/* -*- C++ -*-

 *

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

 *

 * Copyright (C) 2003-2006

 * 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".

  ///

  /// The file to be read 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 (i.e. you don't have to insist on the order in which the

  /// maps are given in the file).

  ///

  /// The reader object assumes that not readed values do 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.skipNodeMap("description", desc);

  ///

  /// 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

  /// into 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 executes 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 uses the given reader as the default skipper.

    GraphReader(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),

	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 uses the given reader as the default skipper.

    GraphReader(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),

	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 uses the given reader as the default skipper.

    GraphReader(LemonReader& _reader, Graph& _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 Give a new node map reading command to the reader.

    ///

    /// Give a new node map reading command to 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 Give a new node map reading command to the reader.

    ///

    /// Give a new node map reading command to 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 Give a new node map skipping command to the reader.

    ///

    /// Give a new node map skipping command to the reader.

    template <typename Reader>

    GraphReader& skipNodeMap(std::string name, 

			     const Reader& reader = Reader()) {

      nodeset_reader.skipNodeMap(name, reader);

      return *this;

    }

    /// \brief Give a new edge map reading command to the reader.

    ///

    /// Give a new edge map reading command to 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 Give a new edge map reading command to the reader.

    ///

    /// Give a new edge map reading command to 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 Give a new edge map skipping command to the reader.

    ///

    /// Give a new edge map skipping command to the reader.

    template <typename Reader>

    GraphReader& skipEdgeMap(std::string name, 

			     const Reader& reader = Reader()) {

      edgeset_reader.skipEdgeMap(name, reader);

      return *this;

    }

    /// \brief Give a new labeled node reading command to the reader.

    ///

    /// Give a new labeled node reading command to the reader.

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

      node_reader.readNode(name, node);

      return *this;

    }

    /// \brief Give a new labeled edge reading command to the reader.

    ///

    /// Give a new labeled edge reading command to the reader.

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

      edge_reader.readEdge(name, edge);

      return *this;

    }

    /// \brief Give a new attribute reading command.

    ///

    ///  Give a new attribute reading command.

    template <typename Value>

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

      attribute_reader.readAttribute(name, value);

      return *this;

    }

    /// \brief Give a new attribute reading command.

    ///

    ///  Give a new attribute reading 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 makes possible to access the

    /// encapsulated \e LemonReader, this way you can attach to this reader

    /// new instances of \e LemonReader::SectionReader. For more details see

    /// the \ref rwbackground "Background of Reading and Writing".

    operator LemonReader&() {

      return *reader;

    }

    /// \brief Executes the reading commands.

    ///

    /// Executes the reading commands.

    void run() {

      reader->run();

    }

    /// \brief Returns true if the reader can give back the items by its label.

    ///

    /// \brief Returns true if the reader can give back the items by its label.

    bool isLabelReader() const {

      return nodeset_reader.isLabelReader() && edgeset_reader.isLabelReader();

    }

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

    ///

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

    /// it. It is possible only if there was read a "label" named node map.

    void readLabel(std::istream& is, Node& node) const {

      nodeset_reader.readLabel(is, node);

    } 

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

    ///

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

    /// it. It is possible only if there was read a "label" named edge map.

    void readLabel(std::istream& is, Edge& edge) const {

      return edgeset_reader.readLabel(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;

  };

  /// \brief Read a graph from the input.

  ///

  /// It is a helper function to read a graph from the given input

  /// stream. It gives back an GraphReader object and this object

  /// can read more maps, labeled nodes, edges and attributes.

  ///

  /// \warning Do not forget to call the \c run() function.

  ///

  /// \param is The input stream.

  /// \param g The graph.

  template<typename Graph>

  GraphReader<Graph> graphReader(std::istream& is, Graph &g) {

    return GraphReader<Graph>(is, g);

  }

  /// \brief Read a graph from the input.

  ///

  /// It is a helper function to read a graph from the given input

  /// file. It gives back an GraphReader object and this object

  /// can read more maps, labeled nodes, edges and attributes.

  ///

  /// \warning Do not forget to call the \c run() function.

  ///

  /// \param fn The input filename.

  /// \param g The graph.

  template<typename Graph>

  GraphReader<Graph> graphReader(const std::string& fn, Graph &g) {

    return GraphReader<Graph>(fn, g);

  }

  /// \brief The undirected graph reader class.

  ///

  /// The \c UGraphReader 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".

