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# -*- Mode: Cperl -*- |
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# InvertedIndex.pm -- |
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# ITIID : $ITI$ $Header $__Header$ |
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# Author : Ulrich Pfeifer |
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# Created On : Thu Aug 8 13:05:10 1996 |
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# Last Modified By: Ulrich Pfeifer |
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# Last Modified On: Sun Nov 22 18:44:42 1998 |
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# Language : CPerl |
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# Status : Unknown, Use with caution! |
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# |
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# Copyright (c) 1996-1997, Ulrich Pfeifer |
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# |
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|
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package WAIT::InvertedIndex; |
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use strict; |
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use DB_File; |
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use Fcntl; |
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use WAIT::Filter; |
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use Carp; |
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use vars qw(%FUNC); |
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|
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my $O = pack('C', 0xff)."o"; # occurances |
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my $M = pack('C', 0xff)."m"; # maxtf |
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|
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sub new { |
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my $type = shift; |
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my %parm = @_; |
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my $self = {}; |
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|
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$self->{file} = $parm{file} or croak "No file specified"; |
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$self->{attr} = $parm{attr} or croak "No attributes specified"; |
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$self->{filter} = $parm{filter}; |
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$self->{'name'} = $parm{'name'}; |
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$self->{records} = 0; |
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for (qw(intervall prefix)) { |
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if (exists $parm{$_}) { |
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if (ref $parm{$_}) { |
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$self->{$_} = [@{$parm{$_}}] # clone |
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} else { |
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$self->{$_} = $parm{$_} |
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} |
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} |
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} |
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bless $self, ref($type) || $type; |
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} |
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|
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sub name {$_[0]->{'name'}} |
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|
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sub _split_pos { |
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my ($text, $pos) = @{$_[0]}; |
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my @result; |
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|
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$text =~ s/(^\s+)// and $pos += length($1); |
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while ($text =~ s/(^\S+)//) { |
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my $word = $1; |
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push @result, [$word, $pos]; |
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$pos += length($word); |
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$text =~ s/(^\s+)// and $pos += length($1); |
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} |
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@result; |
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} |
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|
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sub _xfiltergen { |
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my $filter = pop @_; |
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|
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# Oops, we cannot overrule the user's choice. Other filters may kill |
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# stopwords, such as isotr clobbers "isn't" to "isnt". |
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|
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# if ($filter eq 'stop') { # avoid the slow stopword elimination |
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# return _xfiltergen(@_); # it's cheaper to look them up afterwards |
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# } |
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if (@_) { |
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if ($filter =~ /^split(\d*)/) { |
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if ($1) { |
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"grep(length(\$_->[0])>=$1, map(&WAIT::Filter::split_pos(\$_), " . _xfiltergen(@_) .'))' ; |
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} else { |
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"map(&WAIT::Filter::split_pos(\$_), " . _xfiltergen(@_) .')' ; |
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} |
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} else { |
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"map ([&WAIT::Filter::$filter(\$_->[0]), \$_->[1]]," ._xfiltergen(@_) .')'; |
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} |
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} else { |
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if ($filter =~ /^split(\d*)/) { |
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if ($1) { |
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"grep(length(\$_->[0])>=$1, map(&WAIT::Filter::split_pos(\$_), [\$_[0], 0]))" ; |
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} else { |
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"map(&WAIT::Filter::split_pos(\$_), [\$_[0], 0])" ; |
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} |
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} else { |
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"map ([&WAIT::Filter::$filter(\$_->[0]), \$_->[1]], [\$_[0], 0])"; |
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} |
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} |
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} |
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|
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sub parse_pos { |
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my $self = shift; |
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|
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unless (exists $self->{xfunc}) { |
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$self->{xfunc} = |
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eval sprintf("sub {%s}", _xfiltergen(@{$self->{filter}})); |
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#printf "\nsub{%s}$@\n", _xfiltergen(@{$self->{filter}}); |
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} |
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&{$self->{xfunc}}($_[0]); |
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} |
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|
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sub _filtergen { |
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my $filter = pop @_; |
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|
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if (@_) { |
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"map(&WAIT::Filter::$filter(\$_), " . _filtergen(@_) . ')'; |
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} else { |
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"map(&WAIT::Filter::$filter(\$_), \@_)"; |
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} |
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} |
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|
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sub drop { |
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my $self = shift; |
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if ((caller)[0] eq 'WAIT::Table') { # Table knows about this |
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my $file = $self->{file}; |
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|
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! (!-e $file or unlink $file); |
