Re: [PATCH] prompt: support generic non-visible regions

[Felipe Contreras <felipe.contreras@gmail.com>]

On Wed, Aug 10, 2022 at 1:59 PM Mikael Magnusson <mikachu@gmail.com> wrote:
>
> On 8/10/22, Felipe Contreras <felipe.contreras@gmail.com> wrote:
> > readline assumes anything between \001 (start of header) and \002 (start
> > of text) is non-visible characters.
> >
> > In zsh we do this with `%F{color}`, but we could support
> > `\001\e[31m\002` as well.
> >
> > Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
> > ---
> >
> > I don't know if this is the right way to do it, but in my limited
> > testing it seems to work fine.
>
> The commit message seems a bit confused, %F has nothing to do with
> marking characters as 0-width, rather everything between %{ and %}
> will be treated as such. You can use %{%} (or \001 and \002) to set
> colors via the specific \e [ Ps m code, but also to send any other
> codes handled by the terminal.

If I do PS1='%F{red}foo' putpromptchar() will call
set_colour_attribute(), which eventually calls this:

  if (!bv->dontcount) {
      addbufspc(1);
      *bv->bp++ = Inpar;
  }
  tputs(tgoto(tcstr[tc], colour, colour), 1, putstr);
  if (!bv->dontcount) {
      addbufspc(1);
      *bv->bp++ = Outpar;
  }

I can do the same thing fputs() is doing with PS1=$'\e[31mfoo', but
now zsh will think my prompt is bigger than it actually is and the
shell will be screwed. So I have to put that inside %{%}.

Therefore "%F{red}" = $'%{\e[31m%}'

> That aside, I don't really see a reason to add support for
> bash-specific prompt sequences that are more cumbersome to use than
> the already existing zsh ones. Bash prompts are already completely
> incompatible anyway.

The prompts are not compatible, but the functions used in those prompts can be.

  __git_ps1_test () {
    local branch='master'
    local red=$'\001\e[31m\002'
    local clear=$'\001\e[m\002'
    echo "${red}${branch}${clear}"
  }

The function above works perfectly fine in bash and zsh with my patch,
and I can add $(__git_ps1_test) to both of my prompts.

-- 
Felipe Contreras