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package solver.explanations.strategies;
import solver.ICause;
import solver.Solver;
import solver.exception.ContradictionException;
import solver.search.loop.lns.neighbors.RandomNeighborhood;
import solver.search.loop.monitors.IMonitorUpBranch;
import solver.search.strategy.assignments.DecisionOperator;
import solver.search.strategy.decision.Decision;
import solver.search.strategy.decision.fast.FastDecision;
import solver.variables.IntVar;
/**
* This class extends {@link solver.search.loop.lns.neighbors.RandomNeighborhood}, but, instead of instantiating variables
* to values, it builds a fake decision path, this enables plugging explanation in.
* <br/>
*
* @author Charles Prud'homme
* @since 03/07/13
*/
public class RandomNeighborhood4Explanation extends RandomNeighborhood implements IMonitorUpBranch {
private Decision duplicator;
private Decision last; // needed to catch up the case when a subtree is closed, and this imposes the fgmt
public RandomNeighborhood4Explanation(Solver aSolver, IntVar[] vars, int level, long seed) {
super(aSolver, vars, level, seed);
mSolver.plugMonitor(this);
}
@Override
public void recordSolution() {
super.recordSolution();
if (duplicator == null) {
duplicator = mSolver.getSearchLoop().getLastDecision().duplicate();
}
}
@Override
public void fixSomeVariables(ICause cause) throws ContradictionException {
last = null;
super.fixSomeVariables(cause);
}
@Override
protected void impose(int id, ICause cause) throws ContradictionException {
FastDecision d = (FastDecision) duplicator.duplicate();
d.set(vars[id], bestSolution[id], DecisionOperator.int_eq);
last = d;
ExplanationToolbox.imposeDecisionPath(mSolver, d);
}
@Override
public void restrictLess() {
last = null;
super.restrictLess();
}
@Override
public void beforeUpBranch() {
}
@Override
public void afterUpBranch() {
// we need to catch up that case when the sub tree is closed and this imposes a fragment
if (last != null && mSolver.getSearchLoop().getLastDecision().getId() == last.getId()) {
mSolver.getSearchLoop().restart();
}
}
}