Re: [PATCH] Feature improvement for CLOSE, FETCH, MOVE tab completion - Mailing list pgsql-hackers

On 2021/01/07 17:28, Shinya11.Kato@nttdata.com wrote:
>> On Thu, Jan 7, 2021 at 1:30 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>>>
>>> On 2021/01/07 12:42, Masahiko Sawada wrote:
>>>> On Thu, Jan 7, 2021 at 10:59 AM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>>>>>
>>>>> On 2021/01/07 10:01, Masahiko Sawada wrote:
>>>>>> On Wed, Jan 6, 2021 at 3:37 PM <Shinya11(dot)Kato(at)nttdata(dot)com> wrote:
>>>>>>>
>>>>>>>> +#define Query_for_list_of_cursors \
>>>>>>>> +" SELECT name FROM pg_cursors"\
>>>>>>>>
>>>>>>>> This query should be the following?
>>>>>>>>
>>>>>>>> " SELECT pg_catalog.quote_ident(name) "\
>>>>>>>> " FROM pg_catalog.pg_cursors "\
>>>>>>>> " WHERE substring(pg_catalog.quote_ident(name),1,%d)='%s'"
>>>>>>>>
>>>>>>>> +/* CLOSE */
>>>>>>>> + else if (Matches("CLOSE"))
>>>>>>>> + COMPLETE_WITH_QUERY(Query_for_list_of_cursors
>>>>>>>> + " UNION ALL SELECT 'ALL'");
>>>>>>>>
>>>>>>>> "UNION ALL" should be "UNION"?
>>>>>>>
>>>>>>> Thank you for your advice, and I corrected them.
>>>>>>>
>>>>>>>>> + COMPLETE_WITH_QUERY(Query_for_list_of_cursors
>>>>>>>>> + " UNION SELECT 'ABSOLUTE'"
>>>>>>>>> + " UNION SELECT 'BACKWARD'"
>>>>>>>>> + " UNION SELECT 'FORWARD'"
>>>>>>>>> + " UNION SELECT 'RELATIVE'"
>>>>>>>>> + " UNION SELECT 'ALL'"
>>>>>>>>> + " UNION SELECT 'NEXT'"
>>>>>>>>> + " UNION SELECT 'PRIOR'"
>>>>>>>>> + " UNION SELECT 'FIRST'"
>>>>>>>>> + " UNION SELECT 'LAST'"
>>>>>>>>> + " UNION SELECT 'FROM'"
>>>>>>>>> + " UNION SELECT 'IN'");
>>>>>>>>>
>>>>>>>>> This change makes psql unexpectedly output "FROM" and "IN" just after "FETCH".
>>>>>>>>
>>>>>>>> I think "FROM" and "IN" can be placed just after "FETCH". According to
>>>>>>>> the documentation, the direction can be empty. For instance, we can do
>>>>>>>> like:
>>>>>>>
>>>>>>> Thank you!
>>>>>>>
>>>>>>>> I've attached the patch improving the tab completion for DECLARE as an
>>>>>>>> example. What do you think?
>>>>>>>>
>>>>>>>> BTW according to the documentation, the options of DECLARE statement
>>>>>>>> (BINARY, INSENSITIVE, SCROLL, and NO SCROLL) are order-sensitive.
>>>>>>>>
>>>>>>>> DECLARE name [ BINARY ] [ INSENSITIVE ] [ [ NO ] SCROLL ]
>>>>>>>> CURSOR [ { WITH | WITHOUT } HOLD ] FOR query
>>>>>>>>
>>>>>>>> But I realized that these options are actually order-insensitive. For
>>>>>>>> instance, we can declare a cursor like:
>>>>>>>>
>>>>>>>> =# declare abc scroll binary cursor for select * from pg_class;
>>>>>>>> DECLARE CURSOR
>>>>>>>>
>>>>>>>> The both parser code and documentation has been unchanged from 2003.
>>>>>>>> Is it a documentation bug?
>>>>>>>
>>>>>>> Thank you for your patch, and it is good.
>>>>>>> I cannot find the description "(BINARY, INSENSITIVE, SCROLL, and NO SCROLL) are order-sensitive."
>>>>>>> I saw "The key words BINARY, INSENSITIVE, and SCROLL can appear in any order." , according to the
documentation.
>>>>>>
>>>>>> Thanks, you're right. I missed that sentence. I still don't think the
>>>>>> syntax of DECLARE statement in the documentation doesn't match its
