deque-empty? ( deque -- ? )
Factor handbook » The language » Collections » Deques

Prev:	peek-back ( deque -- obj )
Next:	deque-member? ( value deque -- ? )

Vocabulary
deques

Inputs

deque

a deque

Outputs

?

a boolean

Generic word contract
Returns true if a deque is empty.

Notes
This operation is O(1).

Examples

USING: deques prettyprint unrolled-lists ; <unrolled-list> deque-empty? .
t

Definition

IN: deques

GENERIC: deque-empty? ( deque -- ? )

Methods

USING: accessors deques dlists kernel ;

M: dlist deque-empty? front>> not ; inline


USING: accessors deques search-deques ;

M: search-deque deque-empty? deque>> deque-empty? ;


USING: accessors deques kernel unrolled-lists ;

M: unrolled-list deque-empty?
    dup [ front>> ] [ back>> ] bi dup [
        eq?
        [ [ front-pos>> ] [ back-pos>> ] bi eq? ] [ drop f ] if
    ] [ 3drop t ] if ;