package MooseX::Storage::Engine;
{
$MooseX::Storage::Engine::VERSION = '0.44';
}
BEGIN {
$MooseX::Storage::Engine::AUTHORITY = 'cpan:STEVAN';
}
# ABSTRACT: The meta-engine to handle collapsing and expanding objects
use Moose;
use Scalar::Util qw(refaddr);
# the class marker when
# serializing an object.
our $CLASS_MARKER = '__CLASS__';
has 'storage' => (
is => 'ro',
isa => 'HashRef',
default => sub {{}}
);
has 'seen' => (
is => 'ro',
isa => 'HashRef[Int]', # int is the refaddr
default => sub {{}}
);
has 'object' => (is => 'rw', isa => 'Object', predicate => '_has_object');
has 'class' => (is => 'rw', isa => 'Str');
## this is the API used by other modules ...
sub collapse_object {
my ( $self, %options ) = @_;
# NOTE:
# mark the root object as seen ...
$self->seen->{refaddr $self->object} = undef;
$self->map_attributes('collapse_attribute', \%options);
$self->storage->{$CLASS_MARKER} = $self->object->meta->identifier;
return $self->storage;
}
sub expand_object {
my ($self, $data, %options) = @_;
$options{check_version} = 1 unless exists $options{check_version};
$options{check_authority} = 1 unless exists $options{check_authority};
# NOTE:
# mark the root object as seen ...
$self->seen->{refaddr $data} = undef;
$self->map_attributes('expand_attribute', $data, \%options);
return $self->storage;
}
## this is the internal API ...
sub collapse_attribute {
my ($self, $attr, $options) = @_;
my $value = $self->collapse_attribute_value($attr, $options);
return if !defined($value);
$self->storage->{$attr->name} = $value;
}
sub expand_attribute {
my ($self, $attr, $data, $options) = @_;
my $value = $self->expand_attribute_value($attr, $data->{$attr->name}, $options);
$self->storage->{$attr->name} = defined $value ? $value : return;
}
sub collapse_attribute_value {
my ($self, $attr, $options) = @_;
# Faster, but breaks attributes without readers, do we care?
#my $value = $attr->get_read_method_ref->($self->object);
my $value = $attr->get_value($self->object);
# NOTE:
# this might not be enough, we might
# need to make it possible for the
# cycle checker to return the value
$self->check_for_cycle_in_collapse($attr, $value)
if ref $value;
if (defined $value && $attr->has_type_constraint) {
my $type_converter = $self->find_type_handler($attr->type_constraint, $value);
(defined $type_converter)
|| confess "Cannot convert " . $attr->type_constraint->name;
$value = $type_converter->{collapse}->($value, $options);
}
return $value;
}
sub expand_attribute_value {
my ($self, $attr, $value, $options) = @_;
# NOTE:
# (see comment in method above ^^)
if( ref $value and not(
$options->{disable_cycle_check} or
$self->class->does('MooseX::Storage::Traits::DisableCycleDetection')
)) {
$self->check_for_cycle_in_collapse($attr, $value)
}
if (defined $value && $attr->has_type_constraint) {
my $type_converter = $self->find_type_handler($attr->type_constraint, $value);
$value = $type_converter->{expand}->($value, $options);
}
return $value;
}
# NOTE:
# possibly these two methods will
# be used by a cycle supporting
# engine. However, I am not sure
# if I can make a cycle one work
# anyway.
sub check_for_cycle_in_collapse {
my ($self, $attr, $value) = @_;
(!exists $self->seen->{refaddr $value})
|| confess "Basic Engine does not support cycles in class("
. ($attr->associated_class->name) . ").attr("
. ($attr->name) . ") with $value";
$self->seen->{refaddr $value} = undef;
}
sub check_for_cycle_in_expansion {
my ($self, $attr, $value) = @_;
(!exists $self->seen->{refaddr $value})
|| confess "Basic Engine does not support cycles in class("
. ($attr->associated_class->name) . ").attr("
. ($attr->name) . ") with $value";
$self->seen->{refaddr $value} = undef;
}
# util methods ...
sub map_attributes {
my ($self, $method_name, @args) = @_;
map {
$self->$method_name($_, @args)
} grep {
# Skip our special skip attribute :)
!$_->does('MooseX::Storage::Meta::Attribute::Trait::DoNotSerialize')
} ($self->_has_object ? $self->object : $self->class)->meta->get_all_attributes;
