public override bool Fallback(char charUnknownHigh, char charUnknownLow, int index)
{
// Double check input surrogate pair
if (!Char.IsHighSurrogate(charUnknownHigh))
throw new ArgumentOutOfRangeException("charUnknownHigh",
Environment.GetResourceString("ArgumentOutOfRange_Range",
0xD800, 0xDBFF));
if (!Char.IsLowSurrogate(charUnknownLow))
throw new ArgumentOutOfRangeException("CharUnknownLow",
Environment.GetResourceString("ArgumentOutOfRange_Range",
0xDC00, 0xDFFF));
// If we had a buffer already we're being recursive, throw, it's probably at the suspect
// character in our array.
if (fallbackCount >= 1)
ThrowLastCharRecursive(Char.ConvertToUtf32(charUnknownHigh, charUnknownLow));
// Go ahead and get our fallback
fallbackCount = strDefault.Length;
fallbackIndex = -1;
return fallbackCount != 0;
}