// -*- c++ -*-

 #ifndef LEMON_LIST_GRAPH_H

 #define LEMON_LIST_GRAPH_H

 #include <lemon/erasable_graph_extender.h>

 #include <lemon/clearable_graph_extender.h>

 #include <lemon/extendable_graph_extender.h>

 #include <lemon/idmappable_graph_extender.h>

 #include <lemon/iterable_graph_extender.h>

 #include <lemon/alteration_observer_registry.h>

 #include <lemon/default_map.h>

 namespace lemon {

   class ListGraphBase {

     struct NodeT {

       int first_in,first_out;

       int prev, next;

     };

     struct EdgeT {

       int head, tail;

       int prev_in, prev_out;

       int next_in, next_out;

     };

     std::vector<NodeT> nodes;

     int first_node;

     int first_free_node;

     std::vector<EdgeT> edges;

     int first_free_edge;

   public:

     typedef ListGraphBase Graph;

     class Node {

       friend class Graph;

     protected:

       int id;

       Node(int pid) { id = pid;}

     public:

       Node() {}

       Node (Invalid) { id = -1; }

       bool operator==(const Node& node) const {return id == node.id;}

       bool operator!=(const Node& node) const {return id != node.id;}

       bool operator<(const Node& node) const {return id < node.id;}

     };

     class Edge {

       friend class Graph;

     protected:

       int id;

       Edge(int pid) { id = pid;}

     public:

       Edge() {}

       Edge (Invalid) { id = -1; }

       bool operator==(const Edge& edge) const {return id == edge.id;}

       bool operator!=(const Edge& edge) const {return id != edge.id;}

       bool operator<(const Edge& edge) const {return id < edge.id;}

     };

     ListGraphBase()

       : nodes(), first_node(-1),

 	first_free_node(-1), edges(), first_free_edge(-1) {}

     ///it possible to avoid the superfluous memory allocation.

     void reserveEdge(int n) { edges.reserve(n); };

     /// Maximum node ID.

     /// Maximum node ID.

     ///\sa id(Node)

     int maxNodeId() const { return nodes.size()-1; } 

     /// Maximum edge ID.

     /// Maximum edge ID.

     ///\sa id(Edge)

     int maxEdgeId() const { return edges.size()-1; }

     Node tail(Edge e) const { return edges[e.id].tail; }

     Node head(Edge e) const { return edges[e.id].head; }

     void first(Node& node) const { 

       node.id = first_node;

     }

     void next(Node& node) const {

       node.id = nodes[node.id].next;

     }

     void first(Edge& e) const { 

       int n;

       for(n = first_node; 

 	  n!=-1 && nodes[n].first_in == -1; 

 	  n = nodes[n].next);

       e.id = (n == -1) ? -1 : nodes[n].first_in;

     }

     void next(Edge& edge) const {

       if (edges[edge.id].next_in != -1) {

 	edge.id = edges[edge.id].next_in;

       } else {

 	int n;

 	for(n = nodes[edges[edge.id].head].next;

 	  n!=-1 && nodes[n].first_in == -1; 

 	  n = nodes[n].next);

 	edge.id = (n == -1) ? -1 : nodes[n].first_in;

       }      

     }

     void firstOut(Edge &e, const Node& v) const {

       e.id = nodes[v.id].first_out;

     }

     void nextOut(Edge &e) const {

       e.id=edges[e.id].next_out;

     }

     void firstIn(Edge &e, const Node& v) const {

       e.id = nodes[v.id].first_in;

     }

     void nextIn(Edge &e) const {

       e.id=edges[e.id].next_in;

     }

     static int id(Node v) { return v.id; }

     static int id(Edge e) { return e.id; }

     /// Adds a new node to the graph.

     /// \warning It adds the new node to the front of the list.

     /// (i.e. the lastly added node becomes the first.)

     Node addNode() {     

       int n;

       if(first_free_node==-1) {

 	n = nodes.size();

 	nodes.push_back(NodeT());

       } else {

 	n = first_free_node;

 	first_free_node = nodes[n].next;

       }

       nodes[n].next = first_node;

       if(first_node != -1) nodes[first_node].prev = n;

       first_node = n;

       nodes[n].prev = -1;

       nodes[n].first_in = nodes[n].first_out = -1;

       return Node(n);

     }

     Edge addEdge(Node u, Node v) {

       int n;      

       if (first_free_edge == -1) {

 	n = edges.size();

 	edges.push_back(EdgeT());

       } else {

 	n = first_free_edge;

 	first_free_edge = edges[n].next_in;

       }

       edges[n].tail = u.id; 

       edges[n].head = v.id;

       edges[n].next_out = nodes[u.id].first_out;

       if(nodes[u.id].first_out != -1) {

 	edges[nodes[u.id].first_out].prev_out = n;

       }

       edges[n].next_in = nodes[v.id].first_in;

       if(nodes[v.id].first_in != -1) {

 	edges[nodes[v.id].first_in].prev_in = n;

       }

       edges[n].prev_in = edges[n].prev_out = -1;

       nodes[u.id].first_out = nodes[v.id].first_in = n;

       return Edge(n);

     }

     void erase(const Node& node) {

       int n = node.id;

       if(nodes[n].next != -1) {

 	nodes[nodes[n].next].prev = nodes[n].prev;

       }

       if(nodes[n].prev != -1) {

 	nodes[nodes[n].prev].next = nodes[n].next;

       } else {

 	first_node = nodes[n].next;

       }

       nodes[n].next = first_free_node;

       first_free_node = n;

     }

     void erase(const Edge& edge) {

       int n = edge.id;

       if(edges[n].next_in!=-1) {

 	edges[edges[n].next_in].prev_in = edges[n].prev_in;

       }

       if(edges[n].prev_in!=-1) {

 	edges[edges[n].prev_in].next_in = edges[n].next_in;

       } else {

 	nodes[edges[n].head].first_in = edges[n].next_in;

       }

       if(edges[n].next_out!=-1) {

 	edges[edges[n].next_out].prev_out = edges[n].prev_out;

       } 

       if(edges[n].prev_out!=-1) {

 	edges[edges[n].prev_out].next_out = edges[n].next_out;

       } else {

 	nodes[edges[n].tail].first_out = edges[n].next_out;

       }

       edges[n].next_in = first_free_edge;

       first_free_edge = n;      

     }

     void clear() {

       edges.clear();

       nodes.clear();

       first_node = first_free_node = first_free_edge = -1;

     }

   };

   typedef AlterableGraphExtender<ListGraphBase> AlterableListGraphBase;

   typedef IterableGraphExtender<AlterableListGraphBase> IterableListGraphBase;

   typedef IdMappableGraphExtender<IterableListGraphBase> IdMappableListGraphBase;

   typedef DefaultMappableGraphExtender<IdMappableListGraphBase> MappableListGraphBase;

   typedef ExtendableGraphExtender<MappableListGraphBase> ExtendableListGraphBase;

   typedef ClearableGraphExtender<ExtendableListGraphBase> ClearableListGraphBase;

   typedef ErasableGraphExtender<ClearableListGraphBase> ErasableListGraphBase;

   typedef ErasableListGraphBase ListGraph;

 }

 #endif