Special characters lose their special meaning inside sets of characters.
"-" lose its special meaning if it's placed as the first or last
character.
Follow up to 7c6b66383d.
Special thanks to Hannes Ljungberg for finding multiple implementation
gaps.
Thanks also to Simon Charette, Adam Johnson, and Mariusz Felisiak for
reviews.
Thanks Simon Charette, Tim Graham, and Adam Johnson for reviews.
Co-authored-by: Florian Apolloner <florian@apolloner.eu>
Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
The introduction of the Expression.empty_aggregate_value interface
allows the compilation stage to enable the EmptyResultSet optimization
if all the aggregates expressions implement it.
This also removes unnecessary RegrCount/Count.convert_value() methods.
Disabling the empty result set aggregation optimization when it wasn't
appropriate prevented None returned for a Count aggregation value.
Thanks Nick Pope for the review.
Thanks to Adam Johnson, Carlton Gibson, Mariusz Felisiak, and Raphael
Michel for mentoring this Google Summer of Code 2019 project and
everyone else who helped with the patch.
Special thanks to Mads Jensen, Nick Pope, and Simon Charette for
extensive reviews.
Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