>>>>>> implementation but I agree that it's order-insensitive.
>>>>>>
>>>>>>> I made a new patch, but the amount of codes was large due to order-insensitive.
>>>>>>
>>>>>> Thank you for updating the patch!
>>>>>>
>>>>>> Yeah, I'm also afraid a bit that conditions will exponentially
>>>>>> increase when a new option is added to DECLARE statement in the
>>>>>> future. Looking at the parser code for DECLARE statement, we can put
>>>>>> the same options multiple times (that's also why I don't think it
>>>>>> matches). For instance,
>>>>>>
>>>>>> postgres(1:44758)=# begin;
>>>>>> BEGIN
>>>>>> postgres(1:44758)=# declare test binary binary binary cursor for
>>>>>> select * from pg_class;
>>>>>> DECLARE CURSOR
>>>>>>
>>>>>> So how about simplify the above code as follows?
>>>>>>
>>>>>> @@ -3005,8 +3014,23 @@ psql_completion(const char *text, int start, int end)
>>>>>> else if (Matches("DECLARE", MatchAny))
>>>>>> COMPLETE_WITH("BINARY", "INSENSITIVE", "SCROLL", "NO SCROLL",
>>>>>> "CURSOR");
>>>>>> + /*
>>>>>> + * Complete DECLARE <name> with one of BINARY, INSENSITIVE, SCROLL,
>>>>>> + * NO SCROLL, and CURSOR. The tail doesn't match any keywords for
>>>>>> + * DECLARE, assume we want options.
>>>>>> + */
>>>>>> + else if (HeadMatches("DECLARE", MatchAny, "*") &&
>>>>>> + TailMatches(MatchAnyExcept("CURSOR|WITH|WITHOUT|HOLD|FOR")))
>>>>>> + COMPLETE_WITH("BINARY", "INSENSITIVE", "SCROLL", "NO SCROLL",
>>>>>> + "CURSOR");
>>>>>
>>>>> This change seems to cause "DECLARE ... CURSOR FOR SELECT <tab>" to
>>>>> unexpectedly output BINARY, INSENSITIVE, etc.
>>>>
>>>> Indeed. Is the following not complete but much better?
>>>
>>> Yes, I think that's better.
>>>
>>>>
>>>> @@ -3002,11 +3011,18 @@ psql_completion(const char *text, int start, int end)
>>>> " UNION SELECT 'ALL'");
>>>>
>>>> /* DECLARE */
>>>> - else if (Matches("DECLARE", MatchAny))
>>>> - COMPLETE_WITH("BINARY", "INSENSITIVE", "SCROLL", "NO SCROLL",
>>>> - "CURSOR");
>>>> + /*
>>>> + * Complete DECLARE <name> with one of BINARY, INSENSITIVE, SCROLL,
>>>> + * NO SCROLL, and CURSOR. If the tail is any one of options, assume we
>>>> + * still want options.
>>>> + */
>>>> + else if (Matches("DECLARE", MatchAny) ||
>>>> + TailMatches("BINARY|INSENSITIVE|SCROLL|NO"))
>>>> + COMPLETE_WITH("BINARY", "INSENSITIVE", "SCROLL", "NO SCROLL", "CURSOR");
>>>
>>> This change seems to cause "DECLARE ... NO <tab>" to unexpectedly output
>>> "NO SCROLL". Also this change seems to cause "COPY ... (FORMAT BINARY <tab>"
>>> to unexpectedly output BINARY, CURSOR, etc.
>>
>> Oops, I missed the HeadMatches(). Thank you for pointing this out.
>>
>> I've attached the updated patch including Kato-san's changes. I
>> think the tab completion support for DECLARE added by this patch
>> works better.

Thanks!

+    /* Complete with more options */
+    else if (HeadMatches("DECLARE", MatchAny, "BINARY|INSENSITIVE|SCROLL|NO") &&
+             TailMatches("BINARY|INSENSITIVE|SCROLL|NO"))

Seems "MatchAny, "BINARY|INSENSITIVE|SCROLL|NO"" is not necessary. Right?

If this is true, I'd like to refactor the code a bit.
What about the attached patch?

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION