# HG changeset patch
# User deba
# Date 1116503382 0
# Node ID 4283998fb2be8e4f4ff82c53dce18a1b8e7e6d5d
# Parent  9ba88ddc629c4740598c95e1f3fb1a70a58b3daa
Able to read edge from undirected edgeset
Graph reader and graph writer can resolve items by id.

It makes possible:

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

reader.readNodeMap....

NewEdgeSetAdaptor<Graph> edgeset(graph);
UndirEdgeSetReader<Graph> unir_edgeset_reader(reader, edgeset, reader);

reader.run();

It reads the graph and an additional edgeset in to the edgeset.

diff -r 9ba88ddc629c -r 4283998fb2be src/lemon/bits/item_reader.h
--- a/src/lemon/bits/item_reader.h	Thu May 19 11:46:42 2005 +0000
+++ b/src/lemon/bits/item_reader.h	Thu May 19 11:49:42 2005 +0000
@@ -348,7 +348,7 @@
     
     void read(std::istream& is, Value& value) const {
       char c;
-      if (!(is >> c)) return;
+      if (!(is >> std::ws >> c)) return;
       is.putback(c);
       switch (c) {
       case '\"':
diff -r 9ba88ddc629c -r 4283998fb2be src/lemon/bits/item_writer.h
--- a/src/lemon/bits/item_writer.h	Thu May 19 11:46:42 2005 +0000
+++ b/src/lemon/bits/item_writer.h	Thu May 19 11:49:42 2005 +0000
@@ -177,6 +177,10 @@
     }
   };
 
+  template <>
+  class DefaultWriter<std::string> 
+    : public QuotedStringWriter<std::string> {};
+
   template <typename Item>
   class DefaultWriter<std::vector<Item> > 
     : public IterableWriter<std::vector<Item> > {};
diff -r 9ba88ddc629c -r 4283998fb2be src/lemon/graph_reader.h
--- a/src/lemon/graph_reader.h	Thu May 19 11:46:42 2005 +0000
+++ b/src/lemon/graph_reader.h	Thu May 19 11:49:42 2005 +0000
@@ -299,6 +299,22 @@
       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;
@@ -673,6 +689,13 @@
     /// \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);
     }
@@ -713,6 +736,32 @@
       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;
diff -r 9ba88ddc629c -r 4283998fb2be src/lemon/graph_writer.h
--- a/src/lemon/graph_writer.h	Thu May 19 11:46:42 2005 +0000
+++ b/src/lemon/graph_writer.h	Thu May 19 11:49:42 2005 +0000
@@ -238,6 +238,22 @@
       writer->run();
     }
 
+    /// \brief Write the id of the given node.
+    ///
+    /// It writes the id of the given node. If there was written an "id"
+    /// named node map then it will write the map value belongs to the node.
+    void writeId(std::ostream& os, const Node& item) const {
+      nodeset_writer.writeId(os, item);
+    } 
+
+    /// \brief Write the id of the given edge.
+    ///
+    /// It writes the id of the given edge. If there was written an "id"
+    /// named edge map then it will write the map value belongs to the edge.
+    void writeId(std::ostream& os, const Edge& item) const {
+      edgeset_writer.writeId(os, item);
+    } 
+
   private:
 
     LemonWriter* writer;
@@ -547,6 +563,13 @@
     /// \brief Add a new labeled edge writer for the writer.
     ///
     /// Add a new labeled edge writer for the writer.
+    UndirGraphWriter& writeEdge(std::string name, const Edge& edge) {
+      undir_edge_writer.writeEdge(name, edge);
+    }
+
+    /// \brief Add a new labeled undirected edge writer for the writer.
+    ///
+    /// Add a new labeled undirected edge writer for the writer.
     UndirGraphWriter& writeUndirEdge(std::string name, const UndirEdge& edge) {
       undir_edge_writer.writeUndirEdge(name, edge);
     }
@@ -587,6 +610,32 @@
       writer->run();
     }
 
+    /// \brief Write the id of the given node.
+    ///
+    /// It writes the id of the given node. If there was written an "id"
+    /// named node map then it will write the map value belongs to the node.
+    void writeId(std::ostream& os, const Node& item) const {
+      nodeset_writer.writeId(os, item);
+    } 
+
+    /// \brief Write the id of the given edge.
+    ///
+    /// It writes the id of the given edge. If there was written an "id"
+    /// named edge map then it will write the map value belongs to the edge.
+    void writeId(std::ostream& os, const Edge& item) const {
+      undir_edgeset_writer.writeId(os, item);
+    } 
+
+    /// \brief Write the id of the given undirected edge.
+    ///
+    /// It writes the id of the given undirected edge. If there was written 
+    /// an "id" named edge map then it will write the map value belongs to 
+    /// the edge.
+    void writeId(std::ostream& os, const UndirEdge& item) const {
+      undir_edgeset_writer.writeId(os, item);
+    } 
+
+
   private:
 
