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package Search::Dict;
require 5.000;
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(look);
=head1 NAME
Search::Dict, look - search for key in dictionary file
=head1 SYNOPSIS
use Search::Dict;
look *FILEHANDLE, $key, $dict, $fold;
=head1 DESCRIPTION
Sets file position in FILEHANDLE to be first line greater than or equal
(stringwise) to I<$key>. Returns the new file position, or -1 if an error
occurs.
The flags specify dictionary order and case folding:
If I<$dict> is true, search by dictionary order (ignore anything but word
characters and whitespace).
If I<$fold> is true, ignore case.
=cut
sub look {
local(*FH,$key,$dict,$fold) = @_;
local($_);
my(@stat) = stat(FH)
or return -1;
my($size, $blksize) = @stat[7,11];
$blksize ||= 8192;
$key =~ s/[^\w\s]//g if $dict;
$key = lc $key if $fold;
my($min, $max, $mid) = (0, int($size / $blksize));
while ($max - $min > 1) {
$mid = int(($max + $min) / 2);
seek(FH, $mid * $blksize, 0)
or return -1;
<FH> if $mid; # probably a partial line
$_ = <FH>;
chop;
s/[^\w\s]//g if $dict;
$_ = lc $_ if $fold;
if (defined($_) && $_ lt $key) {
$min = $mid;
}
else {
$max = $mid;
}
}
$min *= $blksize;
seek(FH,$min,0)
or return -1;
<FH> if $min;
for (;;) {
$min = tell(FH);
defined($_ = <FH>)
or last;
chop;
s/[^\w\s]//g if $dict;
$_ = lc $_ if $fold;
last if $_ ge $key;
}
seek(FH,$min,0);
$min;
}
1;
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