COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/hugo/list_graph.h @ 909:6a22e0dfd453

Last change on this file since 909:6a22e0dfd453 was 909:6a22e0dfd453, checked in by Balazs Dezso, 18 years ago

New symmetric Graph concept.
New symmetric list and smart graph.
Symmetric Graph tests based on the Graph Tests.

File size: 40.3 KB
Line 
1/* -*- C++ -*-
2 * src/hugo/list_graph.h - Part of HUGOlib, a generic C++ optimization library
3 *
4 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Combinatorial Optimization Research Group, EGRES).
6 *
7 * Permission to use, modify and distribute this software is granted
8 * provided that this copyright notice appears in all copies. For
9 * precise terms see the accompanying LICENSE file.
10 *
11 * This software is provided "AS IS" with no warranty of any kind,
12 * express or implied, and with no claim as to its suitability for any
13 * purpose.
14 *
15 */
16
17#ifndef HUGO_LIST_GRAPH_H
18#define HUGO_LIST_GRAPH_H
19
20///\ingroup graphs
21///\file
22///\brief ListGraph, SymListGraph, NodeSet and EdgeSet classes.
23
24#include <vector>
25#include <climits>
26
27#include <hugo/invalid.h>
28
29#include <hugo/map_registry.h>
30#include <hugo/array_map.h>
31
32#include <hugo/map_defines.h>
33
34
35namespace hugo {
36
37/// \addtogroup graphs
38/// @{
39
40  ///A list graph class.
41
42  ///This is a simple and fast erasable graph implementation.
43  ///
44  ///It conforms to the
45  ///\ref skeleton::ErasableGraph "ErasableGraph" concept.
46  ///\sa skeleton::ErasableGraph.
47  class ListGraph {
48
49    //Nodes are double linked.
50    //The free nodes are only single linked using the "next" field.
51    struct NodeT
52    {
53      int first_in,first_out;
54      int prev, next;
55    };
56    //Edges are double linked.
57    //The free edges are only single linked using the "next_in" field.
58    struct EdgeT
59    {
60      int head, tail;
61      int prev_in, prev_out;
62      int next_in, next_out;
63    };
64
65    std::vector<NodeT> nodes;
66    //The first node
67    int first_node;
68    //The first free node
69    int first_free_node;
70    std::vector<EdgeT> edges;
71    //The first free edge
72    int first_free_edge;
73   
74  public:
75   
76    typedef ListGraph Graph;
77   
78    class Node;
79    class Edge;
80
81   
82  public:
83
84    class NodeIt;
85    class EdgeIt;
86    class OutEdgeIt;
87    class InEdgeIt;
88
89    // Create map registries.
90    CREATE_MAP_REGISTRIES;
91    // Create node and edge maps.
92    CREATE_MAPS(ArrayMap);
93
94  public:
95
96    ListGraph()
97      : nodes(), first_node(-1),
98        first_free_node(-1), edges(), first_free_edge(-1) {}
99
100    ListGraph(const ListGraph &_g)
101      : nodes(_g.nodes), first_node(_g.first_node),
102        first_free_node(_g.first_free_node), edges(_g.edges),
103        first_free_edge(_g.first_free_edge) {}
104   
105    ///Number of nodes.
106    int nodeNum() const { return nodes.size(); }
107    ///Number of edges.
108    int edgeNum() const { return edges.size(); }
109
110    ///Set the expected maximum number of edges.
111
112    ///With this function, it is possible to set the expected number of edges.
113    ///The use of this fasten the building of the graph and makes
114    ///it possible to avoid the superfluous memory allocation.
115    void reserveEdge(int n) { edges.reserve(n); };
116   
117    /// Maximum node ID.
118   
119    /// Maximum node ID.
120    ///\sa id(Node)
121    int maxNodeId() const { return nodes.size()-1; }
122    /// Maximum edge ID.
123   
124    /// Maximum edge ID.
125    ///\sa id(Edge)
126    int maxEdgeId() const { return edges.size()-1; }
127
128    Node tail(Edge e) const { return edges[e.n].tail; }
129    Node head(Edge e) const { return edges[e.n].head; }
130
131    NodeIt& first(NodeIt& v) const {
132      v=NodeIt(*this); return v; }
133    EdgeIt& first(EdgeIt& e) const {
134      e=EdgeIt(*this); return e; }
135    OutEdgeIt& first(OutEdgeIt& e, const Node v) const {
136      e=OutEdgeIt(*this,v); return e; }
137    InEdgeIt& first(InEdgeIt& e, const Node v) const {
138      e=InEdgeIt(*this,v); return e; }
139
140    /// Node ID.
141   
142    /// The ID of a valid Node is a nonnegative integer not greater than
143    /// \ref maxNodeId(). The range of the ID's is not surely continuous
144    /// and the greatest node ID can be actually less then \ref maxNodeId().
145    ///
146    /// The ID of the \ref INVALID node is -1.
147    ///\return The ID of the node \c v.
148    static int id(Node v) { return v.n; }
149    /// Edge ID.
150   
151    /// The ID of a valid Edge is a nonnegative integer not greater than
152    /// \ref maxEdgeId(). The range of the ID's is not surely continuous
153    /// and the greatest edge ID can be actually less then \ref maxEdgeId().
154    ///
155    /// The ID of the \ref INVALID edge is -1.
156    ///\return The ID of the edge \c e.
157    static int id(Edge e) { return e.n; }
158
159    /// Adds a new node to the graph.
160
161    /// \warning It adds the new node to the front of the list.
162    /// (i.e. the lastly added node becomes the first.)
163    Node addNode() {
164      int n;
165     
166      if(first_free_node==-1)
167        {
168          n = nodes.size();
169          nodes.push_back(NodeT());
170        }
171      else {
172        n = first_free_node;
173        first_free_node = nodes[n].next;
174      }
175     
176      nodes[n].next = first_node;
177      if(first_node != -1) nodes[first_node].prev = n;
178      first_node = n;
179      nodes[n].prev = -1;
180     
181      nodes[n].first_in = nodes[n].first_out = -1;
182     
183      Node nn; nn.n=n;
184
185      //Update dynamic maps
186      node_maps.add(nn);
187
188      return nn;
189    }
190   
191    Edge addEdge(Node u, Node v) {
192      int n;
193     
194      if(first_free_edge==-1)
195        {
196          n = edges.size();
197          edges.push_back(EdgeT());
198        }
199      else {
200        n = first_free_edge;
201        first_free_edge = edges[n].next_in;
202      }
203     
204      edges[n].tail = u.n; edges[n].head = v.n;
205
206      edges[n].next_out = nodes[u.n].first_out;
207      if(nodes[u.n].first_out != -1) edges[nodes[u.n].first_out].prev_out = n;
208      edges[n].next_in = nodes[v.n].first_in;
209      if(nodes[v.n].first_in != -1) edges[nodes[v.n].first_in].prev_in = n;
210      edges[n].prev_in = edges[n].prev_out = -1;
211       
212      nodes[u.n].first_out = nodes[v.n].first_in = n;
213
214      Edge e; e.n=n;
215
216      //Update dynamic maps
217      edge_maps.add(e);
218
219      return e;
220    }
221   
222    /// Finds an edge between two nodes.
