/// <summary>
/// If arg is another Functor, then succeed (yield once) if this and arg have the
/// same name and all functor args unify, otherwise fail (don't yield).
/// If arg is a Variable, then call its unify to unify with this.
/// Otherwise fail (don't yield).
/// </summary>
/// <param name="arg"></param>
/// <returns></returns>
public IEnumerable <bool> unify(object arg)
{
arg = YP.getValue(arg);
if (arg is Functor)
{
Functor argFunctor = (Functor)arg;
if (_name.Equals(argFunctor._name))
{
return(YP.unifyArrays(_args, argFunctor._args));
}
else
{
return(YP.fail());
}
}
else if (arg is Variable)
{
return(((Variable)arg).unify(this));
}
else
{
return(YP.fail());
}
}
public bool lessThan(Functor functor)
{
// Do the equal check first since it is faster.
if (!_name.Equals(functor._name))
return _name.lessThan(functor._name);
if (_args.Length != functor._args.Length)
return _args.Length < functor._args.Length;
for (int i = 0; i < _args.Length; ++i)
{
if (!YP.termEqual(_args[i], functor._args[i]))
return YP.termLessThan(_args[i], functor._args[i]);
}
return false;
}