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package Data::Hierarchy;
$VERSION = '0.21';
use strict;
use Clone qw(clone);
=head1 NAME
Data::Hierarchy - Handle data in a hierarchical structure
=head1 SYNOPSIS
my $tree = Data::Hierarchy->new();
$tree->store ('/', {access => 'all'});
$tree->store ('/private', {access => 'auth',
'.sticky' => 'this is private});
$info = $tree->get ('/private/somewhere/deep');
# return actual data points in list context
($info, @fromwhere) = $tree->get ('/private/somewhere/deep');
my @items = $tree->find ('/', {access => qr/.*/});
# override all children
$tree->store_recursively ('/', {access => 'all'});
my $hashref = $tree->dump;
=head1 DESCRIPTION
Data::Hierarchy provides a simple interface for manipulating
inheritable data attached to a hierarchical environment (like
filesystem).
=cut
sub new {
my $class = shift;
# allow shorthand of ->new({...}) to mean ->new(hash => {...})
unshift @_, 'hash' if @_ % 2;
my $self = bless {@_}, $class;
$self->{sep} ||= '/';
$self->{hash} ||= {};
$self->{sticky} ||= {};
return $self;
}
sub key_safe {
if (length ($_[1]) > 1 and rindex($_[1], $_[0]->{sep}) == length ($_[1])) {
require Carp;
Carp::confess('key unsafe');
}
$_[1] =~ s/\Q$_[0]->{sep}\E+$//;
}
sub store_single {
my ($self, $key, $value) = @_;
$self->key_safe ($key);
$self->{hash}{$key} = $value;
}
sub _store {
my ($self, $key, $value) = @_;
$self->key_safe ($key);
my $oldvalue = $self->{hash}{$key} if exists $self->{hash}{$key};
my $hash = {%{$oldvalue||{}}, %$value};
for (keys %$hash) {
if (index($_, '.') == 0) {
defined $hash->{$_} ?
$self->{sticky}{$key}{$_} = $hash->{$_} :
delete $self->{sticky}{$key}{$_};
delete $hash->{$_};
}
else {
delete $hash->{$_}
unless defined $hash->{$_};
}
}
$self->{hash}{$key} = $hash;
delete $self->{hash}{$key} unless %{$self->{hash}{$key}};
delete $self->{sticky}{$key} unless keys %{$self->{sticky}{$key}};
}
sub merge {
my ($self, $other, $path) = @_;
my %datapoints = map {$_ => 1} ($self->descendents ($path),
$other->descendents ($path));
for my $key (reverse sort keys %datapoints) {
my $value = $self->get ($key);
my $nvalue = $other->get ($key);
for (keys %$value) {
$nvalue->{$_} = undef
unless defined $nvalue->{$_};
}
$self->store ($key, $nvalue);
}
}
sub _descendents {
my ($self, $hash, $key) = @_;
# If finding for everything, don't bother grepping
return sort keys %$hash unless length($key);
return sort grep {index($_.$self->{sep}, $key.$self->{sep}) == 0}
keys %$hash;
}
sub descendents {
my ($self, $key) = @_;
my $both = {%{$self->{hash}}, %{$self->{sticky} || {}}};
# If finding for everything, don't bother grepping
return sort keys %$both unless length($key);
return sort grep {index($_.$self->{sep}, $key.$self->{sep}) == 0}
keys %$both;
}
# empty the overridden values on descendents for hash
sub _store_recursively {
my ($self, $key, $value, $hash) = @_;
$self->key_safe ($key);
my @datapoints = $self->_descendents ($hash, $key);
for (@datapoints) {
my $vhash = $hash->{$_};
delete $vhash->{$_} for keys %$value;
delete $hash->{$_} unless %{$hash->{$_}};
}
}
# use store_fast to avoid trimming duplicated value with ancestors
sub store_fast {
my $self = shift;
$self->store (@_, 1);
}
sub store {
my ($self, $key, $value, $fast) = @_;
unless ($fast) {
my $ovalue = $self->get ($key);
for (keys %$value) {
next unless defined $value->{$_};
delete $value->{$_}
if exists $ovalue->{$_} && $ovalue->{$_} eq $value->{$_};
}
}
return unless keys %$value;
$self->_store_recursively ($key, $value, $self->{hash})
unless $fast;
$self->_store ($key, $value);
}
sub store_override {
my ($self, $key, $value) = @_;
my ($ovalue, @datapoints) = $self->get ($key);
for (keys %$value) {
next unless defined $value->{$_};
if (exists $ovalue->{$_} && $ovalue->{$_} eq $value->{$_}) {
# if the parent has the property already
if ($#datapoints > 0 && exists $self->{hash}{$datapoints[-1]}{$_}) {
$value->{$_} = undef;
}
else {
delete $value->{$_};
}
}
}
return unless keys %$value;
$self->_store ($key, $value);
}
# Useful for removing sticky properties.
sub store_recursively {
my ($self, $key, $value) = @_;
$self->_store_recursively ($key, $value, $self->{hash});
$self->_store_recursively ($key, $value, $self->{sticky});
$self->_store ($key, $value);
}
sub find {
my ($self, $key, $value) = @_;
$self->key_safe ($key);
my @items;
my @datapoints = $self->descendents($key);
for my $entry (@datapoints) {
my $matched = 1;
for (keys %$value) {
my $lookat = (index($_, '.') == 0) ?
$self->{sticky}{$entry} : $self->{hash}{$entry};
$matched = 0
unless exists $lookat->{$_}
&& $lookat->{$_} =~ m/$value->{$_}/;
last unless $matched;
}
push @items, $entry
if $matched;
}
return @items;
}
sub get_single {
my ($self, $key) = @_;
return clone ($self->{hash}{$key} || {});
}
sub get {
my ($self, $key, $rdonly) = @_;
$self->key_safe ($key);
my $value = {};
# XXX: could build cached pointer for fast traversal
my @datapoints = sort grep {index($key.$self->{sep}, $_.$self->{sep}) == 0}
keys %{$self->{hash}};
for (@datapoints) {
my $newv = $self->{hash}{$_};
$newv = clone $newv unless $rdonly;
$value = {%$value, %$newv};
}
if (exists $self->{sticky}{$key}) {
my $newv = $self->{sticky}{$key};
$newv = clone $newv unless $rdonly;
$value = {%$value, %$newv}
}
return wantarray ? ($value, @datapoints) : $value;
}
sub dump {
my ($self) = @_;
return $self->{hash};
}
1;
=head1 AUTHORS
Chia-liang Kao E<lt>clkao@clkao.orgE<gt>
=head1 COPYRIGHT
Copyright 2003 by Chia-liang Kao E<lt>clkao@clkao.orgE<gt>.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See L<http://www.perl.com/perl/misc/Artistic.html>
=cut
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