#ifndef LIST_GRAPH_HH

 #define LIST_GRAPH_HH

 #include <iostream>

 namespace marci {

   template <typename It>

   int count(It it) { 

     int i=0;

     for( ; it.valid(); ++it) { ++i; } 

     return i;

   }

   class ListGraph {

     class node_item;

     class edge_item;

   public:

     class NodeIt;

     class EachNodeIt;

     class EdgeIt;

     class EachEdgeIt;

     class OutEdgeIt;

     class InEdgeIt;

     class SymEdgeIt;

     template <typename ValueType> class NodeMap;

     template <typename ValueType> class EdgeMap;

   private:

     template <typename ValueType> friend class NodeMap;

     template <typename ValueType> friend class EdgeMap;

     template <typename ValueType>

     class NodeMap {

       const ListGraph& G; 

       std::vector<ValueType> container;

     public:

       NodeMap(const ListGraph& _G) : G(_G), container(_G.node_id) { }

       NodeMap(const ListGraph& _G, const ValueType a) : 

 	G(_G), container(_G.node_id, a) { }

       void set(const NodeIt nit, const ValueType a) { container[G.id(nit)]=a; }

       ValueType get(const NodeIt nit) const { return container[G.id(nit)]; }

     };

     template <typename ValueType>

     class EdgeMap {

       const ListGraph& G; 

       std::vector<ValueType> container;

     public:

       EdgeMap(const ListGraph& _G) : G(_G), container(_G.edge_id) { }

       EdgeMap(const ListGraph& _G, const ValueType a) : 

 	G(_G), container(_G.edge_id, a) { }

       void set(const EdgeIt eit, const ValueType a) { container[G.id(eit)]=a; }

       ValueType get(const EdgeIt eit) const { return container[G.id(eit)]; }

     };

     int node_id;

     int edge_id;

     int _node_num;

     int _edge_num;

     node_item* _first_node;

     node_item* _last_node;

     class node_item {

       friend class ListGraph;

       friend class NodeIt;

       friend class EachNodeIt;

       friend class EdgeIt;

       friend class EachEdgeIt;

       friend class OutEdgeIt;

       friend class InEdgeIt;

       friend class SymEdgeIt;

       friend std::ostream& operator<<(std::ostream& os, const NodeIt& i);

       friend std::ostream& operator<<(std::ostream& os, const EdgeIt& i);

       //ListGraph* G;

       int id;

       edge_item* _first_out_edge;

       edge_item* _last_out_edge;

       edge_item* _first_in_edge;

       edge_item* _last_in_edge;

       node_item* _next_node;

       node_item* _prev_node;

     public:

       node_item() { }

     };

     class edge_item {

       friend class ListGraph;

       friend class NodeIt;

       friend class EachNodeIt;

       friend class EdgeIt;

       friend class EachEdgeIt;

       friend class OutEdgeIt;

       friend class InEdgeIt;

       friend class SymEdgeIt;

       friend std::ostream& operator<<(std::ostream& os, const EdgeIt& i);

       //ListGraph* G;

       int id;

       node_item* _tail;

       node_item* _head;

       edge_item* _next_out;

       edge_item* _prev_out;

       edge_item* _next_in;

       edge_item* _prev_in;

     public:

       edge_item() { }

     };

     node_item* _add_node() { 

       node_item* p=new node_item;

       p->id=node_id++;

       p->_first_out_edge=0;

       p->_last_out_edge=0;

       p->_first_in_edge=0;

       p->_last_in_edge=0;

       p->_prev_node=_last_node;

       p->_next_node=0;

       if (_last_node) _last_node->_next_node=p;

       _last_node=p;

       if (!_first_node) _first_node=p;

       ++_node_num;

       return p;

