public static bool IsValidLanguageID(char[] value, int startPos, int length)
{
int len = length;
if (len < 2)
{
return(false);
}
bool fSeenLetter = false;
int i = startPos;
XmlCharType xmlCharType = XmlCharType.Instance;
char ch = value[i];
if (xmlCharType.IsLetter(ch))
{
if (xmlCharType.IsLetter(value[++i]))
{
if (len == 2)
{
return(true);
}
len--;
i++;
}
else if (('I' != ch && 'i' != ch) && ('X' != ch && 'x' != ch))
{ //IANA or custom Code
return(false);
}
if (value[i] != '-')
{
return(false);
}
len -= 2;
while (len-- > 0)
{
ch = value[++i];
if (xmlCharType.IsLetter(ch))
{
fSeenLetter = true;
}
else if (ch == '-' && fSeenLetter)
{
fSeenLetter = false;
}
else
{
return(false);
}
}
if (fSeenLetter)
{
return(true);
}
}
return(false);
}