/// <summary>
/// Construct a fact, ground or variable, from a GdlExpression. Returns a
/// GroundFact if there were no variables in the GdlExpression, and a
/// VariableFact otherwise.
/// </summary>
/// <param name="exp">The expression from which to construct the fact.</param>
/// <returns>The fact constructed from GdlExpression <paramref name="exp"/>.</returns>
public static Fact FromExpression(GdlExpression exp)
{
// When in doubt, it's probably a variable fact.
// Besides, the variable fact factory takes care of turning
// things into ground facts if there are no variables.
return VariableFact.FromExpression(exp);
}
public static new Fact FromExpression(GdlExpression exp)
{
if (exp is GdlAtom)
return GroundFact.FromExpression(exp);
var list = exp as GdlList;
if (list != null)
return FromList(list);
// unknown expression type
throw new Exception("GroundFact.fromExpression: don't know how to handle expressions of type " + exp.GetType().Name);
}
private void ExamineTerm(GdlExpression exp)
{
var atom = exp as GdlAtom;
if (atom != null)
ExamineAtomTerm(atom);
else if (exp is GdlVariable)
ExamineVariableTerm();
else
{
var list = exp as GdlList;
if (list != null)
ExamineListTerm(list);
else
throw new Exception("MetaGdl.examineTerm: can't handle expressions of type " + exp.GetType().Name);
}
}
public Expression ExamineRelation(GdlExpression relation)
{
var atom = relation as GdlAtom;
if (atom != null)
return ExamineAtomRelation(atom);
// else, must be a variable
var list = (GdlList)relation;
return ExamineListRelation((GdlList)relation, ((GdlAtom)list[0]).GetToken());
}
