template <typename BGR>

   class BpGraphReader;

   template <typename TBGR>

   BpGraphReader<TBGR> bpGraphReader(TBGR& graph, std::istream& is = std::cin);

   template <typename TBGR>

   BpGraphReader<TBGR> bpGraphReader(TBGR& graph, const std::string& fn);

   template <typename TBGR>

   BpGraphReader<TBGR> bpGraphReader(TBGR& graph, const char *fn);

   /// \ingroup lemon_io

   ///

   /// \brief \ref lgf-format "LGF" reader for bipartite graphs

   ///

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

   ///

   /// It can be used almost the same way as \c GraphReader, but it

   /// reads the red and blue nodes from separate sections, and these

   /// sections can contain different set of maps.

   ///

   /// The red and blue maps are read from the corresponding

   /// sections. If a map is defined with the same name in both of

   /// these sections, then it can be read as a node map.

   template <typename BGR>

   class BpGraphReader {

   public:

     typedef BGR Graph;

   private:

     TEMPLATE_BPGRAPH_TYPEDEFS(BGR);

     std::istream* _is;

     bool local_is;

     std::string _filename;

     BGR& _graph;

     std::string _nodes_caption;

     std::string _edges_caption;

     std::string _attributes_caption;

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

     NodeIndex _node_index;

     typedef std::map<std::string, Edge> EdgeIndex;

     EdgeIndex _edge_index;

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

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

     NodeMaps _red_maps;

     NodeMaps _blue_maps;

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

       _reader_bits::MapStorageBase<Edge>*> > EdgeMaps;

     EdgeMaps _edge_maps;

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

       Attributes;

     Attributes _attributes;

     bool _use_nodes;

     bool _use_edges;

     bool _skip_nodes;

     bool _skip_edges;

     int line_num;

     std::istringstream line;

   public:

     /// \brief Constructor

     ///

     /// Construct an undirected graph reader, which reads from the given

     /// input stream.

     BpGraphReader(BGR& graph, std::istream& is = std::cin)

       : _is(&is), local_is(false), _graph(graph),

         _use_nodes(false), _use_edges(false),

         _skip_nodes(false), _skip_edges(false) {}

     /// \brief Constructor

     ///

     /// Construct an undirected graph reader, which reads from the given

     /// file.

     BpGraphReader(BGR& graph, const std::string& fn)

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

         _filename(fn), _graph(graph),

         _use_nodes(false), _use_edges(false),

         _skip_nodes(false), _skip_edges(false) {

       if (!(*_is)) {

         delete _is;

         throw IoError("Cannot open file", fn);

       }

     }

     /// \brief Constructor

     ///

     /// Construct an undirected graph reader, which reads from the given

     /// file.

     BpGraphReader(BGR& graph, const char* fn)

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

         _filename(fn), _graph(graph),

         _use_nodes(false), _use_edges(false),

         _skip_nodes(false), _skip_edges(false) {

       if (!(*_is)) {

         delete _is;

         throw IoError("Cannot open file", fn);

       }

     }

     /// \brief Destructor

     ~BpGraphReader() {

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

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

         delete it->second;

       }

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

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

         delete it->second;

       }

       for (typename EdgeMaps::iterator it = _edge_maps.begin();

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

         delete it->second;

       }

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

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

         delete it->second;

       }

       if (local_is) {

         delete _is;

       }

     }

   private:

     template <typename TBGR>

     friend BpGraphReader<TBGR> bpGraphReader(TBGR& graph, std::istream& is);

     template <typename TBGR>

     friend BpGraphReader<TBGR> bpGraphReader(TBGR& graph,

                                              const std::string& fn);

     template <typename TBGR>

     friend BpGraphReader<TBGR> bpGraphReader(TBGR& graph, const char *fn);

     BpGraphReader(BpGraphReader& other)

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

         _use_nodes(other._use_nodes), _use_edges(other._use_edges),

         _skip_nodes(other._skip_nodes), _skip_edges(other._skip_edges) {

       other._is = 0;

       other.local_is = false;

