Function byte_column_to_position 

pub fn byte_column_to_position(
    source: &str,
    row: usize,
    byte_column: usize,
    byte_offset: usize,
) -> Position

Convert a tree-sitter node boundary into a Position, without rescanning the file.

byte_offset_to_position walks from byte 0 on every call, which is fine once per request but quadratic when a whole syntax tree is converted node by node. Tree-sitter already reports row and a byte_column measured from the start of that row, so the line begins at byte_offset - byte_column and only that prefix has to be measured.

Taking row from tree-sitter also keeps the result in the same line model as the tree being walked; TextIndex treats U+2028/U+2029 as line terminators and tree-sitter does not, so deriving the row here instead would put symbols on a different line than the node they came from.