Re: [Flashforth-devel] For-next and do-loop practise

[Mikael N. <mik...@pp...>]

Hi,
This is my untested quick take on this.

Of course if you are translating DO LOOP code
mechanically a direct template is good to have.

In general in FF I would not write code that
loops from A to B.

Usually I have a starting value A and a count N
Much code that uses do loops has the same and
must convert it to a A B=A+N pair before using the DO LOOP.

P is just a special variable which is saved on the return stack to
support nesting. J is implemented below without
nesting support. By saving it on the return stack
before FOR, it can also be made nestable.

-- Mike

On 16.6.2011 16:36, om1zz wrote:
> Hi, in order not to invent wheel (and maybe quite useful for other
> ffters too) I would ask the practisioners for an advice how to best
> translate following constructs into FF's for-next:
>
> a)   B A do ... loop
        B A - 1- for ... next
>
>
> b)   B A do I ... loop
        B A dup !p>r - 1- for @p p+ ... next r>p
>
>
> c)   D C do
>          B A do ... I J ... loop
>      loop

        variable j
        D C dup !p>r - 1- for
            B A dup j ! - 1- for
                @p j @ ... p+ 1 j +!
            next r>p
        next
>
>
> d)   B A do ... K +loop
        B A -  K / for ... next
>
>
> e)   D C do
>          B A do ... I J ... K +loop
>      L +loop

        variable j
        D C dup !p>r - K / for
            B A dup j ! L / for
                @p j @ ... K p++ L j +!
            next r>p
        next

>
> f)   B A ?do ... loop
        B A - dup if 1- for ... next then
>
>
> Thanks,
> I.
>
>