extra/sequences/rotated/rotated.factor

   1 ! Copyright (C) 2012 John Benediktsson
   2 ! See https://factorcode.org/license.txt for BSD license
   3 USING: accessors kernel math sequences ;
   4 IN: sequences.rotated
   5
   6 TUPLE: rotated < sequence-view
   7 { n integer read-only } ;
   8
   9 C: <rotated> rotated
  10
  11 M: rotated virtual@
  12     [ n>> + ] [ seq>> ] bi [
  13         length over 0 < [ + ] [
  14             2dup >= [ - ] [ drop ] if
  15         ] if
  16     ] keep ;
  17
  18 : all-rotations ( seq -- seq' )
  19     dup length <iota> [ <rotated> ] with map ;