       _node_index.swap(other._node_index);

       _edge_index.swap(other._edge_index);

       _red_maps.swap(other._red_maps);

       _blue_maps.swap(other._blue_maps);

       _edge_maps.swap(other._edge_maps);

       _attributes.swap(other._attributes);

       _nodes_caption = other._nodes_caption;

       _edges_caption = other._edges_caption;

       _attributes_caption = other._attributes_caption;

     }

     BpGraphReader& operator=(const BpGraphReader&);

   public:

     /// \name Reading Rules

     /// @{

     /// \brief Node map reading rule

     ///

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

     template <typename Map>

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

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

       _reader_bits::MapStorageBase<Node>* red_storage =

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

       _red_maps.push_back(std::make_pair(caption, red_storage));

       _reader_bits::MapStorageBase<Node>* blue_storage =

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

       _blue_maps.push_back(std::make_pair(caption, blue_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>

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

                            const Converter& converter = Converter()) {

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

       _reader_bits::MapStorageBase<Node>* red_storage =

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

       _red_maps.push_back(std::make_pair(caption, red_storage));

       _reader_bits::MapStorageBase<Node>* blue_storage =

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

       _blue_maps.push_back(std::make_pair(caption, blue_storage));

       return *this;

     }

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

     template <typename Map>

     BpGraphReader& redMap(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);

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

       return *this;

     }

     /// \brief Red map reading rule

     ///

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

     /// reader.

     template <typename Map, typename Converter>

     BpGraphReader& redMap(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);

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

       return *this;

     }

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

     template <typename Map>

     BpGraphReader& blueMap(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);

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

       return *this;

     }

     /// \brief Blue map reading rule

     ///

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

     /// reader.

     template <typename Map, typename Converter>

     BpGraphReader& blueMap(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);

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

       return *this;

     }

     /// \brief Edge map reading rule

     ///

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

     template <typename Map>

     BpGraphReader& edgeMap(const std::string& caption, Map& map) {

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

       _reader_bits::MapStorageBase<Edge>* storage =

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

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

       return *this;

     }

     /// \brief Edge map reading rule

     ///

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

     /// reader.

     template <typename Map, typename Converter>

     BpGraphReader& edgeMap(const std::string& caption, Map& map,

                           const Converter& converter = Converter()) {

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

       _reader_bits::MapStorageBase<Edge>* storage =

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

       _edge_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>

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

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

       _reader_bits::MapStorageBase<Edge>* forward_storage =

         new _reader_bits::GraphArcMapStorage<Graph, true, Map>(_graph, map);

       _edge_maps.push_back(std::make_pair('+' + caption, forward_storage));

       _reader_bits::MapStorageBase<Edge>* backward_storage =

         new _reader_bits::GraphArcMapStorage<BGR, false, Map>(_graph, map);

       _edge_maps.push_back(std::make_pair('-' + caption, backward_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>

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

                           const Converter& converter = Converter()) {

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

       _reader_bits::MapStorageBase<Edge>* forward_storage =

         new _reader_bits::GraphArcMapStorage<BGR, true, Map, Converter>

         (_graph, map, converter);

       _edge_maps.push_back(std::make_pair('+' + caption, forward_storage));

       _reader_bits::MapStorageBase<Edge>* backward_storage =

         new _reader_bits::GraphArcMapStorage<BGR, false, Map, Converter>

         (_graph, map, converter);

       _edge_maps.push_back(std::make_pair('-' + caption, backward_storage));

       return *this;

     }

     /// \brief Attribute reading rule

     ///

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

     template <typename Value>

     BpGraphReader& 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>

     BpGraphReader& 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.

     BpGraphReader& 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 Edge reading rule

     ///

     /// Add an edge reading rule to reader.

