private Diff.Change reBuildDiffIfNeeded() throws FilesTooBigForDiffException {
    if (myChange == TOO_BIG_FILE) throw new FilesTooBigForDiffException();
    if (myChange == null) {
      String[] oldLines = getOldLines();
      String[] newLines = Diff.splitLines(myNewString);
      try {
        myChange = Diff.buildChanges(oldLines, newLines);
      }
      catch (FilesTooBigForDiffException e) {
        myChange = TOO_BIG_FILE;
        throw e;
      }
    }
    return myChange;
  }
private Diff.Change reBuildDiffIfNeeded()