/[webpac2]/trunk/lib/WebPAC/Input.pm
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revision 3 by dpavlin, Sat Jul 16 11:07:38 2005 UTC revision 496 by dpavlin, Sun May 14 19:45:26 2006 UTC
# Line 3  package WebPAC::Input; Line 3  package WebPAC::Input;
3  use warnings;  use warnings;
4  use strict;  use strict;
5    
6    use WebPAC::Common;
7    use base qw/WebPAC::Common/;
8    use Text::Iconv;
9    use Data::Dumper;
10    
11  =head1 NAME  =head1 NAME
12    
13  WebPAC::Input - core module for input file format  WebPAC::Input - read different file formats into WebPAC
14    
15  =head1 VERSION  =head1 VERSION
16    
17  Version 0.01  Version 0.04
18    
19  =cut  =cut
20    
21  our $VERSION = '0.01';  our $VERSION = '0.04';
22    
23  =head1 SYNOPSIS  =head1 SYNOPSIS
24    
25  This module will load particular loader module and execute it's functions.  This module implements input as database which have fixed and known
26    I<size> while indexing and single unique numeric identifier for database
27    position ranging from 1 to I<size>.
28    
29    Simply, something that is indexed by unmber from 1 .. I<size>.
30    
31    Examples of such databases are CDS/ISIS files, MARC files, lines in
32    text file, and so on.
33    
34    Specific file formats are implemented using low-level interface modules,
35    located in C<WebPAC::Input::*> namespace which export C<open_db>,
36    C<fetch_rec> and optional C<init> functions.
37    
38  Perhaps a little code snippet.  Perhaps a little code snippet.
39    
40      use WebPAC::Input;      use WebPAC::Input;
41    
42      my $db = WebPAC::Input->new(      my $db = WebPAC::Input->new(
43          format => 'NULL',          module => 'WebPAC::Input::ISIS',
44          config => $config,                  config => $config,
45                    lookup => $lookup_obj,
46                    low_mem => 1,
47      );      );
48    
49      $db->open('/path/to/database');      $db->open('/path/to/database');
50      print "database size: ",$db->size,"\n";          print "database size: ",$db->size,"\n";
51      while (my $row = $db->fetch) {          while (my $rec = $db->fetch) {
52          ...                  # do something with $rec
53      }          }
54      $db->close;  
55    
56    
57  =head1 FUNCTIONS  =head1 FUNCTIONS
58    
# Line 41  Perhaps a little code snippet. Line 60  Perhaps a little code snippet.
60    
61  Create new input database object.  Create new input database object.
62    
63    my $db = new WebPAC::Input( format => 'NULL' );    my $db = new WebPAC::Input(
64            module => 'WebPAC::Input::MARC',
65            code_page => 'ISO-8859-2',
66            low_mem => 1,
67            recode => 'char pairs',
68            no_progress_bar => 1,
69      );
70    
71    C<module> is low-level file format module. See L<WebPAC::Input::Isis> and
72    L<WebPAC::Input::MARC>.
73    
74    Optional parametar C<code_page> specify application code page (which will be
75    used internally). This should probably be your terminal encoding, and by
76    default, it C<ISO-8859-2>.
77    
78    Default is not to use C<low_mem> options (see L<MEMORY USAGE> below).
79    
80  This function will load needed wrapper module and  C<recode> is optional string constisting of character or words pairs that
81    should be replaced in input stream.
82    
83    C<no_progress_bar> disables progress bar output on C<STDOUT>
84    
85    This function will also call low-level C<init> if it exists with same
86    parametars.
87    
88  =cut  =cut
89    
90  sub new {  sub new {
91          my $class = shift;          my $class = shift;
92          my $self = {@_};          my $self = {@_};
93          bless($self, $class);          bless($self, $class);
94    
95            my $log = $self->_get_logger;
96    
97            $log->logconfess("specify low-level file format module") unless ($self->{module});
98            my $module = $self->{module};
99            $module =~ s#::#/#g;
100            $module .= '.pm';
101            $log->debug("require low-level module $self->{module} from $module");
102    
103            require $module;
104            #eval $self->{module} .'->import';
105    
106            # check if required subclasses are implemented
107            foreach my $subclass (qw/open_db fetch_rec init/) {
108                    my $n = $self->{module} . '::' . $subclass;
109                    if (! defined &{ $n }) {
110                            my $missing = "missing $subclass in $self->{module}";
111                            $self->{$subclass} = sub { $log->logwarn($missing) };
112                    } else {
113                            $self->{$subclass} = \&{ $n };
114                    }
115            }
116    
117            if ($self->{init}) {
118                    $log->debug("calling init");
119                    $self->{init}->($self, @_);
120            }
121    
122            $self->{'code_page'} ||= 'ISO-8859-2';
123    
124            # running with low_mem flag? well, use DBM::Deep then.
