Function unicode_bidi::initial_scan

pub fn initial_scan(paragraph: &str, para_level: Option<u8>) -> InitialProperties

Find the paragraph embedding level, and the BidiClass for each character.

http://www.unicode.org/reports/tr9/#The_Paragraph_Level

Also sets the class for each First Strong Isolate initiator (FSI) to LRI or RLI if a strong character is found before the matching PDI. If no strong character is found, the class will remain FSI, and it's up to later stages to treat these as LRI when needed.