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} else { # notify our database |
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croak ref($self)."::drop called directly"; |
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} |
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} |
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|
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sub open { |
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my $self = shift; |
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my $file = $self->{file}; |
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|
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if (defined $self->{dbh}) { |
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$self->{dbh}; |
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} else { |
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$self->{func} = |
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eval sprintf("sub {grep /./, %s}", _filtergen(@{$self->{filter}})); |
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$self->{dbh} = tie(%{$self->{db}}, 'DB_File', $file, |
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$self->{mode}, 0664, $DB_BTREE); |
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# tie(%{$self->{cache}}, 'DB_File', undef, |
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# $self->{mode}, 0664, $DB_BTREE) |
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$self->{cache} = {} |
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if $self->{mode} & O_RDWR; |
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# tie(%{$self->{cdict}}, 'DB_File', undef, |
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# $self->{mode}, 0664, $DB_BTREE) |
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$self->{cdict} = {} |
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if $self->{mode} & O_RDWR; |
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$self->{cached} = 0; |
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} |
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} |
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|
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sub insert { |
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my $self = shift; |
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my $key = shift; |
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my %occ; |
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|
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defined $self->{db} or $self->open; |
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grep $occ{$_}++, &{$self->{func}}(@_); |
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my ($word, $noc); |
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$self->{records}++; |
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while (($word, $noc) = each %occ) { |
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if (defined $self->{cache}->{$word}) { |
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$self->{cdict}->{$O,$word}++; |
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$self->{cache}->{$word} .= pack 'w2', $key, $noc; |
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} else { |
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$self->{cdict}->{$O,$word} = 1; |
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$self->{cache}->{$word} = pack 'w2', $key, $noc; |
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} |
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$self->{cached}++; |
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} |
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$self->sync if $self->{cached} > 100_000; |
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my $maxtf = 0; |
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for (values %occ) { |
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$maxtf = $_ if $_ > $maxtf; |
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} |
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$self->{db}->{$M, $key} = $maxtf; |
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} |
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|
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sub delete { |
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my $self = shift; |
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my $key = shift; |
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my %occ; |
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|
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defined $self->{db} or $self->open; |
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$self->sync; |
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$self->{records}--; |
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grep $occ{$_}++, &{$self->{func}}(@_); |
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for (keys %occ) { |
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# may reorder posting list |
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my %post = unpack 'w*', $self->{db}->{$_}; |
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$self->{db}->{$O,$_}--; |
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delete $post{$key}; |
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$self->{db}->{$_} = pack 'w*', %post; |
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} |
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delete $self->{db}->{$M, $key}; |
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} |
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|
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sub intervall { |
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my ($self, $first, $last) = @_; |
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my $value = ''; |
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my $word = ''; |
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my @result; |
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|
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return unless exists $self->{'intervall'}; |
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|
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defined $self->{db} or $self->open; |
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$self->sync; |
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my $dbh = $self->{dbh}; # for convenience |
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|
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if (ref $self->{'intervall'}) { |
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unless (exists $self->{'ifunc'}) { |
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$self->{'ifunc'} = |
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eval sprintf("sub {grep /./, %s}", _filtergen(@{$self->{intervall}})); |
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} |
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($first) = &{$self->{'ifunc'}}($first) if $first; |
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($last) = &{$self->{'ifunc'}}($last) if $last; |
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} |
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if (defined $first and $first ne '') { # set the cursor to $first |
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$dbh->seq($first, $value, R_CURSOR); |
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} else { |
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$dbh->seq($first, $value, R_FIRST); |
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} |
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# We assume that word do not start with the character \377 |
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# $last = pack 'C', 0xff unless defined $last and $last ne ''; |
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return () if defined $last and $first gt $last; # $first would be after the last word |
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|
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push @result, $first; |
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while (!$dbh->seq($word, $value, R_NEXT)) { |
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# We should limit this to a "resonable" number of words |
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last if (defined $last and $word gt $last) or $word =~ /^($M|$O)/o; |
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push @result, $word; |
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} |
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\@result; # speed |
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} |
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|
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sub prefix { |
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my ($self, $prefix) = @_; |
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my $value = ''; |
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my $word = ''; |
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my @result; |
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|
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return () unless defined $prefix; # Full dictionary requested !! |