     }

     edge_item* _add_edge(node_item* _tail, node_item* _head) {

       edge_item* e=new edge_item;

       e->id=edge_id++;

       e->_tail=_tail;

       e->_head=_head;

       e->_prev_out=_tail->_last_out_edge;

       if (_tail->_last_out_edge) (_tail->_last_out_edge)->_next_out=e;

       _tail->_last_out_edge=e;

       if (!_tail->_first_out_edge) _tail->_first_out_edge=e; 

       e->_next_out=0;

       e->_prev_in=_head->_last_in_edge;

       if (_head->_last_in_edge) (_head->_last_in_edge)->_next_in=e;

       _head->_last_in_edge=e;

       if (!_head->_first_in_edge) { _head->_first_in_edge=e; } 

       e->_next_in=0;

       ++_edge_num;

       return e;

     }

     //deletes a node which has no out edge and no in edge

     void _delete_node(node_item* v) {

       if (v->_next_node) (v->_next_node)->_prev_node=v->_prev_node; else 

 	_last_node=v->_prev_node;

       if (v->_prev_node) (v->_prev_node)->_next_node=v->_next_node; else 

 	_first_node=v->_next_node;

       delete v;

       --_node_num;

     }

     void _delete_edge(edge_item* e) {

       if (e->_next_out) (e->_next_out)->_prev_out=e->_prev_out; else 

 	(e->_tail)->_last_out_edge=e->_prev_out;

       if (e->_prev_out) (e->_prev_out)->_next_out=e->_next_out; else 

 	(e->_tail)->_first_out_edge=e->_next_out;

       if (e->_next_in) (e->_next_in)->_prev_in=e->_prev_in; else 

 	(e->_head)->_last_in_edge=e->_prev_in;

       if (e->_prev_in) (e->_prev_in)->_next_in=e->_next_in; else 

 	(e->_head)->_first_in_edge=e->_next_in;

       delete e;

       --_edge_num;

     }

     void _set_tail(edge_item* e, node_item* _tail) {

       if (e->_next_out) (e->_next_out)->_prev_out=e->_prev_out; else 

 	(e->_tail)->_last_out_edge=e->_prev_out;

       if (e->_prev_out) (e->_prev_out)->_next_out=e->_next_out; else 

 	(e->_tail)->_first_out_edge=e->_next_out;

       e->_tail=_tail;

       e->_prev_out=_tail->_last_out_edge;

       if (_tail->_last_out_edge) (_tail->_last_out_edge)->_next_out=e;

       _tail->_last_out_edge=e;

       if (!_tail->_first_out_edge) _tail->_first_out_edge=e; 

       e->_next_out=0;

     }

     void _set_head(edge_item* e, node_item* _head) {

       if (e->_next_in) (e->_next_in)->_prev_in=e->_prev_in; else 

 	(e->_head)->_last_in_edge=e->_prev_in;

       if (e->_prev_in) (e->_prev_in)->_next_in=e->_next_in; else 

 	(e->_head)->_first_in_edge=e->_next_in;

       e->_head=_head;

       e->_prev_in=_head->_last_in_edge;

       if (_head->_last_in_edge) (_head->_last_in_edge)->_next_in=e;

       _head->_last_in_edge=e;

       if (!_head->_first_in_edge) { _head->_first_in_edge=e; } 

       e->_next_in=0;

     }

   public:

     /* default constructor */

     ListGraph() : node_id(0), edge_id(0), _node_num(0), _edge_num(0), _first_node(0), _last_node(0) { }

     ~ListGraph() { 

       while (first<EachNodeIt>().valid()) deleteNode(first<EachNodeIt>());

