# File lib/ferret/index.rb, line 402
402:     def doc(*arg)
403:       @dir.synchronize do
404:         id = arg[0]
405:         if id.kind_of?(String) or id.kind_of?(Symbol)
406:           ensure_reader_open()
407:           term_doc_enum = @reader.term_docs_for(@id_field, id.to_s)
408:           return term_doc_enum.next? ? @reader[term_doc_enum.doc] : nil
409:         else
410:           ensure_reader_open(false)
411:           return @reader[*arg]
412:         end
413:       end
414:     end