COIN-OR::LEMON - Graph Library

source: lemon-1.0/lemon/concepts/path.h @ 289:d91884dcd572

Last change on this file since 289:d91884dcd572 was 281:e9b4fbe163f5, checked in by Alpar Juttner <alpar@…>, 11 years ago

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1/* -*- mode: C++; indent-tabs-mode: nil; -*-
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///\ingroup concept
20///\file
21///\brief Classes for representing paths in digraphs.
22///
23
24#ifndef LEMON_CONCEPT_PATH_H
25#define LEMON_CONCEPT_PATH_H
26
27#include <lemon/core.h>
28#include <lemon/concept_check.h>
29
30namespace lemon {
31  namespace concepts {
32
33    /// \addtogroup concept
34    /// @{
35
36    /// \brief A skeleton structure for representing directed paths in
37    /// a digraph.
38    ///
39    /// A skeleton structure for representing directed paths in a
40    /// digraph.
41    /// \tparam _Digraph The digraph type in which the path is.
42    ///
43    /// In a sense, the path can be treated as a list of arcs. The
44    /// lemon path type stores just this list. As a consequence it
45    /// cannot enumerate the nodes in the path and the zero length
46    /// paths cannot store the source.
47    ///
48    template <typename _Digraph>
49    class Path {
50    public:
51
52      /// Type of the underlying digraph.
53      typedef _Digraph Digraph;
54      /// Arc type of the underlying digraph.
55      typedef typename Digraph::Arc Arc;
56
57      class ArcIt;
58
59      /// \brief Default constructor
60      Path() {}
61
62      /// \brief Template constructor
63      template <typename CPath>
64      Path(const CPath& cpath) {}
65
66      /// \brief Template assigment
67      template <typename CPath>
68      Path& operator=(const CPath& cpath) {
69        ignore_unused_variable_warning(cpath);
70        return *this;
71      }
72
73      /// Length of the path ie. the number of arcs in the path.
74      int length() const { return 0;}
75
76      /// Returns whether the path is empty.
77      bool empty() const { return true;}
78
79      /// Resets the path to an empty path.
80      void clear() {}
81
82      /// \brief LEMON style iterator for path arcs
83      ///
84      /// This class is used to iterate on the arcs of the paths.
85      class ArcIt {
86      public:
87        /// Default constructor
88        ArcIt() {}
89        /// Invalid constructor
90        ArcIt(Invalid) {}
91        /// Constructor for first arc
92        ArcIt(const Path &) {}
93
94        /// Conversion to Arc
95        operator Arc() const { return INVALID; }
96
97        /// Next arc
98        ArcIt& operator++() {return *this;}
99
100        /// Comparison operator
101        bool operator==(const ArcIt&) const {return true;}
102        /// Comparison operator
103        bool operator!=(const ArcIt&) const {return true;}
104        /// Comparison operator
105        bool operator<(const ArcIt&) const {return false;}
106
107      };
108
109      template <typename _Path>
110      struct Constraints {
111        void constraints() {
112          Path<Digraph> pc;
113          _Path p, pp(pc);
114          int l = p.length();
115          int e = p.empty();
116          p.clear();
117
118          p = pc;
119
120          typename _Path::ArcIt id, ii(INVALID), i(p);
121
122          ++i;
123          typename Digraph::Arc ed = i;
124
125          e = (i == ii);
126          e = (i != ii);
127          e = (i < ii);
128
129          ignore_unused_variable_warning(l);
130          ignore_unused_variable_warning(pp);
131          ignore_unused_variable_warning(e);
132          ignore_unused_variable_warning(id);
133          ignore_unused_variable_warning(ii);
134          ignore_unused_variable_warning(ed);
135        }
136      };
137
138    };
139
140    namespace _path_bits {
141
142      template <typename _Digraph, typename _Path, typename RevPathTag = void>
143      struct PathDumperConstraints {
144        void constraints() {
145          int l = p.length();
146          int e = p.empty();
147
148          typename _Path::ArcIt id, i(p);
149
150          ++i;
151          typename _Digraph::Arc ed = i;
152
153          e = (i == INVALID);
154          e = (i != INVALID);
155
156          ignore_unused_variable_warning(l);
157          ignore_unused_variable_warning(e);
158          ignore_unused_variable_warning(id);
159          ignore_unused_variable_warning(ed);
160        }
161        _Path& p;
162      };
163
164      template <typename _Digraph, typename _Path>
165      struct PathDumperConstraints<
166        _Digraph, _Path,
167        typename enable_if<typename _Path::RevPathTag, void>::type