223
224    /// Finds an edge from node \c u to node \c v.
225    ///
226    /// If \c prev is \ref INVALID (this is the default value), then
227    /// It finds the first edge from \c u to \c v. Otherwise it looks for
228    /// the next edge from \c u to \c v after \c prev.
229    /// \return The found edge or INVALID if there is no such an edge.
230    Edge findEdge(Node u,Node v, Edge prev = INVALID)
231    {
232      int e = (prev.n==-1)? nodes[u.n].first_out : edges[prev.n].next_out;
233      while(e!=-1 && edges[e].tail!=v.n) e = edges[e].next_out;
234      prev.n=e;
235      return prev;
236    }
237   
238  private:
239    void eraseEdge(int n) {
240     
241      if(edges[n].next_in!=-1)
242        edges[edges[n].next_in].prev_in = edges[n].prev_in;
243      if(edges[n].prev_in!=-1)
244        edges[edges[n].prev_in].next_in = edges[n].next_in;
245      else nodes[edges[n].head].first_in = edges[n].next_in;
246     
247      if(edges[n].next_out!=-1)
248        edges[edges[n].next_out].prev_out = edges[n].prev_out;
249      if(edges[n].prev_out!=-1)
250        edges[edges[n].prev_out].next_out = edges[n].next_out;
251      else nodes[edges[n].tail].first_out = edges[n].next_out;
252     
253      edges[n].next_in = first_free_edge;
254      first_free_edge = n;     
255
256      //Update dynamic maps
257      Edge e; e.n=n;
258      edge_maps.erase(e);
259
260    }
261     
262  public:
263
264    void erase(Node nn) {
265      int n=nn.n;
266     
267      int m;
268      while((m=nodes[n].first_in)!=-1) eraseEdge(m);
269      while((m=nodes[n].first_out)!=-1) eraseEdge(m);
270
271      if(nodes[n].next != -1) nodes[nodes[n].next].prev = nodes[n].prev;
272      if(nodes[n].prev != -1) nodes[nodes[n].prev].next = nodes[n].next;
273      else first_node = nodes[n].next;
274     
275      nodes[n].next = first_free_node;
276      first_free_node = n;
277
278      //Update dynamic maps
279      node_maps.erase(nn);
280
281    }
282   
283    void erase(Edge e) { eraseEdge(e.n); }
284
285    void clear() {
286      edge_maps.clear();
287      edges.clear();
288      node_maps.clear();
289      nodes.clear();
290      first_node=first_free_node=first_free_edge=-1;
291    }
292
293    class Node {
294      friend class ListGraph;
295      template <typename T> friend class NodeMap;
296       
297      friend class Edge;
298      friend class OutEdgeIt;
299      friend class InEdgeIt;
300      friend class SymEdge;
301
302    protected:
303      int n;
304      friend int ListGraph::id(Node v);
305      Node(int nn) {n=nn;}
306    public:
307      Node() {}
308      Node (Invalid) { n=-1; }
309      bool operator==(const Node i) const {return n==i.n;}
310      bool operator!=(const Node i) const {return n!=i.n;}
311      bool operator<(const Node i) const {return n<i.n;}
312      //      ///Validity check
313      //      operator bool() { return n!=-1; }
314    };
315   
316    class NodeIt : public Node {
317      const ListGraph *G;
318      friend class ListGraph;
319    public:
320      NodeIt() : Node() { }
321      NodeIt(Invalid i) : Node(i) { }
322      NodeIt(const ListGraph& _G) : Node(_G.first_node), G(&_G) { }
323      NodeIt(const ListGraph& _G,Node n) : Node(n), G(&_G) { }
324      NodeIt &operator++() {
325        n=G->nodes[n].next;
326        return *this;
327      }
328      //      ///Validity check
329      //      operator bool() { return Node::operator bool(); }     
330    };
331
332    class Edge {
333      friend class ListGraph;
334      template <typename T> friend class EdgeMap;
335
336      friend class SymListGraph;
337     
338      friend class Node;
339      friend class NodeIt;
340    protected:
341      int n;
342      friend int ListGraph::id(Edge e);
343
344    public:
345      /// An Edge with id \c n.
346
347      /// \bug It should be
348      /// obtained by a member function of the Graph.
349      Edge(int nn) {n=nn;}
350
351      Edge() { }
352      Edge (Invalid) { n=-1; }
353      bool operator==(const Edge i) const {return n==i.n;}
354      bool operator!=(const Edge i) const {return n!=i.n;}
355      bool operator<(const Edge i) const {return n<i.n;}
356      //      ///Validity check
357      //      operator bool() { return n!=-1; }
358   };
359   
360    class EdgeIt : public Edge {
361      const ListGraph *G;
362      friend class ListGraph;
363    public:
364      EdgeIt(const ListGraph& _G) : Edge(), G(&_G) {
365        int m;
366        for(m=_G.first_node;
367            m!=-1 && _G.nodes[m].first_in == -1; m = _G.nodes[m].next);
368        n = (m==-1)?-1:_G.nodes[m].first_in;
369      }
370      EdgeIt (Invalid i) : Edge(i) { }
371      EdgeIt(const ListGraph& _G, Edge e) : Edge(e), G(&_G) { }
372      EdgeIt() : Edge() { }
373      EdgeIt &operator++() {
374        if(G->edges[n].next_in!=-1) n=G->edges[n].next_in;
375        else {
376          int nn;
377          for(nn=G->nodes[G->edges[n].head].next;
378              nn!=-1 && G->nodes[nn].first_in == -1;
379              nn = G->nodes[nn].next) ;
380          n = (nn==-1)?-1:G->nodes[nn].first_in;
381        }
382        return *this;
383      }
384      //      ///Validity check
385      //      operator bool() { return Edge::operator bool(); }     
386    };
387   
388    class OutEdgeIt : public Edge {
389      const ListGraph *G;
390      friend class ListGraph;
391    public:
392      OutEdgeIt() : Edge() { }
393      OutEdgeIt(const ListGraph& _G, Edge e) : Edge(e), G(&_G) { }
394      OutEdgeIt (Invalid i) : Edge(i) { }
395
396      OutEdgeIt(const ListGraph& _G,const Node v)
397        : Edge(_G.nodes[v.n].first_out), G(&_G) {}
398      OutEdgeIt &operator++() { n=G->edges[n].next_out; return *this; }
399      //      ///Validity check
400      //      operator bool() { return Edge::operator bool(); }     
401    };
402   
403    class InEdgeIt : public Edge {
404      const ListGraph *G;
405      friend class ListGraph;
406    public:
407      InEdgeIt() : Edge() { }
408      InEdgeIt(const ListGraph& _G, Edge e) : Edge(e), G(&_G) { }
409      InEdgeIt (Invalid i) : Edge(i) { }
410      InEdgeIt(const ListGraph& _G,Node v)
411        : Edge(_G.nodes[v.n].first_in), G(&_G) { }
412      InEdgeIt &operator++() { n=G->edges[n].next_in; return *this; }
413      //      ///Validity check
414      //      operator bool() { return Edge::operator bool(); }     
415    };
416  };
417
418  ///Graph for bidirectional edges.
