/// <summary>
/// Creates a deep copy of the substitution.
/// </summary>
/// <returns>A copy of the substitution.</returns>
public ISubstitution Clone()
{
Substitution newSubstitution = new Substitution();
foreach (var item in this)
{
newSubstitution.Add(item.Key, item.Value);
}
return(newSubstitution);
}
/// <summary>
/// Creates a substitution from the given parameters and substituted constants.
/// </summary>
/// <param name="parameters">Parameters.</param>
/// <param name="constNames">Constant names.</param>
/// <returns>New substitution.</returns>
public ISubstitution CreateSubstitution(Parameters parameters, params string[] constNames)
{
Debug.Assert(parameters.Count == constNames.Length);
ISubstitution substitution = new Substitution();
for (int i = 0; i < parameters.Count; ++i)
{
if (!string.IsNullOrEmpty(constNames[i]))
{
substitution.Add(parameters[i].ParameterNameId, CreateConstant(constNames[i]));
}
}
return(substitution);
}
/// <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);
}