     LemonWriter* writer;
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
diff -r 9ba88ddc629c -r 4283998fb2be src/lemon/lemon_writer.h
--- a/src/lemon/lemon_writer.h	Thu May 19 11:46:42 2005 +0000
+++ b/src/lemon/lemon_writer.h	Thu May 19 11:49:42 2005 +0000
@@ -243,7 +243,7 @@
 	: idWriter(_idWriter) {}
 
       virtual void write(std::ostream& os, const Item& item) const {
-	return idWriter.writeId(os, item);
+	idWriter.writeId(os, item);
       }
     };
   };
@@ -273,7 +273,7 @@
 
     typedef _Graph Graph;
     typedef _Traits Traits;
-    typedef typename Graph::Node Item;
+    typedef typename Graph::Node Node;
 
     /// \brief Constructor.
     ///
@@ -319,7 +319,7 @@
     NodeSetWriter& writeNodeMap(std::string name, const Map& map, 
 			    const Writer& writer = Writer()) {
       writers.push_back(
-	make_pair(name, new MapWriter<Item, Map, Writer>(map, writer)));
+	make_pair(name, new MapWriter<Node, Map, Writer>(map, writer)));
       return *this;
     }
 
@@ -379,7 +379,7 @@
     /// named map then it will write the map value belongs to the node.
     /// Otherwise if the \c forceId parameter was true it will write
     /// its id in the graph. 
-    void writeId(std::ostream& os, const Item& item) const {
+    void writeId(std::ostream& os, const Node& item) const {
       if (forceIdMap) {
 	os << graph.id(item);
       } else {
@@ -389,10 +389,10 @@
 
   private:
 
-    typedef std::vector<std::pair<std::string, WriterBase<Item>*> > MapWriters;
+    typedef std::vector<std::pair<std::string, WriterBase<Node>*> > MapWriters;
     MapWriters writers;
 
-    WriterBase<Item>* idMap;
+    WriterBase<Node>* idMap;
     bool forceIdMap;
    
     typename SmartConstReference<Graph>::Type graph;   
@@ -430,7 +430,8 @@
 
     typedef _Graph Graph;
     typedef _Traits Traits;
-    typedef typename Graph::Edge Item;
+    typedef typename Graph::Node Node;
+    typedef typename Graph::Edge Edge;
 
     /// \brief Constructor.
     ///
@@ -446,8 +447,7 @@
 		  bool _forceIdMap = true)
       : Parent(_writer), idMap(0), forceIdMap(_forceIdMap),
 	graph(_graph), id(_id),
-	nodeIdWriter(new IdWriter<typename Graph::Node, NodeIdWriter>
-		     (_nodeIdWriter)) {} 
+	nodeIdWriter(new IdWriter<Node, NodeIdWriter>(_nodeIdWriter)) {} 
 
     /// \brief Destructor.
     ///
@@ -481,7 +481,7 @@
     EdgeSetWriter& writeEdgeMap(std::string name, const Map& map, 
 			    const Writer& writer = Writer()) {
       writers.push_back(
-	make_pair(name, new MapWriter<Item, Map, Writer>(map, writer)));
+	make_pair(name, new MapWriter<Edge, Map, Writer>(map, writer)));
       return *this;
     }
 
@@ -546,7 +546,7 @@
     /// named map then it will write the map value belongs to the edge.
     /// Otherwise if the \c forceId parameter was true it will write
     /// its id in the graph. 
-    void writeId(std::ostream& os, const Item& item) const {
+    void writeId(std::ostream& os, const Edge& item) const {
       if (forceIdMap) {
 	os << graph.id(item);
       } else {
@@ -556,16 +556,16 @@
 
   private:
 
-    typedef std::vector<std::pair<std::string, WriterBase<Item>*> > MapWriters;
+    typedef std::vector<std::pair<std::string, WriterBase<Edge>*> > MapWriters;
     MapWriters writers;
 
-    WriterBase<Item>* idMap;
+    WriterBase<Edge>* idMap;
     bool forceIdMap;
    
     typename SmartConstReference<Graph>::Type graph;   
     std::string id;
 
