# $Id$
# Hash tied to provide additional keys/values than the original.
# 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::Merge;
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);


sub TIEHASH($@)
{
my($class,@parents)=@_;

	my $self=bless {},$class;
	for my $parent (@parents) {
		# Possibly upgrade unref("HASH")es:
		$parent=$class->SUPER::TIEHASH($parent)->{"parent"};
		push @{$self->{"parents"}},$parent;
		}
	return $self;
}

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

	my $count=0;
	my $first;
	for my $parent (@{$self->{"parents"}}) {
		next if !exists $parent->{$key};
		$count++;
		$first||=$parent;
		}
	# 0 IS allowed here.
	cluck "Duplicity ($count-icity) for key: $key" if $count>=2;
	$first||=$self->{"parents"}[0];
	return $first;
}

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

	my $first=$this->key_find($key);
	$first->{$key}=$value;
}

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

	my $first=$this->key_find($key);
	return if !$first;
	return $first->{$key};
}

sub FIRSTKEY($)
{
my($this)=@_;

confess "TODO: Not yet implemented.";
}

sub NEXTKEY($$)
{
my($this,$lastkey)=@_;

confess "TODO: Not yet implemented.";
}

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

	my $first=$this->key_find($key);
	$first||={};
	return exists $first->{$key};
}

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

	my $first=$this->key_find($key);
	delete $first->{$key};
}

sub CLEAR($)
{
my($this)=@_;

confess "TODO: Not yet implemented.";
}

sub SCALAR
{
my($this)=@_;

confess "TODO: Not yet implemented.";
}

1;