  ///

  /// 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 UGraphReader is very similar

  /// to the UGraphWriter but the reading method does not depend on the

  /// order of 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

  /// UGraphReader<ListUGraph> 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.skipNodeMap("description", desc);

  ///

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

  ///\endcode

  ///

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

  /// uedge map reading command similar to the NodeMaps. 

  ///

  ///\code

  /// reader.readUEdgeMap("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 readUEdge() functions you can read 

  /// labeled Nodes and UEdges.

  ///

  ///\code

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

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

  ///

  /// reader.readUEdge("observed", uEdge);

  ///\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 UGraphWriter

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

  ///

  /// \author Balazs Dezso

  template <typename _Graph, typename _ReaderTraits = DefaultReaderTraits> 

  class UGraphReader {

  public:

    typedef _Graph Graph;

    typedef typename Graph::Node Node;

    typedef typename Graph::Edge Edge;

    typedef typename Graph::UEdge UEdge;

    typedef _ReaderTraits ReaderTraits;

    typedef typename ReaderTraits::Skipper DefaultSkipper;

    /// \brief Construct a new UGraphReader.

    ///

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

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

    UGraphReader(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),

	u_edgeset_reader(*reader, _graph, nodeset_reader, 

			     std::string(), skipper),

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

	u_edge_reader(*reader, u_edgeset_reader, std::string()),

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

    /// \brief Construct a new UGraphReader.

    ///

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

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

    UGraphReader(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),

	u_edgeset_reader(*reader, _graph, nodeset_reader, 

			     std::string(), skipper),

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

	u_edge_reader(*reader, u_edgeset_reader, std::string()),

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

    /// \brief Construct a new UGraphReader.

    ///

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

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

    UGraphReader(LemonReader& _reader, Graph& _graph, 

		     const DefaultSkipper& _skipper = DefaultSkipper()) 

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

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

	u_edgeset_reader(*reader, _graph, nodeset_reader, 

			     std::string(), skipper),

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

	u_edge_reader(*reader, u_edgeset_reader, std::string()),

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

    /// \brief Destruct the graph reader.

    ///

    /// Destruct the graph reader.

    ~UGraphReader() {

      if (own_reader) 

	delete reader;

    }

    /// \brief Give a new node map reading command to the reader.

    ///

    /// Give a new node map reading command to the reader.

    template <typename Map>

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

      nodeset_reader.readNodeMap(name, map);

      return *this;

    }

    template <typename Map>

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

      nodeset_reader.readNodeMap(name, map);

      return *this;

    }

    /// \brief Give a new node map reading command to the reader.

    ///

    /// Give a new node map reading command to the reader.

    template <typename Reader, typename Map>

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

				  const Reader& reader = Reader()) {

      nodeset_reader.readNodeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

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

				  const Reader& reader = Reader()) {

      nodeset_reader.readNodeMap(name, map, reader);

      return *this;

    }

    /// \brief Give a new node map skipping command to the reader.

    ///

    /// Give a new node map skipping command to the reader.

    template <typename Reader>

    UGraphReader& skipNodeMap(std::string name, 

			     const Reader& reader = Reader()) {

      nodeset_reader.skipNodeMap(name, reader);

      return *this;

    }

    /// \brief Give a new undirected edge map reading command to the reader.

    ///

    /// Give a new undirected edge map reading command to the reader.

    template <typename Map>

    UGraphReader& readUEdgeMap(std::string name, Map& map) { 

      u_edgeset_reader.readUEdgeMap(name, map);

      return *this;

    }

    template <typename Map>

    UGraphReader& readUEdgeMap(std::string name, const Map& map) { 

      u_edgeset_reader.readUEdgeMap(name, map);

      return *this;

    }

    /// \brief Give a new undirected edge map reading command to the reader.

    ///

    /// Give a new undirected edge map reading command to the reader.

    template <typename Reader, typename Map>

    UGraphReader& readUEdgeMap(std::string name, Map& map,

				       const Reader& reader = Reader()) {

      u_edgeset_reader.readUEdgeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

    UGraphReader& readUEdgeMap(std::string name, const Map& map,

				       const Reader& reader = Reader()) {

      u_edgeset_reader.readUEdgeMap(name, map, reader);

      return *this;

    }

    /// \brief Give a new undirected edge map skipping command to the reader.

    ///

    /// Give a new undirected edge map skipping command to the reader.

    template <typename Reader>

    UGraphReader& skipUEdgeMap(std::string name,

				       const Reader& reader = Reader()) {

      u_edgeset_reader.skipUMap(name, reader);

      return *this;

    }

    /// \brief Give a new edge map reading command to the reader.