-    std::auto_ptr<IdWriterBase<typename Graph::Node> > nodeIdWriter;
+    std::auto_ptr<IdWriterBase<Node> > nodeIdWriter;
   };
 
   /// \ingroup io_group
@@ -604,7 +604,9 @@
 
     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;
 
     /// \brief Constructor.
     ///
@@ -620,8 +622,7 @@
 		       bool _forceIdMap = true)
       : Parent(_writer), idMap(0), forceIdMap(_forceIdMap),
 	graph(_graph), id(_id),
-	nodeIdWriter(new IdWriter<typename Graph::Node, NodeIdWriter>
-		     (_nodeIdWriter)) {} 
+	nodeIdWriter(new IdWriter<Node, NodeIdWriter>(_nodeIdWriter)) {} 
 
     /// \brief Destructor.
     ///
@@ -655,7 +656,7 @@
     UndirEdgeSetWriter& writeUndirEdgeMap(std::string name, const Map& map, 
 					  const Writer& writer = Writer()) {
       writers.push_back(
-	make_pair(name, new MapWriter<Item, Map, Writer>(map, writer)));
+	make_pair(name, new MapWriter<UndirEdge, Map, Writer>(map, writer)));
       return *this;
     }
 
@@ -742,7 +743,27 @@
     /// an "id" named map then it will write the map value belongs to the 
     /// undirected edge. Otherwise if the \c forceId parameter was true it 
     /// will write its id in the graph. 
-    void writeId(std::ostream& os, const Item& item) const {
+    void writeId(std::ostream& os, const UndirEdge& item) const {
+      if (forceIdMap) {
+	os << graph.id(item);
+      } else {
+	idMap->write(os, item);
+      }
+    } 
+
+    /// \brief Write the id of the given edge.
+    ///
+    /// It writes the id of the given edge. If there was written 
+    /// an "id" named map then it will write the map value belongs to the 
+    /// edge. Otherwise if the \c forceId parameter was true it 
+    /// will write its id in the graph. If the edge is forward map
+    /// then its prefix character is \c '+' elsewhere \c '-'.
+    void writeId(std::ostream& os, const Edge& item) const {
+      if (graph.forward(item)) {
+	os << "+ ";
+      } else {
+	os << "- ";
+      }
       if (forceIdMap) {
 	os << graph.id(item);
       } else {
@@ -752,16 +773,17 @@
 
   private:
 
-    typedef std::vector<std::pair<std::string, WriterBase<Item>*> > MapWriters;
+    typedef std::vector<std::pair<std::string, 
+				  WriterBase<UndirEdge>*> > MapWriters;
     MapWriters writers;
 
-    WriterBase<Item>* idMap;
+    WriterBase<UndirEdge>* idMap;
     bool forceIdMap;
    
     typename SmartConstReference<Graph>::Type graph;   
     std::string id;
 
-    std::auto_ptr<IdWriterBase<typename Graph::Node> > nodeIdWriter;
+    std::auto_ptr<IdWriterBase<Node> > nodeIdWriter;
   };
 
   /// \ingroup io_group
@@ -778,7 +800,7 @@
   class NodeWriter : public CommonSectionWriterBase {
     typedef CommonSectionWriterBase Parent;
     typedef _Graph Graph;
-    typedef typename Graph::Node Item;
+    typedef typename Graph::Node Node;
   public:
     
     /// \brief Constructor.
@@ -806,7 +828,7 @@
     /// \brief Add a node writer command for the NodeWriter.
     ///
     /// Add a node writer command for the NodeWriter.
-    void writeNode(const std::string& name, const Item& item) {
+    void writeNode(const std::string& name, const Node& item) {
       writers.push_back(make_pair(name, &item));
     }
 
@@ -835,9 +857,9 @@
 
     std::string id;
 
-    typedef std::vector<std::pair<std::string, const Item*> > ItemWriters;
-    ItemWriters writers;
-    std::auto_ptr<IdWriterBase<Item> > idWriter;
+    typedef std::vector<std::pair<std::string, const Node*> > NodeWriters;
+    NodeWriters writers;
+    std::auto_ptr<IdWriterBase<Node> > idWriter;
   };
 
   /// \ingroup io_group
@@ -854,7 +876,7 @@
   class EdgeWriter : public CommonSectionWriterBase {
     typedef CommonSectionWriterBase Parent;
     typedef _Graph Graph;
-    typedef typename Graph::Edge Item;
+    typedef typename Graph::Edge Edge;
   public:
     
