extra/sequences/padded/padded.factor

   1 ! Copyright (C) 2020 John Benediktsson
   2 ! See http://factorcode.org/license.txt for BSD license
   3 USING: accessors kernel math math.order sequences sequences.private ;
   4 IN: sequences.padded
   5
   6 TUPLE: padded
   7 { underlying sequence read-only }
   8 { length integer read-only }
   9 { elt object read-only } ;
  10
  11 TUPLE: padded-head < padded ;
  12 TUPLE: padded-tail < padded ;
  13
  14 C: <padded-head> padded-head
  15 C: <padded-tail> padded-tail
  16
  17 M: padded length
  18     [ underlying>> length ] [ length>> ] bi max ;
  19
  20 M: padded-head nth-unsafe
  21     [ [ length>> ] [ underlying>> ] bi [ length [-] - ] keep ] keep
  22     2over bounds-check? [ drop nth-unsafe ] [ 2nip elt>> ] if ;
  23
  24 M: padded-tail nth-unsafe
  25     [ underlying>> ] keep 2over bounds-check?
  26     [ drop nth-unsafe ] [ 2nip elt>> ] if ;
  27
  28 INSTANCE: padded immutable-sequence
  29