RhodeCode

/* -*- C++ -*-

 *

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

 *

 * Copyright (C) 2003-2008

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

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

 *

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

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

 * precise terms see the accompanying LICENSE file.

 *

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

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

 * purpose.

 *

 */

///\ingroup lemon_io

///\file

///\brief \ref lgf-format "Lemon Graph Format" reader.

#ifndef LEMON_LGF_READER_H

#define LEMON_LGF_READER_H

#include <iostream>

#include <fstream>

#include <sstream>

#include <set>

#include <map>

#include <lemon/assert.h>

#include <lemon/graph_utils.h>

#include <lemon/lgf_writer.h>

#include <lemon/concept_check.h>

#include <lemon/concepts/maps.h>

namespace lemon {

  namespace _reader_bits {

    template <typename Value>

    struct DefaultConverter {

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

	std::istringstream is(str);

	Value value;

	is >> value;

	char c;

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

	  throw DataFormatError("Remaining characters in token");

	}

	return value;

      }

    };

    template <>

    struct DefaultConverter<std::string> {

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

	return str;

      }

    };

    template <typename _Item>    

    class MapStorageBase {

    public:

      typedef _Item Item;

    public:

      MapStorageBase() {}

      virtual ~MapStorageBase() {}

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

    };

    template <typename _Item, typename _Map, 

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

    class MapStorage : public MapStorageBase<_Item> {

    public:

      typedef _Map Map;

      typedef _Converter Converter;

      typedef _Item Item;

    private:

      Map& _map;

      Converter _converter;

    public:

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

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

      virtual ~MapStorage() {}

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

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

      }

    };

    template <typename _Graph, bool _dir, typename _Map, 

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

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

    public:

      typedef _Map Map;

      typedef _Converter Converter;

      typedef _Graph Graph;

      typedef typename Graph::Edge Item;

      static const bool dir = _dir;

    private:

      const Graph& _graph;

      Map& _map;

      Converter _converter;

    public:

      GraphArcMapStorage(const Graph& graph, Map& map, 

			 const Converter& converter = Converter()) 

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

      virtual ~GraphArcMapStorage() {}

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

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

      }

    };

    class ValueStorageBase {

    public:

      ValueStorageBase() {}

      virtual ~ValueStorageBase() {}

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

    };

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

    class ValueStorage : public ValueStorageBase {

    public:

      typedef _Value Value;

      typedef _Converter Converter;

    private:

      Value& _value;

      Converter _converter;

    public:

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

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

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

	_value = _converter(value);

      }

    };

    template <typename Value>

    struct MapLookUpConverter {

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

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

        : _map(map) {}

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

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

          _map.find(str);

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

          std::ostringstream msg;

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

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

        }

        return it->second;

      }

    };

    template <typename Graph>

    struct GraphArcLookUpConverter {

      const Graph& _graph;

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

      GraphArcLookUpConverter(const Graph& graph, 

			      const std::map<std::string,

			                     typename Graph::Edge>& map) 

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

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

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

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

	}

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

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

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

	  throw DataFormatError("Item not found");

	}

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

      }

    };

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

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

    }

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

    }

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

      return c - '0';

    }

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

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

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

    }

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

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

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

      return c - 'A' + 10;

    }

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

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

    }

      return isIdentifierFirstChar(c) ||

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

    }

      char c;

      if (!is.get(c))

	throw DataFormatError("Escape format error");

      switch (c) {

      case '\\':

	return '\\';

      case '\"':

	return '\"';

      case '\'':

	return '\'';

      case '\?':

	return '\?';

      case 'a':

	return '\a';

      case 'b':

	return '\b';

      case 'f':

	return '\f';

      case 'n':

	return '\n';

      case 'r':

	return '\r';

      case 't':

	return '\t';

      case 'v':

	return '\v';

      case 'x':

	{

	  int code;

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

	    throw DataFormatError("Escape format error");

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

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

	  return code;

	}

      default:

	{

	  int code;

	  if (!isOct(c)) 

	    throw DataFormatError("Escape format error");

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

	    is.putback(c);

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

	    is.putback(c);

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

	  return code;

	}	      

      } 

    }

      std::ostringstream os;

      char c;

      is >> std::ws;

      if (!is.get(c)) 

	return is;

      if (c == '\"') {

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

	  if (c == '\\') 

	    c = readEscape(is);

	  os << c;

	}

	if (!is) 

	  throw DataFormatError("Quoted format error");

      } else {

	is.putback(c);

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

	  if (c == '\\') 

	    c = readEscape(is);

	  os << c;

	}

	if (!is) {

	  is.clear();

	} else {

	  is.putback(c);

	}

      }

      str = os.str();

      return is;

    }

    class Section {

    public:

      virtual ~Section() {}

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

    };

    template <typename Functor>

    class LineSection : public Section {

    private:

      Functor _functor;

    public:

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

      virtual ~LineSection() {}

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

	char c;

	std::string line;

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

	  if (c == '\n') {

	    ++line_num;

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

	    getline(is, line);

	    ++line_num;

	  } else if (!isWhiteSpace(c)) {

	    is.putback(c);

	    getline(is, line);

	    _functor(line);

	    ++line_num;

	  }

	}

	if (is) is.putback(c);

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

      }

    };

    template <typename Functor>

    class StreamSection : public Section {

    private:

      Functor _functor;

    public:

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

      virtual ~StreamSection() {} 

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

	_functor(is, line_num);

	char c;

	std::string line;

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

	  if (c == '\n') {

	    ++line_num;

	  } else if (!isWhiteSpace(c)) {

	    getline(is, line);

	    ++line_num;

	  }

	}

	if (is) is.putback(c);

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

      }

    };

  }

  template <typename Digraph>

  class DigraphReader;

  template <typename Digraph>

  DigraphReader<Digraph> digraphReader(std::istream& is, Digraph& digraph);

  template <typename Digraph>

  DigraphReader<Digraph> digraphReader(const std::string& fn, Digraph& digraph);

  template <typename Digraph>

  DigraphReader<Digraph> digraphReader(const char *fn, Digraph& digraph);

  /// \ingroup lemon_io

  ///  

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

  ///

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

  ///

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

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

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

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

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

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

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

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

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

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

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

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

  /// rules.

  ///

  ///\code

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

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

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

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

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

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

  ///   run();

  ///\endcode

  ///

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

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

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

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

  ///

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

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

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

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

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

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

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

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

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

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

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

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

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

  /// maps are read.

  template <typename _Digraph>

  class DigraphReader {

  public:

    typedef _Digraph Digraph;

    TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);

  private:

    std::istream* _is;

    bool local_is;

    Digraph& _digraph;

    std::string _nodes_caption;

    std::string _arcs_caption;

    std::string _attributes_caption;

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

    NodeIndex _node_index;

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

    ArcIndex _arc_index;

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

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

    NodeMaps _node_maps; 

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

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

    ArcMaps _arc_maps;

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

      Attributes;

    Attributes _attributes;

    bool _use_nodes;

    bool _use_arcs;

    bool _skip_nodes;

    bool _skip_arcs;

    int line_num;

    std::istringstream line;

  public:

    /// \brief Constructor

    ///

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

    /// input stream.

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

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

	_use_nodes(false), _use_arcs(false),

	_skip_nodes(false), _skip_arcs(false) {}

    /// \brief Constructor

    ///

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

    /// file.

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

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

    	_use_nodes(false), _use_arcs(false),

	_skip_nodes(false), _skip_arcs(false) {}

    /// \brief Constructor

    ///

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

    /// file.

