/[jsFind]/trunk/jsFind.pm
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Revision 7 - (show annotations)
Wed Jul 21 15:34:03 2004 UTC (19 years, 9 months ago) by dpavlin
File size: 15625 byte(s)
documentaton fix and better info message

1 package jsFind;
2
3 use 5.008004;
4 use strict;
5 use warnings;
6
7 our $VERSION = '0.01';
8
9 =head1 NAME
10
11 jsFind - generate index for jsFind using B-Tree
12
13 =head1 SYNOPSIS
14
15 use jsFind;
16
17
18
19 =head1 DESCRIPTION
20
21 This module can be used to create index files for jsFind, powerful tool for
22 adding a search engine to a CDROM archive or catalog without requiring the
23 user to install anything.
24
25 Main difference between this module and scripts delivered with jsFind are:
26
27 =over 5
28
29 =item *
30
31 You don't need to use swish-e to create index
32
33 =item *
34
35 You can programatically (and incrementaly) create index for jsFind
36
37 =back
38
39 =head1 METHODS
40
41 This module contains two packages C<jsFind> and C<jsFind::Node>.
42
43 =head2 jsFind methods
44
45 =cut
46
47 use Exporter 'import';
48 use Carp;
49
50 our @ISA = qw(Exporter);
51
52 BEGIN {
53 import 'jsFind::Node';
54 }
55
56 =head3 new
57
58 Create new tree. Arguments are C<B> which is maximum numbers of keys in
59 each node and optional C<Root> node. Each root node may have child nodes.
60
61 All nodes are objects from C<jsFind::Node>.
62
63 my $t = new jsFind(B => 4);
64
65 =cut
66
67 my $DEBUG = 1;
68
69 sub new {
70 my $package = shift;
71 my %ARGV = @_;
72 croak "Usage: {$package}::new(B => number [, Root => root node ])"
73 unless exists $ARGV{B};
74 if ($ARGV{B} % 2) {
75 my $B = $ARGV{B} + 1;
76 carp "B must be an even number. Using $B instead.";
77 $ARGV{B} = $B;
78 }
79
80 my $B = $ARGV{B};
81 my $Root = exists($ARGV{Root}) ? $ARGV{Root} : jsFind::Node->emptynode;
82 bless { B => $B, Root => $Root } => $package;
83 }
84
85 =head3 B_search
86
87 Search, insert, append or replace data in B-Tree
88
89 $t->B_search(
90 Key => 'key value',
91 Data => { "path" => {
92 "t" => "title of document",
93 "f" => 99,
94 },
95 },
96 Insert => 1,
97 Append => 1,
98 );
99
100 Semantics:
101
102 If key not found, insert it iff C<Insert> argument is present.
103
104 If key B<is> found, replace existing data iff C<Replace> argument
105 is present or add new datum to existing iff C<Append> argument is present.
106
107 =cut
108
109 sub B_search {
110 my $self = shift;
111 my %args = @_;
112 my $cur_node = $self->root;
113 my $k = $args{Key};
114 my $d = $args{Data};
115 my @path;
116
117 if ($cur_node->is_empty) { # Special case for empty root
118 if ($args{Insert}) {
119 $cur_node->kdp_insert($k => $d);
120 return $d;
121 } else {
122 return undef;
123 }
124 }
125
126 # Descend tree to leaf
127 for (;;) {
128
129 # Didn't hit bottom yet.
130
131 my($there, $where) = $cur_node->locate_key($k);
132 if ($there) { # Found it!
133 if ($args{Replace}) {
134 $cur_node->kdp_replace($where, $k => $d);
135 } elsif ($args{Append}) {
136 $cur_node->kdp_append($where, $k => $d);
137 }
138 return $cur_node->data($where);
139 }
140
141 # Not here---must be in a subtree.
142
143 if ($cur_node->is_leaf) { # But there are no subtrees
144 return undef unless $args{Insert}; # Search failed
145 # Stuff it in
146 $cur_node->kdp_insert($k => $d);
147 if ($self->node_overfull($cur_node)) { # Oops--there was no room.
148 $self->split_and_promote($cur_node, @path);
149 }
150 return $d;
151 }
152
153 # There are subtrees, and the key is in one of them.
154
155 push @path, [$cur_node, $where]; # Record path from root.
156
157 # Move down to search the subtree
158 $cur_node = $cur_node->subnode($where);
159
160 # and start over.
161 } # for (;;) ...
