RhodeCode

      _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 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

    /// \c 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

    /// \c 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;

    }

    /// \brief Skips 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 arc set

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

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

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

    DigraphReader& skipNodes() {

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

      _skip_nodes = true;

      return *this;

    }

    /// \brief Skips the reading of arc section

    ///

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

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

    /// will not be constructed.

    DigraphReader& skipArcs() {

      LEMON_ASSERT(!_skip_arcs, "Skip arcs already set");

      _skip_arcs = 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();

      }

    }

    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 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 node map: " << map;

            throw FormatError(msg.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: " << _node_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 = _digraph.addNode();

          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>(_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 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 arc map: " << map;

            throw FormatError(msg.str());

          }

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

          ++index;

        }

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

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

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

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

            std::ostringstream msg;

            msg << "Map not found: " << _arc_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("Source not found");

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

          throw FormatError("Target 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");

        Arc a;

        if (!_use_arcs) {

          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;

          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;

          a = _digraph.addArc(source, target);

          if (label_index != -1)

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

      return *this;

    }

    /// \brief Node reading rule

    ///

    /// Add a node reading rule to reader.

    GraphReader& 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.

    GraphReader& 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.

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

      typedef _reader_bits::GraphArcLookUpConverter<Graph> 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.

    GraphReader& 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.

    GraphReader& 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.

    GraphReader& 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>

    GraphReader& 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>

    GraphReader& 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>

    GraphReader& 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>

    GraphReader& 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.

    GraphReader& 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.

    GraphReader& 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();

      }

    }

    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 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 node map: " << map;

            throw FormatError(msg.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: " << _node_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.addNode();

          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>(_node_maps.size()); ++i) {

          _node_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("Node u not found");

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

          throw FormatError("Node v 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;

          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;

          e = _graph.addEdge(source, target);

          if (label_index != -1)

    }

    /// @}

  };

  class SectionReader;

  SectionReader sectionReader(std::istream& is);

  SectionReader sectionReader(const std::string& fn);

  SectionReader sectionReader(const char* fn);

  /// \ingroup lemon_io

  ///

  /// \brief Section reader class

  ///

  /// In the \ref lgf-format "LGF" file extra sections can be placed,

  /// which contain any data in arbitrary format. Such sections can be

  /// read with this class. A reading rule can be added to the class

  /// with two different functions. With the \c sectionLines() function a

  /// functor can process the section line-by-line, while with the \c

  /// sectionStream() member the section can be read from an input

  /// stream.

  class SectionReader {

  private:

    std::istream* _is;

    bool local_is;

    std::string _filename;

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

    Sections _sections;

    int line_num;

    std::istringstream line;

  public:

    /// \brief Constructor

    ///

    /// Construct a section reader, which reads from the given input

    /// stream.

    SectionReader(std::istream& is)

      : _is(&is), local_is(false) {}

    /// \brief Constructor

    ///

    /// Construct a section reader, which reads from the given file.

    SectionReader(const std::string& fn)

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

        _filename(fn) {

      if (!(*_is)) {

        delete _is;

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

      }

    }

    /// \brief Constructor

    ///

    /// Construct a section reader, which reads from the given file.

    SectionReader(const char* fn)

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

        _filename(fn) {

      if (!(*_is)) {

        delete _is;

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

      }

    }

    /// \brief Destructor

    ~SectionReader() {

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

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

        delete it->second;

      }

      if (local_is) {

        delete _is;

      }

    }

  private:

    friend SectionReader sectionReader(std::istream& is);

    friend SectionReader sectionReader(const std::string& fn);

    friend SectionReader sectionReader(const char* fn);

    SectionReader(SectionReader& other)

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

      other._is = 0;

      other.local_is = false;

      _sections.swap(other._sections);

    }

    SectionReader& operator=(const SectionReader&);

  public:

    /// \name Section readers

    /// @{

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

    ///

    /// 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 trimmed 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 a 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>

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

      LEMON_ASSERT(!type.empty(), "Type is empty.");

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

                   "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

    ///

    /// The first parameter is the type of the section, the second is

    /// a functor, which takes an \c std::istream& and an \c 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>

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

      LEMON_ASSERT(!type.empty(), "Type is empty.");

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

                   "Multiple reading of section.");

      _sections.insert(std::make_pair(type,

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

      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();

      }

    }

  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");

      std::set<std::string> extra_sections;

      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 (extra_sections.find(section) != extra_sections.end()) {

            std::ostringstream msg;

            msg << "Multiple occurence of section: " << section;

            throw FormatError(msg.str());

          }

          Sections::iterator it = _sections.find(section);

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

            extra_sections.insert(section);

            it->second->process(*_is, line_num);

          }

          readLine();

          skipSection();

        } catch (FormatError& error) {

          error.line(line_num);

          error.file(_filename);

          throw;

        }

      }

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

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

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

          std::ostringstream os;

          os << "Cannot find section: " << it->first;

          throw FormatError(os.str());

        }

      }

    }

    /// @}

  };

  /// \brief Return a \ref SectionReader class

  ///

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

  /// \relates SectionReader

  inline SectionReader sectionReader(std::istream& is) {

    SectionReader tmp(is);

    return tmp;

  }

  /// \brief Return a \ref SectionReader class

  ///

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

  /// \relates SectionReader

  inline SectionReader sectionReader(const std::string& fn) {

    SectionReader tmp(fn);

    return tmp;

  }

  /// \brief Return a \ref SectionReader class

  ///

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

  /// \relates SectionReader

  inline SectionReader sectionReader(const char* fn) {

    SectionReader tmp(fn);

    return tmp;

  }

  /// \ingroup lemon_io

  ///

  /// \brief Reader for the contents of the \ref lgf-format "LGF" file

  ///

  /// This class can be used to read the sections, the map names and

  /// the attributes from a file. Usually, the LEMON programs know

  /// that, which type of graph, which maps and which attributes

  /// should be read from a file, but in general tools (like glemon)

  /// the contents of an LGF file should be guessed somehow. This class

  /// reads the graph and stores the appropriate information for

  /// reading the graph.

  ///

  ///\code

  /// LgfContents contents("graph.lgf");

  /// contents.run();

  ///

  /// // Does it contain any node section and arc section?

  /// if (contents.nodeSectionNum() == 0 || contents.arcSectionNum()) {

  ///   std::cerr << "Failure, cannot find graph." << std::endl;

  ///   return -1;

  /// }

  /// std::cout << "The name of the default node section: "

  ///           << contents.nodeSection(0) << std::endl;

  /// std::cout << "The number of the arc maps: "

  ///           << contents.arcMaps(0).size() << std::endl;

  /// std::cout << "The name of second arc map: "

  ///           << contents.arcMaps(0)[1] << std::endl;

  ///\endcode

  class LgfContents {

  private:

    std::istream* _is;

    bool local_is;

    std::vector<std::string> _node_sections;

    std::vector<std::string> _edge_sections;

    std::vector<std::string> _attribute_sections;

    std::vector<std::string> _extra_sections;

    std::vector<bool> _arc_sections;

    std::vector<std::vector<std::string> > _node_maps;

    std::vector<std::vector<std::string> > _edge_maps;

    std::vector<std::vector<std::string> > _attributes;

    int line_num;

    std::istringstream line;