peek-back* ( deque -- obj ? )

Vocabulary

deques

Inputs

deque

a deque

Outputs

obj	an object
?	a boolean

Generic word contract

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

Definition

IN: deques

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

Methods

USING: accessors deques dlists kernel ;

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


USING: accessors deques search-deques ;

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


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

M: unrolled-list peek-back*
    dup back>>
    [ [ back-pos>> 1 - ] dip data>> nth-unsafe t ] [ drop f f ]
    if* ;