/[Biblio-Isis]/trunk/lib/Biblio/Isis.pm
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trunk/IsisDB.pm revision 10 by dpavlin, Wed Dec 29 16:04:07 2004 UTC trunk/lib/Biblio/Isis.pm revision 45 by dpavlin, Thu Jul 6 20:31:46 2006 UTC
# Line 1  Line 1 
1  package IsisDB;  package Biblio::Isis;
2  use strict;  use strict;
3    
4  use Carp;  use Carp;
5  use Data::Dumper;  use File::Glob qw(:globally :nocase);
6    
7  BEGIN {  BEGIN {
8          use Exporter ();          use Exporter ();
9          use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);          use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
10          $VERSION     = 0.03;          $VERSION     = 0.14;
11          @ISA         = qw (Exporter);          @ISA         = qw (Exporter);
12          #Give a hoot don't pollute, do not export more than needed by default          #Give a hoot don't pollute, do not export more than needed by default
13          @EXPORT      = qw ();          @EXPORT      = qw ();
# Line 18  BEGIN { Line 18  BEGIN {
18    
19  =head1 NAME  =head1 NAME
20    
21  IsisDB - Read CDS/ISIS database  Biblio::Isis - Read CDS/ISIS, WinISIS and IsisMarc database
22    
23  =head1 SYNOPSIS  =head1 SYNOPSIS
24    
25    use IsisDB    use Biblio::Isis;
26    my $isis = new IsisDB(  
27      my $isis = new Biblio::Isis(
28          isisdb => './cds/cds',          isisdb => './cds/cds',
29    );    );
30    
31      for(my $mfn = 1; $mfn <= $isis->count; $mfn++) {
32            print $isis->to_ascii($mfn),"\n";
33      }
34    
35  =head1 DESCRIPTION  =head1 DESCRIPTION
36    
37  This module will read CDS/ISIS databases and create hash values out of it.  This module will read ISIS databases created by DOS CDS/ISIS, WinIsis or
38  It can be used as perl-only alternative to OpenIsis module.  IsisMarc. It can be used as perl-only alternative to OpenIsis module which
39    seems to depriciate it's old C<XS> bindings for perl.
40    
41    It can create hash values from data in ISIS database (using C<to_hash>),
42    ASCII dump (using C<to_ascii>) or just hash with field names and packed
43    values (like C<^asomething^belse>).
44    
45    Unique feature of this module is ability to C<include_deleted> records.
46    It will also skip zero sized fields (OpenIsis has a bug in XS bindings, so
47    fields which are zero sized will be filled with random junk from memory).
48    
49    It also has support for identifiers (only if ISIS database is created by
50    IsisMarc), see C<to_hash>.
51    
52    This module will always be slower than OpenIsis module which use C
53    library. However, since it's written in perl, it's platform independent (so
54    you don't need C compiler), and can be easily modified. I hope that it
55    creates data structures which are easier to use than ones created by
56    OpenIsis, so reduced time in other parts of the code should compensate for
57    slower performance of this module (speed of reading ISIS database is
58    rarely an issue).
59    
60  =head1 METHODS  =head1 METHODS
61    
# Line 50  It can be used as perl-only alternative Line 75  It can be used as perl-only alternative
75  # some binary reads  # some binary reads
76  #  #
77    
 sub Read32 {  
         my $self = shift;  
   
         my $f = shift || die "Read32 needs file handle";  
         read($$f,$b,4) || die "can't read 4 bytes from $$f from position ".tell($f);  
         return unpack("l",$b);  
 }  
   
78  =head2 new  =head2 new
79    
80  Open CDS/ISIS database  Open ISIS database
81    
82   my $isis = new IsisDB(   my $isis = new Biblio::Isis(
83          isisdb => './cds/cds',          isisdb => './cds/cds',
84          read_fdt => 1,          read_fdt => 1,
         debug => 1,  
85          include_deleted => 1,          include_deleted => 1,
86            hash_filter => sub {
87                    my $v = shift;
88                    $v =~ s#foo#bar#g;
89            },
90            debug => 1,
91   );   );
92    
93  Options are described below:  Options are described below:
# Line 75  Options are described below: Line 96  Options are described below:
96    
97  =item isisdb  =item isisdb
98    
99  Prefix path to CDS/ISIS. It should contain full or relative path to database  This is full or relative path to ISIS database files which include
100  and common prefix of C<.FDT>, C<.MST>, C<.CNT>, C<.XRF> and C<.MST> files.  common prefix of C<.MST>, and C<.XRF> and optionally C<.FDT> (if using
101    C<read_fdt> option) files.
102    
103    In this example it uses C<./cds/cds.MST> and related files.
104    
105  =item read_fdt  =item read_fdt
106    
107  Boolean flag to specify if field definition table should be read. It's off  Boolean flag to specify if field definition table should be read. It's off
108  by default.  by default.
109    
110  =item debug  =item include_deleted
111    
112  Dump a C<lot> of debugging output.  Don't skip logically deleted records in ISIS.
113    
114  =item include_deleted  =item hash_filter
115    
116  Don't skip logically deleted records.  Filter code ref which will be used before data is converted to hash.
117    
118  =back  =item debug
119    
120  It will also set C<$isis-E<gt>{'maxmfn'}> which is maximum MFN stored in database.  Dump a B<lot> of debugging output.
121    
122    =back
123    
124  =cut  =cut
125    
# Line 104  sub new { Line 130  sub new {
130    
131          croak "new needs database name (isisdb) as argument!" unless ({@_}->{isisdb});          croak "new needs database name (isisdb) as argument!" unless ({@_}->{isisdb});
132    
133          foreach my $v (qw{isisdb debug include_deleted}) {          foreach my $v (qw{isisdb debug include_deleted hash_filter}) {
134                  $self->{$v} = {@_}->{$v};                  $self->{$v} = {@_}->{$v};
135          }          }
136    
137            my @isis_files = grep(/\.(FDT|MST|XRF|CNT)$/i,glob($self->{isisdb}."*"));
138    
139            foreach my $f (@isis_files) {
140                    my $ext = $1 if ($f =~ m/\.(\w\w\w)$/);
141                    $self->{lc($ext)."_file"} = $f;
142            }
143    
144            my @must_exist = qw(mst xrf);
145            push @must_exist, "fdt" if ($self->{read_fdt});
146    
147            foreach my $ext (@must_exist) {
148                    unless ($self->{$ext."_file"}) {
149                            carp "missing ",uc($ext)," file in ",$self->{isisdb};
150                            return;
151                    }
152            }
153    
154            if ($self->{debug}) {
155                    print STDERR "## using files: ",join(" ",@isis_files),"\n";
156                    eval "use Data::Dump";
157    
158                    if (! $@) {
159                            *Dumper = *Data::Dump::dump;
160                    } else {
161                            use Data::Dumper;
162                    }
163            }
164    
165          # if you want to read .FDT file use read_fdt argument when creating class!          # if you want to read .FDT file use read_fdt argument when creating class!
166          if ({@_}->{read_fdt} && -e $self->{isisdb}.".FDT") {          if ($self->{read_fdt} && -e $self->{fdt_file}) {
167    
168                  # read the $db.FDT file for tags                  # read the $db.FDT file for tags
169                  my $fieldzone=0;                  my $fieldzone=0;
170    
171                  open(fileFDT, $self->{isisdb}.".FDT") || croak "can't read '$self->{isisdb}.FDT': $!";                  open(my $fileFDT, $self->{fdt_file}) || croak "can't read '$self->{fdt_file}': $!";
172                    binmode($fileFDT);
173    
174                  while (<fileFDT>) {                  while (<$fileFDT>) {
175                          chomp;                          chomp;
176                          if ($fieldzone) {                          if ($fieldzone) {
177                                  my $name=substr($_,0,30);                                  my $name=substr($_,0,30);
# Line 133  sub new { Line 188  sub new {
188                          }                          }
189                  }                  }
190                                    
191                  close(fileFDT);                  close($fileFDT);
192          }          }
193    
194          # Get the Maximum MFN from $db.MST          # Get the Maximum MFN from $db.MST
195    
196          open(fileMST,$self->{isisdb}.".MST") || croak "can't read '$self->{isisdb}.MST': $!";          open($self->{'fileMST'}, $self->{mst_file}) || croak "can't open '$self->{mst_file}': $!";
197            binmode($self->{'fileMST'});
198    
199          # MST format:   (* = 32 bit signed)          # MST format:   (* = 32 bit signed)
200          # CTLMFN*       always 0          # CTLMFN*       always 0
# Line 146  sub new { Line 202  sub new {
202          # NXTMFB*       last block allocated to master file          # NXTMFB*       last block allocated to master file
203          # NXTMFP        offset to next available position in last block          # NXTMFP        offset to next available position in last block
204          # MFTYPE        always 0 for user db file (1 for system)          # MFTYPE        always 0 for user db file (1 for system)
205          seek(fileMST,4,0);          seek($self->{'fileMST'},4,0) || croak "can't seek to offset 0 in MST: $!";
         $self->{'NXTMFN'}=$self->Read32(\*fileMST) || carp "NXTNFN is zero";  
   
         # save maximum MFN  
         $self->{'maxmfn'} = $self->{'NXTMFN'} - 1;  
206    
207          close(fileMST);          my $buff;
   
         # Get the index information from $db.CNT  
     
         open(fileCNT, $self->{isisdb}.".CNT") || croak "can't read '$self->{isisdb}.CNT': $!";  
208    
209          # There is two 26 Bytes fixed lenght records          read($self->{'fileMST'}, $buff, 4) || croak "can't read NXTMFN from MST: $!";
210            $self->{'NXTMFN'}=unpack("V",$buff) || croak "NXTNFN is zero";
211    
212          #  0: IDTYPE    BTree type                              16          print STDERR "## self ",Dumper($self),"\n" if ($self->{debug});
         #  2: ORDN      Nodes Order                             16  
         #  4: ORDF      Leafs Order                             16  
         #  6: N         Number of Memory buffers for nodes      16  
         #  8: K         Number of buffers for first level index 16  
         # 10: LIV       Current number of Index Levels          16  
         # 12: POSRX*    Pointer to Root Record in N0x           32  
         # 16: NMAXPOS*  Next Available position in N0x          32  
         # 20: FMAXPOS*  Next available position in L0x          32  
         # 24: ABNORMAL  Formal BTree normality indicator        16  
         # length: 26 bytes  
   
         sub unpack_cnt {  
                 my $self = shift;  
   
                 my @flds = qw(ORDN ORDF N K LIV POSRX NMAXPOS FMAXPOS ABNORMAL);  
   
                 my $buff = shift || return;  
                 my @arr = unpack("ssssssllls", $buff);  
   
                 print "unpack_cnt: ",join(" ",@arr),"\n" if ($self->{'debug'});  
   
                 my $IDTYPE = shift @arr;  
                 foreach (@flds) {  
                         $self->{$IDTYPE}->{$_} = abs(shift @arr);  
                 }  
         }  
   
