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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, 2008
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 { namespace Int { namespace Bool {
35
36 /*
37 * Boolean clause propagator (disjunctive, true)
38 *
39 */
40
41 template<class VX, class VY>
42 forceinline
43 ClauseTrue<VX,VY>::ClauseTrue(Home home,
44 ViewArray<VX>& x0, ViewArray<VY>& y0)
45 : MixBinaryPropagator<VX,PC_BOOL_VAL,VY,PC_BOOL_VAL>
46 (home,x0[x0.size()-1],y0[y0.size()-1]), x(x0), y(y0) {
47 assert((x.size() > 0) && (y.size() > 0));
48 x.size(x.size()-1); y.size(y.size()-1);
49 }
50
51 template<class VX, class VY>
52 PropCost
53 ClauseTrue<VX,VY>::cost(const Space&, const ModEventDelta&) const {
54 return PropCost::binary(PropCost::LO);
55 }
56
57 template<class VX, class VY>
58 forceinline
59 ClauseTrue<VX,VY>::ClauseTrue(Space& home, ClauseTrue<VX,VY>& p)
60 : MixBinaryPropagator<VX,PC_BOOL_VAL,VY,PC_BOOL_VAL>(home,p) {
61 x.update(home,p.x);
62 y.update(home,p.y);
63 }
64
65 template<class VX, class VY>
66 Actor*
67 ClauseTrue<VX,VY>::copy(Space& home) {
68 {
69 int n = x.size();
70 if (n > 0) {
71 // Eliminate all zeros and find a one
72 for (int i=n; i--; )
73 if (x[i].one()) {
74 // Only keep the one
75 x[0]=x[i]; n=1; break;
76 } else if (x[i].zero()) {
77 // Eliminate the zero
78 x[i]=x[--n];
79 }
80 x.size(n);
81 }
82 }
83 {
84 int n = y.size();
85 if (n > 0) {
86 // Eliminate all zeros and find a one
87 for (int i=n; i--; )
88 if (y[i].one()) {
89 // Only keep the one
90 y[0]=y[i]; n=1; break;
91 } else if (y[i].zero()) {
92 // Eliminate the zero
93 y[i]=y[--n];
94 }
95 y.size(n);
96 }
97 }
98 if ((x.size() == 0) && (y.size() == 0))
99 return new (home) BinOrTrue<VX,VY>(home,*this,x0,x1);
100 else
101 return new (home) ClauseTrue<VX,VY>(home,*this);
102 }
103
104 template<class VX, class VY>
105 inline ExecStatus
106 ClauseTrue<VX,VY>::post(Home home, ViewArray<VX>& x, ViewArray<VY>& y) {
107 for (int i=x.size(); i--; )
108 if (x[i].one())
109 return ES_OK;
110 else if (x[i].zero())
111 x.move_lst(i);
112 if (x.size() == 0)
113 return NaryOrTrue<VY>::post(home,y);
114 for (int i=y.size(); i--; )
115 if (y[i].one())
116 return ES_OK;
117 else if (y[i].zero())
118 y.move_lst(i);
119 if (y.size() == 0)
120 return NaryOrTrue<VX>::post(home,x);
121 if ((x.size() == 1) && (y.size() == 1)) {
122 return BinOrTrue<VX,VY>::post(home,x[0],y[0]);
123 } else if (!shared(x,y)) {
124 (void) new (home) ClauseTrue(home,x,y);
125 }
126 return ES_OK;
127 }
128
129 template<class VX, class VY>
130 forceinline size_t
131 ClauseTrue<VX,VY>::dispose(Space& home) {
132 (void) MixBinaryPropagator<VX,PC_BOOL_VAL,VY,PC_BOOL_VAL>::dispose(home);
133 return sizeof(*this);
134 }
135
136 template<class VX, class VY>
137 forceinline ExecStatus
138 resubscribe(Space& home, Propagator& p,
139 VX& x0, ViewArray<VX>& x,
140 VY& x1, ViewArray<VY>& y) {
141 if (x0.zero()) {
142 int n = x.size();
143 for (int i=n; i--; )
144 if (x[i].one()) {
145 x.size(n);
146 return home.ES_SUBSUMED(p);
147 } else if (x[i].zero()) {
148 x[i] = x[--n];
149 } else {
150 // Rewrite if there is just one view left
151 if ((i == 0) && (y.size() == 0)) {
152 VX z = x[0]; x.size(0);
153 GECODE_REWRITE(p,(BinOrTrue<VX,VY>::post(home(p),z,x1)));
154 }
155 // Move to x0 and subscribe
156 x0=x[i]; x[i]=x[--n];
157 x.size(n);
158 x0.subscribe(home,p,PC_BOOL_VAL,false);
159 return ES_FIX;
160 }
161 // All x-views have been assigned!