419
420  ///The purpose of this graph structure is to handle graphs
421  ///having bidirectional edges. Here the function \c addEdge(u,v) adds a pair
422  ///of oppositely directed edges.
423  ///There is a new edge map type called
424  ///\ref SymListGraph::SymEdgeMap "SymEdgeMap"
425  ///that complements this
426  ///feature by
427  ///storing shared values for the edge pairs. The usual
428  ///\ref Graph::EdgeMap "EdgeMap"
429  ///can be used
430  ///as well.
431  ///
432  ///The oppositely directed edge can also be obtained easily
433  ///using \ref opposite.
434  ///
435  ///Here erase(Edge) deletes a pair of edges.
436  ///
437  ///\todo this date structure need some reconsiderations. Maybe it
438  ///should be implemented independently from ListGraph.
439  /* 
440  class SymListGraph : public ListGraph
441  {
442  public:
443
444    typedef SymListGraph Graph;
445
446    // Create symmetric map registry.
447    CREATE_SYM_EDGE_MAP_REGISTRY;
448    // Create symmetric edge map.
449    CREATE_SYM_EDGE_MAP(ArrayMap);
450
451    SymListGraph() : ListGraph() { }
452    SymListGraph(const ListGraph &_g) : ListGraph(_g) { }
453    ///Adds a pair of oppositely directed edges to the graph.
454    Edge addEdge(Node u, Node v)
455    {
456      Edge e = ListGraph::addEdge(u,v);
457      Edge f = ListGraph::addEdge(v,u);
458      sym_edge_maps.add(e);
459      sym_edge_maps.add(f);
460     
461      return e;
462    }
463
464    void erase(Node n) { ListGraph::erase(n);}
465    ///The oppositely directed edge.
466
467    ///Returns the oppositely directed
468    ///pair of the edge \c e.
469    static Edge opposite(Edge e)
470    {
471      Edge f;
472      f.n = e.n - 2*(e.n%2) + 1;
473      return f;
474    }
475   
476    ///Removes a pair of oppositely directed edges to the graph.
477    void erase(Edge e) {
478      Edge f = opposite(e);
479      sym_edge_maps.erase(e);
480      sym_edge_maps.erase(f);
481      ListGraph::erase(f);
482      ListGraph::erase(e);
483    }   
484    };*/
485
486  class SymListGraph : public ListGraph {
487    typedef ListGraph Parent;
488  public:
489
490    typedef SymListGraph Graph;
491
492    typedef ListGraph::Node Node;
493    typedef ListGraph::NodeIt NodeIt;
494
495    class SymEdge;
496    class SymEdgeIt;
497
498    class Edge;
499    class EdgeIt;
500    class OutEdgeIt;
501    class InEdgeIt;
502
503    template <typename Value>
504    class NodeMap : public Parent::NodeMap<Value> {     
505    public:
506      NodeMap(const SymListGraph& g)
507        : SymListGraph::Parent::NodeMap<Value>(g) {}
508      NodeMap(const SymListGraph& g, Value v)
509        : SymListGraph::Parent::NodeMap<Value>(g, v) {}
510      template<typename TT>
511      NodeMap(const NodeMap<TT>& copy)
512        : SymListGraph::Parent::NodeMap<Value>(copy) { }           
513    };
514
515    template <typename Value>
516    class SymEdgeMap : public Parent::EdgeMap<Value> {
517    public:
518      typedef SymEdge KeyType;
519
520      SymEdgeMap(const SymListGraph& g)
521        : SymListGraph::Parent::EdgeMap<Value>(g) {}
522      SymEdgeMap(const SymListGraph& g, Value v)
523        : SymListGraph::Parent::EdgeMap<Value>(g, v) {}
524      template<typename TT>
525      SymEdgeMap(const SymEdgeMap<TT>& copy)
526        : SymListGraph::Parent::EdgeMap<Value>(copy) { }
527     
528    };
529
530    // Create edge map registry.
531    CREATE_EDGE_MAP_REGISTRY;
532    // Create edge maps.
533    CREATE_EDGE_MAP(ArrayMap);
534
535    class Edge {
536      friend class SymListGraph;
537      friend class SymListGraph::EdgeIt;
538      friend class SymListGraph::OutEdgeIt;
539      friend class SymListGraph::InEdgeIt;
540     
541    protected:
542      int id;
543
544      Edge(int pid) { id = pid; }
545
546    public:
547      /// An Edge with id \c n.
