eqv.cpp
Go to the documentation of this file.
/* -*- 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
Gecode::Actor
Base-class for both propagators and branchers.
Definition core.hpp:628
Gecode::BinaryPropagator< BoolView, PC_BOOL_VAL >::x0
BoolView x0
Definition pattern.hpp:87
Gecode::BinaryPropagator< BoolView, PC_BOOL_VAL >::x1
BoolView x1
Definition pattern.hpp:87
Gecode::Home
Home class for posting propagators
Definition core.hpp:856
Gecode::Int::Bool::Eq::post
static ExecStatus post(Home home, BVA x0, BVB x1)
Post propagator .
Definition eq.hpp:60
Gecode::Int::Bool::NaryEqv::propagate
virtual ExecStatus propagate(Space &home, const ModEventDelta &med)
Perform propagation.
Definition eqv.cpp:81
Gecode::Int::Bool::NaryEqv::resubscribe
void resubscribe(Space &home, BoolView &x0)
Update subscription.
Definition eqv.hpp:178
Gecode::Int::Bool::NaryEqv::NaryEqv
NaryEqv(Home home, ViewArray< BoolView > &x, int pm2)
Constructor for posting.
Definition eqv.hpp:158
Gecode::Int::Bool::NaryEqv::cost
virtual PropCost cost(const Space &home, const ModEventDelta &med) const
Cost function (defined as low binary).
Definition eqv.cpp:44
Gecode::Int::Bool::NaryEqv::copy
virtual Actor * copy(Space &home)
Copy propagator during cloning.
Definition eqv.cpp:49
Gecode::Int::Bool::NaryEqv::pm2
int pm2
Parity information mod 2.
Definition bool.hh:460
Gecode::Int::Bool::NaryEqv::x
ViewArray< BoolView > x
Views not yet subscribed to.
Definition bool.hh:458
Gecode::Int::Bool::NaryEqv::post
static ExecStatus post(Home home, ViewArray< BoolView > &x, int pm2)
Post propagator .
Definition eqv.cpp:54
Gecode::Int::NegBoolView
Negated Boolean view.
Definition view.hpp:1574
Gecode::PropCost::binary
static PropCost binary(PropCost::Mod m)
Two variables for modifier pcm.
Definition core.hpp:4809
Gecode::PropCost::LO
@ LO
Cheap.
Definition core.hpp:513
Gecode::Propagator::Space
friend class Space
Definition core.hpp:1066
Gecode::ViewArray
View arrays.
Definition array.hpp:253
Gecode::Space::ES_SUBSUMED
ExecStatus ES_SUBSUMED(Propagator &p)
Definition core.hpp:3563
Gecode::ModEventDelta
int ModEventDelta
Modification event deltas.
Definition core.hpp:89
GECODE_ME_CHECK
#define GECODE_ME_CHECK(me)
Check whether modification event me is failed, and forward failure.
Definition macros.hpp:52
bool.hh
Gecode::Int::Bool
Boolean propagators.
Gecode::Int
Finite domain integers.
Gecode
Gecode toplevel namespace
Gecode::ExecStatus
ExecStatus
Definition core.hpp:472
Gecode::ES_OK
@ ES_OK
Execution is okay.
Definition core.hpp:476
Gecode::ES_FIX
@ ES_FIX
Propagation has computed fixpoint.
Definition core.hpp:477
Gecode::ES_FAILED
@ ES_FAILED
Execution has resulted in failure.
Definition core.hpp:474