168      > {
169        void constraints() {
170          int l = p.length();
171          int e = p.empty();
172
173          typename _Path::RevArcIt id, i(p);
174
175          ++i;
176          typename _Digraph::Arc ed = i;
177
178          e = (i == INVALID);
179          e = (i != INVALID);
180
181          ignore_unused_variable_warning(l);
182          ignore_unused_variable_warning(e);
183          ignore_unused_variable_warning(id);
184          ignore_unused_variable_warning(ed);
185        }
186        _Path& p;
187      };
188
189    }
190
191
192    /// \brief A skeleton structure for path dumpers.
193    ///
194    /// A skeleton structure for path dumpers. The path dumpers are
195    /// the generalization of the paths. The path dumpers can
196    /// enumerate the arcs of the path wheter in forward or in
197    /// backward order.  In most time these classes are not used
198    /// directly rather it used to assign a dumped class to a real
199    /// path type.
200    ///
201    /// The main purpose of this concept is that the shortest path
202    /// algorithms can enumerate easily the arcs in reverse order.
203    /// If we would like to give back a real path from these
204    /// algorithms then we should create a temporarly path object. In
205    /// LEMON such algorithms gives back a path dumper what can
206    /// assigned to a real path and the dumpers can be implemented as
207    /// an adaptor class to the predecessor map.
208
209    /// \tparam _Digraph  The digraph type in which the path is.
210    ///
211    /// The paths can be constructed from any path type by a
212    /// template constructor or a template assignment operator.
213    ///
214    template <typename _Digraph>
215    class PathDumper {
216    public:
217
218      /// Type of the underlying digraph.
219      typedef _Digraph Digraph;
220      /// Arc type of the underlying digraph.
221      typedef typename Digraph::Arc Arc;
222
223      /// Length of the path ie. the number of arcs in the path.
224      int length() const { return 0;}
225
226      /// Returns whether the path is empty.
227      bool empty() const { return true;}
228
229      /// \brief Forward or reverse dumping
230      ///
231      /// If the RevPathTag is defined and true then reverse dumping
232      /// is provided in the path dumper. In this case instead of the
233      /// ArcIt the RevArcIt iterator should be implemented in the
234      /// dumper.
235      typedef False RevPathTag;
236
237      /// \brief LEMON style iterator for path arcs
238      ///
239      /// This class is used to iterate on the arcs of the paths.
240      class ArcIt {
241      public:
242        /// Default constructor
243        ArcIt() {}
244        /// Invalid constructor
245        ArcIt(Invalid) {}
246        /// Constructor for first arc
247        ArcIt(const PathDumper&) {}
248
249        /// Conversion to Arc
250        operator Arc() const { return INVALID; }
251
252        /// Next arc
253        ArcIt& operator++() {return *this;}
254
255        /// Comparison operator
256        bool operator==(const ArcIt&) const {return true;}
257        /// Comparison operator
258        bool operator!=(const ArcIt&) const {return true;}
259        /// Comparison operator
260        bool operator<(const ArcIt&) const {return false;}
261
262      };
263
264      /// \brief LEMON style iterator for path arcs
265      ///
266      /// This class is used to iterate on the arcs of the paths in
267      /// reverse direction.
268      class RevArcIt {
269      public:
270        /// Default constructor
271        RevArcIt() {}
272        /// Invalid constructor
273        RevArcIt(Invalid) {}
274        /// Constructor for first arc
275        RevArcIt(const PathDumper &) {}
276
277        /// Conversion to Arc
278        operator Arc() const { return INVALID; }
279
280        /// Next arc
281        RevArcIt& operator++() {return *this;}
282
283        /// Comparison operator
284        bool operator==(const RevArcIt&) const {return true;}
285        /// Comparison operator
286        bool operator!=(const RevArcIt&) const {return true;}
287        /// Comparison operator
288        bool operator<(const RevArcIt&) const {return false;}
289
290      };
291
292      template <typename _Path>
293      struct Constraints {
294        void constraints() {
295          function_requires<_path_bits::
296            PathDumperConstraints<Digraph, _Path> >();
297        }
298      };
299
300    };
301
302
303    ///@}
304  }
305
306} // namespace lemon
307
308#endif // LEMON_CONCEPT_PATH_H
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