count-neighbors ( grid -- counts )

Vocabulary

game-of-life

Inputs

grid

an object

Outputs

counts

an object

Definition

USING: arrays bit-arrays byte-arrays kernel kernel.private math
sequences sequences.private ;

IN: game-of-life

:: count-neighbors ( grid -- counts )
    grid grid-dim { fixnum fixnum } declare
    :> ( rows cols ) rows [ cols <byte-array> ] replicate
    :> neighbors grid { array } declare [| row j |
        j rows adjacent-indices
        [ neighbors nth-unsafe { byte-array } declare ] tri@
        :> ( above same below ) row { bit-array } declare [|
        cell i |
            cell [
                i cols adjacent-indices
                [ [ above ~quotation~ change-nth-unsafe ] tri@ ] 
                [
                    nip
                    [ same ~quotation~ change-nth-unsafe ] bi@
                ]
                [ [ below ~quotation~ change-nth-unsafe ] tri@ ]
                3tri
            ] when
        ] each-index
    ] each-index neighbors ;