forward-cursor? ( object -- ? )

Vocabulary

cursors

Inputs and outputs

object	an object
?	a boolean

Word description

Tests if the object is an instance of the forward-cursor class.

Definition

USING: classes.tuple.private kernel slots.private ;

IN: cursors

: forward-cursor? ( object -- ? )
    dup dup tuple? [
        layout-of
        7
        slot
        dup
        \ zip-cursor
        eq?
        [ drop t ]
        [
            dup \ hashtable-cursor eq?
            [ drop t ] [
                dup \ map-cursor eq?
                [ drop t ] [ \ hash-set-cursor eq? ] if
            ] if
        ]
        if
    ] [ drop f ] if
    [ drop t ] [
        dup stream-cursor?
        [ drop t ] [ bidirectional-cursor? ] if
    ] if ;