[ANN] push-decoding of bencoded messages

[Jorge <xxopxe@...>]

Bencode is a lightweight serialization protocol, with several 
interesting properties (I found a nice writeup on bencode here: 
http://jeelabs.org/2012/10/05/whats-the-deal-with-bencode/).

Usually, what you do to work with bencode is to go with 
https://bitbucket.org/wilhelmy/lua-bencode/ .

But, suppose you have the following scenario:

* You are reading rather big objects in the relation to the total memory 
you have.
* You are receiving rather long strings, but the reading is made in tiny 
chunks (say, over a slow serial line).
* You can process said chunks as they arrive, say, compute a CRC or feed 
it to load()

(Bear with my, this could happen)

In these cases a push-parser could be more adequate. There is a 
coroutine based example at 
http://jeelabs.org/2012/10/18/push-scannin-with-coroutines/, but it's 
blocking.

So I wrote mine own, available here:

https://github.com/xopxe/lua-bencode-push

Internally, it's a tail-call based state machine. It attempts to fiddle 
as little as possible with strings (no concatenations). It returns 
string in fragments as they arrive, signalling the end with an empty 
string. It also pushes the total string length prior to pushing the 
fragments, if you're interested in such a thing.

It misses any kind of error checks, and no encoder is provided (yet).

Greetings,

Jorge