factor/extra/sets/extras/extras.factor

! Copyright (C) 2013 Doug Coleman.
! See http://factorcode.org/license.txt for BSD license.
USING: assocs fry hash-sets kernel locals sequences
sequences.extras sets ;
IN: sets.extras

: setwise-xor ( seq1 seq2 -- set )
    [ append members ] [ intersect ] 2bi diff ;

: symmetric-diff ( set1 set2 -- set )
    [ union ] [ intersect ] 2bi diff ;

: proper-subset? ( set1 set2 -- ? )
    2dup subset? [ swap subset? not ] [ 2drop f ] if ;

: superset? ( set1 set2 -- ? )
    swap subset? ;

: disjoint? ( set1 set2 -- ? )
    intersects? not ;

:: non-repeating ( seq -- seq' )
    HS{ } clone :> visited
    0 seq new-resizable :> accum
    seq [
        accum over visited ?adjoin
        [ push ] [ remove-first! drop ] if
    ] each accum seq like ;

: adjoin-at* ( value key assoc -- set )
    [ [ HS{ } clone ] unless* [ adjoin ] keep dup ] change-at ;

: mapped-set ( ... seq quot: ( ... elt -- ... newelt ) -- ... set )
    over length <hash-set> [
        '[ @ _ adjoin ] each
    ] keep ; inline

: duplicates-by ( seq quot: ( elt -- key ) -- seq' )
    over length <hash-set> '[ @ _ ?adjoin ] filter ; inline