    DigraphReader(const char* fn, Digraph& digraph) 

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

    	_use_nodes(false), _use_arcs(false),

	_skip_nodes(false), _skip_arcs(false) {}

    /// \brief Destructor

    ~DigraphReader() {

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

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

	delete it->second;

      }

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

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

	delete it->second;

      }

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

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

	delete it->second;

      }

      if (local_is) {

	delete _is;

      }

    }

  private:

    friend DigraphReader<Digraph> digraphReader<>(std::istream& is, 

						  Digraph& digraph);    

    friend DigraphReader<Digraph> digraphReader<>(const std::string& fn, 

						  Digraph& digraph);   

    friend DigraphReader<Digraph> digraphReader<>(const char *fn, 

						  Digraph& digraph);    

    DigraphReader(DigraphReader& other) 

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

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

	_skip_nodes(other._skip_nodes), _skip_arcs(other._skip_arcs) {

      other._is = 0;

      other.local_is = false;

      _node_index.swap(other._node_index);

      _arc_index.swap(other._arc_index);

      _node_maps.swap(other._node_maps);

      _arc_maps.swap(other._arc_maps);

      _attributes.swap(other._attributes);

      _nodes_caption = other._nodes_caption;

      _arcs_caption = other._arcs_caption;

      _attributes_caption = other._attributes_caption;

    }

    DigraphReader& operator=(const DigraphReader&);

  public:

    /// \name Reading rules

    /// @{

    /// \brief Node map reading rule

    ///

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

    template <typename Map>

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

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

      _reader_bits::MapStorageBase<Node>* storage = 

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

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

      return *this;

    }

    /// \brief Node map reading rule

    ///

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

    /// reader.

    template <typename Map, typename Converter>

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

			   const Converter& converter = Converter()) {

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

      _reader_bits::MapStorageBase<Node>* storage = 

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

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

      return *this;

    }

    /// \brief Arc map reading rule

    ///

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

    template <typename Map>

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

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

      _reader_bits::MapStorageBase<Arc>* storage = 

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

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

      return *this;

    }

    /// \brief Arc map reading rule

    ///

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

    /// reader.

    template <typename Map, typename Converter>

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

			  const Converter& converter = Converter()) {

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

      _reader_bits::MapStorageBase<Arc>* storage = 

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

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

      return *this;

    }

    /// \brief Attribute reading rule

    ///

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

    template <typename Value>

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

      _reader_bits::ValueStorageBase* storage = 

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

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

      return *this;

    }

    /// \brief Attribute reading rule

    ///

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

    /// reader.

    template <typename Value, typename Converter>

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

			     const Converter& converter = Converter()) {

      _reader_bits::ValueStorageBase* storage = 

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

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

      return *this;

    }

    /// \brief Node reading rule

    ///

    /// Add a node reading rule to reader.

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

      typedef _reader_bits::MapLookUpConverter<Node> Converter;

      Converter converter(_node_index);

      _reader_bits::ValueStorageBase* storage = 

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

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

      return *this;

    }

/* -*- C++ -*-

 *

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

 *

 * Copyright (C) 2003-2008

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

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

 *

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

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

 * precise terms see the accompanying LICENSE file.

 *

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

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

 * purpose.

 *

 */

///\ingroup lemon_io

///\file

///\brief \ref lgf-format "Lemon Graph Format" writer.

#ifndef LEMON_LGF_WRITER_H

#define LEMON_LGF_WRITER_H

#include <iostream>

#include <fstream>

#include <sstream>

#include <algorithm>

#include <vector>

#include <functional>

#include <lemon/assert.h>

#include <lemon/graph_utils.h>

namespace lemon {

  namespace _writer_bits {

    template <typename Value>

    struct DefaultConverter {

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

	std::ostringstream os;

	os << value;

	return os.str();

      }

    };

    template <typename T>

    bool operator<(const T&, const T&) {

      throw DataFormatError("Label map is not comparable");

    }

    template <typename _Map>

    class MapLess {

    public:

      typedef _Map Map;

      typedef typename Map::Key Item;

    private:

      const Map& _map;

    public:

      MapLess(const Map& map) : _map(map) {}

      bool operator()(const Item& left, const Item& right) {

	return _map[left] < _map[right];