}
## ------------------------------------------------------------------
## This is all the type handler stuff, it is in a state of flux
## right now, so this may change, or it may just continue to be
## improved upon. Comments and suggestions are welcomed.
## ------------------------------------------------------------------
# NOTE:
# these are needed by the
# ArrayRef and HashRef handlers
# below, so I need easy access
my %OBJECT_HANDLERS = (
expand => sub {
my ($data, $options) = @_;
(exists $data->{$CLASS_MARKER})
|| confess "Serialized item has no class marker";
# check the class more thoroughly here ...
my ($class, $version, $authority) = (split '-' => $data->{$CLASS_MARKER});
my $meta = eval { $class->meta };
confess "Class ($class) is not loaded, cannot unpack" if $@;
if ($options->{check_version}) {
my $meta_version = $meta->version;
if (defined $meta_version && $version) {
if ($options->{check_version} eq 'allow_less_than') {
($meta_version <= $version)
|| confess "Class ($class) versions is not less than currently available."
. " got=($version) available=($meta_version)";
}
elsif ($options->{check_version} eq 'allow_greater_than') {
($meta->version >= $version)
|| confess "Class ($class) versions is not greater than currently available."
. " got=($version) available=($meta_version)";
}
else {
($meta->version == $version)
|| confess "Class ($class) versions don't match."
. " got=($version) available=($meta_version)";
}
}
}
if ($options->{check_authority}) {
my $meta_authority = $meta->authority;
($meta->authority eq $authority)
|| confess "Class ($class) authorities don't match."
. " got=($authority) available=($meta_authority)"
if defined $meta_authority && defined $authority;
}
# all is well ...
$class->unpack($data, %$options);
},
collapse => sub {
my ( $obj, $options ) = @_;
# ($obj->can('does') && $obj->does('MooseX::Storage::Basic'))
# || confess "Bad object ($obj) does not do MooseX::Storage::Basic role";
($obj->can('pack'))
|| confess "Object ($obj) does not have a &pack method, cannot collapse";
$obj->pack(%$options);
},
);
my %TYPES = (
# NOTE:
# we need to make sure that we properly numify the numbers
# before and after them being futzed with, because some of
# the JSON engines are stupid/annoying/frustrating
'Int' => { expand => sub { $_[0] + 0 }, collapse => sub { $_[0] + 0 } },
'Num' => { expand => sub { $_[0] + 0 }, collapse => sub { $_[0] + 0 } },
# These are boring ones, so they use the identity function ...
'Str' => { expand => sub { shift }, collapse => sub { shift } },
'Bool' => { expand => sub { shift }, collapse => sub { shift } },
# These are the trickier ones, (see notes)
# NOTE:
# Because we are nice guys, we will check
# your ArrayRef and/or HashRef one level
# down and inflate any objects we find.
# But this is where it ends, it is too
# expensive to try and do this any more
# recursively, when it is probably not
# nessecary in most of the use cases.
# However, if you need more then this, subtype
# and add a custom handler.
'ArrayRef' => {
expand => sub {
my ( $array, @args ) = @_;
foreach my $i (0 .. $#{$array}) {
next unless ref($array->[$i]) eq 'HASH'
&& exists $array->[$i]->{$CLASS_MARKER};
$array->[$i] = $OBJECT_HANDLERS{expand}->($array->[$i], @args);
}
$array;
},
collapse => sub {
my ( $array, @args ) = @_;
# NOTE:
# we need to make a copy cause
# otherwise it will affect the
# other real version.
[ map {
blessed($_)
? $OBJECT_HANDLERS{collapse}->($_, @args)
: $_
} @$array ]
}
},
'HashRef' => {
expand => sub {
my ( $hash, @args ) = @_;
foreach my $k (keys %$hash) {
next unless ref($hash->{$k}) eq 'HASH'
&& exists $hash->{$k}->{$CLASS_MARKER};
$hash->{$k} = $OBJECT_HANDLERS{expand}->($hash->{$k}, @args);
}
$hash;
},
collapse => sub {
my ( $hash, @args ) = @_;
# NOTE:
# we need to make a copy cause
# otherwise it will affect the
# other real version.
+{ map {
blessed($hash->{$_})
? ($_ => $OBJECT_HANDLERS{collapse}->($hash->{$_}, @args))
: ($_ => $hash->{$_})
