subset? ( set1 set2 -- ? )
Factor handbook » The language » Collections » Sets » Operations on sets

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Vocabulary
sets

Inputs

set1	a set
set2	a set

Outputs

?

a boolean

Word description
Tests if every element of set1 is contained in set2.

Notes
If set1 is empty, the result is always t.

Definition

IN: sets

GENERIC: subset? ( set1 set2 -- ? )

Methods

USING: bit-sets kernel sets ;

M: bit-set subset? [ intersect ] keep = ;


USING: generic hash-sets hash-sets.private kernel math sequences
sets ;

M: hash-set subset?
    over hash-set? [
        2dup [ cardinality ] bi@ >
        [ 2drop f ] [ array/tester and-tombstones all? ] if
    ] [ M\ hash-set subset? (call-next-method) ] if ;


USING: generic kernel ranges ranges.private sequences sets ;

M: range subset?
    over range?
    [ over empty? [ 2drop t ] [ dupd intersect-range = ] if ]
    [ M\ range subset? (call-next-method) ] if ;


USING: kernel math sets sets.private ;

M: set subset?
    2dup [ cardinality ] bi@ > [ 2drop f ] [ (subset?) ] if ;