548
549      Edge() { }
550      Edge (Invalid) { id = -1; }
551
552      operator SymEdge(){ return SymEdge(id >> 1);}
553     
554      bool operator==(const Edge i) const {return id == i.id;}
555      bool operator!=(const Edge i) const {return id != i.id;}
556      bool operator<(const Edge i) const {return id < i.id;}
557      //      ///Validity check
558      //      operator bool() { return n!=-1; }
559    };
560
561    class SymEdge : public ListGraph::Edge {
562      friend class SymListGraph;
563      friend class SymListGraph::Edge;
564      typedef ListGraph::Edge Parent;
565
566    protected:     
567      SymEdge(int pid) : Parent(pid) {}
568    public:
569
570      SymEdge() { }
571      SymEdge(const ListGraph::Edge& i) : Parent(i) {}
572      SymEdge (Invalid) : Parent(INVALID) {}
573
574    };
575
576    class OutEdgeIt {
577      Parent::OutEdgeIt out;
578      Parent::InEdgeIt in;     
579    public:
580      OutEdgeIt() {}
581      OutEdgeIt(const SymListGraph& g, Edge e) {
582        if (e.id & 1 == 0) {   
583          out = Parent::OutEdgeIt(g, SymEdge(e));
584          in = Parent::InEdgeIt(g, g.tail(e));
585        } else {
586          out = Parent::OutEdgeIt(INVALID);
587          in = Parent::InEdgeIt(g, SymEdge(e));
588        }
589      }
590      OutEdgeIt (Invalid i) : out(INVALID), in(INVALID) { }
591
592      OutEdgeIt(const SymListGraph& g, const Node v)
593        : out(g, v), in(g, v) {}
594      OutEdgeIt &operator++() {
595        if (out != INVALID) {
596          ++out;
597        } else {
598          ++in;
599        }
600        return *this;
601      }
602
603      operator Edge() const {
604        if (out == INVALID && in == INVALID) return INVALID;
605        return out != INVALID ? forward(out) : backward(in);
606      }
607
608      bool operator==(const Edge i) const {return Edge(*this) == i;}
609      bool operator!=(const Edge i) const {return Edge(*this) != i;}
610      bool operator<(const Edge i) const {return Edge(*this) < i;}
611    };
612
613    class InEdgeIt {
614      Parent::OutEdgeIt out;
615      Parent::InEdgeIt in;     
616    public:
617      InEdgeIt() {}
618      InEdgeIt(const SymListGraph& g, Edge e) {
619        if (e.id & 1 == 0) {   
620          out = Parent::OutEdgeIt(g, SymEdge(e));
621          in = Parent::InEdgeIt(g, g.tail(e));
622        } else {
623          out = Parent::OutEdgeIt(INVALID);
624          in = Parent::InEdgeIt(g, SymEdge(e));
625        }
626      }
627      InEdgeIt (Invalid i) : out(INVALID), in(INVALID) { }
628
629      InEdgeIt(const SymListGraph& g, const Node v)
630        : out(g, v), in(g, v) {}
631
632      InEdgeIt &operator++() {
633        if (out != INVALID) {
634          ++out;
635        } else {
636          ++in;
637        }
638        return *this;
639      }
640
641      operator Edge() const {
642        if (out == INVALID && in == INVALID) return INVALID;
643        return out != INVALID ? backward(out) : forward(in);
644      }
645
646      bool operator==(const Edge i) const {return Edge(*this) == i;}
647      bool operator!=(const Edge i) const {return Edge(*this) != i;}
648      bool operator<(const Edge i) const {return Edge(*this) < i;}
649    };
650
651    class SymEdgeIt : public Parent::EdgeIt {
652
653    public:
654      SymEdgeIt() {}
655
656      SymEdgeIt(const SymListGraph& g)
657        : SymListGraph::Parent::EdgeIt(g) {}
658
659      SymEdgeIt(const SymListGraph& g, SymEdge e)
660        : SymListGraph::Parent::EdgeIt(g, e) {}
661
662      SymEdgeIt(Invalid i)
663        : SymListGraph::Parent::EdgeIt(INVALID) {}
664
665      SymEdgeIt& operator++() {
666        SymListGraph::Parent::EdgeIt::operator++();
667        return *this;
668      }
669
670      operator SymEdge() const {
671        return SymEdge
672          (static_cast<const SymListGraph::Parent::EdgeIt&>(*this));
673      }
674      bool operator==(const SymEdge i) const {return SymEdge(*this) == i;}
675      bool operator!=(const SymEdge i) const {return SymEdge(*this) != i;}
676      bool operator<(const SymEdge i) const {return SymEdge(*this) < i;}
677    };
678
679    class EdgeIt {
680      SymEdgeIt it;
681      bool fw;
682    public:
683      EdgeIt(const SymListGraph& g) : it(g), fw(true) {}
684      EdgeIt (Invalid i) : it(i) { }
685      EdgeIt(const SymListGraph& g, Edge e)
686        : it(g, SymEdge(e)), fw(id(e) & 1 == 0) { }
687      EdgeIt() { }
688      EdgeIt& operator++() {
689        fw = !fw;
690        if (fw) ++it;
691        return *this;
692      }
693      operator Edge() const {
694        if (it == INVALID) return INVALID;
695        return fw ? forward(it) : backward(it);
696      }
697      bool operator==(const Edge i) const {return Edge(*this) == i;}
698      bool operator!=(const Edge i) const {return Edge(*this) != i;}
699      bool operator<(const Edge i) const {return Edge(*this) < i;}
700
701    };
702
703    ///Number of nodes.
704    int nodeNum() const { return Parent::nodeNum(); }
705    ///Number of edges.
706    int edgeNum() const { return 2*Parent::edgeNum(); }
707    ///Number of symmetric edges.
708    int symEdgeNum() const { return Parent::edgeNum(); }
709
710    ///Set the expected maximum number of edges.
711
712    ///With this function, it is possible to set the expected number of edges.
713    ///The use of this fasten the building of the graph and makes
714    ///it possible to avoid the superfluous memory allocation.
715    void reserveSymEdge(int n) { Parent::reserveEdge(n); };
716   
717    /// Maximum node ID.
718   
719    /// Maximum node ID.
720    ///\sa id(Node)
721    int maxNodeId() const { return Parent::maxNodeId(); }
722    /// Maximum edge ID.
723   
724    /// Maximum edge ID.
725    ///\sa id(Edge)
726    int maxEdgeId() const { return 2*Parent::maxEdgeId(); }
727    /// Maximum symmetric edge ID.
728   
729    /// Maximum symmetric edge ID.
730    ///\sa id(SymEdge)
731    int maxSymEdgeId() const { return Parent::maxEdgeId(); }
732
733
734    Node tail(Edge e) const {
735      return e.id & 1 == 0 ?
736        Parent::tail(SymEdge(e)) : Parent::head(SymEdge(e));
737    }
738
739    Node head(Edge e) const {
740      return e.id & 1 == 0 ?
741        Parent::head(SymEdge(e)) : Parent::tail(SymEdge(e));
742    }
743
744    Node tail(SymEdge e) const {
745      return Parent::tail(e);
746    }
747
748    Node head(SymEdge e) const {
749      return Parent::head(e);
750    }
751
752    NodeIt& first(NodeIt& v) const {
753      v=NodeIt(*this); return v; }
754    EdgeIt& first(EdgeIt& e) const {
755      e=EdgeIt(*this); return e; }
756    SymEdgeIt& first(SymEdgeIt& e) const {
757      e=SymEdgeIt(*this); return e; }
758    OutEdgeIt& first(OutEdgeIt& e, const Node v) const {
759      e=OutEdgeIt(*this,v); return e; }
760    InEdgeIt& first(InEdgeIt& e, const Node v) const {
761      e=InEdgeIt(*this,v); return e; }
762
763    /// Node ID.
