#-*- 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 IO::LogFileDB;

use strict;
use vars qw(@ISA @EXPORT @EXPORT_OK $AUTOLOAD);
use Carp;

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 _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 NAME

IO::LogFileDB.pm - what is this

=head1 SYNOPSIS

   use IO::LogFileDB;
   $db = new IO::LogFileDB { file => 'cache.txt' };

   # all entries with the key = 'rudo'
   @values = $db->grep( rudo );

or

   use IO::LogFileDB;
   tie %db, 'IO::LogFileDB', { 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 IO::LogFileDB;
   tie %db, 'IO::LogFileDB', { 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 IO::LogFileDB;
   tie %db, 'IO::LogFileDB', { last_match => 1, file => 'cache.txt' };
   print $db{ rudo }, "\n";



=head1 DESCRIPTION

=head2 new

=item Function()


=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

IO::LogFileDB.pm appeared in fml5.

=cut

1;
