+Hash tied to restrict access to the specified keys list.

diff --git a/Hash/Makefile.am b/Hash/Makefile.am
index 0c70402..7a7d772 100644 (file)
--- a/Hash/Makefile.am
+++ b/Hash/Makefile.am
@@ -19,7 +19,8 @@
 include $(top_srcdir)/Makefile-head.am
 
 EXTRA_DIST+= \
-               Push.pm
-               Sub.pm
-               Readonly.pm
+               Push.pm \
+               Sub.pm \
+               Readonly.pm \
+               RestrictTo.pm
 

diff --git a/Hash/RestrictTo.pm b/Hash/RestrictTo.pm
new file mode 100644 (file)
index 0000000..d11501b
--- /dev/null
+++ b/Hash/RestrictTo.pm
@@ -0,0 +1,106 @@
+# $Id$
+# Hash tied to restrict access to the specified keys list.
+# 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::RestrictTo;
+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($$@)
+{
+my($class,$parent,@keys)=@_;
+
+       my $self=$class->SUPER::TIEHASH($parent);
+       $self->{"keyshash"}={ map(($_=>1),@keys) };
+       return $self;
+}
+
+sub STORE($$$)
+{
+my($this,$key,$value)=@_;
+
+       confess "Key not permitted: $key" if !$this->{"keyshash"}{$key};
+       return $this->pass("STORE",$key,$value);
+}
+
+sub FETCH($$)
+{
+my($this,$key)=@_;
+
+       confess "Key not permitted: $key" if !$this->{"keyshash"}{$key};
+       return $this->pass("FETCH",$key);
+}
+
+sub FIRSTKEY($)
+{
+my($this)=@_;
+
+       my $a=keys(%{$this->{"keyshash"}});
+       return $this->NEXTKEY($this,undef());
+}
+
+sub NEXTKEY($$)
+{
+my($this,$lastkey)=@_;
+
+cluck "TODO: Enumeration may not be expected.";
+       for (;;) {
+               my $key=each(%{$this->{"keyshash"}});
+               return if !defined $key;
+               return $key if exists $this->{"parent"}{$key};
+               }
+}
+
+sub EXISTS($$)
+{
+my($this,$key)=@_;
+
+       confess "Key not permitted: $key" if !$this->{"keyshash"}{$key};
+       return $this->pass("EXISTS",$key);
+}
+
+sub DELETE($$)
+{
+my($this,$key)=@_;
+
+       confess "Key not permitted: $key" if !$this->{"keyshash"}{$key};
+       return $this->pass("DELETE",$key);
+}
+
+sub CLEAR($)
+{
+my($this)=@_;
+
+cluck "TODO: Enumeration may not be expected.";
+       delete $this->{"parent"}{$_} for keys(%{$this->{"keyshash"}});
+}
+
+sub SCALAR
+{
+my($this)=@_;
+
+confess "TODO: Not yet implemented.";
+}
+
+1;