Mojo function 🡭

visual_runs

fn def visual_runs(codepoints: List[Int], base_level: Int) -> List[BidiRun]

The line’s level runs, left to right, each still holding its characters in logical order.

This is rule L2 applied at run granularity rather than to single positions, which is the same reordering: a maximal span of positions at or above some level is always a whole number of level runs, so reversing the runs and then reversing inside each odd-level run reproduces visual_order’s sequence exactly. Splitting it that way is what lets a caller shape each run against its logical neighbors – Arabic joining and ligature formation are defined there, not against the reversed sequence – and reorder afterwards.

Args:

• codepoints (List[Int]): A line’s Unicode codepoints, in logical order.
• base_level (Int): The paragraph’s base embedding level – 0 for LTR, 1 for RTL, typically from detect_base_level.

Returns:

List[BidiRun]: The runs in visual order. A pure left-to-right line is one run.