extra/sequences/padded/padded.factor

   1 ! Copyright (C) 2020 John Benediktsson
   2 ! See http://factorcode.org/license.txt for BSD license
   3 USING: accessors arrays kernel math math.order sequences
   4 sequences.private ;
   5 IN: sequences.padded
   6
   7 TUPLE: padded
   8 { underlying sequence read-only }
   9 { length integer read-only }
  10 { elt object read-only } ;
  11
  12 TUPLE: padded-head < padded ;
  13 TUPLE: padded-tail < padded ;
  14
  15 C: <padded-head> padded-head
  16 C: <padded-tail> padded-tail
  17
  18 M: padded length
  19     [ underlying>> length ] [ length>> ] bi max ;
  20
  21 M: padded-head nth-unsafe
  22     [ [ length>> ] [ underlying>> ] bi [ length [-] - ] keep ] keep
  23     2over bounds-check? [ drop nth-unsafe ] [ 2nip elt>> ] if ;
  24
  25 M: padded-tail nth-unsafe
  26     [ underlying>> ] keep 2over bounds-check?
  27     [ drop nth-unsafe ] [ 2nip elt>> ] if ;
  28
  29 INSTANCE: padded immutable-sequence
  30