1 ! Copyright (C) 2008 Alex Chapman
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors arrays kernel math sequences sequences.private ;
8 GENERIC: modified-nth ( n seq -- elt )
10 M: modified nth modified-nth ;
11 M: modified nth-unsafe modified-nth ;
13 GENERIC: modified-set-nth ( elt n seq -- )
15 M: modified set-nth modified-set-nth ;
16 M: modified set-nth-unsafe modified-set-nth ;
18 INSTANCE: modified virtual-sequence
20 TUPLE: 1modified < modified seq ;
22 M: 1modified length seq>> length ;
23 M: 1modified set-length seq>> set-length ;
24 M: 1modified virtual-exemplar seq>> ;
26 TUPLE: scaled < 1modified c ;
30 : scale ( seq c -- new-seq )
31 dupd <scaled> swap like ;
33 M: scaled modified-nth
34 [ seq>> nth ] [ c>> * ] bi ;
36 M: scaled modified-set-nth
38 [ nip c>> / ] [ seq>> set-nth ] 2bi ;
40 TUPLE: offset < 1modified n ;
44 : seq-offset ( seq n -- new-seq )
45 dupd <offset> swap like ;
47 M: offset modified-nth
48 [ seq>> nth ] [ n>> + ] bi ;
50 M: offset modified-set-nth
51 [ nip n>> - ] [ seq>> set-nth ] 2bi ;
53 TUPLE: summed < modified seqs ;
57 M: summed length seqs>> longest length ;
59 M: summed modified-nth
60 seqs>> [ ?nth [ + ] when* ] with 0 swap reduce ;
62 M: summed modified-set-nth immutable ;
65 seqs>> [ set-length ] with each ;
67 M: summed virtual-exemplar
70 : <2summed> ( seq seq -- summed-seq ) 2array <summed> ;
72 : <3summed> ( seq seq seq -- summed-seq ) 3array <summed> ;