/// <summary>Processes numeric escaped chars to find out if they are a control character.</summary>
/// <param name="ch">a char</param>
/// <returns>Returns the char directly or as replacement for the escaped sequence.</returns>
private char ProcessChar(char ch)
{
switch (state)
{
case STATE_START: {
if (ch == '&')
{
state = STATE_AMP;
}
return(ch);
}
case STATE_AMP: {
if (ch == '#')
{
state = STATE_HASH;
}
else
{
state = STATE_ERROR;
}
return(ch);
}
case STATE_HASH: {
if (ch == 'x')
{
control = 0;
digits = 0;
state = STATE_HEX;
}
else
{
if ('0' <= ch && ch <= '9')
{
control = JavaUtil.CharacterDigit(ch, 10);
digits = 1;
state = STATE_DIG1;
}
else
{
state = STATE_ERROR;
}
}
return(ch);
}
case STATE_DIG1: {
if ('0' <= ch && ch <= '9')
{
control = control * 10 + JavaUtil.CharacterDigit(ch, 10);
digits++;
if (digits <= 5)
{
state = STATE_DIG1;
}
else
{
state = STATE_ERROR;
}
}
else
{
// sequence too long
if (ch == ';' && Utils.IsControlChar((char)control))
{
state = STATE_START;
return((char)control);
}
else
{
state = STATE_ERROR;
}
}
return(ch);
}
case STATE_HEX: {
if (('0' <= ch && ch <= '9') || ('a' <= ch && ch <= 'f') || ('A' <= ch && ch <= 'F'))
{
control = control * 16 + JavaUtil.CharacterDigit(ch, 16);
digits++;
if (digits <= 4)
{
state = STATE_HEX;
}
else
{
state = STATE_ERROR;
}
}
else
{
// sequence too long
if (ch == ';' && Utils.IsControlChar((char)control))
{
state = STATE_START;
return((char)control);
}
else
{
state = STATE_ERROR;
}
}
return(ch);
}
case STATE_ERROR: {
state = STATE_START;
return(ch);
}
default: {
// not reachable
return(ch);
}
}
}
