IEnumerable <CutState> Prover(Structure goal)
{
if (goal == null)
{
return(CutStateSequencer.Succeed());
}
return(context.Prove(goal));
}
/// <summary>
/// Attempts to prove all woken goals, in the order they were woken.
///
/// </summary>
internal IEnumerable <CutState> ProveAllWokenGoals()
{
if (this.wokenStack == null || this.wokenStack.Count == 0)
{
return(CutStateSequencer.Succeed());
}
WokenGoal[] goals = wokenStack.ToArray();
wokenStack.Clear();
return(ProveWokenGoalsInternal(goals, 0));
}
internal static System.Collections.Generic.IEnumerable<CutState> Retract(object term, PrologContext context)
{
ELNode foundNode;
ELNodeEnumerator enumerator;
if (!TryQuery(term, context, out foundNode, out enumerator))
return CutStateSequencer.Fail();
if (foundNode != null)
{
foundNode.DeleteSelf();
return CutStateSequencer.Succeed();
}
return DeleteSuccessive(enumerator);
}
internal static IEnumerable <CutState> Retract(object term, PrologContext context)
{
ELNode foundNode;
ELNodeEnumerator enumerator;
if (!TryQuery(term, context, out foundNode, out enumerator))
{
return(CutStateSequencer.Fail());
}
if (foundNode != null)
{
foundNode.DeleteSelf();
return(CutStateSequencer.Succeed());
}
return(DeleteSuccessive(enumerator));
}
internal static IEnumerable <CutState> SetImplementation(object[] args, PrologContext context)
{
if (args.Length != 2)
{
throw new ArgumentCountException("set", args, new object[] { "Variable", "NewValue" });
}
object value = Term.CopyInstantiation(args[1]);
if (value is LogicVariable)
{
throw new UninstantiatedVariableException((LogicVariable)args[1], "Value argument should be a data object, not an uninstantiated (unbound) variable.");
}
var functor = Term.Deref(args[0]) as Symbol;
if (functor == null)
{
throw new ArgumentTypeException("set", "functor", args[0], typeof(Symbol));
}
List <KnowledgeBaseEntry> entries = context.KnowledgeBase.EntryListForStoring(new PredicateIndicator(functor, 1));
switch (entries.Count)
{
case 0:
entries.Add(new KnowledgeBaseVariable(value));
return(CutStateSequencer.Succeed());
case 1:
var v = entries[0] as KnowledgeBaseVariable;
if (v == null)
{
throw new ArgumentException("Functor is not a variable; it has another entry defined for it.");
}
v.CurrentValue = value;
return(CutStateSequencer.Succeed());
default:
throw new ArgumentException("Functor is not a variable; it has multiple entries defined for it.");
}
}
