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package solver.constraints.nary.nogood;
import gnu.trove.list.TIntList;
import gnu.trove.list.array.TIntArrayList;
import gnu.trove.map.hash.TIntObjectHashMap;
import solver.constraints.Propagator;
import solver.constraints.PropagatorPriority;
import solver.exception.ContradictionException;
import solver.explanations.Deduction;
import solver.explanations.Explanation;
import solver.explanations.ValueRemoval;
import solver.explanations.VariableState;
import solver.variables.IntVar;
import solver.variables.events.IntEventType;
import util.ESat;
import util.objects.queues.CircularQueue;
import java.util.ArrayList;
import java.util.List;
/**
* A propagator for the specific Nogood store designed to store ONLY positive decisions.
* <p/>
* Related to "Nogood Recording from Restarts", C. Lecoutre et al.
* <br/>
*
* @author Charles Prud'homme
* @since 20/06/13
*/
public class PropNogoodStore extends Propagator<IntVar> {
List<INogood> units;
List<INogood> allnogoods;
TIntObjectHashMap<TIntList> vars2nogood;
TIntObjectHashMap<TIntList> vars2idxinng;
CircularQueue<IntVar> hasChanged;
public PropNogoodStore(IntVar[] vars) {
super(vars, PropagatorPriority.VERY_SLOW, true);
vars2nogood = new TIntObjectHashMap<TIntList>();
vars2idxinng = new TIntObjectHashMap<TIntList>();
allnogoods = new ArrayList<INogood>();
units = new ArrayList<INogood>();
hasChanged = new CircularQueue<IntVar>(8);
}
@Override
public boolean advise(int idxVarInProp, int mask) {
return super.advise(idxVarInProp, mask) && vars2nogood.get(vars[idxVarInProp].getId()) != null;
}
@Override
public int getPropagationConditions(int vIdx) {
return IntEventType.instantiation();
}
@Override
public void propagate(int evtmask) throws ContradictionException {
for (INogood ng : allnogoods) {
ng.propagate(this);
}
}
@Override
public void propagate(int idxVarInProp, int mask) throws ContradictionException {
hasChanged.clear();
hasChanged.addLast(vars[idxVarInProp]);
while (!hasChanged.isEmpty()) {
IntVar var = hasChanged.pollFirst();
TIntList nogoods = vars2nogood.get(var.getId());
TIntList indices = vars2idxinng.get(var.getId());
for (int i = 0; i < nogoods.size(); i++) {
INogood ng = allnogoods.get(nogoods.get(i));
int idx = ng.awakeOnInst(indices.get(i), this);
if (idx > -1) {
hasChanged.addLast(ng.getVar(idx));
} else if (idx == -99) { // a call to unwatch has been done!
i--;
} else {
assert ng.isEntailed() != ESat.FALSE;
}
}
}
}
public void unitPropagation() throws ContradictionException {
for (INogood ng : units) {
ng.propagate(this);
}
}
@Override
public ESat isEntailed() {
for (INogood ng : allnogoods) {
ESat sat = ng.isEntailed();
if (!sat.equals(ESat.TRUE)) {
return sat;
}
}
return ESat.TRUE;
}
@Override
public void explain(Deduction d, Explanation e) {
e.add(solver.getExplainer().getPropagatorActivation(this));
e.add(this);
if (d != null && d.getmType() == Deduction.Type.ValRem) {
ValueRemoval vr = (ValueRemoval) d;
IntVar var = (IntVar) vr.getVar();
int val = vr.getVal();
TIntList nogoods = vars2nogood.get(var.getId());
TIntList indices = vars2idxinng.get(var.getId());
for (int i = 0; i < nogoods.size(); i++) {
INogood ng = allnogoods.get(nogoods.get(i));
int idx = indices.get(i);
if (val == ng.getVal(idx)) {
for (int j = 0; j < ng.size(); j++) {
if (ng.getVar(j) != var) {
// ng.getVar(j).explain(VariableState.REM, ng.getVal(j), e);
ng.getVar(j).explain(VariableState.DOM, e);
}
}
}
}
} else {
super.explain(d, e);
}
}
///*****************************************************************************************************************
/// DEDICATED TO NOGOOD RECORDING *********************************************************************************
///*****************************************************************************************************************
public void addNogood(INogood ng) throws ContradictionException {
if (ng.isUnit()) {
units.add(ng);
}
int ngidx = allnogoods.size();
allnogoods.add(ng);
ng.setIdx(ngidx);
hasChanged.clear();
int idx = ng.propagate(this);
if (idx > -1) {
hasChanged.addLast(ng.getVar(idx));
}
while (!hasChanged.isEmpty()) {
IntVar var = hasChanged.pollFirst();
TIntList nogoods = vars2nogood.get(var.getId());
TIntList indices = vars2idxinng.get(var.getId());
for (int i = 0; i < nogoods.size(); i++) {
ng = allnogoods.get(nogoods.get(i));
idx = ng.awakeOnInst(indices.get(i), this);
if (idx > -1) {
hasChanged.addLast(ng.getVar(idx));
} else {
assert ng.isEntailed() != ESat.FALSE;
}
}
}
}
public void watch(IntVar var, Nogood ng, int idxInNG) {
TIntList nogoods = vars2nogood.get(var.getId());
if (nogoods == null) {
nogoods = new TIntArrayList();
vars2nogood.put(var.getId(), nogoods);
}
nogoods.add(ng.getIdx());
TIntList indices = vars2idxinng.get(var.getId());
if (indices == null) {
indices = new TIntArrayList();
vars2idxinng.put(var.getId(), indices);
}
indices.add(idxInNG);
}
public void unwatch(IntVar var, Nogood ng) {
TIntList nogoods = vars2nogood.get(var.getId());
if (nogoods != null) {
int ni = nogoods.indexOf(ng.getIdx());
if (ni > -1) {
nogoods.removeAt(ni);
TIntList indices = vars2idxinng.get(var.getId());
indices.removeAt(ni);
}
}
}
}