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bloom-filters: minor style improvements.

db4
John Benediktsson 2013-04-03 15:20:49 -07:00
parent 2e40bffccf
commit 8c8d8d0c14
1 changed files with 6 additions and 9 deletions
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15
extra/bloom-filters/bloom-filters.factor
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@ -72,8 +72,8 @@ ERROR: invalid-n-objects n-objects ;
! If the number of hashes isn't positive, we haven't found
! anything smaller than the identity configuration.
: validate-sizes ( 2seq -- )
first 0 <= [ capacity-error ] when ;
: check-capacity ( 2seq -- 2seq )
dup first 0 <= [ capacity-error ] when ;
! The consensus on the tradeoff between increasing the number of
! bits and increasing the number of hash functions seems to be
@ -83,14 +83,11 @@ ERROR: invalid-n-objects n-objects ;
! seen any usage studies from the implementations that made this
! tradeoff to support it, and I haven't done my own, but we'll
! go with it anyway.
!
: size-bloom-filter ( error-rate number-objects -- number-hashes number-bits )
[ n-hashes-range identity-configuration ] 2dip
'[ dup [ _ _ bits-to-satisfy-error-rate ]
call 2array smaller-second ]
reduce
dup validate-sizes
first2 ;
[ n-hashes-range identity-configuration ] 2dip '[
dup _ _ bits-to-satisfy-error-rate
2array smaller-second
] reduce check-capacity first2 ;
: check-n-objects ( n-objects -- n-objects )
dup 0 <= [ invalid-n-objects ] when ;