void appendPrefix(char c) {
   checkValid();
   myOffsets.appendPrefix(c);
   synchronized (myList) {
     myPresentableArranger.prefixChanged(this);
   }
   requestResize();
   refreshUi(false, true);
   ensureSelectionVisible(true);
 }
  public boolean performGuardedChange(Runnable change) {
    checkValid();
    assert !myChangeGuard : "already in change";

    myEditor.getDocument().startGuardedBlockChecking();
    myChangeGuard = true;
    boolean result;
    try {
      result = myOffsets.performGuardedChange(change);
    } finally {
      myEditor.getDocument().stopGuardedBlockChecking();
      myChangeGuard = false;
    }
    if (!result || myDisposed) {
      hide();
      return false;
    }
    if (isVisible()) {
      HintManagerImpl.updateLocation(this, myEditor, myUi.calculatePosition().getLocation());
    }
    checkValid();
    return true;
  }
  public boolean showLookup() {
    ApplicationManager.getApplication().assertIsDispatchThread();
    checkValid();
    LOG.assertTrue(!myShown);
    myShown = true;
    myStampShown = System.currentTimeMillis();

    if (ApplicationManager.getApplication().isUnitTestMode()) return true;

    if (!myEditor.getContentComponent().isShowing()) {
      hide();
      return false;
    }

    myAdComponent.showRandomText();

    myUi = new LookupUi(this, myAdComponent, myList, myProject);
    myUi.setCalculating(myCalculating);
    Point p = myUi.calculatePosition().getLocation();
    try {
      HintManagerImpl.getInstanceImpl()
          .showEditorHint(
              this,
              myEditor,
              p,
              HintManager.HIDE_BY_ESCAPE | HintManager.UPDATE_BY_SCROLLING,
              0,
              false,
              HintManagerImpl.createHintHint(myEditor, p, this, HintManager.UNDER)
                  .setAwtTooltip(false));
    } catch (Exception e) {
      LOG.error(e);
    }

    if (!isVisible() || !myList.isShowing()) {
      hide();
      return false;
    }

    DaemonCodeAnalyzer.getInstance(myProject).disableUpdateByTimer(this);

    return true;
  }
  private boolean updateList(boolean onExplicitAction, boolean reused) {
    if (!ApplicationManager.getApplication().isUnitTestMode()) {
      ApplicationManager.getApplication().assertIsDispatchThread();
    }
    checkValid();

    CollectionListModel<LookupElement> listModel = getListModel();

    Pair<List<LookupElement>, Integer> pair;
    synchronized (myList) {
      pair = myPresentableArranger.arrangeItems(this, onExplicitAction || reused);
    }

    List<LookupElement> items = pair.first;
    Integer toSelect = pair.second;
    if (toSelect == null || toSelect < 0 || items.size() > 0 && toSelect >= items.size()) {
      LOG.error(
          "Arranger "
              + myPresentableArranger
              + " returned invalid selection index="
              + toSelect
              + "; items="
              + items);
      toSelect = 0;
    }

    myOffsets.checkMinPrefixLengthChanges(items, this);
    List<LookupElement> oldModel = listModel.toList();

    listModel.removeAll();
    if (!items.isEmpty()) {
      listModel.add(items);
    } else {
      addEmptyItem(listModel);
    }

    updateListHeight(listModel);

    myList.setSelectedIndex(toSelect);
    return !ContainerUtil.equalsIdentity(oldModel, items);
  }