     BpGraphReader& edge(const std::string& caption, Edge& edge) {

       typedef _reader_bits::MapLookUpConverter<Edge> Converter;

       Converter converter(_edge_index);

       _reader_bits::ValueStorageBase* storage =

         new _reader_bits::ValueStorage<Edge, Converter>(edge, converter);

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

       return *this;

     }

     /// \brief Arc reading rule

     ///

     /// Add an arc reading rule to reader.

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

       typedef _reader_bits::GraphArcLookUpConverter<BGR> Converter;

       Converter converter(_graph, _edge_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.

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

       _nodes_caption = caption;

       return *this;

     }

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

     ///

     /// Set \c \@edges section to be read.

     BpGraphReader& edges(const std::string& caption) {

       _edges_caption = caption;

       return *this;

     }

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

     ///

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

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

       _attributes_caption = caption;

       return *this;

     }

     /// @}

     /// \name Using Previously Constructed Node or Edge Set

     /// @{

     /// \brief Use previously constructed node set

     ///

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

     /// label map.

     template <typename Map>

     BpGraphReader& 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(_graph); 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

     /// \c std::string.

     template <typename Map, typename Converter>

     BpGraphReader& 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(_graph); n != INVALID; ++n) {

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

       }

       return *this;

     }

     /// \brief Use previously constructed edge set

     ///

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

     /// label map.

     template <typename Map>

     BpGraphReader& useEdges(const Map& map) {

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

       LEMON_ASSERT(!_use_edges, "Multiple usage of useEdges() member");

       _use_edges = true;

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

       for (EdgeIt a(_graph); a != INVALID; ++a) {

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

       }

       return *this;

     }

     /// \brief Use previously constructed edge set

     ///

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

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

     /// \c std::string.

     template <typename Map, typename Converter>

     BpGraphReader& useEdges(const Map& map,

                             const Converter& converter = Converter()) {

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

       LEMON_ASSERT(!_use_edges, "Multiple usage of useEdges() member");

       _use_edges = true;

       for (EdgeIt a(_graph); a != INVALID; ++a) {

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

       }

       return *this;

     }

     /// \brief Skip the reading of node section

     ///

     /// Omit the reading of the node section. This implies that each node

     /// map reading rule will be abandoned, and the nodes of the graph

     /// will not be constructed, which usually cause that the edge set

     /// could not be read due to lack of node name

     /// could not be read due to lack of node name resolving.

     /// Therefore \c skipEdges() function should also be used, or

     /// \c useNodes() should be used to specify the label of the nodes.

     BpGraphReader& skipNodes() {

       LEMON_ASSERT(!_skip_nodes, "Skip nodes already set");

       _skip_nodes = true;

       return *this;

     }

     /// \brief Skip the reading of edge section

     ///

     /// Omit the reading of the edge section. This implies that each edge

     /// map reading rule will be abandoned, and the edges of the graph

     /// will not be constructed.

     BpGraphReader& skipEdges() {

       LEMON_ASSERT(!_skip_edges, "Skip edges already set");

       _skip_edges = true;

       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();

       }

       if (readSuccess()) {

         line.putback(c);

       }

     }

     void readRedNodes() {

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

       int map_num, label_index;

       char c;

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

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

         if (!_red_maps.empty())

           throw FormatError("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 red map: " << map;

             throw FormatError(msg.str());

           }

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

           ++index;

         }

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

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

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

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

             std::ostringstream msg;

             msg << "Map not found: " << _red_maps[i].first;

             throw FormatError(msg.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 FormatError(msg.str());

           }

         }

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

           throw FormatError("Extra character at the end of line");

         Node n;

         if (!_use_nodes) {

           n = _graph.addRedNode();

           if (label_index != -1)

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

         } else {

           if (label_index == -1)

             throw FormatError("Label map not found");

           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 FormatError(msg.str());

           }

           n = it->second;

         }

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

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

         }

       }

       if (readSuccess()) {

         line.putback(c);

       }

     }

     void readBlueNodes() {

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

       int map_num, label_index;

       char c;

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

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

         if (!_blue_maps.empty())

           throw FormatError("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 blue map: " << map;

             throw FormatError(msg.str());

           }

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

           ++index;

