Re: Invisible PROMPT2

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