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dekker.one
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, 2012
8 *
9 * This file is part of Gecode, the generic constraint
10 * development environment:
11 * http://www.gecode.org
12 *
13 * Permission is hereby granted, free of charge, to any person obtaining
14 * a copy of this software and associated documentation files (the
15 * "Software"), to deal in the Software without restriction, including
16 * without limitation the rights to use, copy, modify, merge, publish,
17 * distribute, sublicense, and/or sell copies of the Software, and to
18 * permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
20 *
21 * The above copyright notice and this permission notice shall be
22 * included in all copies or substantial portions of the Software.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
28 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
29 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
30 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
31 *
32 */
33
34namespace Gecode {
35
36 /**
37 * \defgroup TaskBranchView Generic brancher based on view selection
38 *
39 * Implements view-based brancher for an array of views and value.
40 * \ingroup TaskActor
41 */
42 //@{
43 /// Position information
44 class Pos {
45 public:
46 /// Position of view
47 const int pos;
48 /// Create position information
49 Pos(int p);
50 /// Create position information
51 Pos(const Pos& p);
52 };
53
54 /// %Choices storing position
55 class GECODE_VTABLE_EXPORT PosChoice : public Choice {
56 private:
57 /// Position information
58 const Pos _pos;
59 protected:
60 /// Initialize
61 PosChoice(const PosChoice& c);
62 public:
63 /// Initialize choice for brancher \a b, number of alternatives \a a, and position \a p
64 PosChoice(const Brancher& b, unsigned int a, const Pos& p);
65 /// Return position in array
66 const Pos& pos(void) const;
67 /// Archive into \a e
68 virtual void archive(Archive& e) const;
69 };
70
71 /**
72 * \brief Generic brancher by view selection
73 *
74 * Defined for views of type \a View and \a n view selectors for
75 * tie-breaking.
76 */
77 template<class View, class Filter, int n>
78 class ViewBrancher : public Brancher {
79 protected:
80 /// The corresponding variable
81 typedef typename View::VarType Var;
82 /// Views to branch on
83 ViewArray<View> x;
84 /// Unassigned views start at x[start]
85 mutable int start;
86 /// View selection objects
87 ViewSel<View>* vs[n];
88 /// Filter function
89 Filter f;
90 /// Return position information
91 Pos pos(Space& home);
92 /// Return view according to position information \a p
93 View view(const Pos& p) const;
94 /// Constructor for cloning \a b
95 ViewBrancher(Space& home, ViewBrancher<View,Filter,n>& b);
96 /// Constructor for creation
97 ViewBrancher(Home home, ViewArray<View>& x, ViewSel<View>* vs[n],
98 BranchFilter<Var> bf);
99 public:
100 /// Check status of brancher, return true if alternatives left
101 virtual bool status(const Space& home) const;
102 /// Delete brancher and return its size
103 virtual size_t dispose(Space& home);
104 };
105
106 //@}
107
108
109 /*
110 * Position information
111 *
112 */
113 forceinline
114 Pos::Pos(int p) : pos(p) {}
115 forceinline
116 Pos::Pos(const Pos& p) : pos(p.pos) {}
117
118 /*
119 * Choice with position
120 *
121 */
122 forceinline
123 PosChoice::PosChoice(const Brancher& b, unsigned int a, const Pos& p)
124 : Choice(b,a), _pos(p) {}
125 forceinline const Pos&
126 PosChoice::pos(void) const {
127 return _pos;
128 }
129 forceinline void
130 PosChoice::archive(Archive& e) const {
131 Choice::archive(e);
132 e << _pos.pos;
133 }
134
135 template<class View, class Filter, int n>
136 forceinline
137 ViewBrancher<View,Filter,n>::ViewBrancher(Home home, ViewArray<View>& x0,
138 ViewSel<View>* vs0[n],
139 BranchFilter<Var> bf)
140 : Brancher(home), x(x0), start(0), f(bf) {
141 for (int i=0; i<n; i++)
142 vs[i] = vs0[i];
143 for (int i=0; i<n; i++)
144 if (f.notice() || vs[i]->notice()) {
145 home.notice(*this,AP_DISPOSE,true);
146 break;
147 }
148 }
149
150 template<class View, class Filter, int n>
151 forceinline
152 ViewBrancher<View,Filter,n>::ViewBrancher(Space& home,
153 ViewBrancher<View,Filter,n>& vb)
154 : Brancher(home,vb), start(vb.start), f(vb.f) {
155 x.update(home,vb.x);
156 for (int i=0; i<n; i++)
157 vs[i] = vb.vs[i]->copy(home);
158 }
159
160 template<class View, class Filter, int n>
161 bool
162 ViewBrancher<View,Filter,n>::status(const Space& home) const {
163 for (int i=start; i < x.size(); i++)
164 if (!x[i].assigned() && f(home,x[i],i)) {
165 start = i;
166 return true;
167 }
168 return false;
169 }
170
171 template<class View, class Filter, int n>
172 inline Pos
173 ViewBrancher<View,Filter,n>::pos(Space& home) {
174 assert(!x[start].assigned());
175 int s;
176 if (f) {
177 if (n == 1) {
178 s = vs[0]->select(home,x,start,f);
179 } else {
180 Region r;
181 int* ties = r.alloc<int>(x.size()-start+1);
182 int n_ties;
183 vs[0]->ties(home,x,start,ties,n_ties,f);
184 for (int i=1; (i < n-1) && (n_ties > 1); i++)
185 vs[i]->brk(home,x,ties,n_ties);
186 if (n_ties > 1)
187 s = vs[n-1]->select(home,x,ties,n_ties);
188 else
189 s = ties[0];
190 }
191 } else {
192 if (n == 1) {
193 s = vs[0]->select(home,x,start);
194 } else {
195 Region r;
196 int* ties = r.alloc<int>(x.size()-start+1);
197 int n_ties;
198 vs[0]->ties(home,x,start,ties,n_ties);
199 for (int i=1; (i < n-1) && (n_ties > 1); i++)
200 vs[i]->brk(home,x,ties,n_ties);
201 if (n_ties > 1)
202 s = vs[n-1]->select(home,x,ties,n_ties);
203 else
204 s = ties[0];
205 }
206 }
207 Pos p(s);
208 return p;
209 }
210
211 template<class View, class Filter, int n>
212 forceinline View
213 ViewBrancher<View,Filter,n>::view(const Pos& p) const {
214 return x[p.pos];
215 }
216
217 template<class View, class Filter, int n>
218 forceinline size_t
219 ViewBrancher<View,Filter,n>::dispose(Space& home) {
220 for (int i=0; i<n; i++)
221 if (f.notice() || vs[i]->notice()) {
222 home.ignore(*this,AP_DISPOSE,true);
223 break;
224 }
225 for (int i=0; i<n; i++)
226 vs[i]->dispose(home);
227 (void) Brancher::dispose(home);
228 return sizeof(ViewBrancher<View,Filter,n>);
229 }
230
231}
232
233// STATISTICS: kernel-branch