COIN-OR::LEMON - Graph Library

source: lemon-1.2/lemon/static_graph.h @ 778:a143f19f465b

Last change on this file since 778:a143f19f465b was 778:a143f19f465b, checked in by Peter Kovacs <kpeter@…>, 10 years ago

Make some graph member functions static (#311, #68)

File size: 11.7 KB
Line 
1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2008
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_STATIC_GRAPH_H
20#define LEMON_STATIC_GRAPH_H
21
22///\ingroup graphs
23///\file
24///\brief StaticDigraph class.
25
26#include <lemon/core.h>
27#include <lemon/bits/graph_extender.h>
28
29namespace lemon {
30
31  class StaticDigraphBase {
32  public:
33
34    StaticDigraphBase()
35      : built(false), node_num(0), arc_num(0),
36        node_first_out(NULL), node_first_in(NULL),
37        arc_source(NULL), arc_target(NULL),
38        arc_next_in(NULL), arc_next_out(NULL) {}
39   
40    ~StaticDigraphBase() {
41      if (built) {
42        delete[] node_first_out;
43        delete[] node_first_in;
44        delete[] arc_source;
45        delete[] arc_target;
46        delete[] arc_next_out;
47        delete[] arc_next_in;
48      }
49    }
50
51    class Node {
52      friend class StaticDigraphBase;
53    protected:
54      int id;
55      Node(int _id) : id(_id) {}
56    public:
57      Node() {}
58      Node (Invalid) : id(-1) {}
59      bool operator==(const Node& node) const { return id == node.id; }
60      bool operator!=(const Node& node) const { return id != node.id; }
61      bool operator<(const Node& node) const { return id < node.id; }
62    };
63
64    class Arc {
65      friend class StaticDigraphBase;     
66    protected:
67      int id;
68      Arc(int _id) : id(_id) {}
69    public:
70      Arc() { }
71      Arc (Invalid) : id(-1) {}
72      bool operator==(const Arc& arc) const { return id == arc.id; }
73      bool operator!=(const Arc& arc) const { return id != arc.id; }
74      bool operator<(const Arc& arc) const { return id < arc.id; }
75    };
76
77    Node source(const Arc& e) const { return Node(arc_source[e.id]); }
78    Node target(const Arc& e) const { return Node(arc_target[e.id]); }
79
80    void first(Node& n) const { n.id = node_num - 1; }
81    static void next(Node& n) { --n.id; }
82
83    void first(Arc& e) const { e.id = arc_num - 1; }
84    static void next(Arc& e) { --e.id; }
85
86    void firstOut(Arc& e, const Node& n) const {
87      e.id = node_first_out[n.id] != node_first_out[n.id + 1] ?
88        node_first_out[n.id] : -1;
89    }
90    void nextOut(Arc& e) const { e.id = arc_next_out[e.id]; }
91
92    void firstIn(Arc& e, const Node& n) const { e.id = node_first_in[n.id]; }
93    void nextIn(Arc& e) const { e.id = arc_next_in[e.id]; }
94
95    static int id(const Node& n) { return n.id; }
96    static Node nodeFromId(int id) { return Node(id); }
97    int maxNodeId() const { return node_num - 1; }
98
99    static int id(const Arc& e) { return e.id; }
100    static Arc arcFromId(int id) { return Arc(id); }
101    int maxArcId() const { return arc_num - 1; }
102
103    typedef True NodeNumTag;
104    typedef True ArcNumTag;
105
106    int nodeNum() const { return node_num; }
107    int arcNum() const { return arc_num; }
108
109  private:
110
111    template <typename Digraph, typename NodeRefMap>
112    class ArcLess {
113    public:
114      typedef typename Digraph::Arc Arc;
115
116      ArcLess(const Digraph &_graph, const NodeRefMap& _nodeRef)
117        : digraph(_graph), nodeRef(_nodeRef) {}
118     
119      bool operator()(const Arc& left, const Arc& right) const {
120        return nodeRef[digraph.target(left)] < nodeRef[digraph.target(right)];
121      }
122    private:
123      const Digraph& digraph;
124      const NodeRefMap& nodeRef;
125    };
126   
127  public:
128
129    typedef True BuildTag;
130   
131    void clear() {
132      if (built) {
133        delete[] node_first_out;
134        delete[] node_first_in;
135        delete[] arc_source;
136        delete[] arc_target;
137        delete[] arc_next_out;
138        delete[] arc_next_in;
139      }
140      built = false;