     }

     int nodeNum() const { return _node_num; }

     int edgeNum() const { return _edge_num; }

     /* functions to construct iterators from the graph, or from each other */

     //EachNodeIt firstNode() const { return EachNodeIt(*this); }

     //EachEdgeIt firstEdge() const { return EachEdgeIt(*this); }

     //OutEdgeIt firstOutEdge(const NodeIt v) const { return OutEdgeIt(v); }

     //InEdgeIt firstInEdge(const NodeIt v) const { return InEdgeIt(v); }

     //SymEdgeIt firstSymEdge(const NodeIt v) const { return SymEdgeIt(v); }

     NodeIt tail(const EdgeIt e) const { return e.tailNode(); }

     NodeIt head(const EdgeIt e) const { return e.headNode(); }

     NodeIt aNode(const OutEdgeIt& e) const { return e.aNode(); }

     NodeIt aNode(const InEdgeIt& e) const { return e.aNode(); }

     NodeIt aNode(const SymEdgeIt& e) const { return e.aNode(); }

     NodeIt bNode(const OutEdgeIt& e) const { return e.bNode(); }

     NodeIt bNode(const InEdgeIt& e) const { return e.bNode(); }

     NodeIt bNode(const SymEdgeIt& e) const { return e.bNode(); }

     //NodeIt invalid_node() { return NodeIt(); }

     //EdgeIt invalid_edge() { return EdgeIt(); }

     //OutEdgeIt invalid_out_edge() { return OutEdgeIt(); }

     //InEdgeIt invalid_in_edge() { return InEdgeIt(); }

     //SymEdgeIt invalid_sym_edge() { return SymEdgeIt(); }

     /* same methods in other style */

     /* for experimental purpose */

     void getFirst(EachNodeIt& v) const { v=EachNodeIt(*this); }

     void getFirst(EachEdgeIt& e) const { e=EachEdgeIt(*this); }

     void getFirst(OutEdgeIt& e, const NodeIt& v) const { e=OutEdgeIt(v); }

     void getFirst(InEdgeIt& e, const NodeIt& v) const { e=InEdgeIt(v); }

     void getFirst(SymEdgeIt& e, const NodeIt& v) const { e=SymEdgeIt(v); }

     void getTail(NodeIt& n, const EdgeIt& e) const { n=tail(e); }

     void getHead(NodeIt& n, const EdgeIt& e) const { n=head(e); }

     void getANode(NodeIt& n, const OutEdgeIt& e) const { n=e.aNode(); }

     void getANode(NodeIt& n, const InEdgeIt& e) const { n=e.aNode(); }

     void getANode(NodeIt& n, const SymEdgeIt& e) const { n=e.aNode(); }

     void getBNode(NodeIt& n, const OutEdgeIt& e) const { n=e.bNode(); }

     void getBNode(NodeIt& n, const InEdgeIt& e) const { n=e.bNode(); }

     void getBNode(NodeIt& n, const SymEdgeIt& e) const { n=e.bNode(); }

     //void get_invalid(NodeIt& n) { n=NodeIt(); }

     //void get_invalid(EdgeIt& e) { e=EdgeIt(); }

     //void get_invalid(OutEdgeIt& e) { e=OutEdgeIt(); }

     //void get_invalid(InEdgeIt& e) { e=InEdgeIt(); }

     //void get_invalid(SymEdgeIt& e) { e=SymEdgeIt(); }

     template< typename It >

     It first() const { 

       It e;

       getFirst(e);

       return e; 

     }

     template< typename It >

     It first(const NodeIt v) const { 

       It e;

       getFirst(e, v);

       return e; 

     }

     /* for getting id's of graph objects */

     /* these are important for the implementation of property vectors */

     int id(const NodeIt v) const { return v.node->id; }

     int id(const EdgeIt e) const { return e.edge->id; }

     /* adding nodes and edges */

     NodeIt addNode() { return NodeIt(_add_node()); }

     EdgeIt addEdge(const NodeIt u, const NodeIt v) {

       return EdgeIt(_add_edge(u.node, v.node)); 

     }

     void deleteNode(const NodeIt i) { 

       while (first<OutEdgeIt>(i).valid()) deleteEdge(first<OutEdgeIt>(i));

       while (first<InEdgeIt>(i).valid()) deleteEdge(first<InEdgeIt>(i));

