Re: Invisible PROMPT2 - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Invisible PROMPT2
Date
Msg-id 20308.1574097713@sss.pgh.pa.us
Whole thread Raw
In response to Re: Invisible PROMPT2  (Thomas Munro <thomas.munro@gmail.com>)
Responses Re: Invisible PROMPT2
List pgsql-hackers
Thomas Munro <thomas.munro@gmail.com> writes:
> On Mon, Nov 18, 2019 at 1:49 PM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
>> On 2019-Nov-18, Thomas Munro wrote:
>>> Nice idea.  Here's one like that, that just does the counting at the
>>> end and looks out for readline control codes.  It's pretty naive about
>>> what "width" means though: you'll get two spaces for UTF-8 encoded é,
>>> and I suppose a complete implementation would know about the half
>>> width/full width thing for Chinese and Japanese etc.

> Yeah.  Maybe pg_wcswidth() would be OK though, and it's available in
> psql, though I guess you'd have to make a copy with the escaped bits
> stripped out.

Right, you should use pg_wcswidth() or the underlying PQdsplen() function
to compute display width.  The latter might be more convenient since
you could apply it character by character rather than making a copy
of the string.

            regards, tom lane



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