125            if ($self->{'low_mem'}) {
126                    $log->info("running with low_mem which impacts performance (<32 Mb memory usage)");
127    
128                    my $db_file = "data.db";
129    
130                    if (-e $db_file) {
131                            unlink $db_file or $log->logdie("can't remove '$db_file' from last run");
132                            $log->debug("removed '$db_file' from last run");
133                    }
134    
135                    require DBM::Deep;
136    
137                    my $db = new DBM::Deep $db_file;
138    
139                    $log->logdie("DBM::Deep error: $!") unless ($db);
140    
141                    if ($db->error()) {
142                            $log->logdie("can't open '$db_file' under low_mem: ",$db->error());
143                    } else {
144                            $log->debug("using file '$db_file' for DBM::Deep");
145                    }
146    
147                    $self->{'db'} = $db;
148            }
149    
150          $self ? return $self : return undef;          $self ? return $self : return undef;
151  }  }
152    
153  =head2 open  =head2 open
154    
155    This function will read whole database in memory and produce lookups.
156    
157     $input->open(
158            path => '/path/to/database/file',
159            code_page => '852',
160            limit => 500,
161            offset => 6000,
162            lookup => $lookup_obj,
163     );
164    
165    By default, C<code_page> is assumed to be C<852>.
166    
167    C<offset> is optional parametar to position at some offset before reading from database.
168    
169    C<limit> is optional parametar to read just C<limit> records from database
170    
171    Returns size of database, regardless of C<offset> and C<limit>
172    parametars, see also C<size>.
173    
174  =cut  =cut
175    
176  sub open {  sub open {
177            my $self = shift;
178            my $arg = {@_};
179    
180            my $log = $self->_get_logger();
181    
182            $log->logcroak("need path") if (! $arg->{'path'});
183            my $code_page = $arg->{'code_page'} || '852';
184    
185            # store data in object
186            $self->{'input_code_page'} = $code_page;
187            foreach my $v (qw/path offset limit/) {
188                    $self->{$v} = $arg->{$v} if ($arg->{$v});
189            }
190    
191            # create Text::Iconv object
192            $self->{iconv} = Text::Iconv->new($code_page,$self->{'code_page'});
193    
194            my $filter_ref;
195    
196            if ($self->{recode}) {
197                    my @r = split(/\s/, $self->{recode});
198                    if ($#r % 2 != 1) {
199                            $log->logwarn("recode needs even number of elements (some number of valid pairs)");
200                    } else {
201                            my $recode;
202                            while (@r) {
203                                    my $from = shift @r;
204                                    my $to = shift @r;
205                                    $recode->{$from} = $to;
206                            }
207    
208                            my $regex = join '|' => keys %{ $recode };
209    
210                            $log->debug("using recode regex: $regex");
211                            
212                            $filter_ref = sub {
213                                    my $t = shift;
214                                    $t =~ s/($regex)/$recode->{$1}/g;
215                                    return $t;
216                            };
217    
218                    }
219    
220            }
221    
222            my ($db, $size) = $self->{open_db}->( $self,
223                    path => $arg->{path},
224                    filter => $filter_ref,
225            );
226    
227            unless (defined($db)) {
228                    $log->logwarn("can't open database $arg->{path}, skipping...");
229                    return;
230            }
231    
232            unless ($size) {
233                    $log->logwarn("no records in database $arg->{path}, skipping...");
234                    return;
235            }
236    
237            my $from_rec = 1;
238            my $to_rec = $size;
239    
240            if (my $s = $self->{offset}) {
241                    $log->info("skipping to MFN $s");
242                    $from_rec = $s;
243            } else {
244                    $self->{offset} = $from_rec;
245            }
246    
247            if ($self->{limit}) {
248                    $log->debug("limiting to ",$self->{limit}," records");