    ///

    /// Give a new edge map reading command to the reader.

    template <typename Map>

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

      u_edgeset_reader.readEdgeMap(name, map);

      return *this;

    }

    template <typename Map>

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

      u_edgeset_reader.readEdgeMap(name, map);

      return *this;

    }

    /// \brief Give a new edge map reading command to the reader.

    ///

    /// Give a new edge map reading command to the reader.

    template <typename Reader, typename Map>

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

				       const Reader& reader = Reader()) {

      u_edgeset_reader.readEdgeMap(name, map, reader);

      return *this;

    }

    template <typename Reader, typename Map>

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

				       const Reader& reader = Reader()) {

      u_edgeset_reader.readEdgeMap(name, map, reader);

      return *this;

    }

    /// \brief Give a new edge map skipping command to the reader.

    ///

    /// Give a new edge map skipping command to the reader.

    template <typename Reader>

    UGraphReader& skipEdgeMap(std::string name,

				       const Reader& reader = Reader()) {

      u_edgeset_reader.skipEdgeMap(name, reader);

      return *this;

    }

    /// \brief Give a new labeled node reading command to the reader.

    ///

    /// Give a new labeled node reading command to the reader.

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

      node_reader.readNode(name, node);

      return *this;

    }

    /// \brief Give a new labeled edge reading command to the reader.

    ///

    /// Give a new labeled edge reading command to the reader.

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

      u_edge_reader.readEdge(name, edge);

    }

    /// \brief Give a new labeled undirected edge reading command to the

    /// reader.

    ///

    /// Give a new labeled undirected edge reading command to the reader.

    UGraphReader& readUEdge(std::string name, UEdge& edge) {

      u_edge_reader.readUEdge(name, edge);

    }

    /// \brief Give a new attribute reading command.

    ///

    ///  Give a new attribute reading command.

    template <typename Value>

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

      attribute_reader.readAttribute(name, value);

      return *this;

    }

    /// \brief Give a new attribute reading command.

    ///

    ///  Give a new attribute reading command.

    template <typename Reader, typename Value>

    UGraphReader& 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 reading commands.

    ///

    /// Executes the reading commands.

    void run() {

      reader->run();

    }

    /// \brief Returns true if the reader can give back the items by its label.

    ///

    /// \brief Returns true if the reader can give back the items by its label.

    bool isLabelReader() const {

      return nodeset_reader.isLabelReader() && 

        u_edgeset_reader.isLabelReader();

    }

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

    ///

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

    /// it. It is possible only if there was read a "label" named node map.

    void readLabel(std::istream& is, Node& node) const {

      return nodeset_reader.readLabel(is, node);

    } 

    /// \brief Gives back the edge by its label

    ///

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

    /// it. It is possible only if there was read a "label" named edge map.

    void readLabel(std::istream& is, Edge& edge) const {

      return u_edgeset_reader.readLabel(is, edge);

    } 

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

    ///

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

    /// belongs to it. It is possible only if there was read a "label" named 

    /// edge map.

    void readLabel(std::istream& is, UEdge& uedge) const {

      return u_edgeset_reader.readLabel(is, uedge);

    } 

  private:

    LemonReader* reader;

    bool own_reader;

    DefaultSkipper skipper;

    NodeSetReader<Graph, ReaderTraits> nodeset_reader;

    UEdgeSetReader<Graph, ReaderTraits> u_edgeset_reader;

    NodeReader<Graph> node_reader;

    UEdgeReader<Graph> u_edge_reader;

    AttributeReader<ReaderTraits> attribute_reader;

  };

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

  ///

  /// It is a helper function to read an undirected graph from the given input

  /// stream. It gives back an UGraphReader object and this object

  /// can read more maps, labeled nodes, edges, undirected edges and

  /// attributes.

  ///

  /// \warning Do not forget to call the \c run() function.

  ///

  /// \param is The input stream.

  /// \param g The graph.

  template<typename Graph>

  UGraphReader<Graph> uGraphReader(std::istream& is, Graph &g) {

    return GraphReader<Graph>(is, g);

  }

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

  ///

  /// It is a helper function to read an undirected graph from the given input

  /// file. It gives back an UGraphReader object and this object

  /// can read more maps, labeled nodes, edges, undirected edges and 

  /// attributes.

  ///

  /// \warning Do not forget to call the \c run() function.

  ///

  /// \param fn The input filename.

  /// \param g The graph.

  template<typename Graph>

  UGraphReader<Graph> uGraphReader(const std::string& fn, Graph &g) {

    return GraphReader<Graph>(fn, g);

  }

  /// @}

}

#endif