regexp_positions()

Hi,

Finding all matches in a string is convenient using regexp_matches() with the 'g' flag.

But if instead wanting to know the start and end positions of the occurrences,
one would have to first call regexp_matches(...,'g') to get all matches,
and then iterate through the results and search using strpos() and length()
repeatedly to find all start and end positions.

Assuming regexp_matches() internally already have knowledge of the occurrences,
maybe we could add a regexp_ranges() function that returns a two-dimensional array,
with all the [[start,end], ...] positions?

Some other databases have a singular regexp_position() function,
that just returns the start positions for the first match.
but I don't think such function adds much value,
but if adding the pluralis one then maybe the singularis should be added as well,
for completeness, since we have array_position() and array_positions().

I just wanted to share this idea now since there is currently a lot of other awesome work on the regex engine,
and hear what others who are currently thinking a lot about regexes think of the idea.

/Joel