1 ! Copyright (C) 2008 Slava Pestov.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: accessors assocs sequences sorting binary-search math
4 math.order arrays combinators kernel ;
9 TUPLE: simple-cord first second ;
12 [ first>> length ] [ second>> length ] bi + ;
14 M: simple-cord virtual-seq first>> ;
16 M: simple-cord virtual@
18 [ first>> ] [ [ first>> length - ] [ second>> ] bi ] if ;
20 TUPLE: multi-cord count seqs ;
22 M: multi-cord length count>> ;
24 M: multi-cord virtual@
26 seqs>> [ first <=> ] with search nip
27 [ first - ] [ second ] bi ;
29 M: multi-cord virtual-seq
30 seqs>> [ f ] [ first second ] if-empty ;
32 : <cord> ( seqs -- cord )
34 first2 simple-cord boa
36 [ 0 [ length + ] accumulate ] keep zip multi-cord boa
41 UNION: cord simple-cord multi-cord ;
43 INSTANCE: cord virtual-sequence
45 INSTANCE: multi-cord virtual-sequence
47 : cord-append ( seq1 seq2 -- cord )
49 { [ over empty? ] [ nip ] }
50 { [ dup empty? ] [ drop ] }
51 { [ 2dup [ cord? ] both? ] [ [ seqs>> values ] bi@ append <cord> ] }
52 { [ over cord? ] [ [ seqs>> values ] dip suffix <cord> ] }
53 { [ dup cord? ] [ seqs>> values swap prefix <cord> ] }
57 : cord-concat ( seqs -- cord )
59 { [ dup empty? ] [ drop f ] }
60 { [ dup length 1 = ] [ first ] }
64 { [ dup cord? ] [ seqs>> values ] }
65 { [ dup empty? ] [ drop { } ] }