162
163 croak ("How did I get here?");
164 }
165
166
167
168 sub split_and_promote_old {
169 my $self = shift;
170 my ($cur_node, @path) = @_;
171
172 for (;;) {
173 my ($newleft, $newright, $kdp) = $cur_node->halves($self->B / 2);
174 my ($up, $where) = @{pop @path};
175 if ($up) {
176 $up->kdp_insert(@$kdp);
177 my ($tthere, $twhere) = $up->locate_key($kdp->[0]);
178 croak "Couldn't find key `$kdp->[0]' in node after just inserting it!"
179 unless $tthere;
180 croak "`$kdp->[0]' went into node at `$twhere' instead of expected `$where'!"
181 unless $twhere == $where;
182 $up->subnode($where, $newleft);
183 $up->subnode($where+1, $newright);
184 return unless $self->node_overfull($up);
185 $cur_node = $up;
186 } else { # We're at the top; make a new root.
187 my $newroot = new jsFind::Node ([$kdp->[0]],
188 [$kdp->[1]],
189 [$newleft, $newright]);
190 $self->root($newroot);
191 return;
192 }
193 }
194
195 }
196
197 sub split_and_promote {
198 my $self = shift;
199 my ($cur_node, @path) = @_;
200
201 for (;;) {
202 my ($newleft, $newright, $kdp) = $cur_node->halves($self->B / 2);
203 my ($up, $where) = @{pop @path} if (@path);
204 if ($up) {
205 $up->kdp_insert(@$kdp);
206 if ($DEBUG) {
207 my ($tthere, $twhere) = $up->locate_key($kdp->[0]);
208 croak "Couldn't find key `$kdp->[0]' in node after just inserting it!"
209 unless $tthere;
210 croak "`$kdp->[0]' went into node at `$twhere' instead of expected `$where'!"
211 unless $twhere == $where;
212 }
213 $up->subnode($where, $newleft);
214 $up->subnode($where+1, $newright);
215 return unless $self->node_overfull($up);
216 $cur_node = $up;
217 } else { # We're at the top; make a new root.
218 my $newroot = new jsFind::Node([$kdp->[0]],
219 [$kdp->[1]],
220 [$newleft, $newright]);
221 $self->root($newroot);
222 return;
223 }
224 }
225 }
226
227 =head3 B
228
229 Return B (maximum number of keys)
230
231 my $max_size = $t->B;
232
233 =cut
234
235 sub B {
236 $_[0]{B};
237 }
238
239 =head3 root
240
241 Returns root node
242
243 my $root = $t->root;
244
245 =cut
246
247 sub root {
248 my ($self, $newroot) = @_;
249 $self->{Root} = $newroot if defined $newroot;
250 $self->{Root};
251 }
252
253 =head3 node_overfull
254
255 Returns if node is overfull
256
257 if ($node->node_overfull) { something }
258
259 =cut
260
261 sub node_overfull {
262 my $self = shift;
263 my $node = shift;
264 $node->size > $self->B;
265 }
266
267 =head3 to_string
268
269 Returns your tree as formatted string.
270
271 my $text = $root->to_string;
272
273 Mostly usefull for debugging as output leaves much to be desired.
274
275 =cut
276
277 sub to_string {
278 $_[0]->root->to_string;
279 }
280
281 =head3 to_dot
282
283 Create Graphviz graph of your tree
284
285 my $dot_graph = $root->to_dot;
286
287 =cut
288
289 sub to_dot {
290 my $self = shift;
291
292 my $dot = qq/digraph dns {\nrankdir=LR;\n/;
293 $dot .= $self->root->to_dot;
294 $dot .= qq/\n}\n/;
295
296 return $dot;
297 }
298
299 =head3 to_jsfind
300
301 Create xml index files for jsFind. This should be called after
302 your B-Tree has been filled with data.
303
304 $root->to_jsfind('/full/path/to/index/dir/');
305
306 Returns number of nodes in created tree.
307
308 =cut
309
310 sub to_jsfind {
311 my $self = shift;
312
313 my $path = shift || confess "to_jsfind need path to your index!";
314
315 $path .= "/" if ($path =~ /\/$/);
316 carp "create directory for index '$path': $!" if (! -w $path);
317
318 return $self->root->to_jsfind($path,"0");
319 }
320
321
322 # private, default cmd function
323 sub default_cmp {
324 $_[0] cmp $_[1];
325 }
326
327 #####################################################################
328
329 =head2 jsFind::Node methods
330
331 Each node has C<k> key-data pairs, with C<B> <= C<k> <= C<2B>, and
332 each has C<k+1> subnodes, which might be null.
