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