141      node_num = 0;
142      arc_num = 0;
143    }
144   
145    template <typename Digraph, typename NodeRefMap, typename ArcRefMap>
146    void build(const Digraph& digraph, NodeRefMap& nodeRef, ArcRefMap& arcRef) {
147      typedef typename Digraph::Node GNode;
148      typedef typename Digraph::Arc GArc;
149
150      built = true;
151
152      node_num = countNodes(digraph);
153      arc_num = countArcs(digraph);
154
155      node_first_out = new int[node_num + 1];
156      node_first_in = new int[node_num];
157
158      arc_source = new int[arc_num];
159      arc_target = new int[arc_num];
160      arc_next_out = new int[arc_num];
161      arc_next_in = new int[arc_num];
162
163      int node_index = 0;
164      for (typename Digraph::NodeIt n(digraph); n != INVALID; ++n) {
165        nodeRef[n] = Node(node_index);
166        node_first_in[node_index] = -1;
167        ++node_index;
168      }
169
170      ArcLess<Digraph, NodeRefMap> arcLess(digraph, nodeRef);
171
172      int arc_index = 0;
173      for (typename Digraph::NodeIt n(digraph); n != INVALID; ++n) {
174        int source = nodeRef[n].id;
175        std::vector<GArc> arcs;
176        for (typename Digraph::OutArcIt e(digraph, n); e != INVALID; ++e) {
177          arcs.push_back(e);
178        }
179        if (!arcs.empty()) {
180          node_first_out[source] = arc_index;
181          std::sort(arcs.begin(), arcs.end(), arcLess);
182          for (typename std::vector<GArc>::iterator it = arcs.begin();
183               it != arcs.end(); ++it) {
184            int target = nodeRef[digraph.target(*it)].id;
185            arcRef[*it] = Arc(arc_index);
186            arc_source[arc_index] = source;
187            arc_target[arc_index] = target;
188            arc_next_in[arc_index] = node_first_in[target];
189            node_first_in[target] = arc_index;
190            arc_next_out[arc_index] = arc_index + 1;
191            ++arc_index;
192          }
193          arc_next_out[arc_index - 1] = -1;
194        } else {
195          node_first_out[source] = arc_index;
196        }
197      }
198      node_first_out[node_num] = arc_num;
199    }
200
201  protected:
202
203    void fastFirstOut(Arc& e, const Node& n) const {
204      e.id = node_first_out[n.id];
205    }
206
207    static void fastNextOut(Arc& e) {
208      ++e.id;
209    }
210    void fastLastOut(Arc& e, const Node& n) const {
211      e.id = node_first_out[n.id + 1];
212    }
213
214  protected:
215    bool built;
216    int node_num;
217    int arc_num;
218    int *node_first_out;
219    int *node_first_in;
220    int *arc_source;
221    int *arc_target;
222    int *arc_next_in;
223    int *arc_next_out;
224  };
225
226  typedef DigraphExtender<StaticDigraphBase> ExtendedStaticDigraphBase;
227
228
229  /// \ingroup graphs
230  ///
231  /// \brief A static directed graph class.
232  ///
233  /// \ref StaticDigraph is a highly efficient digraph implementation,
234  /// but it is fully static.
235  /// It stores only two \c int values for each node and only four \c int
236  /// values for each arc. Moreover it provides faster item iteration than
237  /// \ref ListDigraph and \ref SmartDigraph, especially using \c OutArcIt
238  /// iterators, since its arcs are stored in an appropriate order.
239  /// However it only provides build() and clear() functions and does not
240  /// support any other modification of the digraph.
241  ///
242  /// Since this digraph structure is completely static, its nodes and arcs
243  /// can be indexed with integers from the ranges <tt>[0..nodeNum()-1]</tt>
244  /// and <tt>[0..arcNum()-1]</tt>, respectively.
245  /// The index of an item is the same as its ID, it can be obtained
246  /// using the corresponding \ref index() or \ref concepts::Digraph::id()
247  /// "id()" function. A node or arc with a certain index can be obtained
248  /// using node() or arc().
249  ///
250  /// This type fully conforms to the \ref concepts::Digraph "Digraph concept".
251  /// Most of its member functions and nested classes are documented
252  /// only in the concept class.