       _delete_node(i.node); 

     }

     void deleteEdge(const EdgeIt e) { _delete_edge(e.edge); }

     void setTail(const EdgeIt e, const NodeIt tail) {

       _set_tail(e.edge, tail.node); 

     }

     void setHead(const EdgeIt e, const NodeIt head) {

       _set_head(e.edge, head.node); 

     }

     /* stream operations, for testing purpose */

     friend std::ostream& operator<<(std::ostream& os, const NodeIt& i) { 

       os << i.node->id; return os; 

     }

     friend std::ostream& operator<<(std::ostream& os, const EdgeIt& i) { 

       os << "(" << i.edge->_tail->id << "--" << i.edge->id << "->" << i.edge->_head->id << ")"; 

       return os; 

     }

     class NodeIt {

       friend class ListGraph;

       friend class EdgeIt;

       friend class OutEdgeIt;

       friend class InEdgeIt;

       friend class SymEdgeIt;

     protected:

       node_item* node;

       friend int ListGraph::id(const NodeIt v) const; 

     public:

       NodeIt() : node(0) { }

       NodeIt(node_item* _node) : node(_node) { }

       bool valid() const { return (node!=0); }

       //void makeInvalid() { node=0; }

       friend bool operator==(const NodeIt& u, const NodeIt& v) { 

 	return v.node==u.node; 

       } 

       friend bool operator!=(const NodeIt& u, const NodeIt& v) { 

 	return v.node!=u.node; 

       } 

       friend std::ostream& operator<<(std::ostream& os, const NodeIt& i);

     };

     class EachNodeIt : public NodeIt {

       friend class ListGraph;

     protected:

       EachNodeIt(const ListGraph& G) : NodeIt(G._first_node) { }

     public:

       EachNodeIt() : NodeIt() { }

       EachNodeIt(node_item* v) : NodeIt(v) { }

       EachNodeIt& operator++() { node=node->_next_node; return *this; }

     };

     class EdgeIt {

       friend class ListGraph;

       friend class NodeIt;

       friend class EachNodeIt;

     protected:

       edge_item* edge;

       friend int ListGraph::id(const EdgeIt e) const;

     public:

       EdgeIt() : edge(0) { }

       //EdgeIt() { }

       EdgeIt(edge_item* _edge) : edge(_edge) { }

       bool valid() const { return (edge!=0); }

       //void makeInvalid() { edge=0; }

       friend bool operator==(const EdgeIt& u, const EdgeIt& v) { 

 	return v.edge==u.edge; 

       } 

       friend bool operator!=(const EdgeIt& u, const EdgeIt& v) { 

 	return v.edge!=u.edge; 

       } 

     protected:

       NodeIt tailNode() const { return NodeIt(edge->_tail); }

       NodeIt headNode() const { return NodeIt(edge->_head); }

     public:

       friend std::ostream& operator<<(std::ostream& os, const EdgeIt& i);

     };

     class EachEdgeIt : public EdgeIt {

       friend class ListGraph;

     protected:

       EachEdgeIt(const ListGraph& G) {

 	node_item* v=G._first_node;

 	if (v) edge=v->_first_out_edge; else edge=0;

 	while (v && !edge) { v=v->_next_node; if (v) edge=v->_first_out_edge; }

       }

     public:

       EachEdgeIt() : EdgeIt() { }

       EachEdgeIt(edge_item* _e) : EdgeIt(_e) { }

       EachEdgeIt& operator++() { 

 	node_item* v=edge->_tail;

 	edge=edge->_next_out; 

 	while (v && !edge) { v=v->_next_node; if (v) edge=v->_first_out_edge; }

 	return *this;

       }

     };

     class OutEdgeIt : public EdgeIt {

       friend class ListGraph;

       node_item* v;

     protected:

       OutEdgeIt(const NodeIt& _v) : v(_v.node) { edge=v->_first_out_edge; }

     public:

