58 lines
1.3 KiB
Factor
58 lines
1.3 KiB
Factor
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! Copyright (C) 2005, 2007 Slava Pestov.
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! See http://factorcode.org/license.txt for BSD license.
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IN: queues
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USING: kernel inspector ;
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TUPLE: entry obj next ;
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: <entry> ( obj -- entry ) f entry construct-boa ;
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TUPLE: queue head tail ;
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: <queue> ( -- queue ) queue construct-empty ;
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: queue-empty? ( queue -- ? ) queue-head not ;
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: (enque) ( entry queue -- )
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[ set-queue-head ] 2keep set-queue-tail ;
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: clear-queue ( queue -- )
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f swap (enque) ;
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: enque ( elt queue -- )
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>r <entry> r> dup queue-empty? [
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(enque)
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] [
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[ queue-tail set-entry-next ] 2keep set-queue-tail
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] if ;
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: clear-entry ( entry -- )
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f over set-entry-obj f swap set-entry-next ;
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: (deque) ( queue -- )
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dup queue-head over queue-tail eq? [
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clear-queue
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] [
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dup queue-head dup entry-next rot set-queue-head
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clear-entry
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] if ;
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TUPLE: empty-queue-error ;
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: empty-queue-error ( -- * )
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\ empty-queue-error construct-empty throw ;
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: deque ( queue -- elt )
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dup queue-empty? [
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empty-queue-error
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] [
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dup queue-head entry-obj >r (deque) r>
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] if ;
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M: empty-queue-error summary
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drop "Empty queue" ;
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: queue-each ( queue quot -- )
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over queue-empty?
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[ 2drop ] [ [ >r deque r> call ] 2keep queue-each ] if ;
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inline
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