162 ViewArray<VY> z(home,y.size()+1);
163 for (int i=0; i<y.size(); i++)
164 z[i]=y[i];
165 z[y.size()] = x1;
166 GECODE_REWRITE(p,(NaryOrTrue<VY>::post(home(p),z)));
167 }
168 return ES_FIX;
169 }
170
171 template<class VX, class VY>
172 ExecStatus
173 ClauseTrue<VX,VY>::propagate(Space& home, const ModEventDelta&) {
174 if (x0.one() || x1.one())
175 return home.ES_SUBSUMED(*this);
176 GECODE_ES_CHECK(resubscribe(home,*this,x0,x,x1,y));
177 GECODE_ES_CHECK(resubscribe(home,*this,x1,y,x0,x));
178 return ES_FIX;
179 }
180
181
182 /*
183 * Boolean clause propagator (disjunctive)
184 *
185 */
186
187 /*
188 * Index advisors
189 *
190 */
191 template<class VX, class VY>
192 forceinline
193 Clause<VX,VY>::Tagged::Tagged(Space& home, Propagator& p,
194 Council<Tagged>& c, bool x0)
195 : Advisor(home,p,c), x(x0) {}
196
197 template<class VX, class VY>
198 forceinline
199 Clause<VX,VY>::Tagged::Tagged(Space& home, Tagged& a)
200 : Advisor(home,a), x(a.x) {}
201
202 template<class VX, class VY>
203 forceinline
204 Clause<VX,VY>::Clause(Home home, ViewArray<VX>& x0, ViewArray<VY>& y0,
205 VX z0)
206 : Propagator(home), x(x0), y(y0), z(z0), n_zero(0), c(home) {
207 x.subscribe(home,*new (home) Tagged(home,*this,c,true));
208 y.subscribe(home,*new (home) Tagged(home,*this,c,false));
209 z.subscribe(home,*this,PC_BOOL_VAL);
210 }
211
212 template<class VX, class VY>
213 forceinline
214 Clause<VX,VY>::Clause(Space& home, Clause<VX,VY>& p)
215 : Propagator(home,p), n_zero(p.n_zero) {
216 x.update(home,p.x);
217 y.update(home,p.y);
218 z.update(home,p.z);
219 c.update(home,p.c);
220 }
221
222 template<class VX>
223 forceinline void
224 eliminate_zero(ViewArray<VX>& x, int& n_zero) {
225 if (n_zero > 0) {
226 int n=x.size();
227 // Eliminate all zeros
228 for (int i=n; i--; )
229 if (x[i].zero()) {
230 x[i]=x[--n]; n_zero--;
231 }
232 x.size(n);
233 }
234 }
235
236 template<class VX, class VY>
237 Actor*
238 Clause<VX,VY>::copy(Space& home) {
239 eliminate_zero(x,n_zero);
240 eliminate_zero(y,n_zero);
241 return new (home) Clause<VX,VY>(home,*this);
242 }
243
244 template<class VX, class VY>
245 inline ExecStatus
246 Clause<VX,VY>::post(Home home, ViewArray<VX>& x, ViewArray<VY>& y, VX z) {
247 assert(!shared(x) && !shared(y));
248 if (z.one())
249 return ClauseTrue<VX,VY>::post(home,x,y);
250 if (z.zero()) {
251 for (int i=0; i<x.size(); i++)
252 GECODE_ME_CHECK(x[i].zero(home));
253 for (int i=0; i<y.size(); i++)
254 GECODE_ME_CHECK(y[i].zero(home));
255 return ES_OK;
256 }
257 for (int i=x.size(); i--; )
258 if (x[i].one()) {
259 GECODE_ME_CHECK(z.one_none(home));
260 return ES_OK;
261 } else if (x[i].zero()) {
262 x.move_lst(i);
263 }
264 if (x.size() == 0)
265 return NaryOr<VY,VX>::post(home,y,z);
