backplane-import/backplanejs — Issue #54: Add ability to obtain sub-expressions from an XPath expression
Author: backplane-import
Created: 2011-10-15 02:52:11+00:00
State: open

### Imported from backplanejs Google Code [issue 54](http://code.google.com/p/backplanejs/issues/detail?id=54).

Reporter
markbirbeck

Date
3 May 2010 8:35:46 PM UTC

The dependency-graph tracks dependencies within XPath expressions, so
as to optimise evaluation. This means that we need a function that returns
an array of sub-expressions, given an XPath statement.

For example, given the XPath statement "a[b]" we would want to know that
the expression is dependent on the value of 'b'.

Similarly, if we had "a[b or c]" we would want to know that the expression
is dependent on both the value of 'b' and the value of 'c'.

These values are currently generated by modifications made to Ajaxslt, so
that the sub-expressions are obtained during ordinary XPath evaluation.

However, since we want to replace Ajaxslt (issue 44 and issue 50) then we'll
need to be able to obtain sub-expressions if we're to keep the
dependency-graph correct.