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Dict.pm
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package Search::Dict; require 5.000; require Exporter; my $fc_available; BEGIN { $fc_available = '5.015008'; if ( $] ge $fc_available ) { require feature; 'feature'->import('fc'); # string avoids warning on old Perls <sigh> } } use strict; our $VERSION = '1.07'; our @ISA = qw(Exporter); our @EXPORT = qw(look); =head1 NAME Search::Dict - look - search for key in dictionary file =head1 SYNOPSIS use Search::Dict; look *FILEHANDLE, $key, $dict, $fold; use Search::Dict; look *FILEHANDLE, $params; =head1 DESCRIPTION Sets file position in FILEHANDLE to be first line greater than or equal (stringwise) to I<$key>. Returns the new file position, or -1 if an error occurs. The flags specify dictionary order and case folding: If I<$dict> is true, search by dictionary order (ignore anything but word characters and whitespace). The default is honour all characters. If I<$fold> is true, ignore case. The default is to honour case. If there are only three arguments and the third argument is a hash reference, the keys of that hash can have values C<dict>, C<fold>, and C<comp> or C<xfrm> (see below), and their corresponding values will be used as the parameters. If a comparison subroutine (comp) is defined, it must return less than zero, zero, or greater than zero, if the first comparand is less than, equal, or greater than the second comparand. If a transformation subroutine (xfrm) is defined, its value is used to transform the lines read from the filehandle before their comparison. =cut sub look { my($fh,$key,$dict,$fold) = @_; my ($comp, $xfrm); if (@_ == 3 && ref $dict eq 'HASH') { my $params = $dict; $dict = 0; $dict = $params->{dict} if exists $params->{dict}; $fold = $params->{fold} if exists $params->{fold}; $comp = $params->{comp} if exists $params->{comp}; $xfrm = $params->{xfrm} if exists $params->{xfrm}; } $comp = sub { $_[0] cmp $_[1] } unless defined $comp; local($_); my $fno = fileno $fh; my @stat; if ( defined $fno && $fno >= 0 && ! tied *{$fh} ) { # real, open file @stat = eval { stat($fh) }; # in case fileno lies } my($size, $blksize) = @stat[7,11]; $size = do { seek($fh,0,2); my $s = tell($fh); seek($fh,0,0); $s } unless defined $size; $blksize ||= 8192; $key =~ s/[^\w\s]//g if $dict; if ( $fold ) { $key = $] ge $fc_available ? fc($key) : lc($key); } # find the right block my($min, $max) = (0, int($size / $blksize)); my $mid; while ($max - $min > 1) { $mid = int(($max + $min) / 2); seek($fh, $mid * $blksize, 0) or return -1; <$fh> if $mid; # probably a partial line $_ = <$fh>; $_ = $xfrm->($_) if defined $xfrm; chomp; s/[^\w\s]//g if $dict; if ( $fold ) { $_ = $] ge $fc_available ? fc($_) : lc($_); } if (defined($_) && $comp->($_, $key) < 0) { $min = $mid; } else { $max = $mid; } } # find the right line $min *= $blksize; seek($fh,$min,0) or return -1; <$fh> if $min; for (;;) { $min = tell($fh); defined($_ = <$fh>) or last; $_ = $xfrm->($_) if defined $xfrm; chomp; s/[^\w\s]//g if $dict; if ( $fold ) { $_ = $] ge $fc_available ? fc($_) : lc($_); } last if $comp->($_, $key) >= 0; } seek($fh,$min,0); $min; } 1;