/// <summary>
/// Extracts the parameters from the given atom.
/// </summary>
/// <param name="atom">Atom.</param>
private void ExtractParameters(IAtom atom)
{
foreach (var term in atom.GetTerms())
{
ExtractParameters(term);
}
}
/// <summary>
/// Grounds the atom. The "deep" version of terms grounding is used.
/// </summary>
/// <param name="atom">Function or predicate atom.</param>
/// <param name="substitution">Variables substitution.</param>
/// <param name="referenceState">Reference state.</param>
/// <returns>Grounded atom.</returns>
public IAtom GroundAtomDeep(IAtom atom, ISubstitution substitution, IState referenceState)
{
List <ITerm> groundedTerms = new List <ITerm>();
atom.GetTerms().ForEach(term => groundedTerms.Add(GroundTermDeep(term, substitution, referenceState)));
return(new Atom(atom.GetNameId(), groundedTerms));
}
/// <summary>
/// Grounds the atom.
/// </summary>
/// <param name="atom">Function or predicate atom.</param>
/// <param name="substitution">Variables substitution.</param>
/// <returns>Grounded atom.</returns>
public IAtom GroundAtom(IAtom atom, ISubstitution substitution)
{
List <ITerm> groundedTerms = new List <ITerm>();
atom.GetTerms().ForEach(term => groundedTerms.Add(GroundTerm(term, substitution)));
return(new Atom(atom.GetNameId(), groundedTerms));
}
/// <summary>
/// Checks whether the atom terms need a rename of any parameter and performs the rename.
/// </summary>
/// <param name="atom">Predicate or function atom.</param>
private void CheckAndRenameAtom(IAtom atom)
{
foreach (var term in atom.GetTerms())
{
CheckAndRenameTerm(term);
}
}
public static IGroundedAtom GroundAtom(IAtom atom, ISubstitution substitution, State referenceState)
{
List <int> argumentsList = new List <int>();
foreach (var term in atom.GetTerms())
{
argumentsList.Add(TermGrounder.Ground(term, substitution, referenceState));
}
return(new GroundedAtom(atom.GetNameID(), argumentsList));
}
/// <summary>
/// Gets the unification with the specified atom, i.e. calculates the variable substitution required to ground variable terms of the
/// current atom with the grounded terms (i.e. constants) of the other atom.
/// </summary>
/// <param name="referenceAtom">Reference atom.</param>
/// <returns>Unification in the form of variable substitution.</returns>
public ISubstitution GetUnificationWith(IAtom referenceAtom)
{
Debug.Assert(GetNameId() == referenceAtom.GetNameId() && GetTerms().Count == referenceAtom.GetTerms().Count, "Unification of incompatible atoms!");
ISubstitution unification = new Substitution();
int termIndex = 0;
foreach (var term in GetTerms())
{
VariableTerm variableTerm = term as VariableTerm;
if (variableTerm != null)
{
ConstantTerm valueTerm = referenceAtom.GetTerms()[termIndex] as ConstantTerm;
if (valueTerm != null)
{
unification.Add(variableTerm.NameId, valueTerm.NameId);
}
}
++termIndex;
}
return(unification);
}
