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dekker.one
1/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2/*
3 * Main authors:
4 * Guido Tack <tack@gecode.org>
5 * Christian Schulte <schulte@gecode.org>
6 *
7 * Copyright:
8 * Guido Tack, 2004,2006,2007
9 * Christian Schulte, 2004
10 *
11 * This file is part of Gecode, the generic constraint
12 * development environment:
13 * http://www.gecode.org
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining
16 * a copy of this software and associated documentation files (the
17 * "Software"), to deal in the Software without restriction, including
18 * without limitation the rights to use, copy, modify, merge, publish,
19 * distribute, sublicense, and/or sell copies of the Software, and to
20 * permit persons to whom the Software is furnished to do so, subject to
21 * the following conditions:
22 *
23 * The above copyright notice and this permission notice shall be
24 * included in all copies or substantial portions of the Software.
25 *
26 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
27 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
28 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
29 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
30 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
31 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
32 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
33 *
34 */
35
36namespace Gecode { namespace Set { namespace Element {
37
38 template<class SView, class RView>
39 forceinline
40 ElementUnionConst<SView,RView>::
41 ElementUnionConst(Home home, SView y0,
42 const IntSetArgs& iv0,
43 RView y1)
44 : Propagator(home), x0(y0), n_iv(iv0.size()), x1(y1) {
45 home.notice(*this,AP_DISPOSE);
46 x0.subscribe(home,*this, PC_SET_ANY);
47 x1.subscribe(home,*this, PC_SET_ANY);
48 iv=static_cast<Space&>(home).alloc<IntSet>(n_iv);
49 for (unsigned int i=iv0.size(); i--;)
50 iv[i]=iv0[i];
51 }
52
53 template<class SView, class RView>
54 forceinline
55 ElementUnionConst<SView,RView>::
56 ElementUnionConst(Space& home, ElementUnionConst<SView,RView>& p)
57 : Propagator(home,p), n_iv(p.n_iv) {
58 x0.update(home,p.x0);
59 x1.update(home,p.x1);
60 iv=home.alloc<IntSet>(n_iv);
61 for (unsigned int i=n_iv; i--;)
62 iv[i]=p.iv[i];
63 }
64
65 template<class SView, class RView>
66 PropCost
67 ElementUnionConst<SView,RView>::cost(const Space&, const ModEventDelta&) const {
68 return PropCost::linear(PropCost::HI, n_iv+2);
69 }
70
71 template<class SView, class RView>
72 void
73 ElementUnionConst<SView,RView>::reschedule(Space& home) {
74 x0.reschedule(home,*this, PC_SET_ANY);
75 x1.reschedule(home,*this, PC_SET_ANY);
76 }
77
78 template<class SView, class RView>
79 forceinline size_t
80 ElementUnionConst<SView,RView>::dispose(Space& home) {
81 home.ignore(*this,AP_DISPOSE);
82 if (!home.failed()) {
83 x0.cancel(home,*this, PC_SET_ANY);
84 x1.cancel(home,*this, PC_SET_ANY);
85 }
86 for (unsigned int i=n_iv; i--;)
87 iv[i].~IntSet();
88 (void) Propagator::dispose(home);
89 return sizeof(*this);
90 }
91
92 template<class SView, class RView>
93 ExecStatus
94 ElementUnionConst<SView,RView>::
95 post(Home home, SView x0, const IntSetArgs& xs,
96 RView x1) {
97 int n = xs.size();
98
99 // s2 \subseteq {1,...,n}
100 Iter::Ranges::Singleton s(0, n-1);
101 GECODE_ME_CHECK(x1.intersectI(home,s));
102 (void) new (home)
103 ElementUnionConst<SView,RView>(home,x0,xs,x1);
104 return ES_OK;
105 }
106
107 template<class SView, class RView>
108 Actor*
109 ElementUnionConst<SView,RView>::copy(Space& home) {
110 return new (home) ElementUnionConst<SView,RView>(home,*this);
111 }
112
113 template<class SView, class RView>
114 ExecStatus
115 ElementUnionConst<SView,RView>::propagate(Space& home, const ModEventDelta&) {
116 Region r;
117
118 bool* stillSelected = r.alloc<bool>(n_iv);
119
120 bool loopVar;
121 do {
122 loopVar = false;
123 for (int i=n_iv; i--;)
124 stillSelected[i] = false;
125
126 // Cache the upper bound iterator, as we have to
127 // modify the upper bound while iterating
128 LubRanges<RView> x1ub(x1);
129 Iter::Ranges::Cache x1ubc(r,x1ub);
130 Iter::Ranges::ToValues<Iter::Ranges::Cache>
131 vx1ub(x1ubc);
132
133 GlbRanges<RView> x1lb(x1);
134 Iter::Ranges::Cache x1lbc(r,x1lb);
135 Iter::Ranges::ToValues<Iter::Ranges::Cache>
136 vx1(x1lbc);
137
138 // In the first iteration, compute in before[i] the union
139 // of all the upper bounds of the x_i. At the same time,
140 // exclude inconsistent x_i from x1.