333
334 The node is a blessed reference to a list with three elements:
335
336 ($keylist, $datalist, $subnodelist)
337
338 each is a reference to a list list.
339
340 The null node is represented by a blessed reference to an empty list.
341
342 =cut
343
344 package jsFind::Node;
345
346 use warnings;
347 use strict;
348
349 use Carp;
350 use File::Path;
351
352 my $KEYS = 0;
353 my $DATA = 1;
354 my $SUBNODES = 2;
355
356 =head3 new
357
358 Create New node
359
360 my $node = new jsFind::Node ($keylist, $datalist, $subnodelist);
361
362 You can also mit argument list to create empty node.
363
364 my $empty_node = new jsFind::Node;
365
366 =cut
367
368 sub new {
369 my $self = shift;
370 my $package = ref $self || $self;
371 croak "Internal error: jsFind::Node::new called with wrong number of arguments."
372 unless @_ == 3 || @_ == 0;
373 bless [@_] => $package;
374 }
375
376 =head3 locate_key
377
378 Locate key in node using linear search. This should probably be replaced
379 by binary search for better performance.
380
381 my ($found, $index) = $node->locate_key($key, $cmp_coderef);
382
383 Argument C<$cmp_coderef> is optional reference to custom comparison
384 operator.
385
386 Returns (1, $index) if $key[$index] eq $key.
387
388 Returns (0, $index) if key could be found in $subnode[$index].
389
390 In scalar context, just returns 1 or 0.
391
392 =cut
393
394 sub locate_key {
395 # Use linear search for testing, replace with binary search.
396 my $self = shift;
397 my $key = shift;
398 my $cmp = shift || \&jsFind::default_cmp;
399 my $i;
400 my $cmp_result;
401 my $N = $self->size;
402 for ($i = 0; $i < $N; $i++) {
403 $cmp_result = &$cmp($key, $self->key($i));
404 last if $cmp_result <= 0;
405 }
406
407 # $i is now the index of the first node-key greater than $key
408 # or $N if there is no such. $cmp_result is 0 iff the key was found.
409 (!$cmp_result, $i);
410 }
411
412
413 =head3 emptynode
414
415 Creates new empty node
416
417 $node = $root->emptynode;
418 $new_node = $node->emptynode;
419
420 =cut
421
422 sub emptynode {
423 new($_[0]); # Pass package name, but not anything else.
424 }
425
426 =head3 is_empty
427
428 Test if node is empty
429
430 if ($node->is_empty) { something }
431
432 =cut
433
434 # undef is empty; so is a blessed empty list.
435 sub is_empty {
436 my $self = shift;
437 !defined($self) || $#$self < 0;
438 }
439
440 =head3 key
441
442 Return C<$i>th key from node
443
444 my $key = $node->key($i);
445
446 =cut
447
448 sub key {
449 # my ($self, $n) = @_;
450 # $self->[$KEYS][$n];
451
452 # speedup
453 $_[0]->[$KEYS][$_[1]];
454 }
455
456 =head3 data
457
458 Return C<$i>th data from node
459
460 my $data = $node->data($i);
461
462 =cut
463
464 sub data {
465 my ($self, $n) = @_;
466 $self->[$DATA][$n];
467 }
468
469 =head3 kdp_replace
470
471 Set key data pair for C<$i>th element in node
472
473 $node->kdp_replace($i, "key value" => {
474 "data key 1" => "data value 1",
475 "data key 2" => "data value 2",
476 };
477
478 =cut
479
480 sub kdp_replace {
481 my ($self, $n, $k => $d) = @_;
482 if (defined $k) {
483 $self->[$KEYS][$n] = $k;
484 $self->[$DATA][$n] = $d;
485 }
486 [$self->[$KEYS][$n],
487 $self->[$DATA][$n]];
488 }
489
490 =head3 kdp_insert
491
492 # No return value.
