[xml] Streaming XPath Support

["Stanley Poon (spoon)" <spoon cisco com>]

My understanding is that the current support is mainly for the Selector
in XSD.

Are there any plan to enhance the support for streaming Xpath such as
//, *, simple predicates, etc. Also, is this internal feature added
mainly for performance and for reducing memory usage?

Is the current implementation based on some finite state machine
approach with some path sharing?

Stanley