Function _on_bytes_to_edits

pythonx/UltiSnips/change_provider.py:198–273

Translate one on_bytes event to edit commands. event: (start_row, start_col, old_end_row, old_end_col, new_end_row, new_end_col) Note: column values are UTF-8 BYTE offsets (Neovim convention). old_lines: remembered buffer slice (list of strings, snippet region) new_buf: current

(event, old_lines, new_buf, snippet_start)

def _on_bytes_to_edits(event, old_lines, new_buf, snippet_start):
    """Translate one on_bytes event to edit commands.

    event: (start_row, start_col, old_end_row, old_end_col, new_end_row, new_end_col)
        Note: column values are UTF-8 BYTE offsets (Neovim convention).
    old_lines: remembered buffer slice (list of strings, snippet region)
    new_buf: current full buffer (for reading inserted text)
    snippet_start: absolute line number of snippet start

    Returns list of edit commands using CHARACTER columns (UltiSnips
    convention), or None if the event extends beyond available data
    (caller should fall back to detect_edits/diff).
    """
    start_row, start_col_b, old_end_row, old_end_col_b, new_end_row, new_end_col_b = (
        event
    )
    rel_row = start_row - snippet_start

    # Bounds checks: change must be within the snippet region we know about
    if rel_row < 0 or rel_row >= len(old_lines):
        return None
    if old_end_row > 0 and rel_row + old_end_row >= len(old_lines):
        return None
    if new_end_row > 0 and start_row + new_end_row >= len(new_buf):
        return None

    cmds = []
    # The line at start_row exists in both old and new (change starts AT this
    # row, not above), so byte→char conversion at start_col_b yields the same
    # character position in both.
    start_col = _byte_to_char_col(old_lines[rel_row], start_col_b)

    # --- Deletion ---
    if old_end_row == 0 and old_end_col_b > 0:
        end_col = _byte_to_char_col(old_lines[rel_row], start_col_b + old_end_col_b)
        deleted = old_lines[rel_row][start_col:end_col]
        cmds.append(("D", start_row, start_col, deleted))
    elif old_end_row > 0:
        # Multi-line deletion — all at (start_row, start_col)
        rest = old_lines[rel_row][start_col:]
        if rest:
            cmds.append(("D", start_row, start_col, rest))
        cmds.append(("D", start_row, start_col, "\n"))
        for i in range(1, old_end_row):
            content = old_lines[rel_row + i]
            if content:
                cmds.append(("D", start_row, start_col, content))
            cmds.append(("D", start_row, start_col, "\n"))
        last_line = old_lines[rel_row + old_end_row]
        last_end_col = _byte_to_char_col(last_line, old_end_col_b)
        last = last_line[:last_end_col]
        if last:
            cmds.append(("D", start_row, start_col, last))

    # --- Insertion ---
    if new_end_row == 0 and new_end_col_b > 0:
        end_col = _byte_to_char_col(new_buf[start_row], start_col_b + new_end_col_b)
        inserted = new_buf[start_row][start_col:end_col]