     /// \brief Constructor.
@@ -881,7 +903,7 @@
     /// \brief Add an edge writer command for the EdgeWriter.
     ///
     /// Add an edge writer command for the EdgeWriter.
-    void writeEdge(const std::string& name, const Item& item) {
+    void writeEdge(const std::string& name, const Edge& item) {
       writers.push_back(make_pair(name, &item));
     }
 
@@ -910,10 +932,10 @@
 
     std::string id;
 
-    typedef std::vector<std::pair<std::string, const Item*> > ItemWriters;
-    ItemWriters writers;
+    typedef std::vector<std::pair<std::string, const Edge*> > EdgeWriters;
+    EdgeWriters writers;
 
-    std::auto_ptr<IdWriterBase<Item> > idWriter;
+    std::auto_ptr<IdWriterBase<Edge> > idWriter;
   };
 
   /// \ingroup io_group
@@ -930,7 +952,9 @@
   class UndirEdgeWriter : public CommonSectionWriterBase {
     typedef CommonSectionWriterBase Parent;
     typedef _Graph Graph;
-    typedef typename Graph::UndirEdge Item;
+    typedef typename Graph::Node Node;
+    typedef typename Graph::Edge Edge;
+    typedef typename Graph::UndirEdge UndirEdge;
   public:
     
     /// \brief Constructor.
@@ -943,8 +967,8 @@
     UndirEdgeWriter(LemonWriter& _writer, const _IdWriter& _idWriter, 
 	       const std::string& _id = std::string()) 
       : Parent(_writer), id(_id), 
-	idWriter(new IdWriter<typename Graph::UndirEdge, _IdWriter>
-		 (_idWriter)) {} 
+	undirEdgeIdWriter(new IdWriter<UndirEdge, _IdWriter>(_idWriter)),
+	edgeIdWriter(new IdWriter<Edge, _IdWriter>(_idWriter)) {}
 
     /// \brief Destructor.
     ///
@@ -956,11 +980,18 @@
 
   public:
 
+    /// \brief Add an edge writer command for the UndirEdgeWriter.
+    ///
+    /// Add an edge writer command for the UndirEdgeWriter.
+    void writeEdge(const std::string& name, const Edge& item) {
+      edgeWriters.push_back(make_pair(name, &item));
+    }
+
     /// \brief Add an undirected edge writer command for the UndirEdgeWriter.
     ///
-    /// Add an edge writer command for the UndirEdgeWriter.
-    void writeUndirEdge(const std::string& name, const Item& item) {
-      writers.push_back(make_pair(name, &item));
+    /// Add an undirected edge writer command for the UndirEdgeWriter.
+    void writeUndirEdge(const std::string& name, const UndirEdge& item) {
+      undirEdgeWriters.push_back(make_pair(name, &item));
     }
 
   protected:
@@ -970,16 +1001,21 @@
     /// It gives back true when the header line start with \c \@undiredges,
     /// and the header line's id and the writer's id are the same.
     virtual std::string header() {
-      return "@edges " + id;
+      return "@undiredges " + id;
     }
 
     /// \brief  Writer function of the section.
     ///
     /// Write the content of the section.
     virtual void write(std::ostream& os) {
-      for (int i = 0; i < (int)writers.size(); ++i) {
-	os << writers[i].first << ' ';
-	idWriter->write(os, *(writers[i].second));
+      for (int i = 0; i < (int)undirEdgeWriters.size(); ++i) {
+	os << undirEdgeWriters[i].first << ' ';
+	undirEdgeIdWriter->write(os, *(undirEdgeWriters[i].second));
+	os << std::endl;
+      }
+      for (int i = 0; i < (int)edgeWriters.size(); ++i) {
+	os << edgeWriters[i].first << ' ';
+	edgeIdWriter->write(os, *(edgeWriters[i].second));
 	os << std::endl;
       }
     }
@@ -988,10 +1024,15 @@
 
     std::string id;
 
-    typedef std::vector<std::pair<std::string, const Item*> > ItemWriters;
-    ItemWriters writers;
+    typedef std::vector<std::pair<std::string, 
+				  const UndirEdge*> > UndirEdgeWriters;
+    UndirEdgeWriters undirEdgeWriters;
+    std::auto_ptr<IdWriterBase<UndirEdge> > undirEdgeIdWriter;
 
-    std::auto_ptr<IdWriterBase<Item> > idWriter;
+    typedef std::vector<std::pair<std::string, const Edge*> > EdgeWriters;
+    EdgeWriters edgeWriters;
+    std::auto_ptr<IdWriterBase<Edge> > edgeIdWriter;
+
   };
 
   /// \ingroup io_group