764   
765    /// The ID of a valid Node is a nonnegative integer not greater than
766    /// \ref maxNodeId(). The range of the ID's is not surely continuous
767    /// and the greatest node ID can be actually less then \ref maxNodeId().
768    ///
769    /// The ID of the \ref INVALID node is -1.
770    ///\return The ID of the node \c v.
771    static int id(Node v) { return Parent::id(v); }
772    /// Edge ID.
773   
774    /// The ID of a valid Edge is a nonnegative integer not greater than
775    /// \ref maxEdgeId(). The range of the ID's is not surely continuous
776    /// and the greatest edge ID can be actually less then \ref maxEdgeId().
777    ///
778    /// The ID of the \ref INVALID edge is -1.
779    ///\return The ID of the edge \c e.
780    static int id(Edge e) { return e.id; }
781
782    /// The ID of a valid SymEdge is a nonnegative integer not greater than
783    /// \ref maxSymEdgeId(). The range of the ID's is not surely continuous
784    /// and the greatest edge ID can be actually less then \ref maxSymEdgeId().
785    ///
786    /// The ID of the \ref INVALID symmetric edge is -1.
787    ///\return The ID of the edge \c e.
788    static int id(SymEdge e) { return Parent::id(e); }
789
790    /// Adds a new node to the graph.
791
792    /// \warning It adds the new node to the front of the list.
793    /// (i.e. the lastly added node becomes the first.)
794    Node addNode() {
795      return Parent::addNode();
796    }
797   
798    SymEdge addEdge(Node u, Node v) {
799      SymEdge se = Parent::addEdge(u, v);
800      edge_maps.add(forward(se));
801      edge_maps.add(backward(se));
802      return se;
803    }
804   
805    /// Finds an edge between two nodes.
806
807    /// Finds an edge from node \c u to node \c v.
808    ///
809    /// If \c prev is \ref INVALID (this is the default value), then
810    /// It finds the first edge from \c u to \c v. Otherwise it looks for
811    /// the next edge from \c u to \c v after \c prev.
812    /// \return The found edge or INVALID if there is no such an edge.
813    Edge findEdge(Node u, Node v, Edge prev = INVALID)
814    {     
815      if (prev == INVALID || id(prev) & 1 == 0) {
816        SymEdge se = Parent::findEdge(u, v, SymEdge(prev));
817        if (se != INVALID) return forward(se);
818      } else {
819        SymEdge se = Parent::findEdge(v, u, SymEdge(prev));
820        if (se != INVALID) return backward(se);
821      }
822      return INVALID;
823    }
824
825    /// Finds an symmetric edge between two nodes.
826
827    /// Finds an symmetric edge from node \c u to node \c v.
828    ///
829    /// If \c prev is \ref INVALID (this is the default value), then
830    /// It finds the first edge from \c u to \c v. Otherwise it looks for
831    /// the next edge from \c u to \c v after \c prev.
832    /// \return The found edge or INVALID if there is no such an edge.
833
834//     SymEdge findEdge(Node u, Node v, SymEdge prev = INVALID)
835//     {     
836//       if (prev == INVALID || id(prev) & 1 == 0) {
837//      SymEdge se = Parent::findEdge(u, v, SymEdge(prev));
838//      if (se != INVALID) return se;
839//       } else {
840//      SymEdge se = Parent::findEdge(v, u, SymEdge(prev));
841//      if (se != INVALID) return se;   
842//       }
843//       return INVALID;
844//     }
845   
846  public:
847
848    void erase(Node n) {     
849      for (OutEdgeIt it(*this, n); it != INVALID; ++it) {
850        edge_maps.erase(it);
851        edge_maps.erase(opposite(it));
852      }
853      Parent::erase(n);
854    }
855   
856    void erase(SymEdge e) {
857      edge_maps.erase(forward(e));
858      edge_maps.erase(backward(e));
859      Parent::erase(e);
860    };
861
862    void clear() {
863      edge_maps.clear();
864      Parent::clear();
865    }
866
867    static Edge opposite(Edge e) {
868      return Edge(id(e) ^ 1);
869    }
870
871    static Edge forward(SymEdge e) {
872      return Edge(id(e) << 1);
873    }
874
875    static Edge backward(SymEdge e) {
876      return Edge((id(e) << 1) & 1);
877    }
878
879  };
880
881  ///A graph class containing only nodes.
882
883  ///This class implements a graph structure without edges.
884  ///The most useful application of this class is to be the node set of an
885  ///\ref EdgeSet class.
886  ///
887  ///It conforms to
888  ///the \ref skeleton::ExtendableGraph "ExtendableGraph" concept
889  ///with the exception that you cannot
890  ///add (or delete) edges. The usual edge iterators are exists, but they are
891  ///always \ref INVALID.
892  ///\sa skeleton::ExtendableGraph
893  ///\sa EdgeSet
894  class NodeSet {
895
896    //Nodes are double linked.
897    //The free nodes are only single linked using the "next" field.
898    struct NodeT
899    {
900      int first_in,first_out;
901      int prev, next;
902      //      NodeT() {}
903    };
904
905    std::vector<NodeT> nodes;
906    //The first node
907    int first_node;
908    //The first free node
909    int first_free_node;
910   
911  public:
912
913    typedef NodeSet Graph;
914   
915    class Node;
916    class Edge;
917
918  public:
919
920    class NodeIt;
921    class EdgeIt;
922    class OutEdgeIt;
923    class InEdgeIt;
924   
925    // Create node map registry.
926    CREATE_NODE_MAP_REGISTRY;
927    // Create node maps.
928    CREATE_NODE_MAP(ArrayMap);
929
930    /// Creating empty map structure for edges.
931    template <typename Value>
932    class EdgeMap {
933    public:
934      EdgeMap(const Graph&) {}
935      EdgeMap(const Graph&, const Value&) {}
936
937      EdgeMap(const EdgeMap&) {}
938      template <typename CMap> EdgeMap(const CMap&) {}
939
940      EdgeMap& operator=(const EdgeMap&) {}
941      template <typename CMap> EdgeMap& operator=(const CMap&) {}
942     
943      class ConstIterator {
944      public:
945        bool operator==(const ConstIterator&) {return true;}
946        bool operator!=(const ConstIterator&) {return false;}
947      };
948
949      typedef ConstIterator Iterator;
950     
951      Iterator begin() { return Iterator();}
952      Iterator end() { return Iterator();}
953
954      ConstIterator begin() const { return ConstIterator();}
955      ConstIterator end() const { return ConstIterator();}
956
957    };
958   
959  public:
960
961    ///Default constructor
962    NodeSet()
963      : nodes(), first_node(-1), first_free_node(-1) {}
964    ///Copy constructor
965    NodeSet(const NodeSet &_g)
966      : nodes(_g.nodes), first_node(_g.first_node),
967        first_free_node(_g.first_free_node) {}
968   
969    ///Number of nodes.
