/// <summary>
/// Checks if the subrule will be unapplied vacuously. Vacuous unapplication means that
/// the subrule will actually make changes to the phonetic shape. This is important to know
/// for self-opaquing, simultaneously applying subrules, since we unapply these subrules
/// until they unapply nonvacuously.
/// </summary>
/// <param name="match">The match.</param>
/// <param name="dir">The direction.</param>
/// <returns></returns>
bool CheckVacuousUnapplication(Match match, Direction dir)
{
PhoneticPatternNode rhsNode = m_rhs.GetFirst(dir);
IList <PhoneticShapeNode> nodes = match.EntireMatch;
int i = 0;
while (i < nodes.Count)
{
if (Type == ChangeType.EPENTHESIS)
{
// for epenthesis subrules, simply check if the epenthesized segment is
// already marked as optional
if (!nodes[i++].IsOptional)
{
return(true);
}
}
else
{
switch (rhsNode.Type)
{
case PhoneticPatternNode.NodeType.SIMP_CTXT:
SimpleContext ctxt = rhsNode as SimpleContext;
Segment seg = nodes[i] as Segment;
if (ctxt.IsUnapplicationVacuous(seg, match.VariableValues))
{
return(true);
}
i++;
break;
case PhoneticPatternNode.NodeType.BDRY_CTXT:
break;
}
rhsNode = rhsNode.GetNext(dir);
}
}
return(false);
}
