IMPLEMENTATION MODULE Tabs;(* DEE 2014-01-22/2015-12-01 *)
  CONST TABSPACE = 4;

  PROCEDURE settabs(VAR tabstops: tabtype);
    VAR i: INTEGER;
  BEGIN
    FOR i := 1 TO MAXLINE DO
      tabstops[i] := (i MOD TABSPACE = 1)
    END
  END settabs;

  (*tabpos: return true if col is a tab stop.*)
  PROCEDURE tabpos(col: INTEGER; VAR tabstops: tabtype): BOOLEAN;
  BEGIN
    IF (col > MAXLINE) THEN RETURN TRUE
    ELSE RETURN tabstops[col]
    END
  END tabpos;

  (*Software Tools in Pascal, exercise 1-7a*)
  PROCEDURE setTabPos(col: INTEGER): BOOLEAN;
  BEGIN
    IF (col > MAXLINE) THEN RETURN TRUE
    ELSIF (col MOD TABSPACE = 1) THEN RETURN TRUE
    ELSE RETURN FALSE
    END
  END setTabPos;

END Tabs.