} keys %$hash }
}
},
'Object' => \%OBJECT_HANDLERS,
# NOTE:
# The sanity of enabling this feature by
# default is very questionable.
# - SL
#'CodeRef' => {
# expand => sub {}, # use eval ...
# collapse => sub {}, # use B::Deparse ...
#}
);
sub add_custom_type_handler {
my ($self, $type_name, %handlers) = @_;
(exists $handlers{expand} && exists $handlers{collapse})
|| confess "Custom type handlers need an expand *and* a collapse method";
$TYPES{$type_name} = \%handlers;
}
sub remove_custom_type_handler {
my ($self, $type_name) = @_;
delete $TYPES{$type_name} if exists $TYPES{$type_name};
}
sub find_type_handler {
my ($self, $type_constraint, $value) = @_;
# check if the type is a Maybe and
# if its parent is not parameterized.
# If both is true recurse this method
# using ->type_parameter.
return $self->find_type_handler($type_constraint->type_parameter, $value)
if ($type_constraint->parent && $type_constraint->parent eq 'Maybe'
and not $type_constraint->parent->can('type_parameter'));
# find_type_for is a method of a union type. If we can call that method
# then we are dealign with a union and we need to ascertain which of
# the union's types we need to use for the value we are serializing.
if($type_constraint->can('find_type_for')) {
my $tc = $type_constraint->find_type_for($value);
return $self->find_type_handler($tc, $value) if defined($tc);
}
# this should handle most type usages
# since they they are usually just
# the standard set of built-ins
return $TYPES{$type_constraint->name}
if exists $TYPES{$type_constraint->name};
# the next possibility is they are
# a subtype of the built-in types,
# in which case this will DWIM in
# most cases. It is probably not
# 100% ideal though, but until I
# come up with a decent test case
# it will do for now.
foreach my $type (keys %TYPES) {
return $TYPES{$type}
if $type_constraint->is_subtype_of($type);
}
# NOTE:
# the reason the above will work has to
# do with the fact that custom subtypes
# are mostly used for validation of
# the guts of a type, and not for some
# weird structural thing which would
# need to be accomidated by the serializer.
# Of course, mst or phaylon will probably
# do something to throw this assumption
# totally out the door ;)
# - SL
# NOTE:
# if this method hasnt returned by now
# then we have no been able to find a
# type constraint handler to match
confess "Cannot handle type constraint (" . $type_constraint->name . ")";
}
sub find_type_handler_for {
my ($self, $type_handler_name) = @_;
$TYPES{$type_handler_name}
}
no Moose::Role;
1;
__END__
=pod
=encoding UTF-8
=for :stopwords Chris Prather Stevan Little יובל קוג'מן (Yuval Kogman) Infinity
Interactive, Inc. Plunien Jonathan Rockway Yu Jos Boumans Karen Etheridge
Ricardo SIGNES Signes Robert Boone Shawn M Moore Tomas Doran (t0m) Yuval
Cory Kogman t0m Watson Dagfinn Ilmari Mannsåker Florian Ragwitz Johannes
=head1 NAME
MooseX::Storage::Engine - The meta-engine to handle collapsing and expanding objects
=head1 VERSION
version 0.44
=head1 DESCRIPTION
There really aren't any major user serviceable parts here. However the typical
use case is adding new non-Moose classes to the type registry for
serialization. Here is an example of this for DateTime objects. This
assumes a C<DateTime> type has been registered.
MooseX::Storage::Engine->add_custom_type_handler(
'DateTime' => (
expand => sub { DateTime->new(shift) },
collapse => sub { (shift)->iso8601 },
)
);
=head1 METHODS
=head2 Accessors
=over 4
=item B<class>
=item B<object>
=item B<storage>
=item B<seen>
=back
=head2 API
=over 4
=item B<expand_object>
=item B<collapse_object>
=back
=head2 ...
=over 4
=item B<collapse_attribute>
=item B<collapse_attribute_value>
=item B<expand_attribute>
=item B<expand_attribute_value>
=item B<check_for_cycle_in_collapse>
=item B<check_for_cycle_in_expansion>
=item B<map_attributes>
=back
=head2 Type Constraint Handlers
=over 4
=item B<find_type_handler ($type)>
=item B<find_type_handler_for ($name)>
=item B<add_custom_type_handler ($name, %handlers)>
=item B<remove_custom_type_handler ($name)>
=back
=head2 Introspection
=over 4
=item B<meta>
=back
=head1 BUGS
All complex software has bugs lurking in it, and this module is no
exception. If you find a bug please either email me, or add the bug
to cpan-RT.
=head1 AUTHORS
=over 4
=item *
Chris Prather <chris.prather@iinteractive.com>
=item *
Stevan Little <stevan.little@iinteractive.com>
=item *
יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>
=back
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2007 by Infinity Interactive, Inc..
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut