/* -*- C++ -*-

 * lemon/graph_reader.h - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2005 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 io_group

///\file

///\brief Lemon Graph Format reader.

#ifndef LEMON_GRAPH_READER_H

#define LEMON_GRAPH_READER_H

#include <iostream>

#include <lemon/error.h>

#include <lemon/lemon_reader.h>

namespace lemon {

  /// \addtogroup io_group

  /// @{

  /// \brief The graph reader class.

  ///

  /// The \c GraphReader class provides the graph input. 

  /// Before you read this documentation it might be useful to read the general

  /// description of  \ref graph-io-page "Graph Input-Output".

  /// If you don't need very sophisticated

  /// behaviour then you can use the versions of the public function

  /// \ref readGraph() to read a graph (or a max flow instance etc).

  ///

  /// The given file format may contain several maps and labeled nodes or 

  /// edges.

  ///

  /// If you read a graph you need not read all the maps and items just those

  /// that you need. The interface of the \c GraphReader is very similar to

  /// the GraphWriter but the reading method does not depend on the order the

  /// given commands.

  ///

  /// The reader object suppose that each not readed value does not contain 

  /// whitespaces, therefore it has some extra possibilities to control how

  /// it should skip the values when the string representation contains spaces.

  ///

  /// \code

  /// GraphReader<ListGraph> reader(std::cin, graph);

  /// \endcode

  ///

  /// The \c readNodeMap() function reads a map from the \c \@nodeset section.

  /// If there is a map that you do not want to read from the file and there is

  /// whitespace in the string represenation of the values then you should

  /// call the \c skipNodeMap() template member function with proper 

  /// parameters.

  ///

  /// \code

  /// reader.readNodeMap("coords", coords);

  ///

  /// reader.readNodeMap<QuotedStringReader>("label", labelMap);

  /// reader.skipNodeMap<QuotedStringReader>("description");

  ///

  /// reader.readNodeMap("color", colorMap);

  /// \endcode

  ///

  /// With the \c readEdgeMap() member function you can give an edge map

  /// reading command similar to the NodeMaps. 

  ///

  /// \code

  /// reader.readEdgeMap("weight", weightMap);

  /// reader.readEdgeMap("label", labelMap);

  /// \endcode

  ///

  /// With \c readNode() and \c readEdge() functions you can read 

  /// labeled Nodes and Edges.

  ///

  /// \code

  /// reader.readNode("source", sourceNode);

  /// reader.readNode("target", targetNode);

  ///

  /// reader.readEdge("observed", edge);

  /// \endcode

  ///

  /// With the \c readAttribute() functions you can read an attribute

  /// in a variable. You can specify the reader for the attribute as

  /// the nodemaps.

  ///

  /// After you give all read commands you must call the \c run() member

  /// function, which execute all the commands.

  ///

  /// \code

  /// reader.run();

  /// \endcode

  ///

  /// \see DefaultReaderTraits

  /// \see QuotedStringReader

  /// \see \ref GraphWriter

  /// \see \ref graph-io-page

  /// \author Balazs Dezso

  template <typename _Graph, typename _ReaderTraits = DefaultReaderTraits> 

  class GraphReader {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::Edge Edge;

    typedef _ReaderTraits ReaderTraits;

    typedef typename ReaderTraits::Skipper DefaultSkipper;

    /// \brief Construct a new GraphReader.

    ///

    /// Construct a new GraphReader. It reads into the given graph

    /// and it use the given reader as the default skipper.

    GraphReader(std::istream& _is, 

		typename SmartParameter<Graph>::Type _graph, 

		const DefaultSkipper& _skipper = DefaultSkipper()) 

      : reader(new LemonReader(_is)), own_reader(true), skipper(_skipper),

	nodeset_reader(*reader, _graph, std::string(), skipper),

	edgeset_reader(*reader, _graph, nodeset_reader, 

		       std::string(), skipper),

	node_reader(*reader, nodeset_reader, std::string()),

	edge_reader(*reader, edgeset_reader, std::string()),

	attribute_reader(*reader, std::string()) {}

    /// \brief Construct a new GraphReader.

    ///

    /// Construct a new GraphReader. It reads into the given graph

    /// and it use the given reader as the default skipper.

    GraphReader(const std::string& _filename, 

		typename SmartParameter<Graph>::Type _graph, 

		const DefaultSkipper& _skipper = DefaultSkipper()) 

      : reader(new LemonReader(_filename)), own_reader(true), 

	skipper(_skipper),

	nodeset_reader(*reader, _graph, std::string(), skipper),

	edgeset_reader(*reader, _graph, nodeset_reader, 

		       std::string(), skipper),

	node_reader(*reader, nodeset_reader, std::string()),

	edge_reader(*reader, edgeset_reader, std::string()),

	attribute_reader(*reader, std::string()) {}

    /// \brief Construct a new GraphReader.

    ///

    /// Construct a new GraphReader. It reads into the given graph

    /// and it use the given reader as the default skipper.

    GraphReader(LemonReader& _reader, 

		typename SmartParameter<Graph>::Type _graph, 

		const DefaultSkipper& _skipper = DefaultSkipper()) 

      : reader(_reader), own_reader(false), skipper(_skipper),

	nodeset_reader(*reader, _graph, std::string(), skipper),

	edgeset_reader(*reader, _graph, nodeset_reader, 

		       std::string(), skipper),

	node_reader(*reader, nodeset_reader, std::string()),

	edge_reader(*reader, edgeset_reader, std::string()),

	attribute_reader(*reader, std::string()) {}

    /// \brief Destruct the graph reader.

    ///

    /// Destruct the graph reader.

    ~GraphReader() {

      if (own_reader) 

	delete reader;

    }

    /// \brief Add a new node map reader command for the reader.

    ///

    /// Add a new node map reader command for the reader.

    template <typename Map>

    GraphReader& readNodeMap(std::string name, Map& map) {

      nodeset_reader.readNodeMap(name, map);

      return *this;

    }

    template <typename Map>

    GraphReader& readNodeMap(std::string name, const Map& map) {

      nodeset_reader.readNodeMap(name, map);

      return *this;

    }

    /// \brief Add a new node map reader command for the reader.

    ///

    /// Add a new node map reader command for the reader.

    template <typename Reader, typename Map>

    GraphReader& readNodeMap(std::string name, Map& map, 

			     const Reader& reader = Reader()) {

      nodeset_reader.readNodeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

    GraphReader& readNodeMap(std::string name, const Map& map, 

			     const Reader& reader = Reader()) {

      nodeset_reader.readNodeMap(name, map, reader);

      return *this;

    }

    /// \brief Add a new node map skipper command for the reader.

    ///

    /// Add a new node map skipper command for the reader.

    template <typename Reader>

    GraphReader& skipNodeMap(std::string name, 

			     const Reader& reader = Reader()) {

      nodeset_reader.skipNodeMap(name, reader);

      return *this;

    }

    /// \brief Add a new edge map reader command for the reader.

    ///

    /// Add a new edge map reader command for the reader.

    template <typename Map>

    GraphReader& readEdgeMap(std::string name, Map& map) { 

      edgeset_reader.readEdgeMap(name, map);

      return *this;

    }

    template <typename Map>

    GraphReader& readEdgeMap(std::string name, const Map& map) { 

      edgeset_reader.readEdgeMap(name, map);

      return *this;

    }

    /// \brief Add a new edge map reader command for the reader.

    ///

    /// Add a new edge map reader command for the reader.

    template <typename Reader, typename Map>

    GraphReader& readEdgeMap(std::string name, Map& map,

			     const Reader& reader = Reader()) {

      edgeset_reader.readEdgeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

    GraphReader& readEdgeMap(std::string name, const Map& map,

			     const Reader& reader = Reader()) {

      edgeset_reader.readEdgeMap(name, map, reader);

      return *this;

    }

    /// \brief Add a new edge map skipper command for the reader.

    ///

    /// Add a new edge map skipper command for the reader.

    template <typename Reader>

    GraphReader& skipEdgeMap(std::string name, 

			     const Reader& reader = Reader()) {

      edgeset_reader.skipEdgeMap(name, reader);

      return *this;

    }

    /// \brief Add a new labeled node reader for the reader.

    ///

    /// Add a new labeled node reader for the reader.

    GraphReader& readNode(std::string name, Node& node) {

      node_reader.readNode(name, node);

      return *this;

    }

    /// \brief Add a new labeled edge reader for the reader.

    ///

    /// Add a new labeled edge reader for the reader.

    GraphReader& readEdge(std::string name, Edge& edge) {

      edge_reader.readEdge(name, edge);

      return *this;

    }

    /// \brief Add a new attribute reader command.

    ///

    ///  Add a new attribute reader command.

    template <typename Value>

    GraphReader& readAttribute(std::string name, Value& value) {

      attribute_reader.readAttribute(name, value);

      return *this;

    }

    /// \brief Add a new attribute reader command.

    ///

    ///  Add a new attribute reader command.

    template <typename Reader, typename Value>

    GraphReader& readAttribute(std::string name, Value& value, 

			       const Reader& reader) {

      attribute_reader.readAttribute<Reader>(name, value, reader);

      return *this;

    }

    /// \brief Conversion operator to LemonReader.

    ///

    /// Conversion operator to LemonReader. It make possible

    /// to access the encapsulated \e LemonReader, this way

    /// you can attach to this reader new instances of 

    /// \e LemonReader::SectionReader.

    operator LemonReader&() {

      return *reader;

    }

    /// \brief Executes the reader commands.

    ///

    /// Executes the reader commands.

    void run() {

      reader->run();

    }

    /// \brief Gives back the node by its id.

    ///

    /// It reads an id from the stream and gives back which node belongs to

    /// it. It is possible only if there was read an "id" named node map.

    Node readId(std::istream& is, Node) const {

      return nodeset_reader.readId(is, Node());

    } 

    /// \brief Gives back the edge by its id.

    ///

    /// It reads an id from the stream and gives back which edge belongs to

    /// it. It is possible only if there was read an "id" named edge map.

    Edge readId(std::istream& is, Edge) const {

      return edgeset_reader.readId(is, Edge());

    } 

  private:

    LemonReader* reader;

    bool own_reader;

    DefaultSkipper skipper;

    NodeSetReader<Graph, ReaderTraits> nodeset_reader;

    EdgeSetReader<Graph, ReaderTraits> edgeset_reader;

    NodeReader<Graph> node_reader;

    EdgeReader<Graph> edge_reader;

    AttributeReader<ReaderTraits> attribute_reader;

  };

  ///\anchor readGraph()

  ///

  /// \brief Read a graph from an input stream.

  ///

  /// Read a graph from an input stream.

  /// \param is The input stream.

  /// \param g The graph.

  template<typename Graph>

  void readGraph(std::istream& is, Graph &g) {

    GraphReader<Graph> reader(is, g);

    reader.run();

  }

  /// \brief Read a capacitated graph instance from an input stream.

  /// 

  /// Read a capacitated graph (graph+capacity on the

  /// edges) from an input stream.

  /// \param is The input stream.

  /// \param g The graph.

  /// \param capacity The capacity map.

  template<typename Graph, typename CapacityMap>

  void readGraph(std::istream& is, Graph &g, CapacityMap& capacity) {

    GraphReader<Graph> reader(is, g);

    reader.readEdgeMap("capacity", capacity);

    reader.run();

  }

  /// \brief Read a shortest path instance from an input stream.

  /// 

  /// Read a shortest path instance (graph+capacity on the

  /// edges+designated source) from an input stream.

  /// \param is The input stream.

  /// \param g The graph.

  /// \param capacity The capacity map.

  /// \param s The source node.

  template<typename Graph, typename CapacityMap>

  void readGraph(std::istream& is, Graph &g, CapacityMap& capacity, 

		  typename Graph::Node &s) {

    GraphReader<Graph> reader(is, g);

    reader.readEdgeMap("capacity", capacity);

    reader.readNode("source", s);

    reader.run();

  }

  /// \brief Read a max flow instance from an input stream.

  ///

  /// Read a max flow instance (graph+capacity on the

  /// edges+designated source and target) from an input stream.

  ///

  /// \param is The input stream.

  /// \param g The graph.

  /// \param capacity The capacity map.

  /// \param s The source node.

  /// \param t The target node.

  template<typename Graph, typename CapacityMap>

  void readGraph(std::istream& is, Graph &g, CapacityMap& capacity, 

		  typename Graph::Node &s, typename Graph::Node &t) {

    GraphReader<Graph> reader(is, g);

    reader.readEdgeMap("capacity", capacity);

    reader.readNode("source", s);

    reader.readNode("target", t);

    reader.run();

  }

  /// \brief Read a min cost flow instance from an input stream.

  ///

  /// Read a min cost flow instance (graph+capacity on the edges+cost

  /// function on the edges+designated source and target) from an input stream.

  ///

  /// \param is The input stream.

  /// \param g The graph.

  /// \param capacity The capacity map.

  /// \param s The source node.

  /// \param t The target node.

  /// \param cost The cost map.

  template<typename Graph, typename CapacityMap, typename CostMap>

  void readGraph(std::istream& is, Graph &g, CapacityMap& capacity, 

		  typename Graph::Node &s, typename Graph::Node &t, 

		  CostMap& cost) {

    GraphReader<Graph> reader(is, g);

    reader.readEdgeMap("capacity", capacity);

    reader.readEdgeMap("cost", cost);

    reader.readNode("source", s);

    reader.readNode("target", t);

    reader.run();

  }

  /// \brief The undir graph reader class.

  ///

  /// The given file format may contain several maps and labeled nodes or 

  /// edges.

  ///

  /// If you read a graph you need not read all the maps and items just those

  /// that you need. The interface of the \c GraphReader is very similar to

  /// the GraphWriter but the reading method does not depend on the order the

  /// given commands.

  ///

  /// The reader object suppose that each not readed value does not contain 

  /// whitespaces, therefore it has some extra possibilities to control how

  /// it should skip the values when the string representation contains spaces.

  ///

  /// \code

  /// UndirGraphReader<UndirListGraph> reader(std::cin, graph);

  /// \endcode

  ///

  /// The \c readNodeMap() function reads a map from the \c \@nodeset section.

  /// If there is a map that you do not want to read from the file and there is

  /// whitespace in the string represenation of the values then you should

  /// call the \c skipNodeMap() template member function with proper 

  /// parameters.

  ///

  /// \code

  /// reader.readNodeMap("coords", coords);

  ///

  /// reader.readNodeMap<QuotedStringReader>("label", labelMap);

  /// reader.skipNodeMap<QuotedStringReader>("description");

  ///

  /// reader.readNodeMap("color", colorMap);

  /// \endcode

  ///

  /// With the \c readUndirEdgeMap() member function you can give an 

  /// undir edge map reading command similar to the NodeMaps. 

  ///

  /// \code

  /// reader.readUndirEdgeMap("capacity", capacityMap);

  /// \endcode

  ///

  /// The reading of the directed edge maps is just a syntactical sugar.

  /// It reads two undirected edgemaps into a directed edge map. The 

  /// undirected edge maps' name should be start with the \c '+' and the

  /// \c '-' character and the same.

  ///

  /// \code

  /// reader.readEdgeMap("flow", flowMap);

  /// \endcode 

  ///

  /// With \c readNode() and \c readUndirEdge() functions you can read 

  /// labeled Nodes and UndirEdges.

  ///

  /// \code

  /// reader.readNode("source", sourceNode);

  /// reader.readNode("target", targetNode);

  ///

  /// reader.readUndirEdge("observed", undirEdge);

  /// \endcode

  ///

  /// With the \c readAttribute() functions you can read an attribute

  /// in a variable. You can specify the reader for the attribute as

  /// the nodemaps.

  ///

  /// After you give all read commands you must call the \c run() member

  /// function, which execute all the commands.

  ///

  /// \code

  /// reader.run();

  /// \endcode

  ///

  /// \see GraphReader

  /// \see DefaultReaderTraits

  /// \see \ref UndirGraphWriter

  /// \see \ref graph-io-page

  ///

  /// \author Balazs Dezso

  template <typename _Graph, typename _ReaderTraits = DefaultReaderTraits> 

  class UndirGraphReader {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::Edge Edge;

    typedef typename Graph::UndirEdge UndirEdge;

    typedef _ReaderTraits ReaderTraits;

    typedef typename ReaderTraits::Skipper DefaultSkipper;

    /// \brief Construct a new UndirGraphReader.

    ///

    /// Construct a new UndirGraphReader. It reads into the given graph

    /// and it use the given reader as the default skipper.

    UndirGraphReader(std::istream& _is, Graph& _graph, 

		     const DefaultSkipper& _skipper = DefaultSkipper()) 

      : reader(new LemonReader(_is)), own_reader(true), skipper(_skipper),

	nodeset_reader(*reader, _graph, std::string(), skipper),

	undir_edgeset_reader(*reader, _graph, nodeset_reader, 

			     std::string(), skipper),

	node_reader(*reader, nodeset_reader, std::string()),

	undir_edge_reader(*reader, undir_edgeset_reader, std::string()),

	attribute_reader(*reader, std::string()) {}

    /// \brief Construct a new UndirGraphReader.

    ///

    /// Construct a new UndirGraphReader. It reads into the given graph

    /// and it use the given reader as the default skipper.

    UndirGraphReader(const std::string& _filename, Graph& _graph, 

		     const DefaultSkipper& _skipper = DefaultSkipper()) 

      : reader(new LemonReader(_filename)), own_reader(true), 

	skipper(_skipper),

	nodeset_reader(*reader, _graph, std::string(), skipper),

	undir_edgeset_reader(*reader, _graph, nodeset_reader, 

			     std::string(), skipper),

	node_reader(*reader, nodeset_reader, std::string()),

	undir_edge_reader(*reader, undir_edgeset_reader, std::string()),

	attribute_reader(*reader, std::string()) {}

    /// \brief Construct a new UndirGraphReader.

    ///

    /// Construct a new UndirGraphReader. It reads into the given graph

    /// and it use the given reader as the default skipper.

    UndirGraphReader(LemonReader& _reader, Graph& _graph, 

		     const DefaultSkipper& _skipper = DefaultSkipper()) 

      : reader(_reader), own_reader(false), skipper(_skipper),

	nodeset_reader(*reader, _graph, std::string(), skipper),

	undir_edgeset_reader(*reader, _graph, nodeset_reader, 

			     std::string(), skipper),

	node_reader(*reader, nodeset_reader, std::string()),

	undir_edge_reader(*reader, undir_edgeset_reader, std::string()),

	attribute_reader(*reader, std::string()) {}

    /// \brief Destruct the graph reader.

    ///

    /// Destruct the graph reader.

    ~UndirGraphReader() {

      if (own_reader) 

	delete reader;

    }

    /// \brief Add a new node map reader command for the reader.

    ///

    /// Add a new node map reader command for the reader.

    template <typename Map>

    UndirGraphReader& readNodeMap(std::string name, Map& map) {

      nodeset_reader.readNodeMap(name, map);

      return *this;

    }

    template <typename Map>

    UndirGraphReader& readNodeMap(std::string name, const Map& map) {

      nodeset_reader.readNodeMap(name, map);

      return *this;

    }

    /// \brief Add a new node map reader command for the reader.

