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|
#-*- perl -*-
#
# Copyright (C) 2001 Ken'ichi Fukamachi
# All rights reserved. This program is free software; you can
# redistribute it and/or modify it under the same terms as Perl itself.
#
# $Id$
# $FML$
#
package Tie::JournaledFile;
use strict;
use vars qw(@ISA @EXPORT @EXPORT_OK $AUTOLOAD);
use Carp;
=head1 NAME
Tie::JournaledFile - hash emulation for a log structered file
=head1 SYNOPSIS
use Tie::JournaledFile;
$db = new Tie::JournaledFile { file => 'cache.txt' };
# all entries with the key = 'rudo'
@values = $db->grep( rudo );
or
use Tie::JournaledFile;
tie %db, 'Tie::JournaledFile', { file => 'cache.txt' };
print $db{ rudo }, "\n";
where cache file "cache.txt" format is "key value" for each line.
For example
rudo teddy bear
kenken north fox
.....
By default, FETCH() returns the first value with the key.
use Tie::JournaledFile;
tie %db, 'Tie::JournaledFile', { first_match => 1, file => 'cache.txt' };
print $db{ rudo }, "\n";
if you find the latest value (so at the later line somewhere in the
file) for the $key
use Tie::JournaledFile;
tie %db, 'Tie::JournaledFile', { last_match => 1, file => 'cache.txt' };
print $db{ rudo }, "\n";
=cut
require Exporter;
@ISA = qw(Exporter);
sub new
{
my ($self, $args) = @_;
my ($type) = ref($self) || $self;
my $me = {};
$me->{ _file } = $args->{ file };
if ($args->{ first_match }) {
$me->{ _match_style } = 'first';
}
elsif ($args->{ last_match }) {
$me->{ _match_style } = 'last';
}
else {
$me->{ _match_style } = 'first';
}
return bless $me, $type;
}
sub TIEHASH
{
my ($self, $args) = @_;
my ($type) = ref($self) || $self;
new($self, $args);
}
sub grep
{
my ($self, $key) = @_;
my $rarray = $self->_fetch($key, 'array');
return @$rarray;
}
sub FETCH
{
my ($self, $key) = @_;
$self->_fetch($key, 'scalar');
}
sub STORE
{
my ($self, $key, $value) = @_;
}
sub FIRSTKEY
{
my ($self) = @_;
use IO::File;
my $fh = new IO::File;
$fh->open( $self->{ _file }, "r");
$self->{ _fh } = $fh;
my $r = <$fh>;
my @r = split(/\s+/, $r);
return $r[0];
}
sub NEXTKEY
{
my ($self) = @_;
my $fh = $self->{ _fh };
my $r = <$fh>;
my @r = split(/\s+/, $r);
return $r[0];
}
sub _fetch
{
my ($self, $key, $mode) = @_;
my $prekey = $key;
# the first 1 byte of the key
if ($key =~ /^(.)/) { $prekey = $1;}
use IO::File;
my $fh = new IO::File;
$fh->open( $self->{ _file }, "r");
my ($xkey, $xvalue) = ();
my (@values) = ();
SEARCH:
while (<$fh>) {
next SEARCH if /^\#*$/;
next SEARCH if /^\s*$/;
next SEARCH unless /^$prekey/i;
next SEARCH unless /^$key/i;
chop;
($xkey, $xvalue) = split(/\s+/, $_, 2);
if ($xkey eq $key) {
if ($mode eq 'array') {
push(@values, $xvalue);
}
if ($mode eq 'scalar') {
# firstmatch: exit loop ASAP if the $key is found.
if ($self->{ _match_style } eq 'first') {
last SEARCH;
}
}
}
}
close($fh);
if ($mode eq 'scalar') {
return( $xvalue || undef );
}
if ($mode eq 'array') {
return \@values;
}
}
=head1 AUTHOR
Ken'ichi Fukamachi
=head1 COPYRIGHT
Copyright (C) 2001 Ken'ichi Fukamachi
All rights reserved. This program is free software; you can
redistribute it and/or modify it under the same terms as Perl itself.
=head1 HISTORY
Tie::JournaledFile appeared in fml5 mailing list driver package.
See C<http://www.fml.org/> for more details.
=cut
1;
|