249                    $to_rec = $from_rec + $self->{limit} - 1;
250                    $to_rec = $size if ($to_rec > $size);
251            }
252    
253            # store size for later
254            $self->{size} = ($to_rec - $from_rec) ? ($to_rec - $from_rec + 1) : 0;
255    
256            $log->info("processing $self->{size}/$size records [$from_rec-$to_rec] convert $code_page -> $self->{code_page}");
257    
258            # read database
259            for (my $pos = $from_rec; $pos <= $to_rec; $pos++) {
260    
261                    $log->debug("position: $pos\n");
262    
263                    my $rec = $self->{fetch_rec}->($self, $db, $pos );
264    
265                    $log->debug(sub { Dumper($rec) });
266    
267                    if (! $rec) {
268                            $log->warn("record $pos empty? skipping...");
269                            next;
270                    }
271    
272                    # store
273                    if ($self->{low_mem}) {
274                            $self->{db}->put($pos, $rec);
275                    } else {
276                            $self->{data}->{$pos} = $rec;
277                    }
278    
279                    # create lookup
280                    $self->{'lookup'}->add( $rec ) if ($rec && $self->{'lookup'});
281    
282                    $self->progress_bar($pos,$to_rec) unless ($self->{no_progress_bar});
283    
284            }
285    
286            $self->{pos} = -1;
287            $self->{last_pcnt} = 0;
288    
289            # store max mfn and return it.
290            $self->{max_pos} = $to_rec;
291            $log->debug("max_pos: $to_rec");
292    
293            return $size;
294  }  }
295    
296  =head2 function2  =head2 fetch
297    
298    Fetch next record from database. It will also displays progress bar.
299    
300     my $rec = $isis->fetch;
301    
302    Record from this function should probably go to C<data_structure> for
303    normalisation.
304    
305  =cut  =cut
306    
307  sub function2 {  sub fetch {
308            my $self = shift;
309    
310            my $log = $self->_get_logger();
311    
312            $log->logconfess("it seems that you didn't load database!") unless ($self->{pos});
313    
314            if ($self->{pos} == -1) {
315                    $self->{pos} = $self->{offset};
316            } else {
317                    $self->{pos}++;
318            }
319    
320            my $mfn = $self->{pos};
321    
322            if ($mfn > $self->{max_pos}) {
323                    $self->{pos} = $self->{max_pos};
324                    $log->debug("at EOF");
325                    return;
326            }
327    
328            $self->progress_bar($mfn,$self->{max_pos}) unless ($self->{no_progress_bar});
329    
330            my $rec;
331    
332            if ($self->{low_mem}) {
333                    $rec = $self->{db}->get($mfn);
334            } else {
335                    $rec = $self->{data}->{$mfn};
336            }
337    
338            $rec ||= 0E0;
339  }  }
340    
341    =head2 pos
342    
343    Returns current record number (MFN).
344    
345     print $isis->pos;
346    
347    First record in database has position 1.
348    
349    =cut
350    
351    sub pos {
352            my $self = shift;
353            return $self->{pos};
354    }
355    
356    
357    =head2 size
358    
359    Returns number of records in database
360    
361     print $isis->size;
362    
363    Result from this function can be used to loop through all records
364    
365     foreach my $mfn ( 1 ... $isis->size ) { ... }
366    
367    because it takes into account C<offset> and C<limit>.
368    
369    =cut
370    
371    sub size {
372            my $self = shift;
373            return $self->{size};
374    }
375    
376    =head2 seek
377    
378    Seek to specified MFN in file.
379    
380     $isis->seek(42);
381    
382    First record in database has position 1.
383    
384    =cut
385    
386    sub seek {
387            my $self = shift;
388            my $pos = shift || return;
389    
390            my $log = $self->_get_logger();
391    
392            if ($pos < 1) {
393                    $log->warn("seek before first record");
394                    $pos = 1;
395            } elsif ($pos > $self->{max_pos}) {
396                    $log->warn("seek beyond last record");
397                    $pos = $self->{max_pos};
398            }
399    
400            return $self->{pos} = (($pos - 1) || -1);
401    }
402    
403    
404  =head1 MEMORY USAGE  =head1 MEMORY USAGE
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