Re: [gforth] words backwards

[Anton Ertl]

On Fri, May 19, 2017 at 06:24:13PM +0200, Bernd Paysan wrote:
> Am Freitag, 19. Mai 2017, 18:09:30 CEST schrieb Dennis Ruffer:
> > Since Forth dictionaries are typically, singly linked lists, it would take
> > memory and time to reverse the order.
> 
> Yes, but on a desktop system, we actually have that memory. And time is even 
> less important.  This does it, by converting the list into an array and then 
> stepping backwards through that array:
> 
> Variable words[]
> 
> : words ( -- )
>     [: words[] dup $[]# swap $[] ! true ;] context @ traverse-wordlist
>     source nip 1+ words[] $@ bounds cell- swap cell- U-DO
>       I @ .word
>     cell -LOOP drop
>     words[] $free ;

And here's a version that uses the data stack as intermediate storage
(with the default data stack size, that is good for 4K words; if you
have more, use gforth -d 1M (or whatever you need)):

: words  ( -- )
    0 ['] true context @ traverse-wordlist 0 begin
        over while
            swap .word repeat
    2drop ;