         my $buff;  
         read(fileCNT, $buff, 26);  
         $self->unpack_cnt($buff);  
213    
214          read(fileCNT, $buff, 26);          # open files for later
215          $self->unpack_cnt($buff);          open($self->{'fileXRF'}, $self->{xrf_file}) || croak "can't open '$self->{xrf_file}': $!";
216            binmode($self->{'fileXRF'});
217    
218            $self ? return $self : return undef;
219    }
220    
221          close(fileCNT);  =head2 count
222    
223          print Dumper($self) if ($self->{debug});  Return number of records in database
224    
225          # open files for later    print $isis->count;
         open($self->{'fileXRF'}, $self->{isisdb}.".XRF") || croak "can't open '$self->{isisdb}.XRF': $!";  
226    
227          open($self->{'fileMST'}, $self->{isisdb}.".MST") || croak "can't open '$self->{isisdb}.MST': $!";  =cut
228    
229          $self ? return $self : return undef;  sub count {
230            my $self = shift;
231            return $self->{'NXTMFN'} - 1;
232  }  }
233    
234  =head2 fetch  =head2 fetch
# Line 215  Read record with selected MFN Line 238  Read record with selected MFN
238    my $rec = $isis->fetch(55);    my $rec = $isis->fetch(55);
239    
240  Returns hash with keys which are field names and values are unpacked values  Returns hash with keys which are field names and values are unpacked values
241  for that field.  for that field like this:
242    
243      $rec = {
244        '210' => [ '^aNew York^cNew York University press^dcop. 1988' ],
245        '990' => [ '2140', '88', 'HAY' ],
246      };
247    
248  =cut  =cut
249    
# Line 224  sub fetch { Line 252  sub fetch {
252    
253          my $mfn = shift || croak "fetch needs MFN as argument!";          my $mfn = shift || croak "fetch needs MFN as argument!";
254    
255          print "fetch: $mfn\n" if ($self->{debug});          # is mfn allready in memory?
256            my $old_mfn = $self->{'current_mfn'} || -1;
257            return $self->{record} if ($mfn == $old_mfn);
258    
259            print STDERR "## fetch: $mfn\n" if ($self->{debug});
260    
261          # XXX check this?          # XXX check this?
262          my $mfnpos=($mfn+int(($mfn-1)/127))*4;          my $mfnpos=($mfn+int(($mfn-1)/127))*4;
263    
264          print "seeking to $mfnpos in file '$self->{isisdb}.XRF'\n" if ($self->{debug});          print STDERR "## seeking to $mfnpos in file '$self->{xrf_file}'\n" if ($self->{debug});
265          seek($self->{'fileXRF'},$mfnpos,0);          seek($self->{'fileXRF'},$mfnpos,0);
266    
267            my $buff;
268    
269            # delete old record
270            delete $self->{record};
271    
272          # read XRFMFB abd XRFMFP          # read XRFMFB abd XRFMFP
273          my $pointer=$self->Read32(\*{$self->{'fileXRF'}});          read($self->{'fileXRF'}, $buff, 4);
274            my $pointer=unpack("V",$buff);
275            if (! $pointer) {
276                    if ($self->{include_deleted}) {
277                            return;
278                    } else {
279                            warn "pointer for MFN $mfn is null\n";
280                            return;
281                    }
282            }
283    
284            # check for logically deleted record
285            if ($pointer & 0x80000000) {
286                    print STDERR "## record $mfn is logically deleted\n" if ($self->{debug});
287                    $self->{deleted} = $mfn;
288    
289                    return unless $self->{include_deleted};
290    
291                    # abs
292                    $pointer = ($pointer ^ 0xffffffff) + 1;
293            }
294    
295          my $XRFMFB = int($pointer/2048);          my $XRFMFB = int($pointer/2048);
296          my $XRFMFP = $pointer - ($XRFMFB*2048);          my $XRFMFP = $pointer - ($XRFMFB*2048);
297    
298          print "XRFMFB: $XRFMFB XRFMFP: $XRFMFP\n" if ($self->{debug});          # (XRFMFB - 1) * 512 + XRFMFP
299            # why do i have to do XRFMFP % 1024 ?
300    
301          # XXX fix this to be more readable!!          my $blk_off = (($XRFMFB - 1) * 512) + ($XRFMFP % 512);
         # e.g. (XRFMFB - 1) * 512 + XRFMFP  
   
