factor/basis/interval-maps/interval-maps.factor

60 lines
1.8 KiB
Factor

! Copyright (C) 2008 Daniel Ehrenberg.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel sequences arrays accessors grouping math.order
sorting binary-search math assocs locals namespaces make ;
IN: interval-maps
TUPLE: interval-map array ;
<PRIVATE
: find-interval ( key interval-map -- interval-node )
[ first <=> ] with search nip ;
: interval-contains? ( key interval-node -- ? )
first2 between? ;
: all-intervals ( sequence -- intervals )
[ [ dup number? [ dup 2array ] when ] dip ] { } assoc-map-as ;
: disjoint? ( node1 node2 -- ? )
[ second ] [ first ] bi* < ;
: ensure-disjoint ( intervals -- intervals )
dup [ disjoint? ] monotonic?
[ "Intervals are not disjoint" throw ] unless ;
: >intervals ( specification -- intervals )
[ suffix ] { } assoc>map concat 3 <groups> ;
PRIVATE>
: interval-at* ( key map -- value ? )
[ drop ] [ array>> find-interval ] 2bi
[ nip ] [ interval-contains? ] 2bi
[ third t ] [ drop f f ] if ;
: interval-at ( key map -- value ) interval-at* drop ;
: interval-key? ( key map -- ? ) interval-at* nip ;
: <interval-map> ( specification -- map )
all-intervals [ [ first second ] compare ] sort
>intervals ensure-disjoint interval-map boa ;
: <interval-set> ( specification -- map )
[ dup 2array ] map <interval-map> ;
:: coalesce ( alist -- specification )
! Only works with integer keys, because they're discrete
! Makes 2array keys
[
alist sort-keys unclip first2 dupd roll
[| oldkey oldval key val | ! Underneath is start
oldkey 1+ key =
oldval val = and
[ oldkey 2array oldval 2array , key ] unless
key val
] assoc-each [ 2array ] bi@ ,
] { } make ;