         }

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

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

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

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

             std::ostringstream msg;

             msg << "Map not found: " << _blue_maps[i].first;

             throw FormatError(msg.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 FormatError(msg.str());

           }

         }

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

           throw FormatError("Extra character at the end of line");

         Node n;

         if (!_use_nodes) {

           n = _graph.addBlueNode();

           if (label_index != -1)

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

         } else {

           if (label_index == -1)

             throw FormatError("Label map not found");

           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 FormatError(msg.str());

           }

           n = it->second;

         }

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

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

         }

       }

       if (readSuccess()) {

         line.putback(c);

       }

     }

     void readEdges() {

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

       int map_num, label_index;

       char c;

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

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

         if (!_edge_maps.empty())

           throw FormatError("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 edge map: " << map;

             throw FormatError(msg.str());

           }

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

           ++index;

         }

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

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

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

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

             std::ostringstream msg;

             msg << "Map not found: " << _edge_maps[i].first;

             throw FormatError(msg.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::string source_token;

         std::string target_token;

         if (!_reader_bits::readToken(line, source_token))

           throw FormatError("Red node not found");

         if (!_reader_bits::readToken(line, target_token))

           throw FormatError("Blue node not found");

         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 FormatError(msg.str());

           }

         }

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

           throw FormatError("Extra character at the end of line");

         Edge e;

         if (!_use_edges) {

           typename NodeIndex::iterator it;

           it = _node_index.find(source_token);

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

             std::ostringstream msg;

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

             throw FormatError(msg.str());

           }

           Node source = it->second;

           if (!_graph.red(source)) {

             std::ostringstream msg;

             msg << "Item is not red node: " << source_token;

             throw FormatError(msg.str());

           }

           it = _node_index.find(target_token);

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

             std::ostringstream msg;

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

             throw FormatError(msg.str());

           }

           Node target = it->second;

           if (!_graph.blue(target)) {

             std::ostringstream msg;

             msg << "Item is not red node: " << source_token;

             throw FormatError(msg.str());

           }

           e = _graph.addEdge(source, target);

           if (label_index != -1)

             _edge_index.insert(std::make_pair(tokens[label_index], e));

         } else {

           if (label_index == -1)

             throw FormatError("Label map not found");

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

             _edge_index.find(tokens[label_index]);

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

             std::ostringstream msg;

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

             throw FormatError(msg.str());

           }

           e = it->second;

         }

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

           _edge_maps[i].second->set(e, tokens[map_index[i]]);

         }

       }

       if (readSuccess()) {

         line.putback(c);

       }

     }

     void readAttributes() {

       std::set<std::string> read_attr;

       char c;

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

         line.putback(c);

         std::string attr, token;

         if (!_reader_bits::readToken(line, attr))

           throw FormatError("Attribute name not found");

         if (!_reader_bits::readToken(line, token))

           throw FormatError("Attribute value not found");

         if (line >> c)

           throw FormatError("Extra character at the end of line");

         {

           std::set<std::string>::iterator it = read_attr.find(attr);

           if (it != read_attr.end()) {

             std::ostringstream msg;

             msg << "Multiple occurence of attribute: " << attr;

             throw FormatError(msg.str());

           }

           read_attr.insert(attr);

         }

         {

           typename Attributes::iterator it = _attributes.lower_bound(attr);

           while (it != _attributes.end() && it->first == attr) {

             it->second->set(token);

             ++it;

           }

         }

       }

       if (readSuccess()) {

         line.putback(c);

       }

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

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

         if (read_attr.find(it->first) == read_attr.end()) {

           std::ostringstream msg;

           msg << "Attribute not found: " << it->first;

           throw FormatError(msg.str());

         }

       }

     }

   public:

