diff -r 9ba88ddc629c -r 4283998fb2be src/lemon/lemon_reader.h
--- a/src/lemon/lemon_reader.h	Thu May 19 11:46:42 2005 +0000
+++ b/src/lemon/lemon_reader.h	Thu May 19 11:49:42 2005 +0000
@@ -545,7 +545,7 @@
 	: boxedIdReader(_boxedIdReader) {}
 
       virtual Item read(std::istream& is) const {
-	return boxedIdReader.readId(is);
+	return boxedIdReader.readId(is, Item());
       }
     };
 
@@ -597,7 +597,7 @@
 
     typedef _Graph Graph;
     typedef _Traits Traits;
-    typedef typename Graph::Node Item;
+    typedef typename Graph::Node Node;
     typedef typename Traits::Skipper DefaultSkipper;
 
     /// \brief Constructor.
@@ -652,17 +652,15 @@
     template <typename Reader, typename Map>
     NodeSetReader& readNodeMap(std::string name, Map& map, 
 			       const Reader& reader = Reader()) {
-      return _readMap<
-	typename Traits::template Reader<typename Map::Value>, Map,
-	typename SmartParameter<Map>::Type>(name, map, reader);
+      return _readMap<Reader, Map, typename SmartParameter<Map>::Type>
+	(name, map, reader);
     }
 
     template <typename Reader, typename Map>
     NodeSetReader& readNodeMap(std::string name, const Map& map, 
 			       const Reader& reader = Reader()) {
-      return _readMap<
-	typename Traits::template Reader<typename Map::Value>, Map, 
-	typename SmartParameter<Map>::Type>(name, map, reader);
+      return _readMap<Reader, Map, typename SmartParameter<Map>::Type>
+	(name, map, reader);
     }
 
   private:
@@ -676,7 +674,7 @@
 	throw IOParameterError(msg.message());
       }
       readers.insert(
-	make_pair(name, new MapReader<Item, Map, Reader>(map, reader)));
+	make_pair(name, new MapReader<Node, Map, Reader>(map, reader)));
       return *this;
     }
 
@@ -693,7 +691,7 @@
 	msg << "Multiple read rule for node map: " << name;
 	throw IOParameterError(msg.message());
       }
-      readers.insert(make_pair(name, new SkipReader<Item, Reader>(reader)));
+      readers.insert(make_pair(name, new SkipReader<Node, Reader>(reader)));
       return *this;
     }
 
@@ -716,7 +714,7 @@
     ///
     /// It reads the content of the section.
     virtual void read(std::istream& is) {
-      std::vector<ReaderBase<Item>* > index;
+      std::vector<ReaderBase<Node>* > index;
       std::string line;
 
       getline(is, line);
@@ -734,7 +732,7 @@
 	}
       }
       while (getline(is, line)) {	
-	typename Graph::Node node = graph.addNode();
+	Node node = graph.addNode();
 	std::istringstream ls(line);
 	for (int i = 0; i < (int)index.size(); ++i) {
 	  index[i]->read(ls, node);
@@ -756,20 +754,20 @@
     ///
     /// 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 map.
-    Item readId(std::istream& is) const {
+    Node readId(std::istream& is, Node = Node()) const {
       return inverter->read(is);
     } 
 
   private:
 
-    typedef std::map<std::string, ReaderBase<Item>*> MapReaders;
+    typedef std::map<std::string, ReaderBase<Node>*> MapReaders;
     MapReaders readers;
    
     typename SmartReference<Graph>::Type graph;   
     std::string id;
-    SkipReader<Item, DefaultSkipper> skipper;
+    SkipReader<Node, DefaultSkipper> skipper;
 
-    std::auto_ptr<InverterBase<Item> > inverter;
+    std::auto_ptr<InverterBase<Node> > inverter;
   };
 