         my $offset = $pointer;  
         my $offset2=int($offset/2048)-1;  
         my $offset22=int($offset/4096);  
         my $offset3=$offset-($offset22*4096);  
         if ($offset3>512) {  
                 $offset3=$offset3-2048;  
         }  
         my $offset4=($offset2*512)+$offset3;  
302    
303          print "$offset - $offset2 - $offset3 - $offset4\n" if ($self->{debug});          print STDERR "## pointer: $pointer XRFMFB: $XRFMFB XRFMFP: $XRFMFP offset: $blk_off\n" if ($self->{'debug'});
304    
305          # Get Record Information          # Get Record Information
306    
307          seek($self->{'fileMST'},$offset4,0);          seek($self->{'fileMST'},$blk_off,0) || croak "can't seek to $blk_off: $!";
308    
309          my $value=$self->Read32(\*{$self->{'fileMST'}});          read($self->{'fileMST'}, $buff, 4) || croak "can't read 4 bytes at offset $blk_off from MST file: $!";
310            my $value=unpack("V",$buff);
311    
312            print STDERR "## offset for rowid $value is $blk_off (blk $XRFMFB off $XRFMFP)\n" if ($self->{debug});
313    
314          if ($value!=$mfn) {          if ($value!=$mfn) {
315  print ("Error: The MFN:".$mfn." is not found in MST(".$value.")");                      if ($value == 0) {
316                  return -1;      # XXX deleted record?                          print STDERR "## record $mfn is physically deleted\n" if ($self->{debug});
317          }                          $self->{deleted} = $mfn;
318                            return;
319                    }
320    
321  #       $MFRL=$self->Read16($fileMST);                  carp "Error: MFN ".$mfn." not found in MST file, found $value";    
322  #       $MFBWB=$self->Read32($fileMST);                  return;
323  #       $MFBWP=$self->Read16($fileMST);          }
 #       $BASE=$self->Read16($fileMST);  
 #       $NVF=$self->Read16($fileMST);  
 #       $STATUS=$self->Read16($fileMST);  
324    
         my $buff;  
325          read($self->{'fileMST'}, $buff, 14);          read($self->{'fileMST'}, $buff, 14);
326    
327          my ($MFRL,$MFBWB,$MFBWP,$BASE,$NVF,$STATUS) = unpack("slssss", $buff);          my ($MFRL,$MFBWB,$MFBWP,$BASE,$NVF,$STATUS) = unpack("vVvvvv", $buff);
328    
329          print "MFRL: $MFRL MFBWB: $MFBWB MFBWP: $MFBWP BASE: $BASE NVF: $NVF STATUS: $STATUS\n" if ($self->{debug});          print STDERR "## MFRL: $MFRL MFBWB: $MFBWB MFBWP: $MFBWP BASE: $BASE NVF: $NVF STATUS: $STATUS\n" if ($self->{debug});
330    
331          # delete old record          warn "MFRL $MFRL is not even number" unless ($MFRL % 2 == 0);
         delete $self->{record};  
332    
333          if (! $self->{'include_deleted'} && $MFRL < 0) {          warn "BASE is not 18+6*NVF" unless ($BASE == 18 + 6 * $NVF);
                 print "## logically deleted record $mfn, skipping...\n" if ($self->{debug});  
                 return;  
         }  
334    
335          # Get Directory Format          # Get Directory Format
336    
# Line 295  print ("Error: The MFN:".$mfn." is not f Line 340  print ("Error: The MFN:".$mfn." is not f
340    
341          read($self->{'fileMST'}, $buff, 6 * $NVF);          read($self->{'fileMST'}, $buff, 6 * $NVF);
342    
343          my $fld_len = 0;          my $rec_len = 0;
344    
345          for (my $i = 0 ; $i < $NVF ; $i++) {          for (my $i = 0 ; $i < $NVF ; $i++) {
346    
347  #               $TAG=$self->Read16($fileMST);                  my ($TAG,$POS,$LEN) = unpack("vvv", substr($buff,$i * 6, 6));
 #               $POS=$self->Read16($fileMST);  
 #               $LEN=$self->Read16($fileMST);  
348    
349                  my ($TAG,$POS,$LEN) = unpack("sss", substr($buff,$i * 6, 6));                  print STDERR "## TAG: $TAG POS: $POS LEN: $LEN\n" if ($self->{debug});
   