970    int nodeNum() const { return nodes.size(); }
971    ///Number of edges.
972    int edgeNum() const { return 0; }
973
974    /// Maximum node ID.
975   
976    /// Maximum node ID.
977    ///\sa id(Node)
978    int maxNodeId() const { return nodes.size()-1; }
979    /// Maximum edge ID.
980   
981    /// Maximum edge ID.
982    ///\sa id(Edge)
983    int maxEdgeId() const { return 0; }
984
985    Node tail(Edge e) const { return INVALID; }
986    Node head(Edge e) const { return INVALID; }
987
988    NodeIt& first(NodeIt& v) const {
989      v=NodeIt(*this); return v; }
990    EdgeIt& first(EdgeIt& e) const {
991      e=EdgeIt(*this); return e; }
992    OutEdgeIt& first(OutEdgeIt& e, const Node v) const {
993      e=OutEdgeIt(*this,v); return e; }
994    InEdgeIt& first(InEdgeIt& e, const Node v) const {
995      e=InEdgeIt(*this,v); return e; }
996
997    /// Node ID.
998   
999    /// The ID of a valid Node is a nonnegative integer not greater than
1000    /// \ref maxNodeId(). The range of the ID's is not surely continuous
1001    /// and the greatest node ID can be actually less then \ref maxNodeId().
1002    ///
1003    /// The ID of the \ref INVALID node is -1.
1004    ///\return The ID of the node \c v.
1005    static int id(Node v) { return v.n; }
1006    /// Edge ID.
1007   
1008    /// The ID of a valid Edge is a nonnegative integer not greater than
1009    /// \ref maxEdgeId(). The range of the ID's is not surely continuous
1010    /// and the greatest edge ID can be actually less then \ref maxEdgeId().
1011    ///
1012    /// The ID of the \ref INVALID edge is -1.
1013    ///\return The ID of the edge \c e.
1014    static int id(Edge e) { return -1; }
1015
1016    /// Adds a new node to the graph.
1017
1018    /// \warning It adds the new node to the front of the list.
1019    /// (i.e. the lastly added node becomes the first.)
1020    Node addNode() {
1021      int n;
1022     
1023      if(first_free_node==-1)
1024        {
1025          n = nodes.size();
1026          nodes.push_back(NodeT());
1027        }
1028      else {
1029        n = first_free_node;
1030        first_free_node = nodes[n].next;
1031      }
1032     
1033      nodes[n].next = first_node;
1034      if(first_node != -1) nodes[first_node].prev = n;
1035      first_node = n;
1036      nodes[n].prev = -1;
1037     
1038      nodes[n].first_in = nodes[n].first_out = -1;
1039     
1040      Node nn; nn.n=n;
1041
1042      //Update dynamic maps
1043      node_maps.add(nn);
1044
1045      return nn;
1046    }
1047   
1048    void erase(Node nn) {
1049      int n=nn.n;
1050     
1051      if(nodes[n].next != -1) nodes[nodes[n].next].prev = nodes[n].prev;
1052      if(nodes[n].prev != -1) nodes[nodes[n].prev].next = nodes[n].next;
1053      else first_node = nodes[n].next;
1054     
1055      nodes[n].next = first_free_node;
1056      first_free_node = n;
1057
1058      //Update dynamic maps
1059      node_maps.erase(nn);
1060    }
1061   
1062       
1063    Edge findEdge(Node u,Node v, Edge prev = INVALID)
1064    {
1065      return INVALID;
1066    }
1067   
1068    void clear() {
1069      node_maps.clear();
1070      nodes.clear();
1071      first_node = first_free_node = -1;
1072    }
1073
1074    class Node {
1075      friend class NodeSet;
1076      template <typename T> friend class NodeMap;
1077     
1078      friend class Edge;
1079      friend class OutEdgeIt;
1080      friend class InEdgeIt;
1081
1082    protected:
1083      int n;
1084      friend int NodeSet::id(Node v);
1085      Node(int nn) {n=nn;}
1086    public:
1087      Node() {}
1088      Node (Invalid i) { n=-1; }
1089      bool operator==(const Node i) const {return n==i.n;}
1090      bool operator!=(const Node i) const {return n!=i.n;}
1091      bool operator<(const Node i) const {return n<i.n;}
1092    };
1093   
1094    class NodeIt : public Node {
1095      const NodeSet *G;
1096      friend class NodeSet;
1097    public:
1098      NodeIt() : Node() { }
1099      NodeIt(const NodeSet& _G,Node n) : Node(n), G(&_G) { }
1100      NodeIt(Invalid i) : Node(i) { }
1101      NodeIt(const NodeSet& _G) : Node(_G.first_node), G(&_G) { }
1102      NodeIt &operator++() {
1103        n=G->nodes[n].next;
1104        return *this;
1105      }
1106    };
1107
1108    class Edge {
1109    public:
1110      Edge() { }
1111      Edge (Invalid) { }
1112      bool operator==(const Edge i) const {return true;}
1113      bool operator!=(const Edge i) const {return false;}
1114      bool operator<(const Edge i) const {return false;}
1115    };
1116   
1117    class EdgeIt : public Edge {
1118    public:
1119      EdgeIt(const NodeSet& G) : Edge() { }
1120      EdgeIt(const NodeSet&, Edge) : Edge() { }
1121      EdgeIt (Invalid i) : Edge(i) { }
1122      EdgeIt() : Edge() { }
1123      EdgeIt operator++() { return INVALID; }
1124    };
1125   
1126    class OutEdgeIt : public Edge {
1127      friend class NodeSet;
1128    public:
1129      OutEdgeIt() : Edge() { }
1130      OutEdgeIt(const NodeSet&, Edge) : Edge() { }
1131      OutEdgeIt (Invalid i) : Edge(i) { }
1132      OutEdgeIt(const NodeSet& G,const Node v)  : Edge() {}
1133      OutEdgeIt operator++() { return INVALID; }
1134    };
1135   
1136    class InEdgeIt : public Edge {
1137      friend class NodeSet;
1138    public:
1139      InEdgeIt() : Edge() { }
1140      InEdgeIt(const NodeSet&, Edge) : Edge() { }
1141      InEdgeIt (Invalid i) : Edge(i) { }
1142      InEdgeIt(const NodeSet& G,Node v) :Edge() {}
1143      InEdgeIt operator++() { return INVALID; }
1144    };
1145
1146  };
1147
1148
1149
1150  ///Graph structure using a node set of another graph.