   /// \ingroup io_group
@@ -801,7 +799,8 @@
 
     typedef _Graph Graph;
     typedef _Traits Traits;
-    typedef typename Graph::Edge Item;
+    typedef typename Graph::Node Node;
+    typedef typename Graph::Edge Edge;
     typedef typename Traits::Skipper DefaultSkipper;
 
     /// \brief Constructor.
@@ -819,8 +818,7 @@
 		  const std::string& _id = std::string(),
 		  const DefaultSkipper& _skipper = DefaultSkipper()) 
       : Parent(_reader), graph(_graph), id(_id), skipper(_skipper),
-	nodeIdReader(new IdReader<typename Graph::Node, NodeIdReader>
-		     (_nodeIdReader)) {} 
+	nodeIdReader(new IdReader<Node, NodeIdReader>(_nodeIdReader)) {} 
 
     /// \brief Destructor.
     ///
@@ -861,16 +859,14 @@
     template <typename Reader, typename Map>
     EdgeSetReader& readEdgeMap(std::string name, Map& map, 
 			   const Reader& reader = Reader()) {
-      return _readMap<
-	typename Traits::template Reader<typename Map::Value>, Map,
+      return _readMap<Reader, Map,
 	typename SmartParameter<Map>::Type>(name, map, reader);
     }
 
     template <typename Reader, typename Map>
     EdgeSetReader& readEdgeMap(std::string name, const Map& map, 
 			       const Reader& reader = Reader()) {
-      return _readMap<
-	typename Traits::template Reader<typename Map::Value>, Map,
+      return _readMap<Reader, Map,
 	typename SmartParameter<Map>::Type>(name, map, reader);
     }
 
@@ -885,7 +881,7 @@
 	throw IOParameterError(msg.message());
       }
       readers.insert(
-	make_pair(name, new MapReader<Item, Map, Reader>(map, reader)));
+	make_pair(name, new MapReader<Edge, Map, Reader>(map, reader)));
       return *this;
     }
 
@@ -902,7 +898,7 @@
 	msg << "Multiple read rule for edge map: " << name;
 	throw IOParameterError(msg.message());
       }
-      readers.insert(make_pair(name, new SkipReader<Item, Reader>(reader)));
+      readers.insert(make_pair(name, new SkipReader<Edge, Reader>(reader)));
       return *this;
     }
 
@@ -925,7 +921,7 @@
     ///
     /// It reads the content of the section.
     virtual void read(std::istream& is) {
-      std::vector<ReaderBase<Item>* > index;
+      std::vector<ReaderBase<Edge>* > index;
       std::string line;
 
       getline(is, line);
@@ -944,9 +940,9 @@
       }
       while (getline(is, line)) {	
 	std::istringstream ls(line);
-	typename Graph::Node from = nodeIdReader->read(ls);
-	typename Graph::Node to = nodeIdReader->read(ls);
-	typename Graph::Edge edge = graph.addEdge(from, to);
+	Node from = nodeIdReader->read(ls);
+	Node to = nodeIdReader->read(ls);
+	Edge edge = graph.addEdge(from, to);
 	for (int i = 0; i < (int)index.size(); ++i) {
 	  index[i]->read(ls, edge);
 	}
@@ -967,21 +963,21 @@
     ///
     /// 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 map.
-    Item readId(std::istream& is) const {
+    Edge readId(std::istream& is, Edge = Edge()) const {
       return inverter->read(is);
     } 
 
   private:
 
-    typedef std::map<std::string, ReaderBase<Item>*> MapReaders;
+    typedef std::map<std::string, ReaderBase<Edge>*> MapReaders;
     MapReaders readers;
    
     typename SmartReference<Graph>::Type graph;   
     std::string id;
-    SkipReader<Item, DefaultSkipper> skipper;
+    SkipReader<Edge, DefaultSkipper> skipper;
 