493
494 =cut
495
496 sub kdp_insert {
497 my $self = shift;
498 my ($k => $d) = @_;
499 my ($there, $where) = $self->locate_key($k) unless $self->is_empty;
500
501 if ($there) { croak("Tried to insert `$k => $d' into node where `$k' was already present."); }
502
503 # undef fix
504 $where ||= 0;
505
506 splice(@{$self->[$KEYS]}, $where, 0, $k);
507 splice(@{$self->[$DATA]}, $where, 0, $d);
508 splice(@{$self->[$SUBNODES]}, $where, 0, undef);
509 }
510
511 =head3 kdp_append
512
513 Adds new data keys and values to C<$i>th element in node
514
515 $node->kdp_append($i, "key value" => {
516 "added data key" => "added data value",
517 };
518
519 =cut
520
521 sub kdp_append {
522 my ($self, $n, $k => $d) = @_;
523 if (defined $k) {
524 $self->[$KEYS][$n] = $k;
525 my ($kv,$dv) = %{$d};
526 $self->[$DATA][$n]->{$kv} = $dv;
527 }
528 [$self->[$KEYS][$n],
529 $self->[$DATA][$n]];
530 }
531
532 =head3 subnode
533
534 Set new or return existing subnode
535
536 # return 4th subnode
537 my $my_node = $node->subnode(4);
538
539 # create new subnode 5 from $my_node
540 $node->subnode(5, $my_node);
541
542 =cut
543
544 sub subnode {
545 my ($self, $n, $newnode) = @_;
546 $self->[$SUBNODES][$n] = $newnode if defined $newnode;
547 $self->[$SUBNODES][$n];
548 }
549
550 =head3 is_leaf
551
552 Test if node is leaf
553
554 if ($node->is_leaf) { something }
555
556 =cut
557
558 sub is_leaf {
559 my $self = shift;
560 ! defined $self->[$SUBNODES][0]; # undefined subnode means leaf node.
561 }
562
563 =head3 size
564
565 Return number of keys in the node
566
567 my $nr = $node->size;
568
569 =cut
570
571 sub size {
572 my $self = shift;
573 return scalar(@{$self->[$KEYS]});
574 }
575
576 =head3 halves
577
578 # Accept an index $n
579 # Divide into two nodes so that keys 0 .. $n-1 are in one node
580 # and keys $n+1 ... $size are in the other.
581
582 =cut
583
584 sub halves {
585 my $self = shift;
586 my $n = shift;
587 my $s = $self->size;
588 my @right;
589 my @left;
590
591 $left[$KEYS] = [@{$self->[$KEYS]}[0 .. $n-1]];
592 $left[$DATA] = [@{$self->[$DATA]}[0 .. $n-1]];
593 $left[$SUBNODES] = [@{$self->[$SUBNODES]}[0 .. $n]];
594
595 $right[$KEYS] = [@{$self->[$KEYS]}[$n+1 .. $s-1]];
596 $right[$DATA] = [@{$self->[$DATA]}[$n+1 .. $s-1]];
597 $right[$SUBNODES] = [@{$self->[$SUBNODES]}[$n+1 .. $s]];
598
599 my @middle = ($self->[$KEYS][$n], $self->[$DATA][$n]);
600
601 ($self->new(@left), $self->new(@right), \@middle);
602 }
603
604 =head3 to_string
605
606 Dumps tree as string
607
608 my $str = $root->to_string;
609
610 =cut
611
612 sub to_string {
613 my $self = shift;
614 my $indent = shift || 0;
615 my $I = ' ' x $indent;
616 return '' if $self->is_empty;
617 my ($k, $d, $s) = @$self;
618 my $result = '';
619 $result .= defined($s->[0]) ? $s->[0]->to_string($indent+2) : '';
620 my $N = $self->size;
621 my $i;
622 for ($i = 0; $i < $N; $i++) {
623 # $result .= $I . "$k->[$i] => $d->[$i]\n";
624 $result .= $I . "$k->[$i]\n";
625 $result .= defined($s->[$i+1]) ? $s->[$i+1]->to_string($indent+2) : '';
626 }
627 $result;
628 }
629
630 =begin comment
631
632 use Data::Dumper;
633
634 sub to_string {
635 my $self = shift;
636 my $indent = shift || 0;
637 my $path = shift || '0';
638 return '' if $self->is_empty;
639 my ($k, $d, $s) = @$self;
640 my $result = '';
641 $result .= defined($s->[0]) ? $s->[0]->to_string($indent+1,"$path/0") : '';
642 my $N = $self->size;
643 for (my $i = 0; $i < $N; $i++) {
644 my $dump = Dumper($d->[$i]);
645 $dump =~ s/[\n\r\s]+/ /gs;
