts the label map values to

    /// std::string.

    template <typename Map, typename Converter>

    DigraphReader& useArcs(const Map& map, 

			    const Converter& converter = Converter()) {

      checkConcept<concepts::ReadMap<Arc, typename Map::Value>, Map>();

      LEMON_ASSERT(!_use_arcs, "Multiple usage of useArcs() member"); 

      _use_arcs = true;

      for (ArcIt a(_digraph); a != INVALID; ++a) {

	_arc_index.insert(std::make_pair(converter(map[a]), a));

      }

      return *this;

    }

    /// @}

  private:

    bool readLine() {

      std::string str;

      while(++line_num, std::getline(*_is, str)) {

	line.clear(); line.str(str);

	char c;

	if (line >> std::ws >> c && c != '#') {

	  line.putback(c);

	  return true;

	}

      }

      return false;

    }

    bool readSuccess() {

      return static_cast<bool>(*_is);

    }

    void skipSection() {

      char c;

      while (readSuccess() && line >> c && c != '@') {

	readLine();

      }

      line.putback(c);

    }

    void readNodes() {

      std::vector<int> map_index(_node_maps.size());

      int map_num, label_index;

      char c;

      if (!readLine() || !(line >> c) || c == '@') {

	if (readSuccess() && line) line.putback(c);

	if (!_node_maps.empty()) 

	  throw DataFormatError("Cannot find map names");

	return;

      }

      line.putback(c);

      {

	std::map<std::string, int> maps;

	std::string map;

	int index = 0;

	while (_reader_bits::readToken(line, map)) {

	  if (maps.find(map) != maps.end()) {

	    std::ostringstream msg;

	    msg << "Multiple occurence of node map: " << map;

	    throw DataFormatError(msg.str().c_str());

	  }

	  maps.insert(std::make_pair(map, index));

	  ++index;

	}

	for (int i = 0; i < static_cast<int>(_node_maps.size()); ++i) {

	  std::map<std::string, int>::iterator jt = 

	    maps.find(_node_maps[i].first);

	  if (jt == maps.end()) {

	    std::ostringstream msg;

	    msg << "Map not found in file: " << _node_maps[i].first;

	    throw DataFormatError(msg.str().c_str());

	  }

	  map_index[i] = jt->second;

	}

	{

	  std::map<std::string, int>::iterator jt = maps.find("label");

	  if (jt != maps.end()) {

	    label_index = jt->second;

	  } else {

	    label_index = -1;

	  }

	}

	map_num = maps.size();

      }

      while (readLine() && line >> c && c != '@') {

	line.putback(c);

	std::vector<std::string> tokens(map_num);

	for (int i = 0; i < map_num; ++i) {

	  if (!_reader_bits::readToken(line, tokens[i])) {

	    std::ostringstream msg;

	    msg << "Column not found (" << i + 1 << ")";

	    throw DataFormatError(msg.str().c_str());

	  }

	}

	if (line >> std::ws >> c)

	  throw DataFormatError("Extra character on the end of line");

	Node n;

	if (!_use_nodes) {

	  n = _digraph.addNode();

	  if (label_index != -1)

	    _node_index.insert(std::make_pair(tokens[label_index], n));

	} else {

	  if (label_index == -1) 

	    throw DataFormatError("Label map not found in file");

	  typename std::map<std::string, Node>::iterator it =

	    _node_index.find(tokens[label_index]);

	  if (it == _node_index.end()) {

	    std::ostringstream msg;

	    msg << "Node with label not found: " << tokens[label_index];

	    throw DataFormatError(msg.str().c_str());	    

	  }

	  n = it->second;

	}

	for (int i = 0; i < static_cast<int>(_node_maps.size()); ++i) {

	  _node_maps[i].second->set(n, tokens[map_index[i]]);

	}

      }

      if (readSuccess()) {

	line.putback(c);

      }

    }

    void readArcs() {

      std::vector<int> map_index(_arc_maps.size());

      int map_num, label_index;

      char c;

      if (!readLine() || !(line >> c) || c == '@') {

	if (readSuccess() && line) line.putback(c);

	if (!_arc_maps.empty()) 

	  throw DataFormatError("Cannot find map names");

	return;

      }

      line.putback(c);

      {

	std::map<std::string, int> maps;

	std::string map;

	int index = 0;

	while (_reader_bits::readToken(line, map)) {

	  if (maps.find(map) != maps.end()) {

	    std::ostringstream msg;