COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/lemon/list_graph.h @ 1010:072bddac076e

Last change on this file since 1010:072bddac076e was 1010:072bddac076e, checked in by Alpar Juttner, 16 years ago

reverseEdge() and contract() member-functions added.

File size: 9.9 KB
Line 
1/* -*- C++ -*-
2 * src/lemon/list_graph.h - Part of LEMON, 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 LEMON_LIST_GRAPH_H
18#define LEMON_LIST_GRAPH_H
19
20///\ingroup graphs
21///\file
22///\brief ListGraph, SymListGraph, NodeSet and EdgeSet classes.
23
24#include <lemon/erasable_graph_extender.h>
25#include <lemon/clearable_graph_extender.h>
26#include <lemon/extendable_graph_extender.h>
27
28#include <lemon/iterable_graph_extender.h>
29
30#include <lemon/alteration_observer_registry.h>
31
32#include <lemon/default_map.h>
33
34
35namespace lemon {
36
37  class ListGraphBase {
38
39  protected:
40    struct NodeT {
41      int first_in,first_out;
42      int prev, next;
43    };
44 
45    struct EdgeT {
46      int target, source;
47      int prev_in, prev_out;
48      int next_in, next_out;
49    };
50
51    std::vector<NodeT> nodes;
52
53    int first_node;
54
55    int first_free_node;
56
57    std::vector<EdgeT> edges;
58
59    int first_free_edge;
60   
61  public:
62   
63    typedef ListGraphBase Graph;
64   
65    class Node {
66      friend class ListGraphBase;
67    protected:
68
69      int id;
70      Node(int pid) { id = pid;}
71
72    public:
73      Node() {}
74      Node (Invalid) { id = -1; }
75      bool operator==(const Node& node) const {return id == node.id;}
76      bool operator!=(const Node& node) const {return id != node.id;}
77      bool operator<(const Node& node) const {return id < node.id;}
78    };
79
80    class Edge {
81      friend class ListGraphBase;
82    protected:
83
84      int id;
85      Edge(int pid) { id = pid;}
86
87    public:
88      Edge() {}
89      Edge (Invalid) { id = -1; }
90      bool operator==(const Edge& edge) const {return id == edge.id;}
91      bool operator!=(const Edge& edge) const {return id != edge.id;}
92      bool operator<(const Edge& edge) const {return id < edge.id;}
93    };
94
95
96
97    ListGraphBase()
98      : nodes(), first_node(-1),
99        first_free_node(-1), edges(), first_free_edge(-1) {}
100
101   
102    /// Maximum node ID.
103   
104    /// Maximum node ID.
105    ///\sa id(Node)
106    int maxId(Node = INVALID) const { return nodes.size()-1; }
107
108    /// Maximum edge ID.
109   
110    /// Maximum edge ID.
111    ///\sa id(Edge)
112    int maxId(Edge = INVALID) const { return edges.size()-1; }
113
114    Node source(Edge e) const { return edges[e.id].source; }
115    Node target(Edge e) const { return edges[e.id].target; }
116
117
118    void first(Node& node) const {
119      node.id = first_node;
120    }
121
122    void next(Node& node) const {
123      node.id = nodes[node.id].next;
124    }
125
126
127    void first(Edge& e) const {
128      int n;
129      for(n = first_node;
130          n!=-1 && nodes[n].first_in == -1;
131          n = nodes[n].next);
132      e.id = (n == -1) ? -1 : nodes[n].first_in;
133    }
134
135    void next(Edge& edge) const {
136      if (edges[edge.id].next_in != -1) {
137        edge.id = edges[edge.id].next_in;
138      } else {
139        int n;
140        for(n = nodes[edges[edge.id].target].next;
141          n!=-1 && nodes[n].first_in == -1;
142          n = nodes[n].next);
143        edge.id = (n == -1) ? -1 : nodes[n].first_in;
144      }     
145    }
146
147    void firstOut(Edge &e, const Node& v) const {
148      e.id = nodes[v.id].first_out;
149    }
150    void nextOut(Edge &e) const {
151      e.id=edges[e.id].next_out;
152    }
153
154    void firstIn(Edge &e, const Node& v) const {
155      e.id = nodes[v.id].first_in;
156    }
157    void nextIn(Edge &e) const {
158      e.id=edges[e.id].next_in;
159    }
160
161   
162    static int id(Node v) { return v.id; }
163    static int id(Edge e) { return e.id; }
164
165    /// Adds a new node to the graph.