253  ///
254  /// \sa concepts::Digraph
255  class StaticDigraph : public ExtendedStaticDigraphBase {
256  public:
257
258    typedef ExtendedStaticDigraphBase Parent;
259 
260  public:
261 
262    /// \brief Constructor
263    ///
264    /// Default constructor.
265    StaticDigraph() : Parent() {}
266
267    /// \brief The node with the given index.
268    ///
269    /// This function returns the node with the given index.
270    /// \sa index()
271    static Node node(int ix) { return Parent::nodeFromId(ix); }
272
273    /// \brief The arc with the given index.
274    ///
275    /// This function returns the arc with the given index.
276    /// \sa index()
277    static Arc arc(int ix) { return Parent::arcFromId(ix); }
278
279    /// \brief The index of the given node.
280    ///
281    /// This function returns the index of the the given node.
282    /// \sa node()
283    static int index(Node node) { return Parent::id(node); }
284
285    /// \brief The index of the given arc.
286    ///
287    /// This function returns the index of the the given arc.
288    /// \sa arc()
289    static int index(Arc arc) { return Parent::id(arc); }
290
291    /// \brief Number of nodes.
292    ///
293    /// This function returns the number of nodes.
294    int nodeNum() const { return node_num; }
295
296    /// \brief Number of arcs.
297    ///
298    /// This function returns the number of arcs.
299    int arcNum() const { return arc_num; }
300
301    /// \brief Build the digraph copying another digraph.
302    ///
303    /// This function builds the digraph copying another digraph of any
304    /// kind. It can be called more than once, but in such case, the whole
305    /// structure and all maps will be cleared and rebuilt.
306    ///
307    /// This method also makes possible to copy a digraph to a StaticDigraph
308    /// structure using \ref DigraphCopy.
309    ///
310    /// \param digraph An existing digraph to be copied.
311    /// \param nodeRef The node references will be copied into this map.
312    /// Its key type must be \c Digraph::Node and its value type must be
313    /// \c StaticDigraph::Node.
314    /// It must conform to the \ref concepts::ReadWriteMap "ReadWriteMap"
315    /// concept.
316    /// \param arcRef The arc references will be copied into this map.
317    /// Its key type must be \c Digraph::Arc and its value type must be
318    /// \c StaticDigraph::Arc.
319    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
320    ///
321    /// \note If you do not need the arc references, then you could use
322    /// \ref NullMap for the last parameter. However the node references
323    /// are required by the function itself, thus they must be readable
324    /// from the map.
325    template <typename Digraph, typename NodeRefMap, typename ArcRefMap>
326    void build(const Digraph& digraph, NodeRefMap& nodeRef, ArcRefMap& arcRef) {
327      if (built) Parent::clear();
328      Parent::build(digraph, nodeRef, arcRef);
329    }
330 
331    /// \brief Clear the digraph.
332    ///
333    /// This function erases all nodes and arcs from the digraph.
334    void clear() {
335      Parent::clear();
336    }
337
338  protected:
339
340    using Parent::fastFirstOut;
341    using Parent::fastNextOut;
342    using Parent::fastLastOut;
343   
344  public:
345
346    class OutArcIt : public Arc {
347    public:
348
349      OutArcIt() { }
350
351      OutArcIt(Invalid i) : Arc(i) { }
352
353      OutArcIt(const StaticDigraph& digraph, const Node& node) {
354        digraph.fastFirstOut(*this, node);
355        digraph.fastLastOut(last, node);
356        if (last == *this) *this = INVALID;
357      }
358
359      OutArcIt(const StaticDigraph& digraph, const Arc& arc) : Arc(arc) {
360        if (arc != INVALID) {
361          digraph.fastLastOut(last, digraph.source(arc));
362        }
363      }
364
365      OutArcIt& operator++() {
366        StaticDigraph::fastNextOut(*this);
367        if (last == *this) *this = INVALID;
368        return *this;
369      }
370
371    private:
372      Arc last;
373    };
374
375    Node baseNode(const OutArcIt &arc) const {
376      return Parent::source(static_cast<const Arc&>(arc));
377    }
378
379    Node runningNode(const OutArcIt &arc) const {
380      return Parent::target(static_cast<const Arc&>(arc));
381    }
382
383    Node baseNode(const InArcIt &arc) const {
384      return Parent::target(static_cast<const Arc&>(arc));
385    }
386
387    Node runningNode(const InArcIt &arc) const {
388      return Parent::source(static_cast<const Arc&>(arc));
389    }
390
391  };
392
393}
394
395#endif
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