ui/src/split/Filter.m3


Copyright (C) 1994, Digital Equipment Corp.
 by Steve Glassman, Mark Manasse and Greg Nelson           
<*PRAGMA LL*>

MODULE Filter;

IMPORT VBT, FilterClass, VBTClass;

PROCEDURE Child(v: T): VBT.T RAISES {} =
  BEGIN
    RETURN v.ch
  END Child;

PROCEDURE Replace(v: T; new: VBT.T): VBT.T =
  VAR res := v.ch;
  BEGIN
    IF new # NIL AND new.parent # NIL THEN Crash() END;
    IF new = NIL AND res = NIL THEN RETURN NIL END;
    IF new # NIL THEN
      IF new.st # v.st THEN VBTClass.Rescreen(new, v.st) END
    END;
    v.replace(res, new);
    VBT.Mark(v);
    VBT.NewShape(v);
    RETURN res
  END Replace;

EXCEPTION FatalError;

PROCEDURE Crash () =
  <* FATAL FatalError *>
  BEGIN
    RAISE FatalError;
  END Crash;

BEGIN END Filter.