62 lines
1.4 KiB
Factor
62 lines
1.4 KiB
Factor
! Copyright (C) 2008, 2010 Slava Pestov.
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! See http://factorcode.org/license.txt for BSD license.
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USING: accessors classes.tuple kernel math math.order sequences
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sequences.private ;
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IN: math.ranges
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TUPLE: range
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{ from read-only }
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{ length read-only }
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{ step read-only } ;
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<PRIVATE
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: sign/mod ( x y -- z w )
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[ [ /i ] 2keep pick * - ] keep 0 < [ neg ] when ; inline
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PRIVATE>
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: <range> ( a b step -- range )
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[ over - ] dip
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[ sign/mod 0 < [ 1 + ] unless 0 max ] keep
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range boa ; inline
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M: range length ( seq -- n ) length>> ; inline
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M: range nth-unsafe ( n range -- obj )
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[ step>> * ] keep from>> + ; inline
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! We want M\ tuple hashcode, not M\ sequence hashcode here!
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! sequences hashcode is O(n) in number of elements
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M: range hashcode* tuple-hashcode ;
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INSTANCE: range immutable-sequence
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M: range sum [ length ] [ first ] [ last ] tri + * 2 / ;
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<PRIVATE
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: twiddle ( a b -- a b step ) 2dup > -1 1 ? ; inline
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: (a, ( a b step -- a' b' step ) dup [ + ] curry 2dip ; inline
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: ,b) ( a b step -- a' b' step ) dup [ - ] curry dip ; inline
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PRIVATE>
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: [a,b] ( a b -- range ) twiddle <range> ; inline
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: (a,b] ( a b -- range ) twiddle (a, <range> ; inline
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: [a,b) ( a b -- range ) twiddle ,b) <range> ; inline
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: (a,b) ( a b -- range ) twiddle (a, ,b) <range> ; inline
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: [0,b] ( b -- range ) 0 swap [a,b] ; inline
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: [1,b] ( b -- range ) 1 swap [a,b] ; inline
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: [0,b) ( b -- range ) 0 swap [a,b) ; inline
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: [1,b) ( b -- range ) 1 swap [a,b) ; inline
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