-    std::auto_ptr<InverterBase<Item> > inverter;
-    std::auto_ptr<IdReaderBase<typename Graph::Node> > nodeIdReader;
+    std::auto_ptr<InverterBase<Edge> > inverter;
+    std::auto_ptr<IdReaderBase<Node> > nodeIdReader;
   };
 
   /// \ingroup io_group
@@ -1018,7 +1014,9 @@
 
     typedef _Graph Graph;
     typedef _Traits Traits;
-    typedef typename Graph::UndirEdge Item;
+    typedef typename Graph::Node Node;
+    typedef typename Graph::Edge Edge;
+    typedef typename Graph::UndirEdge UndirEdge;
     typedef typename Traits::Skipper DefaultSkipper;
 
     /// \brief Constructor.
@@ -1036,8 +1034,7 @@
 		       const std::string& _id = std::string(),
 		       const DefaultSkipper& _skipper = DefaultSkipper()) 
       : Parent(_reader), graph(_graph), id(_id), skipper(_skipper),
-	nodeIdReader(new IdReader<typename Graph::Node, NodeIdReader>
-		     (_nodeIdReader)) {} 
+	nodeIdReader(new IdReader<Node, NodeIdReader>(_nodeIdReader)) {} 
 
     /// \brief Destructor.
     ///
@@ -1100,7 +1097,7 @@
 	throw IOParameterError(msg.message());
       }
       readers.insert(
-	make_pair(name, new MapReader<Item, Map, Reader>(map, reader)));
+	make_pair(name, new MapReader<UndirEdge, Map, Reader>(map, reader)));
       return *this;
     }
 
@@ -1117,7 +1114,8 @@
 	msg << "Multiple read rule for node map: " << name;
 	throw IOParameterError(msg.message());
       }
-      readers.insert(make_pair(name, new SkipReader<Item, Reader>(reader)));
+      readers.insert(make_pair(name, 
+			       new SkipReader<UndirEdge, Reader>(reader)));
       return *this;
     }
 
@@ -1199,7 +1197,7 @@
     ///
     /// It reads the content of the section.
     virtual void read(std::istream& is) {
-      std::vector<ReaderBase<Item>* > index;
+      std::vector<ReaderBase<UndirEdge>* > index;
       std::string line;
 
       getline(is, line);
@@ -1218,9 +1216,9 @@
       }
       while (getline(is, line)) {	
 	std::istringstream ls(line);
-	typename Graph::Node from = nodeIdReader->read(ls);
-	typename Graph::Node to = nodeIdReader->read(ls);
-	typename Graph::UndirEdge edge = graph.addEdge(from, to);
+	Node from = nodeIdReader->read(ls);
+	Node to = nodeIdReader->read(ls);
+	UndirEdge edge = graph.addEdge(from, to);
 	for (int i = 0; i < (int)index.size(); ++i) {
 	  index[i]->read(ls, edge);
 	}
@@ -1241,21 +1239,41 @@
     ///
     /// 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 map.
-    Item readId(std::istream& is) const {
+    UndirEdge readId(std::istream& is, UndirEdge = UndirEdge()) const {
       return inverter->read(is);
     } 
 
+    /// \brief Gives back the directed edge by its id.
+    ///
+    /// It reads an id from the stream and gives back which directed edge 
+    /// belongs to it. The directed edge id is the \c '+' or \c '-' character
+    /// and the undirected edge id. It is possible only if there was read 
+    /// an "id" named map.
+    Edge readId(std::istream& is, Edge = Edge()) const {
+      char c;
+      is >> c;
+      UndirEdge undirEdge = inverter->read(is);
+      if (c == '+') {
+	return graph.edgeWithSource(undirEdge, graph.source(undirEdge));
+      } else if (c == '-') {
+	return graph.edgeWithSource(undirEdge, graph.target(undirEdge));
+      } else {
+	throw DataFormatError("Wrong id format for edge "
+			      "in undirected edgeset");
+      }
+    } 
+
   private:
 
