peek-front* ( deque -- obj ? )

Vocabulary

deques

Inputs

deque

a deque

Outputs

obj	an object
?	a boolean

Generic word contract

Returns the object at the front of the deque, and a boolean indicating if an object was found.

Definition

IN: deques

GENERIC: peek-front* ( deque -- obj ? )

Methods

USING: accessors deques dlists kernel ;

M: dlist peek-front* front>> [ obj>> t ] [ f f ] if* ;


USING: accessors deques search-deques ;

M: search-deque peek-front* deque>> peek-front* ;


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

M: unrolled-list peek-front*
    dup front>>
    [ [ front-pos>> ] dip data>> nth-unsafe t ] [ drop f f ] if*
    ;