pub fn diff_marks(head: &str, current: &str) -> Vec<(usize, LineMark)>Expand description
Compute per-line gutter marks between the committed text (head) and the
current buffer (current), keyed by current line index (0-based).
Uses a line diff: inserted runs are LineMark::Added, replaced runs are
LineMark::Modified, and a deletion records a LineMark::Deleted at the
current line where the removed text used to be.