NAME

Data::StackedMap - An object that stores key/value pairs in a stacked fashion

SYNOPSIS

    use Data::StackedMap;
    
    my $data = Data::StackedMap->new();

    $data->set("foo" => 10);
    print $data->get("foo"); # prints '10'

    $data->push();
    print $data->get("foo"); # still prints '10'
    
    $data->set("foo" => 20);
    print $data->get("foo"); # now prints '20'
    
    $data->pop();
    print $data->get("foo"); # prints '10' again

DESCRIPTION

This class implements a simple key/value map where each key can exist multiple times in different layers in a stack.

INTERFACE

CLASS METHODS

new ( $default_hash )

Creates a new instance of this class. The first layer of the stack can be pre-populated by passing a hash ref ($default_hash) whos keys and values will be copied.

INSTANCE METHODS

exists ( $key )

Checks if data with the key $key exists anywhere in the stack. Returns the layer (from the top) in which the key is first found. -1 for top-most layer, -2 for second top-most layer and so forth. Returns 0 if the key is not found at all.

delete ( $key )

Deletes the value of $key at the top of the stack. If an entry with the same key exists down the stack get and exists will operate on that value.

get ( $key )

Returns the value of $key or undef it the key doesn't exist. Will search down the stack to find the value.

set ( $key => $value )

put ( $key => $value )

Sets the value of $key to $value.

keys ()

Returns a list of the keys defined in all layers of the stack.

top_keys ()

Returns a list of the keys defined in just the top layer of the stack.

push ()

Creates a new current map in the stack.

pop ()

Removes the current stack entry and returns it. Will throw an error if called when there is only one map in the stack.

size ()

Returns the length of the stack, i.e. how many layers deep it currently is.

SEE ALSO

Tie::Hash::Stack

Data::StackedHash

BUGS AND LIMITATIONS

Please report any bugs or feature requests to bug-data-stackedmap@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR

Claes Jakobsson <claesjac@cpan.org>

LICENCE AND COPYRIGHT

Copyright (c) 2007, Claes Jakobsson <claesjac@cpan.org>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.