@NotNull
  private Set<VirtualFile> getFilesForFastWordSearch() {
    Set<VirtualFile> resultFiles = VfsUtilCore.createCompactVirtualFileSet();
    for (VirtualFile file : myFilesToScanInitially) {
      if (myFileMask.value(file)) {
        resultFiles.add(file);
      }
    }
    if (!TrigramTextSearchService.useIndexingSearchExtensions()) return resultFiles;
    for (FindInProjectSearchEngine.FindInProjectSearcher searcher : mySearchers) {
      Collection<VirtualFile> virtualFiles = searcher.searchForOccurrences();
      for (VirtualFile file : virtualFiles) {
        if (myFileMask.value(file)) {
          resultFiles.add(file);
        }
      }
    }

    return resultFiles;
  }
@NotNull
  private Set<VirtualFile> getFilesForFastWordSearch()