166
167    /// \warning It adds the new node to the front of the list.
168    /// (i.e. the lastly added node becomes the first.)
169    Node addNode() {     
170      int n;
171     
172      if(first_free_node==-1) {
173        n = nodes.size();
174        nodes.push_back(NodeT());
175      } else {
176        n = first_free_node;
177        first_free_node = nodes[n].next;
178      }
179     
180      nodes[n].next = first_node;
181      if(first_node != -1) nodes[first_node].prev = n;
182      first_node = n;
183      nodes[n].prev = -1;
184     
185      nodes[n].first_in = nodes[n].first_out = -1;
186     
187      return Node(n);
188    }
189   
190    Edge addEdge(Node u, Node v) {
191      int n;     
192
193      if (first_free_edge == -1) {
194        n = edges.size();
195        edges.push_back(EdgeT());
196      } else {
197        n = first_free_edge;
198        first_free_edge = edges[n].next_in;
199      }
200     
201      edges[n].source = u.id;
202      edges[n].target = v.id;
203
204      edges[n].next_out = nodes[u.id].first_out;
205      if(nodes[u.id].first_out != -1) {
206        edges[nodes[u.id].first_out].prev_out = n;
207      }
208     
209      edges[n].next_in = nodes[v.id].first_in;
210      if(nodes[v.id].first_in != -1) {
211        edges[nodes[v.id].first_in].prev_in = n;
212      }
213     
214      edges[n].prev_in = edges[n].prev_out = -1;
215       
216      nodes[u.id].first_out = nodes[v.id].first_in = n;
217
218      return Edge(n);
219    }
220   
221    void erase(const Node& node) {
222      int n = node.id;
223     
224      if(nodes[n].next != -1) {
225        nodes[nodes[n].next].prev = nodes[n].prev;
226      }
227     
228      if(nodes[n].prev != -1) {
229        nodes[nodes[n].prev].next = nodes[n].next;
230      } else {
231        first_node = nodes[n].next;
232      }
233     
234      nodes[n].next = first_free_node;
235      first_free_node = n;
236
237    }
238   
239    void erase(const Edge& edge) {
240      int n = edge.id;
241     
242      if(edges[n].next_in!=-1) {
243        edges[edges[n].next_in].prev_in = edges[n].prev_in;
244      }
245
246      if(edges[n].prev_in!=-1) {
247        edges[edges[n].prev_in].next_in = edges[n].next_in;
248      } else {
249        nodes[edges[n].target].first_in = edges[n].next_in;
250      }
251
252     
253      if(edges[n].next_out!=-1) {
254        edges[edges[n].next_out].prev_out = edges[n].prev_out;
255      }
256
257      if(edges[n].prev_out!=-1) {
258        edges[edges[n].prev_out].next_out = edges[n].next_out;
259      } else {
260        nodes[edges[n].source].first_out = edges[n].next_out;
261      }
262     
263      edges[n].next_in = first_free_edge;
264      first_free_edge = n;     
265
266    }
267
268    void clear() {
269      edges.clear();
270      nodes.clear();
271      first_node = first_free_node = first_free_edge = -1;
272    }
273
274  protected:
275    void _moveTarget(Edge e, Node n)
276    {
277      if(edges[e.id].next_in != -1)
278        edges[edges[e.id].next_in].prev_in = edges[e.id].prev_in;
279      if(edges[e.id].prev_in != -1)
280        edges[edges[e.id].prev_in].next_in = edges[e.id].next_in;
281      else nodes[edges[e.id].target].first_in = edges[e.id].next_in;
282      edges[e.id].target = n.id;
283      edges[e.id].prev_in = -1;
284      edges[e.id].next_in = nodes[n.id].first_in;
285      nodes[n.id].first_in = e.id;
286    }
287    void _moveSource(Edge e, Node n)
288    {
289      if(edges[e.id].next_out != -1)
290        edges[edges[e.id].next_out].prev_out = edges[e.id].prev_out;
291      if(edges[e.id].prev_out != -1)
292        edges[edges[e.id].prev_out].next_out = edges[e.id].next_out;
293      else nodes[edges[e.id].source].first_out = edges[e.id].next_out;
294      edges[e.id].source = n.id;
295      edges[e.id].prev_out = -1;
296      edges[e.id].next_out = nodes[n.id].first_out;
297      nodes[n.id].first_out = e.id;
298    }
299
300  };
301
302  typedef AlterableGraphExtender<ListGraphBase> AlterableListGraphBase;
303  typedef IterableGraphExtender<AlterableListGraphBase> IterableListGraphBase;
304  typedef DefaultMappableGraphExtender<IterableListGraphBase> MappableListGraphBase;
305  typedef ExtendableGraphExtender<MappableListGraphBase> ExtendableListGraphBase;
306  typedef ClearableGraphExtender<ExtendableListGraphBase> ClearableListGraphBase;
307  typedef ErasableGraphExtender<ClearableListGraphBase> ErasableListGraphBase;
308
309/// \addtogroup graphs
310/// @{
311
312  ///A list graph class.
