require 5.000;
require Exporter;
-@ISA = qw(Exporter);
-@EXPORT = qw(look);
+use strict;
-# Usage: look(*FILEHANDLE,$key,$dict,$fold)
+our $VERSION = '1.02';
+our @ISA = qw(Exporter);
+our @EXPORT = qw(look);
-# Sets file position in FILEHANDLE to be first line greater than or equal
-# (stringwise) to $key. Pass flags for dictionary order and case folding.
+=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 correponding 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 {
- local(*FH,$key,$dict,$fold) = @_;
- local($max,$min,$mid,$_);
- local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,
- $blksize,$blocks) = stat(FH);
- $blksize = 8192 unless $blksize;
+ my($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(@stat) = stat($fh)
+ or return -1;
+ my($size, $blksize) = @stat[7,11];
+ $blksize ||= 8192;
$key =~ s/[^\w\s]//g if $dict;
- $key =~ tr/A-Z/a-z/ if $fold;
- $max = int($size / $blksize);
+ $key = lc $key if $fold;
+ # find the right block
+ my($min, $max) = (0, int($size / $blksize));
+ my $mid;
while ($max - $min > 1) {
$mid = int(($max + $min) / 2);
- seek(FH,$mid * $blksize,0);
- $_ = <FH> if $mid; # probably a partial line
- $_ = <FH>;
- chop;
+ seek($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;
- tr/A-Z/a-z/ if $fold;
- if ($_ lt $key) {
+ $_ = lc $_ if $fold;
+ if (defined($_) && $comp->($_, $key) < 0) {
$min = $mid;
}
else {
$max = $mid;
}
}
+ # find the right line
$min *= $blksize;
- seek(FH,$min,0);
- <FH> if $min;
- while (<FH>) {
- chop;
+ seek($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;
- y/A-Z/a-z/ if $fold;
- last if $_ ge $key;
- $min = tell(FH);
+ $_ = lc $_ if $fold;
+ last if $comp->($_, $key) >= 0;
}
- seek(FH,$min,0);
+ seek($fh,$min,0);
$min;
}
1;
-