     /// \name Execution of the Reader

     /// @{

     /// \brief Start the batch processing

     ///

     /// This function starts the batch processing

     void run() {

       LEMON_ASSERT(_is != 0, "This reader assigned to an other reader");

       bool red_nodes_done = _skip_nodes;

       bool blue_nodes_done = _skip_nodes;

       bool edges_done = _skip_edges;

       bool attributes_done = false;

       line_num = 0;

       readLine();

       skipSection();

       while (readSuccess()) {

         try {

           char c;

           std::string section, caption;

           line >> c;

           _reader_bits::readToken(line, section);

           _reader_bits::readToken(line, caption);

           if (line >> c)

             throw FormatError("Extra character at the end of line");

           if (section == "red_nodes" && !red_nodes_done) {

             if (_nodes_caption.empty() || _nodes_caption == caption) {

               readRedNodes();

               red_nodes_done = true;

             }

           } else if (section == "blue_nodes" && !blue_nodes_done) {

             if (_nodes_caption.empty() || _nodes_caption == caption) {

               readBlueNodes();

               blue_nodes_done = true;

             }

           } else if ((section == "edges" || section == "arcs") &&

                      !edges_done) {

             if (_edges_caption.empty() || _edges_caption == caption) {

               readEdges();

               edges_done = true;

             }

           } else if (section == "attributes" && !attributes_done) {

             if (_attributes_caption.empty() || _attributes_caption == caption) {

               readAttributes();

               attributes_done = true;

             }

           } else {

             readLine();

             skipSection();

           }

         } catch (FormatError& error) {

           error.line(line_num);

           error.file(_filename);

           throw;

         }

       }

       if (!red_nodes_done) {

         throw FormatError("Section @red_nodes not found");

       }

       if (!blue_nodes_done) {

         throw FormatError("Section @blue_nodes not found");

       }

       if (!edges_done) {

         throw FormatError("Section @edges not found");

       }

       if (!attributes_done && !_attributes.empty()) {

         throw FormatError("Section @attributes not found");

       }

     }

     /// @}

   };

   /// \ingroup lemon_io

   ///

   /// \brief Return a \ref BpGraphReader class

   ///

   /// This function just returns a \ref BpGraphReader class.

   ///

   /// With this function a graph can be read from an

   /// \ref lgf-format "LGF" file or input stream with several maps and

   /// attributes. For example, there is bipartite weighted matching problem

   /// on a graph, i.e. a graph with a \e weight map on the edges. This

   /// graph can be read with the following code:

   ///

   ///\code

   ///ListBpGraph graph;

   ///ListBpGraph::EdgeMap<int> weight(graph);

   ///bpGraphReader(graph, std::cin).

   ///  edgeMap("weight", weight).

   ///  run();

   ///\endcode

   ///

   /// For a complete documentation, please see the \ref BpGraphReader

   /// class documentation.

   /// \warning Don't forget to put the \ref BpGraphReader::run() "run()"

   /// to the end of the parameter list.

   /// \relates BpGraphReader

   /// \sa bpGraphReader(TBGR& graph, const std::string& fn)

   /// \sa bpGraphReader(TBGR& graph, const char* fn)

   template <typename TBGR>

   BpGraphReader<TBGR> bpGraphReader(TBGR& graph, std::istream& is) {

     BpGraphReader<TBGR> tmp(graph, is);

     return tmp;

   }

   /// \brief Return a \ref BpGraphReader class

   ///

   /// This function just returns a \ref BpGraphReader class.

   /// \relates BpGraphReader

   /// \sa bpGraphReader(TBGR& graph, std::istream& is)

   template <typename TBGR>

   BpGraphReader<TBGR> bpGraphReader(TBGR& graph, const std::string& fn) {

     BpGraphReader<TBGR> tmp(graph, fn);

     return tmp;

   }

   /// \brief Return a \ref BpGraphReader class

   ///

   /// This function just returns a \ref BpGraphReader class.

   /// \relates BpGraphReader

   /// \sa bpGraphReader(TBGR& graph, std::istream& is)

   template <typename TBGR>

   BpGraphReader<TBGR> bpGraphReader(TBGR& graph, const char* fn) {

     BpGraphReader<TBGR> tmp(graph, fn);

     return tmp;

   }