Hi, I am currently using xerces sax parser for c++, (I use DOM too, but
I think SAX is more relevant here) for processing and displaying fairly
large xml files. Usually I give xerces a filename, and it parses it and
thats all good. But the customer needs more features.

Feature 1: A progress display. I have tried a few times now to find a
way of asking xerces how far through a file it is in bytes, but no
luck. (I did try a per element check, but that involves a whole extra
parse at the start just to count the elements). I have tried using the
LocalFileInputSource, and getting its BinInputStream and calling itc
curPos, but its always 0.

Any ideas?

Feature 2: Loading only a "screenful" of the file at a time. I also
would like some sort of random access functionality, so if the user
scrolls down to 75% of the file, the parser skips forward to that
position and starts reading there, and when they scroll back up it goes
up and reads just that little bit of the file.

I am pretty sure feature 1 is possible with normal xerces sax, but I
have no idea how, the documentation is very sparse, naming the
functions etc but not actually saying what they do or how they should
be used.

For feature 2 it might be more complicated. A colleage mentioned some
other "object models" like xparse and xalaron (not sure how thats
pronounced or spelt) some apache project that parses xml in a random
access fashion.

Anyone got any ideas?

Thanks a lot.