Method NextSubShapeString

Returns the next chunk of text till the next ',' or ')' (non-inclusive) or EOF. If a '(' is encountered, then it looks past its matching ')', taking care to handle nested matching parenthesis too. It's designed to be of use to subclasses that wish to get the entire subshape at the current position as a string so that it might be passed to other software that will parse it.

Example:

  OUTER(INNER(3, 5))

If this is called when offset is at the first character, then it will return this whole string. If called at the "I" then it will return "INNER(3, 5)". If called at "3", then it will return "3". In all cases, offset will be positioned at the next position following the returned substring.