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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2011
*
* This file is part of Gecode, the generic constraint
* development environment:
* http://www.gecode.org
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include <gecode/int/bool.hh>
namespace Gecode { namespace Int { namespace Bool {
/*
* N-ary Boolean equivalence propagator
*
*/
PropCost
NaryEqv::cost(const Space&, const ModEventDelta&) const {
return PropCost::binary(PropCost::LO);
}
Actor*
NaryEqv::copy(Space& home) {
return new (home) NaryEqv(home,*this);
}
ExecStatus
NaryEqv::post(Home home, ViewArray<BoolView>& x, int pm2) {
int n = x.size();
for (int i=n; i--; )
if (x[i].assigned()) {
pm2 ^= x[i].val();
x[i] = x[--n];
}
if (n == 0)
return (pm2 == 1) ? ES_OK : ES_FAILED;
if (n == 1) {
GECODE_ME_CHECK(x[0].eq(home,1^pm2));
return ES_OK;
}
if (n == 2) {
if (pm2 == 1) {
return Bool::Eq<BoolView,BoolView>::post(home,x[0],x[1]);
} else {
NegBoolView nx(x[1]);
return Bool::Eq<BoolView,NegBoolView>::post(home,x[0],nx);
}
}
x.size(n);
(void) new (home) NaryEqv(home,x,pm2);
return ES_OK;
}
ExecStatus
NaryEqv::propagate(Space& home, const ModEventDelta&) {
resubscribe(home,x0);
resubscribe(home,x1);
if (x.size() == 0) {
if (x0.assigned() && x1.assigned()) {
return (pm2 == 1) ? home.ES_SUBSUMED(*this) : ES_FAILED;
} else if (x0.assigned()) {
GECODE_ME_CHECK(x1.eq(home,1^pm2));
return home.ES_SUBSUMED(*this);
} else if (x1.assigned()) {
GECODE_ME_CHECK(x0.eq(home,1^pm2));
return home.ES_SUBSUMED(*this);
}
}
return ES_FIX;
}
}}}
// STATISTICS: int-prop
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