javax.constraints.impl.search.goal.GoalAssignValueTimeLimit Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of jsr331 Show documentation

JCP Standard JSR331 “Java Constraint Programming API”. It is used for Modeling and Solving Constraint Satisfaction and Optimization Problems using Java and off-the-shelf Constraint/Linear Solvers

The newest version!

package javax.constraints.impl.search.goal;

import javax.constraints.Constraint;

import javax.constraints.Problem;
import javax.constraints.Solver;
import javax.constraints.ValueSelector;
import javax.constraints.Var;

public class GoalAssignValueTimeLimit extends Goal {
	Var 			var;
	ValueSelector 	valueSelector;

	public GoalAssignValueTimeLimit(Var var,
			                   ValueSelector valueSelector) {
		super(var.getProblem().getSolver(),"AssignValueWithTimeLimit to " + var);
		this.var = var;
		this.valueSelector = valueSelector;
	}

	public Goal execute() throws Exception {
		Problem p = getProblem();
		trace();
		if (var.isBound())
			return null;

		SolverWithGoals solver = getSolver();
		if(solver.checkTimeLimit()){
			if( solver.isTimeLimitExceeded() == false )	{
				solver.setTimeLimitExceeded(true);
				p.log("Time limit " + solver.getTimeLimit() + 
						" has been exceeded while instantiating variable "+var.getName());
			}
			return null;
			//the goal GoalCheckTimeLimit should check if variables are bound
		}

	    int value = valueSelector.select(var);

	    Constraint assign = p.linear(var, "=", value);
		Goal goalAssignValue = new GoalConstraint(assign);
		Constraint remove = p.linear(var, "!=", value);
		Goal goalRemoveValue = new GoalConstraint(remove);
	    return goalAssignValue.or(goalRemoveValue.and(this));
	}

}