646 $dump =~ s/\$VAR1\s*=\s*//;
647 $result .= sprintf("%-5s [%2d] %2s: %s => %s\n", $path, $i, $indent, $k->[$i], $dump);
648 $result .= defined($s->[$i+1]) ? $s->[$i+1]->to_string($indent+1,"$path/$i") : '';
649 }
650 $result;
651 }
652
653 =end comment
654
655 =head3 to_dot
656
657 Recursivly walk nodes of tree
658
659 =cut
660
661 sub to_dot {
662 my $self = shift;
663 my $parent = shift;
664
665 return '' if $self->is_empty;
666
667 my $dot = '';
668
669 my ($k, $d, $s) = @$self;
670 my $N = $self->size;
671
672 my @dot_keys;
673
674 my $node_name = $parent || '_';
675 $node_name =~ s/\W+//g;
676 $node_name .= " [$N]";
677
678 for (my $i = 0; $i <= $N; $i++) {
679 if (my $key = $k->[$i]) {
680 push @dot_keys, qq{<$i>$key};
681 }
682 $dot .= $s->[$i]->to_dot(qq{"$node_name":$i}) if ($s->[$i]);
683 }
684 push @dot_keys, qq{<$N>...} if (! $self->is_leaf);
685
686 my $label = join("|",@dot_keys);
687 $dot .= qq{"$node_name" [ shape=record, label="$label" ];\n};
688
689 $dot .= qq{$parent -> "$node_name";\n} if ($parent);
690
691 $dot;
692 }
693
694 =head3 to_jsfind
695
696 Create jsFind xml files
697
698 my $nr=$tree->to_dot('/path/to/index','0');
699
700 Returns number of elements created
701
702 =cut
703
704 sub to_jsfind {
705 my $self = shift;
706 my ($path,$file) = @_;
707
708 return 0 if $self->is_empty;
709
710 my $nr_keys = 0;
711
712 my ($k, $d, $s) = @$self;
713 my $N = $self->size;
714
715 my ($key_xml, $data_xml) = ("<n>","<d>");
716
717 for (my $i = 0; $i <= $N; $i++) {
718 my $key = lc($k->[$i]);
719
720 if ($key) {
721 $key_xml .= qq{<k>$key</k>};
722 $data_xml .= qq{<e>};
723 #use Data::Dumper;
724 #print Dumper($d->[$i]);
725 foreach my $path (keys %{$d->[$i]}) {
726 $data_xml .= '<l f="'.($d->[$i]->{$path}->{'f'} || 1).'" t="'.($d->[$i]->{$path}->{'t'} || 'no title').'">'.$path.'</l>';
727 $nr_keys++;
728 }
729 $data_xml .= qq{</e>};
730 }
731
732 $nr_keys += $s->[$i]->to_jsfind("$path/$file","$i") if ($s->[$i]);
733 }
734
735 $key_xml .= "</n>";
736 $data_xml .= "</d>";
737
738 if (! -e $path) {
739 mkpath($path) || croak "can't create dir '$path': $!";
740 }
741
742 open(K, "> ${path}/${file}.xml") || croak "can't open '$path/$file.xml': $!";
743 open(D, "> ${path}/_${file}.xml") || croak "can't open '$path/_$file.xml': $!";
744
745 print K $key_xml;
746 print D $data_xml;
747
748 close(K);
749 close(D);
750
751 return $nr_keys;
752 }
753
754 1;
755 __END__
756
757 =head1 SEE ALSO
758
759 jsFind web site L<http://www.elucidsoft.net/projects/jsfind/>
760
761 B-Trees in perl web site L<http://perl.plover.com/BTree/>
762
763 =head1 AUTHORS
764
765 Mark-Jonson Dominus E<lt>mjd@pobox.comE<gt> wrote C<BTree.pm> which was
766 base for this module
767
768 Shawn P. Garbett E<lt>shawn@elucidsoft.netE<gt> wrote jsFind
769
770 Dobrica Pavlinusic E<lt>dpavlin@rot13.orgE<gt> wrote this module
771
772 =head1 COPYRIGHT AND LICENSE
773
774 Copyright (C) 2004 by Dobrica Pavlinusic
775
776 This program is free software; you can redistribute it and/or modify it
777 under the terms of the GNU General Public License as published by the Free
778 Software Foundation; either version 2 of the License, or (at your option)
779 any later version. This program is distributed in the hope that it will be
780 useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
781 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
782 Public License for more details.
783
784 =cut

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