      }

    };

    template <typename _Graph, bool _dir, typename _Map>

    class GraphArcMapLess {

    public:

      typedef _Map Map;

      typedef _Graph Graph;

      typedef typename Graph::Edge Item;

    private:

      const Graph& _graph;

      const Map& _map;

    public:

      GraphArcMapLess(const Graph& graph, const Map& map) 

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

      bool operator()(const Item& left, const Item& right) {

	return _map[_graph.direct(left, _dir)] < 

	  _map[_graph.direct(right, _dir)];

      }

    };

    template <typename _Item>    

    class MapStorageBase {

    public:

      typedef _Item Item;

    public:

      MapStorageBase() {}

      virtual ~MapStorageBase() {}

      virtual std::string get(const Item& item) = 0;

      virtual void sort(std::vector<Item>&) = 0;

    };

    template <typename _Item, typename _Map, 

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

    class MapStorage : public MapStorageBase<_Item> {

    public:

      typedef _Map Map;

      typedef _Converter Converter;

      typedef _Item Item;

    private:

      const Map& _map;

      Converter _converter;

    public:

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

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

      virtual ~MapStorage() {}

      virtual std::string get(const Item& item) {

	return _converter(_map[item]);

      }

      virtual void sort(std::vector<Item>& items) {

	MapLess<Map> less(_map);

	std::sort(items.begin(), items.end(), less);

      }

    };

    template <typename _Graph, bool _dir, typename _Map, 

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

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

    public:

      typedef _Map Map;

      typedef _Converter Converter;

      typedef _Graph Graph;

      typedef typename Graph::Edge Item;

      static const bool dir = _dir;

    private:

      const Graph& _graph;

      const Map& _map;

      Converter _converter;

    public:

      GraphArcMapStorage(const Graph& graph, const Map& map,  

			 const Converter& converter = Converter()) 

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

      virtual ~GraphArcMapStorage() {}

      virtual std::string get(const Item& item) {

	return _converter(_map[_graph.direct(item, dir)]);

      }

      virtual void sort(std::vector<Item>& items) {

	GraphArcMapLess<Graph, dir, Map> less(_graph, _map);

	std::sort(items.begin(), items.end(), less);

      }

    };

    class ValueStorageBase {

    public:

      ValueStorageBase() {}

      virtual ~ValueStorageBase() {}

      virtual std::string get() = 0;      

    };

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

    class ValueStorage : public ValueStorageBase {

    public:

      typedef _Value Value;

      typedef _Converter Converter;

    private:

      const Value& _value;

      Converter _converter;

    public:

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

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

      virtual std::string get() {

	return _converter(_value);

      }

    };

    template <typename Value>

    struct MapLookUpConverter {

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

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

	: _map(map) {}

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

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

	  _map.find(str);

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

	  throw DataFormatError("Item not found");

	}

	return it->second;

      }

    };

    template <typename Graph>

    struct GraphArcLookUpConverter {

      const Graph& _graph;

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

      GraphArcLookUpConverter(const Graph& graph, 

			      const std::map<typename Graph::Edge, 

			                     std::string>& map) 

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

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

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

	  ::const_iterator it = _map.find(val);

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

	  throw DataFormatError("Item not found");

	}

	return (_graph.direction(val) ? '+' : '-') + it->second;

      }

    };

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

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

    }

      return c == '\\' || c == '\"' || c == '\'' || 

	c == '\a' || c == '\b';

    }

      switch (c) {

      case '\\':

	os << "\\\\";

	return;

      case '\"':

	os << "\\\"";

	return;

      case '\a':

	os << "\\a";

	return;

      case '\b':

	os << "\\b";

	return;

      case '\f':

	os << "\\f";

	return;

      case '\r':

	os << "\\r";

	return;

      case '\n':

	os << "\\n";

	return;

      case '\t':

	os << "\\t";

	return;

      case '\v':

	os << "\\v";

	return;

      default:

	if (c < 0x20) {

	  std::ios::fmtflags flags = os.flags();

	  os << '\\' << std::oct << static_cast<int>(c);

	  os.flags(flags);

