bug#71716: [PATCH] Add new completion-preview-insert-{word, sexp} commands

[Eli Zaretskii]

> Cc: 71716@debbugs.gnu.org
> From: Jules Tamagnan <jtamagnan@gmail.com>
> Date: Sun, 23 Jun 2024 15:08:43 -0700
> 
> +(defcustom completion-preview-context-variables '(char-script-table
> +                                                  forward-sexp-function
> +                                                  
> find-word-boundary-function-table
> +                                                  inhibit-field-text-motion)
> +  "List of variables which can change the functionality of `forward-word'
> +or `forward-sexp'."
> +  :type '(repeat (variable :tag "Variable" :value char-script-table))
> +  :version "30.1")

I don't think we will install new features on the emacs-30 branch, so
this :version tag should be updated.  And the previous one as well, I
guess.

> +(defun completion-preview--determine-substring (command string)
> +  "A helper function to determine what parts of a STRING come before and
> +after the point when a certain COMMAND has been performed on that STRING"

The first line of a doc string should be a single complete sentence.
That's because some help commands, like "M-x apropos", show only the
first line of the doc strings.