266 for (int i=y.size(); i--; )
267 if (y[i].one()) {
268 GECODE_ME_CHECK(z.one_none(home));
269 return ES_OK;
270 } else if (y[i].zero()) {
271 y.move_lst(i);
272 }
273 if (y.size() == 0)
274 return NaryOr<VX,VX>::post(home,x,z);
275 if ((x.size() == 1) && (y.size() == 1)) {
276 return Or<VX,VY,VX>::post(home,x[0],y[0],z);
277 } else if (shared(x,y)) {
278 GECODE_ME_CHECK(z.one_none(home));
279 } else {
280 (void) new (home) Clause<VX,VY>(home,x,y,z);
281 }
282 return ES_OK;
283 }
284
285 template<class VX, class VY>
286 PropCost
287 Clause<VX,VY>::cost(const Space&, const ModEventDelta&) const {
288 return PropCost::unary(PropCost::LO);
289 }
290
291 template<class VX, class VY>
292 forceinline void
293 Clause<VX,VY>::cancel(Space& home) {
294 for (Advisors<Tagged> as(c); as(); ++as) {
295 if (as.advisor().x)
296 x.cancel(home,as.advisor());
297 else
298 y.cancel(home,as.advisor());
299 as.advisor().dispose(home,c);
300 }
301 c.dispose(home);
302 z.cancel(home,*this,PC_BOOL_VAL);
303 }
304
305 template<class VX, class VY>
306 forceinline size_t
307 Clause<VX,VY>::dispose(Space& home) {
308 cancel(home);
309 (void) Propagator::dispose(home);
310 return sizeof(*this);
311 }
312
313
314 template<class VX, class VY>
315 ExecStatus
316 Clause<VX,VY>::advise(Space&, Advisor& _a, const Delta& d) {
317 Tagged& a = static_cast<Tagged&>(_a);
318 // Decides whether the propagator must be run
319 if ((a.x && VX::zero(d)) || (!a.x && VY::zero(d)))
320 if (++n_zero < x.size() + y.size())
321 return ES_FIX;
322 return ES_NOFIX;
323 }
324
325 template<class VX, class VY>
326 void
327 Clause<VX,VY>::reschedule(Space& home) {
328 z.reschedule(home,*this,PC_BOOL_VAL);
329 if (n_zero == x.size() + y.size())
330 VX::schedule(home,*this,ME_BOOL_VAL);
331 for (int i=0; i<x.size(); i++)
332 if (x[i].one()) {
333 VX::schedule(home,*this,ME_BOOL_VAL);
334 return;
335 }
336 for (int i=0; i<y.size(); i++)
337 if (y[i].one()) {
338 VX::schedule(home,*this,ME_BOOL_VAL);
339 return;
340 }
341 }
342
343 template<class VX, class VY>
344 ExecStatus
345 Clause<VX,VY>::propagate(Space& home, const ModEventDelta&) {
346 if (z.one())
347 GECODE_REWRITE(*this,(ClauseTrue<VX,VY>::post(home(*this),x,y)));
348 if (z.zero()) {
349 for (int i=0; i<x.size(); i++)
350 GECODE_ME_CHECK(x[i].zero(home));
351 for (int i=0; i<y.size(); i++)
352 GECODE_ME_CHECK(y[i].zero(home));
353 c.dispose(home);
354 } else if (n_zero == x.size() + y.size()) {
355 GECODE_ME_CHECK(z.zero_none(home));
356 c.dispose(home);
357 } else {
358 // There is at least one view which is one
359 GECODE_ME_CHECK(z.one_none(home));
360 }
361 return home.ES_SUBSUMED(*this);
362 }
363
364}}}
365
366// STATISTICS: int-prop
367