	} else {

	  os << c;

	}

	return;

      }     

    }

      if (str.empty() || str[0] == '@') return true;

      std::istringstream is(str);

      char c;

      while (is.get(c)) {

	if (isWhiteSpace(c) || isEscaped(c)) {

	  return true;

	}

      }

      return false;

    }

      if (requireEscape(str)) {

	os << '\"';

	for (std::string::const_iterator it = str.begin(); 

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

	  writeEscape(os, *it);

	}	

	os << '\"';

      } else {

	os << str;

      }

      return os;

    }

  }

  template <typename Digraph>

  class DigraphWriter;

  template <typename Digraph>

  DigraphWriter<Digraph> digraphWriter(std::ostream& os, 

				       const Digraph& digraph);

  template <typename Digraph>

  DigraphWriter<Digraph> digraphWriter(const std::string& fn, 

				       const Digraph& digraph);

  template <typename Digraph>

  DigraphWriter<Digraph> digraphWriter(const char *fn, 

				       const Digraph& digraph);

  /// \ingroup lemon_io

  ///  

  /// \brief \ref lgf-format "LGF" writer for directed graphs

  ///

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

  ///

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

  /// writer object, then various writing rules can be added to the

  /// writer, and eventually the writing is executed with the \c run()

  /// member function. A map writing rule can be added to the writer

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

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

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

  /// is set, it will determine how the value type of the map is written to

  /// the output stream. If the functor is not set, then a default

  /// conversion will be used. The \c attribute(), \c node() and \c

  /// arc() functions are used to add attribute writing rules.

  ///

  ///\code

  /// DigraphWriter<Digraph>(std::cout, digraph).

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

  ///   nodeMap("size", size).

  ///   nodeMap("title", title).

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

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

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

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

  ///   run();

  ///\endcode

  ///

  ///

  /// By default, the writer does not write additional captions to the

  /// sections, but they can be give as an optional parameter of

  /// the \c nodes(), \c arcs() or \c

  /// attributes() functions.

  ///

  /// The \c skipNodes() and \c skipArcs() functions forbid the

  /// writing of the sections. If two arc sections should be written

  /// to the output, it can be done in two passes, the first pass

  /// writes the node section and the first arc section, then the

  /// second pass skips the node section and writes just the arc

  /// section to the stream. The output stream can be retrieved with

  /// the \c ostream() function, hence the second pass can append its

  /// output to the output of the first pass.

  template <typename _Digraph>

  class DigraphWriter {

  public:

    typedef _Digraph Digraph;

    TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);

  private:

    std::ostream* _os;

    bool local_os;

    const Digraph& _digraph;

    std::string _nodes_caption;

    std::string _arcs_caption;

    std::string _attributes_caption;

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

    NodeIndex _node_index;

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

    ArcIndex _arc_index;

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

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

    NodeMaps _node_maps; 

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

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

    ArcMaps _arc_maps;

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

      _writer_bits::ValueStorageBase*> > Attributes;

    Attributes _attributes;

    bool _skip_nodes;

    bool _skip_arcs;

  public:

    /// \brief Constructor

    ///

    /// Construct a directed graph writer, which writes to the given

    /// output stream.

    DigraphWriter(std::ostream& is, const Digraph& digraph) 

      : _os(&is), local_os(false), _digraph(digraph),

	_skip_nodes(false), _skip_arcs(false) {}

    /// \brief Constructor

    ///

    /// Construct a directed graph writer, which writes to the given

    /// output file.

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

      : _os(new std::ofstream(fn.c_str())), local_os(true), _digraph(digraph),

	_skip_nodes(false), _skip_arcs(false) {}

    /// \brief Constructor

    ///

    /// Construct a directed graph writer, which writes to the given

    /// output file.

    DigraphWriter(const char* fn, const Digraph& digraph)