! See http://factorcode.org/license.txt for BSD license.
USING: accessors alien.c-types alien.data arrays assocs
byte-arrays byte-vectors combinators combinators.short-circuit
-fry io.backend io.binary kernel locals math math.bitwise
-math.constants math.functions math.order math.ranges namespaces
-sequences sequences.private sets summary system vocabs hints
-typed ;
+fry hashtables hashtables.private hints io.backend io.binary
+kernel locals math math.bitwise math.constants math.functions
+math.order math.ranges namespaces sequences sequences.private
+sets summary system typed vocabs ;
IN: random
SYMBOL: system-random-generator
[ length random-integer ] keep nth
] if-empty ;
+M: assoc random >alist random ;
+
+M: hashtable random
+ dup assoc-size [ drop f ] [
+ [ 0 ] [ array>> ] [ random ] tri* 1 + [
+ [ 2dup array-nth tombstone? [ 2 + ] 2dip ] loop
+ ] times [ 2 - ] dip
+ [ array-nth ] [ [ 1 + ] dip array-nth ] 2bi 2array
+ ] if-zero ;
+
: randomize-n-last ( seq n -- seq )
[ dup length dup ] dip - 1 max '[ dup _ > ]
[ [ random ] [ 1 - ] bi [ pick exchange-unsafe ] keep ]