PROCEDURE Expand_Tabs(VAR Line : Line_Type);
{
This procedure expands tabs to columns: 9, 17, 25, 33, ...
}

CONST
 Tab : CHAR = ^I;

VAR
 Spaces : STRING[8];
 Len : INTEGER;

BEGIN
 I := 1;
 WHILE I <= LENGTH(Line) DO
  BEGIN
   IF Line[I] = Tab THEN
    BEGIN
     Spaces :=
      COPY('        ', 1, ((I - 1) DIV 8 + 1) * 8 - I + 1);
     Len := LENGTH(Line);
     IF I <> 1 THEN
      IF I <> Len THEN
       Line := CONCAT(COPY(Line, 1, I - 1), Spaces,
        COPY(Line, I + 1, Len - I))
      ELSE
       Line := CONCAT(COPY(Line, 1, I - 1), Spaces)
     ELSE
      IF I <> Len THEN
       Line := CONCAT(Spaces, COPY(Line, I + 1, Len - I))
      ELSE
       Line := Spaces;
     I := ((I - 1) DIV 8 + 1) * 8;
    END;
   I := I + 1;
   IF I > Max_line_length THEN
    BEGIN
     WRITELN('Error: Maximum line length exceeded while expanding tabs!');
     HALT;
    END;
  END;
END;