    ///

    /// Add a new node map reader command for the reader.

    template <typename Reader, typename Map>

    UndirGraphReader& readNodeMap(std::string name, Map& map, 

				  const Reader& reader = Reader()) {

      nodeset_reader.readNodeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

    UndirGraphReader& readNodeMap(std::string name, const Map& map, 

				  const Reader& reader = Reader()) {

      nodeset_reader.readNodeMap(name, map, reader);

      return *this;

    }

    /// \brief Add a new node map skipper command for the reader.

    ///

    /// Add a new node map skipper command for the reader.

    template <typename Reader>

    UndirGraphReader& skipNodeMap(std::string name, 

			     const Reader& reader = Reader()) {

      nodeset_reader.skipNodeMap(name, reader);

      return *this;

    }

    /// \brief Add a new undirected edge map reader command for the reader.

    ///

    /// Add a new undirected edge map reader command for the reader.

    template <typename Map>

    UndirGraphReader& readUndirEdgeMap(std::string name, Map& map) { 

      undir_edgeset_reader.readUndirEdgeMap(name, map);

      return *this;

    }

    template <typename Map>

    UndirGraphReader& readUndirEdgeMap(std::string name, const Map& map) { 

      undir_edgeset_reader.readUndirEdgeMap(name, map);

      return *this;

    }

    /// \brief Add a new undirected edge map reader command for the reader.

    ///

    /// Add a new undirected edge map reader command for the reader.

    template <typename Reader, typename Map>

    UndirGraphReader& readUndirEdgeMap(std::string name, Map& map,

				       const Reader& reader = Reader()) {

      undir_edgeset_reader.readUndirEdgeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

    UndirGraphReader& readUndirEdgeMap(std::string name, const Map& map,

				       const Reader& reader = Reader()) {

      undir_edgeset_reader.readUndirEdgeMap(name, map, reader);

      return *this;

    }

    /// \brief Add a new undirected edge map skipper command for the reader.

    ///

    /// Add a new undirected edge map skipper command for the reader.

    template <typename Reader>

    UndirGraphReader& skipUndirEdgeMap(std::string name,

				       const Reader& reader = Reader()) {

      undir_edgeset_reader.skipUndirMap(name, reader);

      return *this;

    }

    /// \brief Add a new edge map reader command for the reader.

    ///

    /// Add a new edge map reader command for the reader.

    template <typename Map>

    UndirGraphReader& readEdgeMap(std::string name, Map& map) { 

      undir_edgeset_reader.readEdgeMap(name, map);

      return *this;

    }

    template <typename Map>

    UndirGraphReader& readEdgeMap(std::string name, const Map& map) { 

      undir_edgeset_reader.readEdgeMap(name, map);

      return *this;

    }

    /// \brief Add a new edge map reader command for the reader.

    ///

    /// Add a new edge map reader command for the reader.

    template <typename Reader, typename Map>

    UndirGraphReader& readEdgeMap(std::string name, Map& map,

				       const Reader& reader = Reader()) {

      undir_edgeset_reader.readEdgeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

    UndirGraphReader& readEdgeMap(std::string name, const Map& map,

				       const Reader& reader = Reader()) {

      undir_edgeset_reader.readEdgeMap(name, map, reader);

      return *this;

    }

    /// \brief Add a new edge map skipper command for the reader.

    ///

    /// Add a new edge map skipper command for the reader.

    template <typename Reader>

    UndirGraphReader& skipEdgeMap(std::string name,

				       const Reader& reader = Reader()) {

      undir_edgeset_reader.skipEdgeMap(name, reader);

      return *this;

    }

    /// \brief Add a new labeled node reader for the reader.

    ///

    /// Add a new labeled node reader for the reader.

