# $Id$
# Hash tied to optionally dynamically generate its values
# Copyright (C) 2005 Jan Kratochvil <project-www.jankratochvil.net@jankratochvil.net>
# 
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; exactly version 2 of June 1991 is required
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


package My::Hash::Push;
our $VERSION=do { my @r=(q$Revision$=~/\d+/g); sprintf "%d.".("%03d"x$#r),@r; };
our $CVS_ID=q$Id$;
use strict;
use warnings;
use My::Web;	# for &Wrequire
Wrequire 'My::Hash';
our @ISA=qw(My::Hash);
use Carp qw(cluck confess);
require Data::Compare;


# You are recommended to STORE all the keys, not to parent-inherit them.


sub _normalize($$)
{
my($self,$val)=@_;

	$val=[] if !defined $val;
	$val=[$val] if "ARRAY" ne ref($val);
	return $val;
}

sub _ours($$)
{
my($self,$key,$state)=@_;

	my $ref=\$self->{"ours"}{$key};
	warn "State change for key \"$key\"; was=".(0+$$ref).",now=".(0+$state)
			if defined($state) && defined($$ref) && $state!=$$ref;
	$$ref=$state if defined $state;
	return $$ref;
}

sub STORE
{
my($this,$key,$value)=@_;

	if ($key=~s/_push$//) {
		$this->_ours($key,1);
		return $this->pass("STORE",$key,[@{$this->_normalize($this->pass("FETCH",$key))},$value]);
		}
	if ($key=~s/_pop$//) {
		$this->_ours($key,1);
		my $val_orig=$this->FETCH($key);
		for my $vali (reverse 0..$#$val_orig) {
			next if Data::Compare::Compare($val_orig->[$vali],$value);
			splice @$val_orig,$vali,1;
			return $this->pass("STORE",$key,$val_orig);
			}
		cluck "value[1] not found in the array[2] of key[0]:\n".Dumper($key,$value,$val_orig);
		return;
		}
	if ($key=~s/_set$//) {
		$this->_ours($key,1);
		return $this->pass("STORE",$key,$this->_normalize($value));
		}
	$this->_ours($key,0);
	return $this->pass("STORE",$key,$value);
}

sub FETCH($$)
{
my($this,$key_orig)=@_;

	my $force=((my $key=$key_orig)=~s/_push$//);
	$this->_ours($key,1) if $force;
	my $val=$this->pass("FETCH",$key);
	return $this->_normalize($val) if $force || $this->_ours($key);
	return $val;
}

1;