Generated on Sat Nov 9 2013 19:18:31 for Gecode by doxygen 1.8.4
dfs.hh
Go to the documentation of this file.
1 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2 /*
3  * Main authors:
4  * Christian Schulte <schulte@gecode.org>
5  *
6  * Copyright:
7  * Christian Schulte, 2009
8  *
9  * Last modified:
10  * $Date: 2013-07-12 18:20:11 +0200 (Fri, 12 Jul 2013) $ by $Author: schulte $
11  * $Revision: 13877 $
12  *
13  * This file is part of Gecode, the generic constraint
14  * development environment:
15  * http://www.gecode.org
16  *
17  * Permission is hereby granted, free of charge, to any person obtaining
18  * a copy of this software and associated documentation files (the
19  * "Software"), to deal in the Software without restriction, including
20  * without limitation the rights to use, copy, modify, merge, publish,
21  * distribute, sublicense, and/or sell copies of the Software, and to
22  * permit persons to whom the Software is furnished to do so, subject to
23  * the following conditions:
24  *
25  * The above copyright notice and this permission notice shall be
26  * included in all copies or substantial portions of the Software.
27  *
28  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
29  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
30  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
31  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
32  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
33  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
34  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
35  *
36  */
37 
38 #ifndef __GECODE_SEARCH_SEQUENTIAL_DFS_HH__
39 #define __GECODE_SEARCH_SEQUENTIAL_DFS_HH__
40 
41 #include <gecode/search.hh>
42 #include <gecode/search/support.hh>
43 #include <gecode/search/worker.hh>
45 
46 namespace Gecode { namespace Search { namespace Sequential {
47 
49  class DFS : public Worker {
50  private:
52  Options opt;
54  Path path;
56  Space* cur;
58  unsigned int d;
59  public:
61  DFS(Space* s, const Options& o);
63  Space* next(void);
65  Statistics statistics(void) const;
67  void reset(Space* s);
69  NoGoods& nogoods(void);
71  ~DFS(void);
72  };
73 
75  DFS::DFS(Space* s, const Options& o)
76  : opt(o), path(static_cast<int>(opt.nogoods_limit)), d(0) {
77  if ((s == NULL) || (s->status(*this) == SS_FAILED)) {
78  fail++;
79  cur = NULL;
80  if (!opt.clone)
81  delete s;
82  } else {
83  cur = snapshot(s,opt);
84  }
85  }
86 
87  forceinline void
89  delete cur;
90  path.reset();
91  d = 0;
92  if ((s == NULL) || (s->status(*this) == SS_FAILED)) {
93  cur = NULL;
94  } else {
95  cur = s;
96  }
97  Worker::reset();
98  }
99 
101  DFS::nogoods(void) {
102  return path;
103  }
104 
106  DFS::next(void) {
107  start();
108  while (true) {
109  while (cur) {
110  if (stop(opt))
111  return NULL;
112  node++;
113  switch (cur->status(*this)) {
114  case SS_FAILED:
115  fail++;
116  delete cur;
117  cur = NULL;
118  break;
119  case SS_SOLVED:
120  {
121  // Deletes all pending branchers
122  (void) cur->choice();
123  Space* s = cur;
124  cur = NULL;
125  return s;
126  }
127  case SS_BRANCH:
128  {
129  Space* c;
130  if ((d == 0) || (d >= opt.c_d)) {
131  c = cur->clone();
132  d = 1;
133  } else {
134  c = NULL;
135  d++;
136  }
137  const Choice* ch = path.push(*this,cur,c);
138  cur->commit(*ch,0);
139  break;
140  }
141  default:
142  GECODE_NEVER;
143  }
144  }
145  do {
146  if (!path.next())
147  return NULL;
148  cur = path.recompute(d,opt.a_d,*this);
149  } while (cur == NULL);
150  }
151  GECODE_NEVER;
152  return NULL;
153  }
154 
156  DFS::statistics(void) const {
157  return *this;
158  }
159 
160  forceinline
161  DFS::~DFS(void) {
162  delete cur;
163  path.reset();
164  }
165 
166 }}}
167 
168 #endif
169 
170 // STATISTICS: search-sequential