141
142 GLBndSet sofarBefore(home);
143 LUBndSet selectedInter(home, IntSet (Limits::min,
144 Limits::max));
145 GLBndSet* before =
146 static_cast<GLBndSet*>(r.ralloc(sizeof(GLBndSet)*n_iv));
147
148 unsigned int maxCard = 0;
149 unsigned int minCard = Limits::card;
150
151 while (vx1ub()) {
152 int i = vx1ub.val();
153
154 IntSetRanges candCardR(iv[i]);
155 unsigned int candidateCard = Iter::Ranges::size(candCardR);
156
157 IntSetRanges candlb(iv[i]);
158 LubRanges<SView> x0ub(x0);
159 Iter::Ranges::Diff<IntSetRanges,
160 LubRanges<SView> > diff(candlb, x0ub);
161
162 bool selectSingleInconsistent = false;
163 if (x1.cardMax() <= 1) {
164 GlbRanges<SView> x0lb(x0);
165 IntSetRanges candub(iv[i]);
166 Iter::Ranges::Diff<GlbRanges<SView>,
167 IntSetRanges > diff2(x0lb, candub);
168 selectSingleInconsistent = diff2() || candidateCard < x0.cardMin();
169 }
170
171 // exclude inconsistent x_i
172 // an x_i is inconsistent if
173 // * at most one x_i can be selected and there are
174 // elements in x_0 that can't be in x_i
175 // (selectSingleInconsistent)
176 // * its min cardinality is greater than maxCard of x0
177 // * inter is not empty (there are elements in x_i
178 // that can't be in x_0)
179 if (selectSingleInconsistent ||
180 candidateCard > x0.cardMax() ||
181 diff()) {
182 ModEvent me = (x1.exclude(home,i));
183 loopVar |= me_modified(me);
184 GECODE_ME_CHECK(me);
185 } else {
186 stillSelected[i] = true;
187 // if x_i is consistent, check whether we know
188 // that its index is in x1
189 if (vx1() && vx1.val()==i) {
190 // x0 >= candidate, candidate <= x0
191 // GlbRanges<SView> candlb(candidate);
192 IntSetRanges candlb(iv[i]);
193 ModEvent me = x0.includeI(home,candlb);
194 loopVar |= me_modified(me);
195 GECODE_ME_CHECK(me);
196 ++vx1;
197 }
198 new (&before[i]) GLBndSet(home);
199 before[i].update(home,sofarBefore);
200 IntSetRanges cub(iv[i]);
201 sofarBefore.includeI(home,cub);
202 IntSetRanges clb(iv[i]);
203 selectedInter.intersectI(home,clb);
204 maxCard = std::max(maxCard, candidateCard);
205 minCard = std::min(minCard, candidateCard);
206 }
207
208 ++vx1ub;
209 }
210
211 if (x1.cardMax()==0) {
212 // Selector is empty, hence the result must be empty
213 {
214 GECODE_ME_CHECK(x0.cardMax(home,0));
215 }
216 for (int i=n_iv; i--;)
217 if (stillSelected[i])
218 before[i].dispose(home);
219 selectedInter.dispose(home);
220 sofarBefore.dispose(home);
221 return home.ES_SUBSUMED(*this);
222 }
223
224 if (x1.cardMin() > 0) {
225 // Selector is not empty, hence the intersection of the
226 // possibly selected lower bounds is contained in x0
227 BndSetRanges si(selectedInter);
228 ModEvent me = x0.includeI(home, si);
229 loopVar |= me_modified(me);
230 GECODE_ME_CHECK(me);
231 me = x0.cardMin(home, minCard);
232 loopVar |= me_modified(me);
233 GECODE_ME_CHECK(me);
234 }
235 selectedInter.dispose(home);
236
237 if (x1.cardMax() <= 1) {
238 ModEvent me = x0.cardMax(home, maxCard);
239 loopVar |= me_modified(me);
240 GECODE_ME_CHECK(me);
241 }
242
243 {
244 // x0 <= sofarBefore
245 BndSetRanges sfB(sofarBefore);
246 ModEvent me = x0.intersectI(home,sfB);
247 loopVar |= me_modified(me);
248 GECODE_ME_CHECK(me);
249 }
250
251 sofarBefore.dispose(home);
252
253 GLBndSet sofarAfter(home);
254
255 // In the second iteration, this time backwards, compute
256 // sofarAfter as the union of all lub(x_j) with j>i
257 for (int i=n_iv; i--;) {
258 if (!stillSelected[i])
259 continue;
260 BndSetRanges b(before[i]);
261 BndSetRanges s(sofarAfter);
262 GlbRanges<SView> x0lb(x0);
263 Iter::Ranges::Union<BndSetRanges, BndSetRanges> inter(b,s);
264 Iter::Ranges::Diff<GlbRanges<SView>,
265 Iter::Ranges::Union<BndSetRanges,BndSetRanges> > diff(x0lb, inter);
266 if (diff()) {
267 ModEvent me = (x1.include(home,i));
268 loopVar |= me_modified(me);
269 GECODE_ME_CHECK(me);
270
271 // candidate != extra
272 IntSetRanges ivi(iv[i]);
273 if (!Iter::Ranges::subset(diff, ivi))
274 GECODE_ME_CHECK(ME_SET_FAILED);
275 }
276
277 IntSetRanges iviub(iv[i]);
278 sofarAfter.includeI(home,iviub);
279 before[i].dispose(home);
280 }
281 sofarAfter.dispose(home);
282
283 } while (loopVar);
284
285 if (x1.assigned()) {
286 assert(x0.assigned());
287 return home.ES_SUBSUMED(*this);
288 }
289
290 return ES_FIX;
291 }
292
293}}}
294
295// STATISTICS: set-prop