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Slightly faster binary-search

db4
Slava Pestov 2009-03-12 20:43:44 -05:00
parent a6b57c495f
commit 91e51f038c
1 changed files with 8 additions and 3 deletions
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basis/binary-search/binary-search.factor
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@ -1,4 +1,4 @@
! Copyright (C) 2008 Slava Pestov. ! Copyright (C) 2008, 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license. ! See http://factorcode.org/license.txt for BSD license.
USING: kernel sequences sequences.private accessors math USING: kernel sequences sequences.private accessors math
math.order combinators hints arrays ; math.order combinators hints arrays ;
@ -16,14 +16,19 @@ IN: binary-search
[ [ from>> ] [ midpoint@ ] bi + ] [ seq>> ] bi [ [ from>> ] [ midpoint@ ] bi + ] [ seq>> ] bi
[ drop ] [ dup ] [ ] tri* nth ; inline [ drop ] [ dup ] [ ] tri* nth ; inline
DEFER: (search)
: keep-searching ( seq quot -- slice )
[ dup midpoint@ ] dip call collapse-slice slice boa (search) ; inline
: (search) ( quot: ( elt -- <=> ) seq -- i elt ) : (search) ( quot: ( elt -- <=> ) seq -- i elt )
dup length 1 <= [ dup length 1 <= [
finish finish
] [ ] [
decide { decide {
{ +eq+ [ finish ] } { +eq+ [ finish ] }
{ +lt+ [ dup midpoint@ head-slice (search) ] } { +lt+ [ [ (head) ] keep-searching ] }
{ +gt+ [ dup midpoint@ tail-slice (search) ] } { +gt+ [ [ (tail) ] keep-searching ] }
} case } case
] if ; inline recursive ] if ; inline recursive