RhodeCode

      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) {}

      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.