public bool Unify(Term t, VarStack varStack, bool occurCheck)
{
if (isUnified) return ULink.Unify(t, varStack, occurCheck);
if (t.isUnified) return Unify(t.ULink, varStack, occurCheck);
//Interpreter.UCount++;
if (hasValue)
{
if (t.hasValue)
{
if (_functor.Equals(t._functor) && arity == t.Arity) // => two cuts will unify as well
{
for (int i = 0; i < arity; i++) if (!args[i].Unify(t.Arg(i), varStack, occurCheck)) return false;
return true;
}
else
return false;
}
// t is an unbound variable (add occur check here if deemed necessary)
t.Bind(this);
varStack.Push(t);
}
else // 'this' is an unbound variable. Add occur check here if deemed necessary
{
this.Bind(t);
varStack.Push(this);
}
return true;
}
private static void DCGGoal(Term t, ref TermNode body, ref Term remainder, ref bool embedded)
{
Term temp;
if (t.IsString || t is Cut)
body.Append(t);
else if (t.Functor == Parser.CURL)
{
while (t.Arity == 2)
{
body.Append(t.Arg(0));
t = t.Arg(1);
embedded = true;
}
}
else if (t.IsList)
{
temp = new Term();
if (t == NULLLIST) t = temp; else t.SetRightmostArg(temp);
if (embedded)
{
body.Append(new Term(Parser.EQ, remainder, t, FType.comp, OType.xfx, 700));
embedded = false;
}
else
remainder.Bind(t); // in this case, nothing is appended to body, which may be left empty (e.g. t-->[x])
remainder = temp;
}
else if (t.IsAtom || t.IsCompound)
{
t = new DCGTerm(t, ref remainder);
body.Append(t);
}
else if (t.IsVar)
PrologIO.Error("Variable not allowed in DCG-clause: {0}", t.VarName());
else
PrologIO.Error("Illegal term in DCG-clause: {0}", t);
}