Expand small value sets to all case permutations in SearchValues<string> #98902
+79
−2
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Implements #98791 (comment)
If we have a set of values like
["ab", "c!"]
, we can expand it to["ab", "Ab" "aB", "AB", "c!", "C!"]
and switch to case-sensitive searching.As long as we're making use of buckets that would otherwise have been empty, this is going to be an improvement as the prefix search loop is a bit simpler due to not needing to deal with casing. In the below benchmark, it means eliminating this step from the loop.
This optimization is a bit niche (unlikely to be applicable often), but it's really cheap to check whether it could apply, and can help cases with many non-letter characters in their prefixes.