                 print "TAG: $TAG POS: $POS LEN: $LEN\n" if ($self->{debug});  
350    
351                  # The TAG does not exists in .FDT so we set it to 0.                  # The TAG does not exists in .FDT so we set it to 0.
352                  #                  #
# Line 321  print ("Error: The MFN:".$mfn." is not f Line 362  print ("Error: The MFN:".$mfn." is not f
362                  push @FieldPOS,$POS;                  push @FieldPOS,$POS;
363                  push @FieldLEN,$LEN;                  push @FieldLEN,$LEN;
364    
365                  $fld_len += $LEN;                  $rec_len += $LEN;
366          }          }
367    
368          # Get Variable Fields          # Get Variable Fields
369    
370          read($self->{'fileMST'},$buff,$fld_len);          read($self->{'fileMST'},$buff,$rec_len);
371    
372            print STDERR "## rec_len: $rec_len poc: ",tell($self->{'fileMST'})."\n" if ($self->{debug});
373    
374          for (my $i = 0 ; $i < $NVF ; $i++) {          for (my $i = 0 ; $i < $NVF ; $i++) {
375                  # skip zero-sized fields                  # skip zero-sized fields
# Line 334  print ("Error: The MFN:".$mfn." is not f Line 377  print ("Error: The MFN:".$mfn." is not f
377    
378                  push @{$self->{record}->{$FieldTAG[$i]}}, substr($buff,$FieldPOS[$i],$FieldLEN[$i]);                  push @{$self->{record}->{$FieldTAG[$i]}}, substr($buff,$FieldPOS[$i],$FieldLEN[$i]);
379          }          }
         close(fileMST);  
380    
381          print Dumper($self) if ($self->{debug});          $self->{'current_mfn'} = $mfn;
382    
383            print STDERR Dumper($self),"\n" if ($self->{debug});
384    
385          return $self->{'record'};          return $self->{'record'};
386  }  }
387    
388  =head2 to_ascii  =head2 to_ascii
389    
390  Dump ascii output of selected MFN  Returns ASCII output of record with specified MFN
391    
392      print $isis->to_ascii(42);
393    
394    This outputs something like this:
395    
396    print $isis->to_ascii(55);    210   ^aNew York^cNew York University press^dcop. 1988
397      990   2140
398      990   88
399      990   HAY
400    
401    If C<read_fdt> is specified when calling C<new> it will display field names
402    from C<.FDT> file instead of numeric tags.
403    
404  =cut  =cut
405    
# Line 354  sub to_ascii { Line 408  sub to_ascii {
408    
409          my $mfn = shift || croak "need MFN";          my $mfn = shift || croak "need MFN";
410    
411          my $rec = $self->fetch($mfn);          my $rec = $self->fetch($mfn) || return;
412    
413          my $out = "0\t$mfn";          my $out = "0\t$mfn";
414    
415          foreach my $f (sort keys %{$rec}) {          foreach my $f (sort keys %{$rec}) {
416                  $out .= "\n$f\t".join("\n$f\t",@{$self->{record}->{$f}});                  my $fn = $self->tag_name($f);
417                    $out .= "\n$fn\t".join("\n$fn\t",@{$self->{record}->{$f}});
418          }          }
419    
420          $out .= "\n";          $out .= "\n";
# Line 367  sub to_ascii { Line 422  sub to_ascii {
422          return $out;          return $out;
423  }  }
424    
425  #  =head2 to_hash
426  # XXX porting from php left-over:  
427  #  Read record with specified MFN and convert it to hash
 # do I *REALLY* need those methods, or should I use  
 # $self->{something} directly?  
 #  
 # Probably direct usage is better!  
 #  
428    
429  sub TagName {    my $hash = $isis->to_hash($mfn);
430    
431    It has ability to convert characters (using C<hash_filter>) from ISIS
432    database before creating structures enabling character re-mapping or quick
433    fix-up of data.
434    
435    This function returns hash which is like this:
436    
437      $hash = {
438        '210' => [
439                   {
440                     'c' => 'New York University press',
441                     'a' => 'New York',
442                     'd' => 'cop. 1988'
443                   }
444                 ],
445        '990' => [
446                   '2140',
447                   '88',
448                   'HAY'
449                 ],
450      };
451    
452    You can later use that hash to produce any output from ISIS data.
453    
454    If database is created using IsisMarc, it will also have to special fields
455    which will be used for identifiers, C<i1> and C<i2> like this:
456    
457      '200' => [
458                 {
459                   'i1' => '1',
460                   'i2' => ' '
461                   'a' => 'Goa',
462                   'f' => 'Valdo D\'Arienzo',
463                   'e' => 'tipografie e tipografi nel XVI secolo',
464                 }
465               ],
466    
467    This method will also create additional field C<000> with MFN.
468    
469    =cut
470    
471    sub to_hash {
472          my $self = shift;          my $self = shift;
473          return $self->{TagName};  
474            my $mfn = shift || confess "need mfn!";
475    
476            # init record to include MFN as field 000
477            my $rec = { '000' => [ $mfn ] };
478    
479            my $row = $self->fetch($mfn) || return;
480    
481            foreach my $k (keys %{$row}) {
482                    foreach my $l (@{$row->{$k}}) {
483    
484                            # filter output
485                            if ($self->{'hash_filter'}) {
486                                    $l = $self->{'hash_filter'}->($l);
487                                    next unless defined($l);
488                            }
489    
490                            my $val;
491    
492                            # has identifiers?
