this repo has no description
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, 2011
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
34#include <gecode/int/bool.hh>
35
36namespace Gecode { namespace Int { namespace Bool {
37
38 /*
39 * N-ary Boolean equivalence propagator
40 *
41 */
42
43 PropCost
44 NaryEqv::cost(const Space&, const ModEventDelta&) const {
45 return PropCost::binary(PropCost::LO);
46 }
47
48 Actor*
49 NaryEqv::copy(Space& home) {
50 return new (home) NaryEqv(home,*this);
51 }
52
53 ExecStatus
54 NaryEqv::post(Home home, ViewArray<BoolView>& x, int pm2) {
55 int n = x.size();
56 for (int i=n; i--; )
57 if (x[i].assigned()) {
58 pm2 ^= x[i].val();
59 x[i] = x[--n];
60 }
61 if (n == 0)
62 return (pm2 == 1) ? ES_OK : ES_FAILED;
63 if (n == 1) {
64 GECODE_ME_CHECK(x[0].eq(home,1^pm2));
65 return ES_OK;
66 }
67 if (n == 2) {
68 if (pm2 == 1) {
69 return Bool::Eq<BoolView,BoolView>::post(home,x[0],x[1]);
70 } else {
71 NegBoolView nx(x[1]);
72 return Bool::Eq<BoolView,NegBoolView>::post(home,x[0],nx);
73 }
74 }
75 x.size(n);
76 (void) new (home) NaryEqv(home,x,pm2);
77 return ES_OK;
78 }
79
80 ExecStatus
81 NaryEqv::propagate(Space& home, const ModEventDelta&) {
82 resubscribe(home,x0);
83 resubscribe(home,x1);
84 if (x.size() == 0) {
85 if (x0.assigned() && x1.assigned()) {
86 return (pm2 == 1) ? home.ES_SUBSUMED(*this) : ES_FAILED;
87 } else if (x0.assigned()) {
88 GECODE_ME_CHECK(x1.eq(home,1^pm2));
89 return home.ES_SUBSUMED(*this);
90 } else if (x1.assigned()) {
91 GECODE_ME_CHECK(x0.eq(home,1^pm2));
92 return home.ES_SUBSUMED(*this);
93 }
94 }
95 return ES_FIX;
96 }
97
98}}}
99
100// STATISTICS: int-prop