1151
1152  ///This structure can be used to establish another graph over a node set
1153  /// of an existing one. The node iterator will go through the nodes of the
1154  /// original graph, and the NodeMap's of both graphs will convert to
1155  /// each other.
1156  ///
1157  ///\warning Adding or deleting nodes from the graph is not safe if an
1158  ///\ref EdgeSet is currently attached to it!
1159  ///
1160  ///\todo Make it possible to add/delete edges from the base graph
1161  ///(and from \ref EdgeSet, as well)
1162  ///
1163  ///\param GG The type of the graph which shares its node set with this class.
1164  ///Its interface must conform to the
1165  ///\ref skeleton::StaticGraph "StaticGraph" concept.
1166  ///
1167  ///It conforms to the
1168  ///\ref skeleton::ExtendableGraph "ExtendableGraph" concept.
1169  ///\sa skeleton::ExtendableGraph.
1170  ///\sa NodeSet.
1171  template<typename GG>
1172  class EdgeSet {
1173
1174    typedef GG NodeGraphType;
1175
1176    NodeGraphType &G;
1177
1178  public:
1179
1180    class Node;
1181    class Edge;
1182    class OutEdgeIt;
1183    class InEdgeIt;
1184    class SymEdge;
1185
1186    typedef EdgeSet Graph;
1187
1188    int id(Node v) const;
1189
1190    class Node : public NodeGraphType::Node {
1191      friend class EdgeSet;
1192     
1193      friend class Edge;
1194      friend class OutEdgeIt;
1195      friend class InEdgeIt;
1196      friend class SymEdge;
1197
1198    public:
1199      friend int EdgeSet::id(Node v) const;
1200    public:
1201      Node() : NodeGraphType::Node() {}
1202      Node (Invalid i) : NodeGraphType::Node(i) {}
1203      Node(const typename NodeGraphType::Node &n) : NodeGraphType::Node(n) {}
1204    };
1205   
1206    class NodeIt : public NodeGraphType::NodeIt {
1207      friend class EdgeSet;
1208    public:
1209      NodeIt() : NodeGraphType::NodeIt() { }
1210      NodeIt(const EdgeSet& _G,Node n) : NodeGraphType::NodeIt(_G.G,n) { }
1211      NodeIt (Invalid i) : NodeGraphType::NodeIt(i) {}
1212      NodeIt(const EdgeSet& _G) : NodeGraphType::NodeIt(_G.G) { }
1213      NodeIt(const typename NodeGraphType::NodeIt &n)
1214        : NodeGraphType::NodeIt(n) {}
1215
1216      operator Node() { return Node(*this);}
1217      NodeIt &operator++()
1218      { this->NodeGraphType::NodeIt::operator++(); return *this;}
1219    };
1220
1221  private:
1222    //Edges are double linked.
1223    //The free edges are only single linked using the "next_in" field.
1224    struct NodeT
1225    {
1226      int first_in,first_out;
1227      NodeT() : first_in(-1), first_out(-1) { }
1228    };
1229
1230    struct EdgeT
1231    {
1232      Node head, tail;
1233      int prev_in, prev_out;
1234      int next_in, next_out;
1235    };
1236
1237   
1238    typename NodeGraphType::template NodeMap<NodeT> nodes;
1239   
1240    std::vector<EdgeT> edges;
1241    //The first free edge
1242    int first_free_edge;
1243   
1244  public:
1245   
1246    class Node;
1247    class Edge;
1248
1249    class NodeIt;
1250    class EdgeIt;
1251    class OutEdgeIt;
1252    class InEdgeIt;
1253
1254
1255    // Create edge map registry.
1256    CREATE_EDGE_MAP_REGISTRY;
1257    // Create edge maps.
1258    CREATE_EDGE_MAP(ArrayMap);
1259
1260    // Import node maps from the NodeGraphType.
1261    IMPORT_NODE_MAP(NodeGraphType, graph.G, EdgeSet, graph);
1262   
1263   
1264  public:
1265
1266    ///Constructor
1267   
1268    ///Construates a new graph based on the nodeset of an existing one.
1269    ///\param _G the base graph.
1270    explicit EdgeSet(NodeGraphType &_G)
1271      : G(_G), nodes(_G), edges(),
1272        first_free_edge(-1) {}
1273    ///Copy constructor
1274
1275    ///Makes a copy of an EdgeSet.
1276    ///It will be based on the same graph.
1277    explicit EdgeSet(const EdgeSet &_g)
1278      : G(_g.G), nodes(_g.G), edges(_g.edges),
1279        first_free_edge(_g.first_free_edge) {}
1280   
1281    ///Number of nodes.
1282    int nodeNum() const { return G.nodeNum(); }
1283    ///Number of edges.
1284    int edgeNum() const { return edges.size(); }
1285
1286    /// Maximum node ID.
1287   
1288    /// Maximum node ID.
1289    ///\sa id(Node)
1290    int maxNodeId() const { return G.maxNodeId(); }
1291    /// Maximum edge ID.
1292   
1293    /// Maximum edge ID.
1294    ///\sa id(Edge)
1295    int maxEdgeId() const { return edges.size()-1; }
1296
1297    Node tail(Edge e) const { return edges[e.n].tail; }
1298    Node head(Edge e) const { return edges[e.n].head; }
1299
1300    NodeIt& first(NodeIt& v) const {
1301      v=NodeIt(*this); return v; }
1302    EdgeIt& first(EdgeIt& e) const {
1303      e=EdgeIt(*this); return e; }
1304    OutEdgeIt& first(OutEdgeIt& e, const Node v) const {
1305      e=OutEdgeIt(*this,v); return e; }
1306    InEdgeIt& first(InEdgeIt& e, const Node v) const {
1307      e=InEdgeIt(*this,v); return e; }
1308
1309    /// Node ID.
1310   
1311    /// The ID of a valid Node is a nonnegative integer not greater than
1312    /// \ref maxNodeId(). The range of the ID's is not surely continuous
1313    /// and the greatest node ID can be actually less then \ref maxNodeId().
1314    ///
1315    /// The ID of the \ref INVALID node is -1.
1316    ///\return The ID of the node \c v.
1317    int id(Node v) { return G.id(v); }
1318    /// Edge ID.
1319   
1320    /// The ID of a valid Edge is a nonnegative integer not greater than
1321    /// \ref maxEdgeId(). The range of the ID's is not surely continuous
1322    /// and the greatest edge ID can be actually less then \ref maxEdgeId().
