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dpavlin |
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package MARC::Fast; |
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use strict; |
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use Carp; |
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use Data::Dumper; |
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BEGIN { |
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use Exporter (); |
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use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS); |
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dpavlin |
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$VERSION = 0.02; |
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dpavlin |
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@ISA = qw (Exporter); |
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#Give a hoot don't pollute, do not export more than needed by default |
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@EXPORT = qw (); |
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@EXPORT_OK = qw (); |
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%EXPORT_TAGS = (); |
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} |
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=head1 NAME |
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MARC::Fast - Very fast implementation of MARC database reader |
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=head1 SYNOPSIS |
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use MARC::Fast; |
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=head1 DESCRIPTION |
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This is very fast alternative to C<MARC> and C<MARC::Record> modules. |
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It's is also very sutable for random access to MARC records (as opposed to |
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sequential one). |
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=head1 METHODS |
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=head2 new |
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Read MARC database |
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my $marc = new MARC::Fast( |
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marcdb => 'unimarc.iso', |
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quiet => 0, |
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debug => 0, |
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assert => 0, |
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); |
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=cut |
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################################################## subroutine header end ## |
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sub new { |
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my $class = shift; |
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my $self = {@_}; |
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bless ($self, $class); |
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croak "need marcdb parametar" unless ($self->{marcdb}); |
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print STDERR "# opening ",$self->{marcdb},"\n" if ($self->{debug}); |
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open($self->{fh}, $self->{marcdb}) || croak "can't open ",$self->{marcdb},": $!"; |
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$self->{count} = 0; |
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while (! eof($self->{fh})) { |
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$self->{count}++; |
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# save record position |
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push @{$self->{fh_offset}}, tell($self->{fh}); |
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my $leader; |
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read($self->{fh}, $leader, 24); |
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# Byte Name |
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# ---- ---- |
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# 0-4 Record Length |
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# 5 Status (n=new, c=corrected and d=deleted) |
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# 6 Type of Record (a=printed material) |
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# 7 Bibliographic Level (m=monograph) |
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# 8-9 Blanks |
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# 10 Indictator count (2 for monographs) |
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# 11 Subfield code count (2 - 0x1F+subfield code itself) |
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# 12-16 Base address of data |
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# 17 Encoding level (blank=full level, 1=sublevel 1, 2=sublevel 2, |
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# 3=sublevel 3) |
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# 18 Descriptive Cataloguing Form (blank=record is full ISBD, |
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# n=record is in non-ISBD format, i=record is in |
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# an incomplete ISBD format) |
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# 19 Blank |
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# 20 Length of length field in directory (always 4 in UNIMARC) |
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# 21 Length of Starting Character Position in directory (always |
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# 5 in UNIMARC) |
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# 22 Length of implementation defined portion in directory (always |
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# 0 in UNIMARC) |
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# 23 Blank |
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# |
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# |0 45 89 |12 16|1n 450 | |
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# |xxxxxnam 22(.....) 45 <--- |
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print STDERR "REC ",$self->{count},": $leader\n" if ($self->{debug}); |
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# store leader for later |
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push @{$self->{leaders}}, $leader; |
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# skip to next record |
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seek($self->{fh},substr($leader,0,5)-24,1); |
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} |
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return $self; |
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} |
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=head2 count |
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Return number of records in database |
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print $marc->count; |
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=cut |
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sub count { |
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my $self = shift; |
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return $self->{count}; |
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} |
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=head2 fetch |
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Fetch record from database |
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my $hash = $marc->fetch(42); |
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=cut |
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sub fetch { |
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my $self = shift; |
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my $rec_nr = shift || return; |
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my $leader = $self->{leaders}->[$rec_nr - 1]; |
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unless ($leader) { |
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carp "can't find record $rec_nr"; |
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return; |
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}; |
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my $offset = $self->{fh_offset}->[$rec_nr - 1]; |
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unless (defined($offset)) { |
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carp "can't find offset for record $rec_nr"; |
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return; |
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}; |
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my $reclen = substr($leader,0,5); |
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my $base_addr = substr($leader,12,5); |
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print STDERR "# $rec_nr leader: '$leader' reclen: $reclen base addr: $base_addr [dir: ",$base_addr - 24,"]\n" if ($self->{debug}); |
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my $skip = 0; |
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print STDERR "# seeking to $offset + 24\n" if ($self->{debug}); |
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if ( ! seek($self->{fh}, $offset+24, 0) ) { |
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carp "can't seek to $offset: $!"; |
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return; |
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} |
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print STDERR "# reading ",$base_addr-24," bytes of dictionary\n" if ($self->{debug}); |
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my $directory; |
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if( ! read($self->{fh},$directory,$base_addr-24) ) { |
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carp "can't read directory: $!"; |
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$skip = 1; |
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} else { |
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print STDERR "# $rec_nr directory: [",length($directory),"] '$directory'\n" if ($self->{debug}); |
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} |
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print STDERR "# reading ",$reclen-$base_addr," bytes of fields\n" if ($self->{debug}); |
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my $fields; |
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if( ! read($self->{fh},$fields,$reclen-$base_addr) ) { |
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carp "can't read fields: $!"; |
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$skip = 1; |
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} else { |
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print STDERR "# $rec_nr fields: '$fields'\n" if ($self->{debug}); |
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} |
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my $row; |
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while (!$skip && $directory =~ s/(\d{3})(\d{4})(\d{5})//) { |
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my ($tag,$len,$addr) = ($1,$2,$3); |
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if (($addr+$len) > length($fields)) { |
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print STDERR "WARNING: error in dictionary on record $rec_nr skipping...\n" if (! $self->{quiet}); |
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$skip = 1; |
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next; |
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} |
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# take field |
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my $f = substr($fields,$addr,$len); |
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print STDERR "tag/len/addr $tag [$len] $addr: '$f'\n" if ($self->{debug}); |
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dpavlin |
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if ($row->{$tag}) { |
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$row->{$tag} .= $f; |
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} else { |
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$row->{$tag} = $f; |
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} |
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dpavlin |
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my $del = substr($fields,$addr+$len-1,1); |
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# check field delimiters... |
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if ($self->{assert} && $del ne chr(30)) { |
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print STDERR "WARNING: skipping record $rec_nr, can't find delimiter 30 got: '$del'\n" if (! $self->{quiet}); |
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$skip = 1; |
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next; |
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} |
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if ($self->{assert} && length($f) < 2) { |
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print STDERR "WARNING: skipping field $tag from record $rec_nr because it's too short!\n" if (! $self->{quiet}); |
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next; |
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} |
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} |
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return $row; |
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} |
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1; |
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__END__ |
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=head1 BUGS |
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=head1 SUPPORT |
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=head1 AUTHOR |
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Dobrica Pavlinusic |
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CPAN ID: DPAVLIN |
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dpavlin@rot13.org |
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http://www.rot13.org/~dpavlin/ |
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=head1 COPYRIGHT |
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This program is free software; you can redistribute |
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it and/or modify it under the same terms as Perl itself. |
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The full text of the license can be found in the |
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LICENSE file included with this module. |
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=head1 SEE ALSO |
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perl(1). |
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=cut |