    UndirGraphReader& readNode(std::string name, Node& node) {

      node_reader.readNode(name, node);

      return *this;

    }

    /// \brief Add a new labeled edge reader for the reader.

    ///

    /// Add a new labeled edge reader for the reader.

    UndirGraphReader& readEdge(std::string name, Edge& edge) {

      undir_edge_reader.readEdge(name, edge);

    }

    /// \brief Add a new labeled undirected edge reader for the reader.

    ///

    /// Add a new labeled undirected edge reader for the reader.

    UndirGraphReader& readUndirEdge(std::string name, UndirEdge& edge) {

      undir_edge_reader.readUndirEdge(name, edge);

    }

    /// \brief Add a new attribute reader command.

    ///

    ///  Add a new attribute reader command.

    template <typename Value>

    UndirGraphReader& readAttribute(std::string name, Value& value) {

      attribute_reader.readAttribute(name, value);

      return *this;

    }

    /// \brief Add a new attribute reader command.

    ///

    ///  Add a new attribute reader command.

    template <typename Reader, typename Value>

    UndirGraphReader& readAttribute(std::string name, Value& value, 

			       const Reader& reader) {

      attribute_reader.readAttribute<Reader>(name, value, reader);

      return *this;

    }

    /// \brief Conversion operator to LemonReader.

    ///

    /// Conversion operator to LemonReader. It make possible

    /// to access the encapsulated \e LemonReader, this way

    /// you can attach to this reader new instances of 

    /// \e LemonReader::SectionReader.

    operator LemonReader&() {

      return *reader;

    }

    /// \brief Executes the reader commands.

    ///

    /// Executes the reader commands.

    void run() {

      reader->run();

    }

    /// \brief Gives back the node by its id.

    ///

    /// It reads an id from the stream and gives back which node belongs to

    /// it. It is possible only if there was read an "id" named node map.

    Node readId(std::istream& is, Node) const {

      return nodeset_reader.readId(is, Node());

    } 

    /// \brief Gives back the edge by its id.

    ///

    /// It reads an id from the stream and gives back which edge belongs to

    /// it. It is possible only if there was read an "id" named edge map.

    Edge readId(std::istream& is, Edge) const {

      return undir_edgeset_reader.readId(is, Edge());

    } 

    /// \brief Gives back the undirected edge by its id.

    ///

    /// It reads an id from the stream and gives back which undirected edge 

    /// belongs to it. It is possible only if there was read an "id" named 

    /// edge map.

    UndirEdge readId(std::istream& is, UndirEdge) const {

      return undir_edgeset_reader.readId(is, UndirEdge());

    } 

  private:

    LemonReader* reader;

    bool own_reader;

    DefaultSkipper skipper;

    NodeSetReader<Graph, ReaderTraits> nodeset_reader;

    UndirEdgeSetReader<Graph, ReaderTraits> undir_edgeset_reader;

    NodeReader<Graph> node_reader;

    UndirEdgeReader<Graph> undir_edge_reader;

    AttributeReader<ReaderTraits> attribute_reader;

  };

  /// \brief Read an undirected graph from an input stream.

  ///

  /// Read an undirected graph from an input stream.

  /// \param is The input stream.

  /// \param g The graph.

  template<typename Graph>

  void readUndirGraph(std::istream& is, Graph &g) {

    UndirGraphReader<Graph> reader(is, g);

    reader.run();

  }

  /// \brief Read an undirected multigraph (undirected graph + capacity

  /// map on the edges) from an input stream.

  ///

  /// Read an undirected multigraph (undirected graph + capacity

  /// map on the edges) from an input stream.

  /// \param is The input stream.

  /// \param g The graph.

  /// \param capacity The capacity map.

  template<typename Graph, typename CapacityMap>

  void readUndirGraph(std::istream& is, Graph &g, CapacityMap& capacity) {

    UndirGraphReader<Graph> reader(is, g);

    reader.readUndirEdgeMap("capacity", capacity);

    reader.run();

  }

  /// @}

}

#endif