493                            ($val->{'i1'},$val->{'i2'}) = ($1,$2) if ($l =~ s/^([01 #])([01 #])\^/\^/);
494    
495                            # has subfields?
496                            if ($l =~ m/\^/) {
497                                    foreach my $t (split(/\^/,$l)) {
498                                            next if (! $t);
499                                            $val->{substr($t,0,1)} = substr($t,1);
500                                    }
501                            } else {
502                                    $val = $l;
503                            }
504    
505                            push @{$rec->{$k}}, $val;
506                    }
507            }
508    
509            return $rec;
510  }  }
511    
512  sub NextMFN {  =head2 tag_name
513    
514    Return name of selected tag
515    
516     print $isis->tag_name('200');
517    
518    =cut
519    
520    sub tag_name {
521          my $self = shift;          my $self = shift;
522          return $self->{NXTMFN};          my $tag = shift || return;
523            return $self->{'TagName'}->{$tag} || $tag;
524    }
525    
526    
527    =head2 read_cnt
528    
529    Read content of C<.CNT> file and return hash containing it.
530    
531      print Dumper($isis->read_cnt);
532    
533    This function is not used by module (C<.CNT> files are not required for this
534    module to work), but it can be useful to examine your index (while debugging
535    for example).
536    
537    =cut
538    
539    sub read_cnt  {
540            my $self = shift;
541    
542            croak "missing CNT file in ",$self->{isisdb} unless ($self->{cnt_file});
543    
544            # Get the index information from $db.CNT
545      
546            open(my $fileCNT, $self->{cnt_file}) || croak "can't read '$self->{cnt_file}': $!";
547            binmode($fileCNT);
548    
549            my $buff;
550    
551            read($fileCNT, $buff, 26) || croak "can't read first table from CNT: $!";
552            $self->unpack_cnt($buff);
553    
554            read($fileCNT, $buff, 26) || croak "can't read second table from CNT: $!";
555            $self->unpack_cnt($buff);
556    
557            close($fileCNT);
558    
559            return $self->{cnt};
560    }
561    
562    =head2 unpack_cnt
563    
564    Unpack one of two 26 bytes fixed length record in C<.CNT> file.
565    
566    Here is definition of record:
567    
568     off key        description                             size
569      0: IDTYPE     BTree type                              s
570      2: ORDN       Nodes Order                             s
571      4: ORDF       Leafs Order                             s
572      6: N          Number of Memory buffers for nodes      s
573      8: K          Number of buffers for first level index s
574     10: LIV        Current number of Index Levels          s
575     12: POSRX      Pointer to Root Record in N0x           l
576     16: NMAXPOS    Next Available position in N0x          l
577     20: FMAXPOS    Next available position in L0x          l
578     24: ABNORMAL   Formal BTree normality indicator        s
579     length: 26 bytes
580    
581    This will fill C<$self> object under C<cnt> with hash. It's used by C<read_cnt>.
582    
583    =cut
584    
585    sub unpack_cnt {
586            my $self = shift;
587    
588            my @flds = qw(ORDN ORDF N K LIV POSRX NMAXPOS FMAXPOS ABNORMAL);
589    
590            my $buff = shift || return;
591            my @arr = unpack("vvvvvvVVVv", $buff);
592    
593            print STDERR "unpack_cnt: ",join(" ",@arr),"\n" if ($self->{'debug'});
594    
595            my $IDTYPE = shift @arr;
596            foreach (@flds) {
597                    $self->{cnt}->{$IDTYPE}->{$_} = abs(shift @arr);
598            }
599  }  }
600    
601  1;  1;
602    
603  =head1 BUGS  =head1 BUGS
604    
605  This module has been very lightly tested. Use with caution and report bugs.  Some parts of CDS/ISIS documentation are not detailed enough to exmplain
606    some variations in input databases which has been tested with this module.
607    When I was in doubt, I assumed that OpenIsis's implementation was right
608    (except for obvious bugs).
609    
610    However, every effort has been made to test this module with as much
611    databases (and programs that create them) as possible.
612    
613    I would be very greatful for success or failure reports about usage of this
614    module with databases from programs other than WinIsis and IsisMarc. I had
615    tested this against ouput of one C<isis.dll>-based application, but I don't
616    know any details about it's version.
617    
618  =head1 AUTHOR  =head1 AUTHOR
619    
# Line 399  This module has been very lightly tested Line 622  This module has been very lightly tested
622          dpavlin@rot13.org          dpavlin@rot13.org
623          http://www.rot13.org/~dpavlin/          http://www.rot13.org/~dpavlin/
624    
625  This module is based heavily on code from LIBISIS.PHP - Library to read ISIS files V0.1.1  This module is based heavily on code from C<LIBISIS.PHP> library to read ISIS files V0.1.1
626  written in php and (c) 2000 Franck Martin - <franck@sopac.org> released under LGPL.  written in php and (c) 2000 Franck Martin <franck@sopac.org> and released under LGPL.
627    
628  =head1 COPYRIGHT  =head1 COPYRIGHT
629    
# Line 413  LICENSE file included with this module. Line 636  LICENSE file included with this module.
636    
637  =head1 SEE ALSO  =head1 SEE ALSO
638    
639  L<http://www.openisis.org|OpenIsis>, perl(1).  OpenIsis web site L<http://www.openisis.org>
640    
641    perl4lib site L<http://perl4lib.perl.org>
642    
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