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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, 2003
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 Distinct {
35
36 /*
37 * Eliminating singleton variables
38 *
39 */
40 template<class View, bool complete>
41 ExecStatus
42 prop_val(Space& home, ViewArray<View>& x) {
43 assert(x.size() > 1);
44 int n = x.size();
45
46 Region r;
47 int* stack = r.alloc<int>(n);
48 int* c_v = &stack[0];
49 // c_n is the current number of values on stack
50 int c_n = 0;
51
52 // Collect all assigned variables on stack
53 for (int i=n; i--; )
54 if (x[i].assigned()) {
55 c_v[c_n++]=x[i].val(); x[i]=x[--n];
56 }
57
58 // The number of trips
59 int t = 0;
60 do {
61 t++;
62 if (!complete && (t > 16)) {
63 // Give up after sixteen iterations, but the values must be
64 // propagated first
65 // Maybe we are lucky in that this iteration does the trick...
66 ExecStatus es = ES_FIX;
67 while (c_n > 0) {
68 int v = c_v[--c_n];
69 // Check whether value is on stack only once
70 for (int i=0; i<c_n; i++)
71 if (c_v[i] == v)
72 goto failed;
73 // Tell and do not collect new values
74 for (int i=0; i<n; i++) {
75 ModEvent me = x[i].nq(home,v);
76 if (me_failed(me))
77 goto failed;
78 if (me == ME_INT_VAL)
79 es = ES_NOFIX;
80 }
81 }
82 x.size(n);
83 return es;
84 }
85 if (c_n > 31) {
86 // Many values, use full domain operation
87 IntSet d(&c_v[0],c_n);
88 // If the size s of d is different from the number of values,
89 // a value must have appeared multiply: failure
90 if (d.size() != static_cast<unsigned int>(c_n))
91 goto failed;
92 // We do not need the values on the stack any longer, reset
93 c_n = 0;
94 // Tell and collect new values
95 for (int i = n; i--; )
96 if ((d.min() <= x[i].max()) && (d.max() >= x[i].min())) {
97 IntSetRanges dr(d);
98 ModEvent me = x[i].minus_r(home,dr,false);
99 if (me_failed(me))
100 goto failed;
101 if (me == ME_INT_VAL) {
102 c_v[c_n++]=x[i].val(); x[i]=x[--n];
103 }
104 }
105 } else {
106 // Values for next iteration
107 int* n_v = &c_v[c_n];
108 // Stack top for the next iteration
109 int n_n = 0;
110 while (c_n > 0) {
111 int v = c_v[--c_n];
112 // Check whether value is not on current stack
113 for (int i=0; i<c_n; i++)
114 if (c_v[i] == v)
115 goto failed;
116 // Check whether value is not on next stack
117 for (int i=0; i<n_n; i++)
118 if (n_v[i] == v)
119 goto failed;
120 // Tell and collect new values
121 for (int i = n; i--; ) {
122 ModEvent me = x[i].nq(home,v);
123 if (me_failed(me))
124 goto failed;
125 if (me == ME_INT_VAL) {
126 n_v[n_n++]=x[i].val(); x[i]=x[--n];
127 }
128 }
129 }
130 c_v = n_v; c_n = n_n;
131 }
132 } while (c_n > 0);
133 x.size(n);
134 return ES_FIX;
135 failed:
136 x.size(0);
137 return ES_FAILED;
138 }
139
140
141 /*
142 * The propagator proper
143 *
144 */
145 template<class View>
146 forceinline
147 Val<View>::Val(Home home, ViewArray<View>& x)
148 : NaryPropagator<View,PC_INT_VAL>(home,x) {}
149
150 template<class View>
151 forceinline
152 Val<View>::Val(Space& home, Val<View>& p)
153 : NaryPropagator<View,PC_INT_VAL>(home,p) {}
154
155#ifdef GECODE_HAS_CBS
156 template<class View>
157 void
158 Val<View>::solndistrib(Space& home, Propagator::SendMarginal send) const {
159 cbsdistinct(home,this->id(),x,send);
160 }
161
162 template<class View>
163 void
164 Val<View>::domainsizesum(Propagator::InDecision in, unsigned int& size,
165 unsigned int& size_b) const {
166 cbssize(x,in,size,size_b);
167 }
168#endif
169
170 template<class View>
171 Actor*
172 Val<View>::copy(Space& home) {
173 return new (home) Val<View>(home,*this);
174 }
175
176 template<class View>
177 ExecStatus
178 Val<View>::propagate(Space& home, const ModEventDelta&) {
179 GECODE_ES_CHECK((prop_val<View,true>(home,x)));
180 return (x.size() < 2) ? home.ES_SUBSUMED(*this) : ES_FIX;
181 }
182
183 template<class View>
184 ExecStatus
185 Val<View>::post(Home home, ViewArray<View>& x) {
186 if (x.size() == 2)
187 return Rel::Nq<View,View>::post(home,x[0],x[1]);
188 if (x.size() > 2)
189 (void) new (home) Val<View>(home,x);
190 return ES_OK;
191 }
192
193}}}
194
195// STATISTICS: int-prop
196