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return unless exists $self->{'prefix'}; |
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defined $self->{db} or $self->open; |
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$self->sync; |
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my $dbh = $self->{dbh}; |
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|
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if (ref $self->{'prefix'}) { |
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unless (exists $self->{'pfunc'}) { |
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$self->{'pfunc'} = |
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eval sprintf("sub {grep /./, %s}", _filtergen(@{$self->{prefix}})); |
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} |
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($prefix) = &{$self->{'pfunc'}}($prefix); |
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} |
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|
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if ($dbh->seq($word = $prefix, $value, R_CURSOR)) { |
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return (); |
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} |
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return () if $word !~ /^$prefix/; |
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push @result, $word; |
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|
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while (!$dbh->seq($word, $value, R_NEXT)) { |
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# We should limit this to a "resonable" number of words |
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last if $word !~ /^$prefix/; |
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push @result, $word; |
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} |
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\@result; # speed |
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} |
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|
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sub search { |
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my $self = shift; |
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|
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defined $self->{db} or $self->open; |
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$self->sync; |
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$self->search_raw(&{$self->{func}}(@_)); # No call to parse() here |
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} |
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|
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sub parse { |
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my $self = shift; |
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|
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defined $self->{db} or $self->open; |
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&{$self->{func}}(@_); |
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} |
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|
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sub keys { |
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my $self = shift; |
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|
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defined $self->{db} or $self->open; |
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keys %{$self->{db}}; |
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} |
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|
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sub search_prefix { |
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my $self = shift; |
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|
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# print "search_prefix(@_)\n"; |
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defined $self->{db} or $self->open; |
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$self->search_raw(map($self->prefix($_), @_)); |
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} |
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|
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sub search_raw { |
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my $self = shift; |
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my %occ; |
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my %score; |
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|
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return () unless @_; |
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|
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defined $self->{db} or $self->open; |
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$self->sync; |
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grep $occ{$_}++, @_; |
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for (keys %occ) { |
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if (defined $self->{db}->{$_}) { |
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my %post = unpack 'w*', $self->{db}->{$_}; |
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my $idf = log($self->{records}/($self->{db}->{$O,$_} || 1)); |
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my $did; |
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for $did (keys %post) { |
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$score{$did} = 0 unless defined $score{$did}; # perl -w |
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$score{$did} += $post{$did} / $self->{db}->{$M, $did} * $idf |
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if $self->{db}->{$M, $did}; # db may be broken |
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} |
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} |
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} |
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%score; |
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} |
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|
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sub sync { |
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my $self = shift; |
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|
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if ($self->{mode} & O_RDWR) { |
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print STDERR "Flushing $self->{cached} postings\n"; |
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while (my($key, $value) = each %{$self->{cache}}) { |
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$self->{db}->{$key} .= $value; |
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#delete $self->{cache}->{$key}; |
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} |
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while (my($key, $value) = each %{$self->{cdict}}) { |
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$self->{db}->{$key} = 0 unless $self->{db}->{$key}; |
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$self->{db}->{$key} += $value; |
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#delete $self->{cdict}->{$key}; |
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} |
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$self->{cache} = {}; |
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$self->{cdict} = {}; |
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# print STDERR "*** $self->{cache} ", tied(%{$self->{cache}}), "==\n"; |
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$self->{cached} = 0; |
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# $self->{dbh}->sync if $self->{dbh}; |
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} |
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} |
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|
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sub close { |
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my $self = shift; |
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|
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if ($self->{dbh}) { |
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$self->sync; |
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delete $self->{dbh}; |
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untie %{$self->{db}}; |
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delete $self->{db}; |
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delete $self->{func}; |
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delete $self->{cache}; |
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delete $self->{cached}; |
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delete $self->{cdict}; |
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delete $self->{pfunc} if defined $self->{pfunc}; |
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delete $self->{ifunc} if defined $self->{ifunc}; |
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delete $self->{xfunc} if defined $self->{xfunc}; |
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} |
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} |
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|
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1; |
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