/**
* Parses a regular expression character set. This method handles
* the contents of the '[...]' construct in a regular expression.
*
* @return the element representing this character set
*
* @throws RegExpException if an error was encountered in the
* pattern string
*/
private Element ParseCharSet()
{
CharacterSetElement charset;
Element elem;
bool repeat = true;
char start;
char end;
if (PeekChar(0) == '^')
{
ReadChar('^');
charset = new CharacterSetElement(true);
}
else
{
charset = new CharacterSetElement(false);
}
while (PeekChar(0) > 0 && repeat)
{
start = (char)PeekChar(0);
switch (start)
{
case ']':
repeat = false;
break;
case '\\':
elem = ParseEscapeChar();
if (elem is StringElement)
{
charset.AddCharacters((StringElement)elem);
}
else
{
charset.AddCharacterSet((CharacterSetElement)elem);
}
break;
default:
ReadChar(start);
if (PeekChar(0) == '-' &&
PeekChar(1) > 0 &&
PeekChar(1) != ']')
{
ReadChar('-');
end = ReadChar();
charset.AddRange(FixChar(start), FixChar(end));
}
else
{
charset.AddCharacter(FixChar(start));
}
break;
}
}
return(charset);
}
/**
* Adds a character subset to this character set.
*
* @param elem the character set to add
*/
public void AddCharacterSet(CharacterSetElement elem)
{
contents.Add(elem);
}