/// <summary>
/// Constraint that a field value gives to the neighbour field in the given direction.
/// </summary>
public static BimaruValueConstraint GetConstraint(this BimaruValue value, Direction direction)
{
BimaruValueConstraint constraint = BimaruValueConstraint.NO;
if (value.IsShip())
{
if (direction.GetDirectionType() == DirectionType.DIAGONAL)
{
constraint = BimaruValueConstraint.WATER;
}
else if (value == direction.GetFirstShipValue())
{
constraint = BimaruValueConstraint.SHIP;
}
else if (value != BimaruValue.SHIP_MIDDLE &&
value != BimaruValue.SHIP_UNDETERMINED)
{
constraint = BimaruValueConstraint.WATER;
}
}
return(constraint);
}
/// <summary>
/// True, if a new field value does not contradict the old value.
/// For example, the new value WATER would be incompatible with
/// SHIP_UNDETERMINED. However, the new value SHIP_SINGLE would
/// be compatible with SHIP_UNDETERMINED, as it further specifies it.
/// </summary>
public static bool IsCompatibleChangeTo(this BimaruValue oldValue, BimaruValue newValue)
{
return(oldValue == newValue ||
oldValue == BimaruValue.UNDETERMINED ||
(oldValue == BimaruValue.SHIP_UNDETERMINED && newValue.IsShip()));
}