If there aren't any bidi isolation control characters in the paragraph, each level run directly corresponds to one isolating run sequence. (See notes under https://www.unicode.org/reports/tr9/#BD13.) In this case we can take a simplified codepath to process them.
Also, we can avoid the need for a separate pass over the levels array to find level runs by collecting the level runs at the same time as the levels array is being set up, during explicit::compute().
If there aren't any bidi isolation control characters in the paragraph, each level run directly corresponds to one isolating run sequence. (See notes under https://www.unicode.org/reports/tr9/#BD13.) In this case we can take a simplified codepath to process them.
Also, we can avoid the need for a separate pass over the levels array to find level runs by collecting the level runs at the same time as the levels array is being set up, during explicit::compute().