bug#33309: Add flatten-list?

[Basil L. Contovounesios]

Alex Branham <alex.branham@gmail.com> writes:

> Basil, if you want git author credit, feel free to use yourself as the
> author since you wrote the function :-)

No need, thanks. :)

> diff --git a/lisp/subr.el b/lisp/subr.el
> index d3bc007293..52ac475cc6 100644
> --- a/lisp/subr.el
> +++ b/lisp/subr.el
> @@ -5448,5 +5448,25 @@ unmsys--file-name
>      (setq file (concat (substring file 1 2) ":" (substring file 2))))
>    file)
>  
> +(defun flatten-tree (tree)
> +  "Take TREE and \"flatten\" it.
> +This always returns a list containing all the elements of TREE.
> +Dotted pairs are flattened as well, and nil elements are removed.
> +
> +\(flatten-tree \\='(1 (2 . 3) nil (4 5 (6)) 7))
> +=> (1 2 3 4 5 6 7)"
> +    (let (elems)
> +    (setq tree (list tree))
> +    (while (let ((elem (pop tree)))
> +             (cond ((consp elem)
> +                    (setq tree (cons (car elem) (cons (cdr elem) tree))))
> +                   (elem
> +                    (push elem elems)))
> +             tree))

Is it just me, or is the indentation a bit off here?

Thanks,

-- 
Basil