       OutEdgeIt() : EdgeIt(), v(0) { }

       OutEdgeIt(const ListGraph& G, const NodeIt _v) : v(_v.node) { edge=v->_first_out_edge; }

       OutEdgeIt& operator++() { edge=edge->_next_out; return *this; }

     protected:

       NodeIt aNode() const { return NodeIt(v); }

       NodeIt bNode() const { 

 	return (edge->_tail==v) ? NodeIt(edge->_head) : NodeIt(edge->_tail); }

     };

     class InEdgeIt : public EdgeIt {

       friend class ListGraph;

       node_item* v;

     protected:

       InEdgeIt(const NodeIt& _v) : v(_v.node) { edge=v->_first_in_edge; }

     public:

       InEdgeIt() : EdgeIt(), v(0) { }

       InEdgeIt(const ListGraph& G, const NodeIt _v) : v(_v.node) { edge=v->_first_in_edge; }

       InEdgeIt& operator++() { edge=edge->_next_in; return *this; }

     protected:

       NodeIt aNode() const { return NodeIt(v); }

       NodeIt bNode() const { 

 	return (edge->_tail==v) ? NodeIt(edge->_head) : NodeIt(edge->_tail); }

     };

     class SymEdgeIt : public EdgeIt {

       friend class ListGraph;

       bool out_or_in; //1 iff out, 0 iff in

       node_item* v;

     protected:

       SymEdgeIt(const NodeIt& _v) : v(_v.node) { 

 	out_or_in=1;

 	edge=v->_first_out_edge; 

 	if (!edge) { edge=v->_first_in_edge; out_or_in=0; }

       }

     public:

       SymEdgeIt() : EdgeIt(), v(0) { }

       SymEdgeIt(const ListGraph& G, const NodeIt _v) : v(_v.node) { 

 	out_or_in=1;

 	edge=v->_first_out_edge; 

 	if (!edge) { edge=v->_first_in_edge; out_or_in=0; }

       }

       SymEdgeIt& operator++() { 

 	if (out_or_in) { 

 	  edge=edge->_next_out; 

 	  if (!edge) { out_or_in=0; edge=v->_first_in_edge; }

 	} else {

 	  edge=edge->_next_in; 

 	}

 	return *this;

       }

     protected:

       NodeIt aNode() const { return NodeIt(v); }

       NodeIt bNode() const { 

 	return (edge->_tail==v) ? NodeIt(edge->_head) : NodeIt(edge->_tail); }

     };

   };

   /*

   template< typename T >

   T ListGraph::first() const { 

     std::cerr << "Invalid use of template<typemane T> T ListGraph::first<T>();" << std::endl; 

     return T(); 

   }

   template<>

   ListGraph::EachNodeIt ListGraph::first<ListGraph::EachNodeIt>() const { 

     return firstNode(); 

   }

   template<>

   ListGraph::EachEdgeIt ListGraph::first<ListGraph::EachEdgeIt>() const { 

     return firstEdge(); 

   }

   template< typename T >

   T ListGraph::first(ListGraph::NodeIt v) const {

     std::cerr << "Invalid use of template<typemane T> T ListGraph::first<T>(ListGRaph::NodeIt);" << std::endl; 

     return T(); 

   } 

   template<>

   ListGraph::OutEdgeIt ListGraph::first<ListGraph::OutEdgeIt>(const ListGraph::NodeIt v) const { 

     return firstOutEdge(v); 

   }

   template<>

   ListGraph::InEdgeIt ListGraph::first<ListGraph::InEdgeIt>(const ListGraph::NodeIt v) const { 

     return firstInEdge(v); 

   }

   template<>

   ListGraph::SymEdgeIt ListGraph::first<ListGraph::SymEdgeIt>(const ListGraph::NodeIt v) const { 

     return firstSymEdge(v); 

   }

   */

 } //namespace marci

 #endif //LIST_GRAPH_HH