Test for a sentence boundary before UTF-16 index position using SFML's Unicode rules. The start and end are boundaries; the middle of a surrogate pair is not. Isolated surrogate code units are treated as U+FFFD.
Test for a word boundary before UTF-16 index position using SFML's Unicode rules. The start and end are boundaries; the middle of a surrogate pair is not. Isolated surrogate code units are treated as U+FFFD.
Test for a grapheme boundary before UTF-16 index position using SFML's Unicode rules. The start and end are boundaries; the middle of a surrogate pair is not. Isolated surrogate code units are treated as U+FFFD.