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package Git::SVN::Memoize::YAML;
use warnings $ENV{GIT_PERL_FATAL_WARNINGS} ? qw(FATAL all) : ();
use strict;
use YAML::Any ();
 
# based on Memoize::Storable.
 
sub TIEHASH {
	my $package = shift;
	my $filename = shift;
	my $truehash = (-e $filename) ? YAML::Any::LoadFile($filename) : {};
	my $self = {FILENAME => $filename, H => $truehash};
	bless $self => $package;
}
 
sub STORE {
	my $self = shift;
	$self->{H}{$_[0]} = $_[1];
}
 
sub FETCH {
	my $self = shift;
	$self->{H}{$_[0]};
}
 
sub EXISTS {
	my $self = shift;
	exists $self->{H}{$_[0]};
}
 
sub DESTROY {
	my $self = shift;
	YAML::Any::DumpFile($self->{FILENAME}, $self->{H});
}
 
sub SCALAR {
	my $self = shift;
	scalar(%{$self->{H}});
}
 
sub FIRSTKEY {
	'Fake hash from Git::SVN::Memoize::YAML';
}
 
sub NEXTKEY {
	undef;
}
 
1;
__END__
 
=head1 NAME
 
Git::SVN::Memoize::YAML - store Memoized data in YAML format
 
=head1 SYNOPSIS
 
    use Memoize;
    use Git::SVN::Memoize::YAML;
 
    tie my %cache => 'Git::SVN::Memoize::YAML', $filename;
    memoize('slow_function', SCALAR_CACHE => [HASH => \%cache]);
    slow_function(arguments);
 
=head1 DESCRIPTION
 
This module provides a class that can be used to tie a hash to a
YAML file.  The file is read when the hash is initialized and
rewritten when the hash is destroyed.
 
The intent is to allow L<Memoize> to back its cache with a file in
YAML format, just like L<Memoize::Storable> allows L<Memoize> to
back its cache with a file in Storable format.  Unlike the Storable
format, the YAML format is platform-independent and fairly stable.
 
Carps on error.
 
=head1 DIAGNOSTICS
 
See L<YAML::Any>.
 
=head1 DEPENDENCIES
 
L<YAML::Any> from CPAN.
 
=head1 INCOMPATIBILITIES
 
None reported.
 
=head1 BUGS
 
The entire cache is read into a Perl hash when loading the file,
so this is not very scalable.