1323    ///
1324    /// The ID of the \ref INVALID edge is -1.
1325    ///\return The ID of the edge \c e.
1326    static int id(Edge e) { return e.n; }
1327
1328    /// Adds a new node to the graph.
1329    Node addNode() { return G.addNode(); }
1330   
1331    Edge addEdge(Node u, Node v) {
1332      int n;
1333     
1334      if(first_free_edge==-1)
1335        {
1336          n = edges.size();
1337          edges.push_back(EdgeT());
1338        }
1339      else {
1340        n = first_free_edge;
1341        first_free_edge = edges[n].next_in;
1342      }
1343     
1344      edges[n].tail = u; edges[n].head = v;
1345
1346      edges[n].next_out = nodes[u].first_out;
1347      if(nodes[u].first_out != -1) edges[nodes[u].first_out].prev_out = n;
1348      edges[n].next_in = nodes[v].first_in;
1349      if(nodes[v].first_in != -1) edges[nodes[v].first_in].prev_in = n;
1350      edges[n].prev_in = edges[n].prev_out = -1;
1351       
1352      nodes[u].first_out = nodes[v].first_in = n;
1353
1354      Edge e; e.n=n;
1355
1356      //Update dynamic maps
1357      edge_maps.add(e);
1358
1359      return e;
1360    }
1361
1362    /// Finds an edge between two nodes.
1363
1364    /// Finds an edge from node \c u to node \c v.
1365    ///
1366    /// If \c prev is \ref INVALID (this is the default value), then
1367    /// It finds the first edge from \c u to \c v. Otherwise it looks for
1368    /// the next edge from \c u to \c v after \c prev.
1369    /// \return The found edge or INVALID if there is no such an edge.
1370    Edge findEdge(Node u,Node v, Edge prev = INVALID)
1371    {
1372      int e = (prev.n==-1)? nodes[u].first_out : edges[prev.n].next_out;
1373      while(e!=-1 && edges[e].tail!=v) e = edges[e].next_out;
1374      prev.n=e;
1375      return prev;
1376    }
1377   
1378  private:
1379    void eraseEdge(int n) {
1380     
1381      if(edges[n].next_in!=-1)
1382        edges[edges[n].next_in].prev_in = edges[n].prev_in;
1383      if(edges[n].prev_in!=-1)
1384        edges[edges[n].prev_in].next_in = edges[n].next_in;
1385      else nodes[edges[n].head].first_in = edges[n].next_in;
1386     
1387      if(edges[n].next_out!=-1)
1388        edges[edges[n].next_out].prev_out = edges[n].prev_out;
1389      if(edges[n].prev_out!=-1)
1390        edges[edges[n].prev_out].next_out = edges[n].next_out;
1391      else nodes[edges[n].tail].first_out = edges[n].next_out;
1392     
1393      edges[n].next_in = first_free_edge;
1394      first_free_edge = -1;     
1395
1396      //Update dynamic maps
1397      Edge e; e.n = n;
1398      edge_maps.erase(e);
1399    }
1400     
1401  public:
1402
1403    void erase(Edge e) { eraseEdge(e.n); }
1404
1405    ///Clear all edges. (Doesn't clear the nodes!)
1406    void clear() {
1407      edge_maps.clear();
1408      edges.clear();
1409      first_free_edge=-1;
1410    }
1411
1412
1413    class Edge {
1414    public:
1415      friend class EdgeSet;
1416      template <typename T> friend class EdgeMap;
1417
1418      friend class Node;
1419      friend class NodeIt;
1420    protected:
1421      int n;
1422      friend int EdgeSet::id(Edge e) const;
1423
1424      Edge(int nn) {n=nn;}
1425    public:
1426      Edge() { }
1427      Edge (Invalid) { n=-1; }
1428      bool operator==(const Edge i) const {return n==i.n;}
1429      bool operator!=(const Edge i) const {return n!=i.n;}
1430      bool operator<(const Edge i) const {return n<i.n;}
1431    };
1432   
1433    class EdgeIt : public Edge {
1434      friend class EdgeSet;
1435      template <typename T> friend class EdgeMap;
1436   
1437      const EdgeSet *G;
1438    public:
1439      EdgeIt(const EdgeSet& _G) : Edge(), G(&_G) {
1440        NodeIt m;
1441        for(G->first(m);
1442            m!=INVALID && G->nodes[m].first_in == -1;  ++m);
1443        ///\bug AJJAJ! This is a non sense!!!!!!!
1444        this->n = m!=INVALID?-1:G->nodes[m].first_in;
1445      }
1446      EdgeIt(const EdgeSet& _G, Edge e) : Edge(e), G(&_G) { }
1447      EdgeIt (Invalid i) : Edge(i) { }
1448      EdgeIt() : Edge() { }
1449      ///.
1450     
1451      ///\bug UNIMPLEMENTED!!!!!
1452      //
1453      EdgeIt &operator++() {
1454        return *this;
1455      }
1456    };
1457   
1458    class OutEdgeIt : public Edge {
1459      const EdgeSet *G;
1460      friend class EdgeSet;
1461    public:
1462      OutEdgeIt() : Edge() { }
1463      OutEdgeIt (Invalid i) : Edge(i) { }
1464      OutEdgeIt(const EdgeSet& _G, Edge e) : Edge(e), G(&_G) { }
1465
1466      OutEdgeIt(const EdgeSet& _G,const Node v) :
1467        Edge(_G.nodes[v].first_out), G(&_G) { }
1468      OutEdgeIt &operator++() {
1469        Edge::n = G->edges[Edge::n].next_out;
1470        return *this;
1471      }
1472    };
1473   
1474    class InEdgeIt : public Edge {
1475      const EdgeSet *G;
1476      friend class EdgeSet;
1477    public:
1478      InEdgeIt() : Edge() { }
1479      InEdgeIt (Invalid i) : Edge(i) { }
1480      InEdgeIt(const EdgeSet& _G, Edge e) : Edge(e), G(&_G) { }
1481      InEdgeIt(const EdgeSet& _G,Node v)
1482        : Edge(_G.nodes[v].first_in), G(&_G) { }
1483      InEdgeIt &operator++() {
1484        Edge::n = G->edges[Edge::n].next_in;
1485        return *this;
1486      }
1487    };
1488   
1489  };
1490
1491  template<typename GG>
1492  inline int EdgeSet<GG>::id(Node v) const { return G.id(v); }
1493
1494/// @} 
1495
1496} //namespace hugo
1497
1498#endif //HUGO_LIST_GRAPH_H
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