/// <summary>
/// Generates a constraint system based on a variability model. The constraint system can be used to check for satisfiability of configurations as well as optimization.
/// </summary>
/// <param name="variables">Empty input, outputs a list of CSP terms that correspond to the configuration options of the variability model</param>
/// <param name="optionToTerm">A map to get for a given configuration option the corresponding CSP term of the constraint system</param>
/// <param name="termToOption">A map that gives for a given CSP term the corresponding configuration option of the variability model</param>
/// <param name="vm">The variability model for which we generate a constraint system</param>
/// <returns>The generated constraint system consisting of logical terms representing configuration options as well as their boolean constraints.</returns>
internal static ConstraintSystem GetGeneralConstraintSystem(out Dictionary <CspTerm, bool> variables, out Dictionary <ConfigurationOption, CspTerm> optionToTerm, out Dictionary <CspTerm, ConfigurationOption> termToOption, VariabilityModel vm)
{
ConstraintSystem S = ConstraintSystem.CreateSolver();
optionToTerm = new Dictionary <ConfigurationOption, CspTerm>();
termToOption = new Dictionary <CspTerm, ConfigurationOption>();
variables = new Dictionary <CspTerm, bool>();
foreach (ConfigurationOption o in vm.getOptions())
{
CspDomain binDomain = S.DefaultBoolean;
CspTerm temp;
if (o is BinaryOption)
{
temp = S.CreateVariable(binDomain, o);
}
else
{
NumericOption numOpt = (NumericOption)o;
temp = S.CreateVariable(S.CreateIntegerInterval((int)numOpt.Min_value, (int)numOpt.Max_value), o);
}
optionToTerm.Add(o, temp);
termToOption.Add(temp, o);
if (o is NumericOption)
{
variables.Add(temp, false);
}
else
{
variables.Add(temp, true);
}
}
List <List <ConfigurationOption> > alreadyHandledAlternativeOptions = new List <List <ConfigurationOption> >();
//Constraints of a single configuration option
foreach (ConfigurationOption current in vm.getOptions())
{
CspTerm cT = optionToTerm[current];
if (current.Parent == null || current.Parent == vm.Root)
{
if ((current is BinaryOption && ((BinaryOption)current).Optional == false && current.Excluded_Options.Count == 0))
{
S.AddConstraints(S.Implies(S.True, cT));
}
else
{
S.AddConstraints(S.Implies(cT, optionToTerm[vm.Root]));
}
}
if (current.Parent != null && current.Parent != vm.Root)
{
CspTerm parent = optionToTerm[(BinaryOption)current.Parent];
S.AddConstraints(S.Implies(cT, parent));
if (current is BinaryOption && ((BinaryOption)current).Optional == false && current.Excluded_Options.Count == 0)
{
S.AddConstraints(S.Implies(parent, cT));//mandatory child relationship
}
}
// Add numeric integer values
if (current is NumericOption)
{
NumericOption numOpt = (NumericOption)current;
List <double> values = numOpt.getAllValues();
List <CspTerm> equals = new List <CspTerm>();
foreach (double d in values)
{
equals.Add(S.Equal((int)d, cT));
}
S.AddConstraints(S.Or(equals.ToArray()));
}
//Alternative or other exclusion constraints
if (current.Excluded_Options.Count > 0 && current is BinaryOption)
{
BinaryOption binOpt = (BinaryOption)current;
List <ConfigurationOption> alternativeOptions = binOpt.collectAlternativeOptions();
if (alternativeOptions.Count > 0)
{
//Check whether we handled this group of alternatives already
foreach (var alternativeGroup in alreadyHandledAlternativeOptions)
{
foreach (var alternative in alternativeGroup)
{
if (current == alternative)
{
goto handledAlternative;
}
}
}
//It is not allowed that an alternative group has no parent element
CspTerm parent = null;
if (current.Parent == null)
{
parent = S.True;
}
else
{
parent = optionToTerm[(BinaryOption)current.Parent];
}
CspTerm[] terms = new CspTerm[alternativeOptions.Count + 1];
terms[0] = cT;
int i = 1;
foreach (BinaryOption altEle in alternativeOptions)
{
CspTerm temp = optionToTerm[altEle];
terms[i] = temp;
i++;
}
S.AddConstraints(S.Implies(parent, S.ExactlyMofN(1, terms)));
alreadyHandledAlternativeOptions.Add(alternativeOptions);
handledAlternative : { }
}
//Excluded option(s) as cross-tree constraint(s)
List <List <ConfigurationOption> > nonAlternative = binOpt.getNonAlternativeExcludedOptions();
if (nonAlternative.Count > 0)
{
foreach (var excludedOption in nonAlternative)
{
CspTerm[] orTerm = new CspTerm[excludedOption.Count];
int i = 0;
foreach (var opt in excludedOption)
{
CspTerm target = optionToTerm[(BinaryOption)opt];
orTerm[i] = target;
i++;
}
S.AddConstraints(S.Implies(cT, S.Not(S.Or(orTerm))));
}
}
}
//Handle implies
if (current.Implied_Options.Count > 0)
{
foreach (List <ConfigurationOption> impliedOr in current.Implied_Options)
{
CspTerm[] orTerms = new CspTerm[impliedOr.Count];
//Possible error: if a binary option implies a numeric option
for (int i = 0; i < impliedOr.Count; i++)
{
orTerms[i] = optionToTerm[(BinaryOption)impliedOr.ElementAt(i)];
}
S.AddConstraints(S.Implies(optionToTerm[current], S.Or(orTerms)));
}
}
}
//Handle global cross-tree constraints involving multiple options at a time
// the constraints should be in conjunctive normal form
foreach (string constraint in vm.BinaryConstraints)
{
bool and = false;
string[] terms;
if (constraint.Contains("&"))
{
and = true;
terms = constraint.Split('&');
}
else
{
terms = constraint.Split('|');
}
CspTerm[] cspTerms = new CspTerm[terms.Count()];
int i = 0;
foreach (string t in terms)
{
string optName = t.Trim();
if (optName.StartsWith("-") || optName.StartsWith("!"))
{
optName = optName.Substring(1);
BinaryOption binOpt = vm.getBinaryOption(optName);
CspTerm cspElem = optionToTerm[binOpt];
CspTerm notCspElem = S.Not(cspElem);
cspTerms[i] = notCspElem;
}
else
{
BinaryOption binOpt = vm.getBinaryOption(optName);
CspTerm cspElem = optionToTerm[binOpt];
cspTerms[i] = cspElem;
}
i++;
}
if (and)
{
S.AddConstraints(S.And(cspTerms));
}
else
{
S.AddConstraints(S.Or(cspTerms));
}
}
return(S);
}
