Re: Selecting item from history by position and displaying for editing...

[Chet Ramey]

On 7/25/23 12:19 PM, Sam Habiel wrote:
> Hello there,
>
> Quick Intro: We have an interactive CLI for a language called M used in banking 
> and healthcare... I am working on adding readline integration as a nice to have 
> feature. We are an open source project located over here: 
> https://gitlab.com/YottaDB/DB/YDB.
>
> One thing we have in our previous CLI interpreter is the ability to select a 
> line for editing by position and have it re-display and put the cursor at the 
> end. It works like this:
>
> 1. foo
> 2. boo
>
> > rec 2
>
> > boo<cursor>
>
> I tried to use rl_replace_line(h->line, 1) (h is the history item), then 
> rl_redisplay(), but nothing show up.

You might find it easier to let readline do more of the work. There is a
readline function rl_fetch_history (new in readline-8.2 and documented in
the readline user manual as the fetch-history bindable command) that does
pretty much what you want.

In previous readline versions, it was a vi-mode-only command, used to
implement the `G' command.

The history number is interpreted the same way as the bash `history'
command displays it; rl_fetch_history computes the desired position in
the history and calls rl_get_previous_history to go there.

Since it's a bindable command that uses a user-supplied numeric argument,
you'll have to arrange to set rl_explicit_arg to 1 before calling it as

rl_fetch_history (desired_history_number, 0);

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/