'Read more number fields, or do nothing if parsing is done.
Returns number of new added fields.'

def readMoreFields(self, number):

    if (self._field_generator is None):
        return 0
    oldlen = len(self._fields)
    try:
        for index in xrange(number):
            self._addField(self._field_generator.next())
    except HACHOIR_ERRORS as err:
        if (self._fixFeedError(err) is False):
            raise
    except StopIteration:
        self._stopFeeding()
    return (len(self._fields) - oldlen)
