[xml] GSoC using libxml for indexing XML document

[Tomáš Pospíšil <killteck seznam cz>]

Hi Daniel and all hackers,

I'm GSoC student creating new XML index in PostgreSQL which use LibXML for handling XML documents. My idea 
about index is about to use node offsets and Patricia Trie for mapping structural information to our internal 
representation tree index. So how can I get offset of nodes?

P.S. I already searched history and understand that libXml is not implemented for this kind of XML handling, 
but my use scenario is quite different that typical usage. Daniel suggested xmlByteConsumed and 
xmlTextReaderByteConsumed by I see that it's not exactly what I need.

Thanks Tomas