-    typedef std::map<std::string, ReaderBase<Item>*> MapReaders;
+    typedef std::map<std::string, ReaderBase<UndirEdge>*> MapReaders;
     MapReaders readers;
    
     typename SmartReference<Graph>::Type graph;   
     std::string id;
-    SkipReader<Item, DefaultSkipper> skipper;
+    SkipReader<UndirEdge, DefaultSkipper> skipper;
 
-    std::auto_ptr<InverterBase<Item> > inverter;
-    std::auto_ptr<IdReaderBase<typename Graph::Node> > nodeIdReader;
+    std::auto_ptr<InverterBase<UndirEdge> > inverter;
+    std::auto_ptr<IdReaderBase<Node> > nodeIdReader;
   };
 
   /// \ingroup io_group
@@ -1272,7 +1290,7 @@
   class NodeReader : public CommonSectionReaderBase {
     typedef CommonSectionReaderBase Parent;
     typedef _Graph Graph;
-    typedef typename Graph::Node Item;
+    typedef typename Graph::Node Node;
   public:
     
     /// \brief Constructor.
@@ -1301,7 +1319,7 @@
     /// \brief Add a node reader command for the NodeReader.
     ///
     /// Add a node reader command for the NodeReader.
-    void readNode(const std::string& name, Item& item) {
+    void readNode(const std::string& name, Node& item) {
       if (readers.find(name) != readers.end()) {
 	ErrorMessage msg;
 	msg << "Multiple read rule for node: " << name;
@@ -1334,7 +1352,7 @@
 	std::istringstream ls(line);
 	std::string id;
 	ls >> id;
-	typename ItemReaders::iterator it = readers.find(id);
+	typename NodeReaders::iterator it = readers.find(id);
 	if (it != readers.end()) {
 	  *(it->second) = idReader->read(ls); 
 	}	
@@ -1345,9 +1363,9 @@
 
     std::string id;
 
-    typedef std::map<std::string, Item*> ItemReaders;
-    ItemReaders readers;
-    std::auto_ptr<IdReaderBase<Item> > idReader;
+    typedef std::map<std::string, Node*> NodeReaders;
+    NodeReaders readers;
+    std::auto_ptr<IdReaderBase<Node> > idReader;
   };
 
   /// \ingroup io_group
@@ -1364,7 +1382,7 @@
   class EdgeReader : public CommonSectionReaderBase {
     typedef CommonSectionReaderBase Parent;
     typedef _Graph Graph;
-    typedef typename Graph::Edge Item;
+    typedef typename Graph::Edge Edge;
   public:
     
     /// \brief Constructor.
@@ -1392,7 +1410,7 @@
     /// \brief Add an edge reader command for the EdgeReader.
     ///
     /// Add an edge reader command for the EdgeReader.
-    void readEdge(const std::string& name, Item& item) {
+    void readEdge(const std::string& name, Edge& item) {
       if (readers.find(name) != readers.end()) {
 	ErrorMessage msg;
 	msg << "Multiple read rule for edge: " << name;
@@ -1425,7 +1443,7 @@
 	std::istringstream ls(line);
 	std::string id;
 	ls >> id;
-	typename ItemReaders::iterator it = readers.find(id);
+	typename EdgeReaders::iterator it = readers.find(id);
 	if (it != readers.end()) {
 	  *(it->second) = idReader->read(ls); 
 	}	
@@ -1436,9 +1454,9 @@
 
     std::string id;
 
-    typedef std::map<std::string, Item*> ItemReaders;
-    ItemReaders readers;
-    std::auto_ptr<IdReaderBase<Item> > idReader;
+    typedef std::map<std::string, Edge*> EdgeReaders;
+    EdgeReaders readers;
+    std::auto_ptr<IdReaderBase<Edge> > idReader;
   };
 
   /// \ingroup io_group
@@ -1455,7 +1473,8 @@
   class UndirEdgeReader : public CommonSectionReaderBase {
     typedef CommonSectionReaderBase Parent;
     typedef _Graph Graph;
-    typedef typename Graph::UndirEdge Item;
+    typedef typename Graph::Edge Edge;
+    typedef typename Graph::UndirEdge UndirEdge;
   public:
     
     /// \brief Constructor.
@@ -1469,7 +1488,8 @@
     UndirEdgeReader(LemonReader& _reader, const _IdReader& _idReader, 
 	       const std::string& _id = std::string()) 
       : Parent(_reader), id(_id), 
-	idReader(new IdReader<typename Graph::UndirEdge, _IdReader>(_idReader))
+	undirEdgeIdReader(new IdReader<UndirEdge, _IdReader>(_idReader)),
+	edgeIdReader(new IdReader<Edge, _IdReader>(_idReader))
     {} 
 
     /// \brief Destructor.
@@ -1485,13 +1505,25 @@
     /// \brief Add an undirected edge reader command for the UndirEdgeReader.
     ///
     /// Add an undirected edge reader command for the UndirEdgeReader.
-    void readUndirEdge(const std::string& name, Item& item) {
-      if (readers.find(name) != readers.end()) {
+    void readUndirEdge(const std::string& name, UndirEdge& item) {
+      if (undirEdgeReaders.find(name) != undirEdgeReaders.end()) {
+	ErrorMessage msg;
+	msg << "Multiple read rule for undirected edge: " << name;
+	throw IOParameterError(msg.message());
+      }
+      undirEdgeReaders.insert(make_pair(name, &item));
+    }
+
+    /// \brief Add an edge reader command for the UndirEdgeReader.
+    ///
+    /// Add an edge reader command for the UndirEdgeReader.
+    void readEdge(const std::string& name, Edge& item) {
+      if (edgeReaders.find(name) != edgeReaders.end()) {
 	ErrorMessage msg;
 	msg << "Multiple read rule for edge: " << name;
 	throw IOParameterError(msg.message());
       }
-      readers.insert(make_pair(name, &item));
+      edgeReaders.insert(make_pair(name, &item));
     }
 
   protected:
@@ -1506,7 +1538,7 @@
       std::string command;
       std::string name;
       ls >> command >> name;
-      return command == "@edges" && name == id;
+      return command == "@undiredges" && name == id;
     }
 
     /// \brief Reader function of the section.
@@ -1518,10 +1550,19 @@
 	std::istringstream ls(line);
 	std::string id;
 	ls >> id;
-	typename ItemReaders::iterator it = readers.find(id);
-	if (it != readers.end()) {
-	  *(it->second) = idReader->read(ls); 
-	}	
+	{
+	  typename UndirEdgeReaders::iterator it = undirEdgeReaders.find(id);
+	  if (it != undirEdgeReaders.end()) {
+	    *(it->second) = undirEdgeIdReader->read(ls); 
+	    break;
+	  }	
+	} {
+	  typename EdgeReaders::iterator it = edgeReaders.find(id);
+	  if (it != edgeReaders.end()) {
+	    *(it->second) = edgeIdReader->read(ls); 
+	    break;
+	  }	
+	}
       }
     }
     
@@ -1529,9 +1570,13 @@
 
     std::string id;
 
-    typedef std::map<std::string, Item*> ItemReaders;
-    ItemReaders readers;
-    std::auto_ptr<IdReaderBase<Item> > idReader;
+    typedef std::map<std::string, UndirEdge*> UndirEdgeReaders;
+    UndirEdgeReaders undirEdgeReaders;
+    std::auto_ptr<IdReaderBase<UndirEdge> > undirEdgeIdReader;
+
+    typedef std::map<std::string, Edge*> EdgeReaders;
+    EdgeReaders edgeReaders;
+    std::auto_ptr<IdReaderBase<Edge> > edgeIdReader;
   };
 
   /// \ingroup io_group