def each
      @dir.synchronize do
        ensure_reader_open
        (0...@reader.max_doc).each do |i|
          yield @reader[i].load unless @reader.deleted?(i)
        end
      end
    end
def each
      @dir.synchronize do
        ensure_reader_open
        (0...@reader.max_doc).each do |i|
          yield @reader[i].load unless @reader.deleted?(i)
        end
      end
    end
iterate through all documents in the index. This method preloads the
 documents so you don't need to call #load on the document to load all the
 fields.