What is the general goal of the feature?
Add ability to 'parse' elements out of a string based on a delimiter, eg "123.45,67.8"
What are some example use cases for this feature?
Presently you can only extract components from a string using the
substr(string,start,end) function, which require knows the precise start (and end) location within the string. This is only workable if you know apriori the index of the delimiter, eg known fixed prefix like "From:" where the delimiter is always going to be the 5th character. However, this is not the case in general, and there is no equivalent
index(string,char) XPath function which could otherwise be used to determine the index position of the delimiter.
XPath 2 defines the substring-before() and substring-after() functions for this purpose (where a single character delimiter is just the simplest case). These are already supported by Enketo; they would need to be implemented for javaRosa (and libxml2).
[note, you can actually exploit the existing ODK
selected-at() function to effectively parse an non-select string result based on a space delimiter. But this only works for space, and is a bit of a kludge in any case]
What can you contribute to making this feature a reality?
I can do C implementation for libxml2, and probably java one for javaRosa too.