313
314  ///This is a simple and fast erasable graph implementation.
315  ///
316  ///It addition that it conforms to the
317  ///\ref concept::ErasableGraph "ErasableGraph" concept,
318  ///it also provides several additional useful extra functionalities.
319  ///\sa concept::ErasableGraph.
320
321  class ListGraph : public ErasableListGraphBase
322  {
323  public:
324    /// Moves the target of \c e to \c n
325
326    /// Moves the target of \c e to \c n
327    ///
328    ///\note The <tt>Edge</tt>'s and <tt>OutEdge</tt>'s
329    ///referencing the moved edge remain
330    ///valid. However <tt>InEdge</tt>'s are invalidated.
331    void moveTarget(Edge e, Node n) { _moveTarget(e,n); }
332    /// Moves the source of \c e to \c n
333
334    /// Moves the source of \c e to \c n
335    ///
336    ///\note The <tt>Edge</tt>'s and <tt>InEdge</tt>'s
337    ///referencing the moved edge remain
338    ///valid. However <tt>OutEdge</tt>'s are invalidated.
339    void moveSource(Edge e, Node n) { _moveSource(e,n); }
340
341    /// Invert the direction of an edge.
342
343    ///\note The <tt>Edge</tt>'s
344    ///referencing the moved edge remain
345    ///valid. However <tt>OutEdge</tt>'s  and <tt>InEdge</tt>'s are invalidated.
346    void reverseEdge(Edge e) {
347      Node t=target(e);
348      _moveTarget(e,source(e));
349      _moveSource(e,t);
350    }
351
352    ///Using this it possible to avoid the superfluous memory allocation.
353
354    ///Using this it possible to avoid the superfluous memory allocation.
355    ///\todo more docs...
356    void reserveEdge(int n) { edges.reserve(n); };
357
358    ///Contract two nodes.
359
360    ///This function contracts two nodes.
361    ///
362    ///Node \p b will be removed but instead of deleting
363    ///its neighboring edges, they will be joined to \p a.
364    ///The last parameter \p r controls whether to remove loops. \c true
365    ///means that loops will be removed.
366    ///
367    ///\note The <tt>Edge</tt>s
368    ///referencing the moved edge remain
369    ///valid. However <tt>InEdge</tt>'s and <tt>OutEdge</tt>'s
370    ///may be invalidated.
371    void contract(Node a,Node b,bool r=true)
372    {
373      for(OutEdgeIt e(*this,b);e!=INVALID;) {
374        OutEdgeIt f=e;
375        ++f;
376        if(r && target(e)==a) erase(e);
377        else moveSource(e,b);
378        e=f;
379      }
380      for(InEdgeIt e(*this,b);e!=INVALID;) {
381        InEdgeIt f=e;
382        ++f;
383        if(r && source(e)==a) erase(e);
384        else moveTarget(e,b);
385        e=f;
386      }
387      erase(b);
388    }
389  };
390 
391  /// @} 
392} //namespace lemon
393 
394
395#endif
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