PsiBuilderImpl.ErrorItem allocateErrorItem() {
    if (!freeErrorItems.isEmpty()) {
      return (PsiBuilderImpl.ErrorItem)list.get(freeErrorItems.popInt());
    }
    
    PsiBuilderImpl.ErrorItem item = new PsiBuilderImpl.ErrorItem(list.size(), builder);
    list.add(item);
    return item;
  }
PsiBuilderImpl.ErrorItem allocateErrorItem()