/// <summary>
/// Generates up to n solutions of the given variability model.
/// Note that this method could also generate less than n solutions if the variability model does not contain sufficient solutions.
/// Moreover, in the case that <code>n < 0</code>, all solutions are generated.
/// </summary>
/// <param name="vm">The <see cref="VariabilityModel"/> to obtain solutions for.</param>
/// <param name="n">The number of solutions to obtain.</param>
/// <returns>A list of configurations, in which a configuration is a list of SELECTED binary options.</returns>
public List <List <BinaryOption> > GenerateUpToNFast(VariabilityModel vm, int n)
{
// Use the random seed to produce new random seeds
Random random = new Random(Convert.ToInt32(z3RandomSeed));
List <BoolExpr> variables;
Dictionary <BoolExpr, BinaryOption> termToOption;
Dictionary <BinaryOption, BoolExpr> optionToTerm;
Tuple <Context, BoolExpr> z3Tuple = Z3Solver.GetInitializedBooleanSolverSystem(out variables, out optionToTerm, out termToOption, vm, this.henard, random.Next());
Context z3Context = z3Tuple.Item1;
BoolExpr z3Constraints = z3Tuple.Item2;
List <BoolExpr> excludedConfigurations = new List <BoolExpr>();
List <BoolExpr> constraints = Z3Solver.lastConstraints;
List <List <BinaryOption> > configurations = new List <List <BinaryOption> >();
Microsoft.Z3.Solver s = z3Context.MkSolver();
// TODO: The following line works for z3Solver version >= 4.6.0
//solver.Set (RANDOM_SEED, z3RandomSeed);
Params solverParameter = z3Context.MkParams();
if (henard)
{
solverParameter.Add(RANDOM_SEED, NextUInt(random));
}
else
{
solverParameter.Add(RANDOM_SEED, z3RandomSeed);
}
s.Parameters = solverParameter;
s.Assert(z3Constraints);
s.Push();
Model model = null;
while (s.Check() == Status.SATISFIABLE && (configurations.Count < n || n < 0))
{
model = s.Model;
List <BinaryOption> config = RetrieveConfiguration(variables, model, termToOption);
configurations.Add(config);
if (henard)
{
BoolExpr newConstraint = Z3Solver.NegateExpr(z3Context, Z3Solver.ConvertConfiguration(z3Context, config, optionToTerm, vm));
excludedConfigurations.Add(newConstraint);
Dictionary <BoolExpr, BinaryOption> oldTermToOption = termToOption;
// Now, initialize a new one for the next configuration
z3Tuple = Z3Solver.GetInitializedBooleanSolverSystem(out variables, out optionToTerm, out termToOption, vm, this.henard, random.Next());
z3Context = z3Tuple.Item1;
z3Constraints = z3Tuple.Item2;
s = z3Context.MkSolver();
//s.Set (RANDOM_SEED, NextUInt (random));
solverParameter = z3Context.MkParams();
solverParameter.Add(RANDOM_SEED, NextUInt(random));
s.Parameters = solverParameter;
constraints = Z3Solver.lastConstraints;
excludedConfigurations = Z3Solver.ConvertConstraintsToNewContext(oldTermToOption, optionToTerm, excludedConfigurations, z3Context);
constraints.AddRange(excludedConfigurations);
s.Assert(z3Context.MkAnd(Z3Solver.Shuffle(constraints, new Random(random.Next()))));
s.Push();
}
else
{
s.Add(Z3Solver.NegateExpr(z3Context, Z3Solver.ConvertConfiguration(z3Context, config, optionToTerm, vm)));
}
}
return(configurations);
}
