push-front* ( obj deque -- node )
Factor handbook » The language » Collections » Deques

Prev:	deque-member? ( value deque -- ? )
Next:	push-back* ( obj deque -- node )

Vocabulary
deques

Inputs

obj	an object
deque	a deque

Outputs

node

a node

Generic word contract
Push the object onto the front of the deque and return the newly created node.

Notes
This operation is O(1).

Examples

USING: deques dlists kernel prettyprint ; 33 <hashed-dlist> push-front* node-value .
33

Definition

IN: deques

GENERIC: push-front* ( obj deque -- node )

Methods

USING: accessors deques dlists kernel ;

M: dlist push-front*
    [ f swap <dlist-node> dup dup set-next-prev ] change-front
    set-back-to-front ;


USING: accessors assocs deques kernel search-deques ;

M: search-deque push-front*
    2dup assoc>> at*
    [ 2nip ]
    [ drop [ deque>> push-front* dup ] [ assoc>> set-at ] 2bi ]
    if ;


USING: accessors deques kernel unrolled-lists
unrolled-lists.private ;

M: unrolled-list push-front*
    dup [ front>> ] [ front-pos>> 0 eq? not ] bi
    [ drop ] [ and ] 2bi
    [ push-front/existing ] [ drop push-front/new ] if f ;