COIN-OR::LEMON - Graph Library

source: lemon/lemon/path_utils.h @ 97:ee1324c91288

Last change on this file since 97:ee1324c91288 was 97:ee1324c91288, checked in by Alpar Juttner <alpar@…>, 11 years ago

Doc improvements

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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///\ingroup paths
20///\file
21///\brief Classes for representing paths in digraphs.
22///
23
24#ifndef LEMON_PATH_UTILS_H
25#define LEMON_PATH_UTILS_H
26
27#include <lemon/concepts/path.h>
28
29namespace lemon {
30
31  namespace _path_bits {
32
33    template <typename Path, typename Enable = void>
34    struct RevTagIndicator {
35      static const bool value = false;
36    };
37
38    template <typename Digraph>
39    struct RevTagIndicator<
40      Digraph,
41      typename enable_if<typename Digraph::RevTag, void>::type
42    > {
43      static const bool value = true;
44    };
45
46    template <typename Target, typename Source,
47              typename BuildEnable = void, typename RevEnable = void>
48    struct PathCopySelector {
49      static void copy(Target& target, const Source& source) {
50        target.clear();
51        for (typename Source::ArcIt it(source); it != INVALID; ++it) {
52          target.addBack(it);
53        }
54      }
55    };
56
57    template <typename Target, typename Source, typename BuildEnable>
58    struct PathCopySelector<
59      Target, Source, BuildEnable,
60      typename enable_if<typename Source::RevPathTag, void>::type> {
61      static void copy(Target& target, const Source& source) {
62        target.clear();
63        for (typename Source::RevArcIt it(source); it != INVALID; ++it) {
64          target.addFront(it);
65        }
66      }
67    };
68
69    template <typename Target, typename Source, typename RevEnable>
70    struct PathCopySelector<
71      Target, Source,
72      typename enable_if<typename Target::BuildTag, void>::type, RevEnable> {
73      static void copy(Target& target, const Source& source) {
74        target.clear();
75        target.build(source);
76      }
77    };
78
79    template <typename Target, typename Source>
80    struct PathCopySelector<
81      Target, Source,
82      typename enable_if<typename Target::BuildTag, void>::type,
83      typename enable_if<typename Source::RevPathTag, void>::type> {
84      static void copy(Target& target, const Source& source) {
85        target.clear();
86        target.buildRev(source);
87      }
88    };
89
90  }
91
92
93  /// \brief Make a copy of a path.
94  ///
95  ///  This function makes a copy of a path.
96  template <typename Target, typename Source>
97  void copyPath(Target& target, const Source& source) {
98    checkConcept<concepts::PathDumper<typename Source::Digraph>, Source>();
99    _path_bits::PathCopySelector<Target, Source>::copy(target, source);
100  }
101
102  /// \brief Check the consistency of a path.
103  ///
104  /// This function checks that the target of each arc is the same
105  /// as the source of the next one.
106  ///
107  template <typename Digraph, typename Path>
108  bool checkPath(const Digraph& digraph, const Path& path) {
109    typename Path::ArcIt it(path);
110    if (it == INVALID) return true;
111    typename Digraph::Node node = digraph.target(it);
112    ++it;
113    while (it != INVALID) {
114      if (digraph.source(it) != node) return false;
115      node = digraph.target(it);
116      ++it;
117    }
118    return true;
119  }
120
121  /// \brief The source of a path
122  ///
123  /// This function returns the source of the given path.
124  template <typename Digraph, typename Path>
125  typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) {
126    return digraph.source(path.front());
127  }
128
129  /// \brief The target of a path
130  ///
131  /// This function returns the target of the given path.
132  template <typename Digraph, typename Path>
133  typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) {
134    return digraph.target(path.back());
135  }
136
137  /// \brief Class which helps to iterate through the nodes of a path
138  ///
139  /// In a sense, the path can be treated as a list of arcs. The
140  /// lemon path type stores only this list. As a consequence, it
141  /// cannot enumerate the nodes in the path and the zero length paths
142  /// cannot have a source node.
143  ///
144  /// This class implements the node iterator of a path structure. To
145  /// provide this feature, the underlying digraph should be passed to
146  /// the constructor of the iterator.
147  template <typename Path>
148  class PathNodeIt {
149  private:
150    const typename Path::Digraph *_digraph;
151    typename Path::ArcIt _it;
152    typename Path::Digraph::Node _nd;
153
154  public:
155
156    typedef typename Path::Digraph Digraph;
157    typedef typename Digraph::Node Node;
158   
159    /// Default constructor
160    PathNodeIt() {}
161    /// Invalid constructor
162    PathNodeIt(Invalid)
163      : _digraph(0), _it(INVALID), _nd(INVALID) {}
164    /// Constructor
165    PathNodeIt(const Digraph& digraph, const Path& path)
166      : _digraph(&digraph), _it(path) {
167      _nd = (_it != INVALID ? _digraph->source(_it) : INVALID);
168    }
169    /// Constructor
170    PathNodeIt(const Digraph& digraph, const Path& path, const Node& src)
171      : _digraph(&digraph), _it(path), _nd(src) {}
172
173    ///Conversion to Digraph::Node
174    operator Node() const {
175      return _nd;
176    }
177
178    /// Next node
179    PathNodeIt& operator++() {
180      if (_it == INVALID) _nd = INVALID;
181      else {
182        _nd = _digraph->target(_it);
183        ++_it;
184      }
185      return *this;
186    }
187
188    /// Comparison operator
189    bool operator==(const PathNodeIt& n) const {
190      return _it == n._it && _nd == n._nd;
191    }
192    /// Comparison operator
193    bool operator!=(const PathNodeIt& n) const {
194      return _it != n._it || _nd != n._nd;
195    }
196    /// Comparison operator
197    bool operator<(const PathNodeIt& n) const {
198      return (_it < n._it && _nd != INVALID);
199    }
200   
201  };
202 
203}
204
205#endif
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