36 lines
733 B
Factor
36 lines
733 B
Factor
! Copyright (C) 2008, 2010 Slava Pestov.
|
|
! See http://factorcode.org/license.txt for BSD license.
|
|
USING: kernel accessors ;
|
|
IN: boxes
|
|
|
|
TUPLE: box value occupied ;
|
|
|
|
: <box> ( -- box ) box new ;
|
|
|
|
ERROR: box-full box ;
|
|
|
|
: >box ( value box -- )
|
|
dup occupied>>
|
|
[ box-full ] [ t >>occupied value<< ] if ; inline
|
|
|
|
ERROR: box-empty box ;
|
|
|
|
: check-box ( box -- box )
|
|
dup occupied>> [ box-empty ] unless ; inline
|
|
|
|
<PRIVATE
|
|
|
|
: box-unsafe> ( box -- value )
|
|
[ f ] change-value f >>occupied drop ; inline
|
|
|
|
PRIVATE>
|
|
|
|
: box> ( box -- value )
|
|
check-box box-unsafe> ; inline
|
|
|
|
: ?box ( box -- value/f ? )
|
|
dup occupied>> [ box-unsafe> t ] [ drop f f ] if ; inline
|
|
|
|
: if-box? ( box quot -- )
|
|
[ ?box ] dip [ drop ] if ; inline
|