/usr/share/perl5/MooseX/Types/VariantTable.pm is in libmoosex-types-varianttable-perl 0.04-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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package MooseX::Types::VariantTable;
use Moose;
use Hash::Util::FieldHash qw(idhash);
use Scalar::Util qw(refaddr);
use Moose::Util::TypeConstraints;
use namespace::clean -except => 'meta';
with qw(MooseX::Clone);
use Carp qw(croak);
our $VERSION = "0.04";
has _sorted_variants => (
traits => [qw(NoClone)],
#isa => "ArrayRef[ArrayRef[HashRef]]",
is => "ro",
lazy_build => 1,
);
has variants => (
traits => [qw(Copy)],
isa => "ArrayRef[HashRef]",
is => "rw",
init_arg => undef,
default => sub { [] },
trigger => sub { $_[0]->_clear_sorted_variants },
);
has ambigious_match_callback => (
is => 'ro',
isa => 'CodeRef',
default => sub {
sub {
my ($self, $value, @matches) = @_;
croak "Ambiguous match " . join(", ", map { $_->{type} } @matches);
};
},
);
sub BUILD {
my ( $self, $params ) = @_;
if ( my $variants = $params->{variants} ) {
foreach my $variant ( @$variants ) {
$self->add_variant( @{ $variant }{qw(type value)} );
}
}
}
sub merge {
my ( @selves ) = @_; # our @selves reads better =/
my $self = $selves[0];
return ( ref $self )->new(
variants => [ map { @{ $_->variants } } @selves ],
);
}
sub has_type {
my ( $self, $type_or_name ) = @_;
my $type = Moose::Util::TypeConstraints::find_type_constraint($type_or_name)
or croak "No such type constraint: $type_or_name";
foreach my $existing_type ( map { $_->{type} } @{ $self->variants } ) {
return 1 if $type->equals($existing_type);
}
return;
}
sub has_parent {
my ( $self, $type_or_name ) = @_;
my $type = Moose::Util::TypeConstraints::find_type_constraint($type_or_name)
or croak "No such type constraint: $type_or_name";
foreach my $existing_type ( map { $_->{type} } @{ $self->variants } ) {
return 1 if $type->is_subtype_of($existing_type);
}
return;
}
sub add_variant {
my ( $self, $type_or_name, $value ) = @_;
croak "Duplicate variant entry for $type_or_name"
if $self->has_type($type_or_name);
my $type = Moose::Util::TypeConstraints::find_type_constraint($type_or_name)
or croak "No such type constraint: $type_or_name";
my $entry = { type => $type, value => $value };
push @{ $self->variants }, $entry;
$self->_clear_sorted_variants;
return;
}
sub remove_variant {
my ( $self, $type_or_name, $value ) = @_;
my $type = Moose::Util::TypeConstraints::find_type_constraint($type_or_name)
or croak "No such type constraint: $type_or_name";
my $list = $self->variants;
@$list = grep { not $_->{type}->equals($type) } @$list;
$self->_clear_sorted_variants;
return;
}
sub _build__sorted_variants {
my $self = shift;
my @entries = @{ $self->variants };
idhash my %out;
foreach my $entry ( @entries ) {
$out{$entry} = [];
foreach my $other ( @entries ) {
next if refaddr($entry) == refaddr($other);
if ( $other->{type}->is_subtype_of($entry->{type}) ) {
push @{ $out{$entry} }, $other;
}
}
}
my @sorted;
while ( keys %out ) {
my @slot;
foreach my $entry ( @entries ) {
if ( $out{$entry} and not @{ $out{$entry} } ) {
push @slot, $entry;
delete $out{$entry};
}
}
idhash my %filter;
@filter{@slot} = ();
foreach my $entry ( @entries ) {
if ( my $out = $out{$entry} ) {
@$out = grep { not exists $filter{$_} } @$out;
}
}
push @sorted, \@slot;
}
return \@sorted;
}
sub find_variant {
my ( $self, @args ) = @_;
if ( my $entry = $self->_find_variant(@args) ) {
if ( wantarray ) {
return @{ $entry }{qw(value type)};
} else {
return $entry->{value};
}
}
return;
}
sub _find_variant {
my ( $self, $value ) = @_;
foreach my $slot ( @{ $self->_sorted_variants } ) {
my @matches;
foreach my $entry ( @$slot ) {
if ( $entry->{type}->check($value) ) {
push @matches, $entry;
}
}
if ( @matches == 1 ) {
return $matches[0];
} elsif ( @matches > 1 ) {
$self->ambigious_match_callback->($self, $value, @matches);
}
}
return;
}
sub dispatch {
my $self = shift;
my $value = $_[0];
if ( my $result = $self->find_variant($value) ) {
if ( (ref($result)||'') eq 'CODE' ) {
goto &$result;
} else {
return $result;
}
}
return;
}
__PACKAGE__
__END__
=pod
=head1 NAME
MooseX::Types::VariantTable - Type constraint based variant table
=head1 SYNOPSIS
# see also MooseX::Types::VariantTable::Declare for a way to
# declare variant table based methods
use MooseX::Types::VariantTable;
my $dispatch_table = MooseX::Types::VariantTable->new(
variants => [
{ type => "Foo", value => \&foo_handler },
{ type => "Bar", value => \&bar_handler },
{ type => "Item", value => \&fallback },
],
);
# look up the correct handler for $thingy based on the type constraints it passes
my $entry = $dispatch_table->find_variant($thingy);
# or use the 'dispatch' convenience method if the entries are code refs
$dispatch_table->dispatch( $thingy, @args );
=head1 DESCRIPTION
This object implements a simple dispatch table based on L<Moose> type constraints.
Subtypes will be checked before their parents, meaning that the order of the
declaration does not matter.
This object is used internally by L<Moose::Meta::Method::VariantTable> and
L<MooseX::Types::VariantTable::Declare> to provide primitive multi
sub support.
=head1 ATTRIBUTES
=head2 ambigious_match_callback
A code reference that'll be executed when find_variant found more than one
matching variant for a value. It defaults to something that simply croaks with
an error message like this:
Ambiguous match %s
where %s contains a list of stringified types that matched.
=head1 METHODS
=over 4
=item new
=item add_variant $type, $value
Registers C<$type>, such that C<$value> will be returned by C<find_variant> for
items passing $type.
Subtyping is respected in the table.
=item find_variant $value
Returns the registered value for the most specific type that C<$value> passes.
=item dispatch $value, @args
A convenience method for when the registered values are code references.
Calls C<find_variant> and if the result is a code reference, it will C<goto>
this code reference with the value and any additional arguments.
=item has_type $type
Returns true if an entry for C<$type> is registered.
=item has_parent $type
Returns true if a parent type of C<$type> is registered.
=back
=head1 TODO
The meta method composes in multiple inheritence but not yet with roles due to
extensibility issues with the role application code.
When L<Moose::Meta::Role> can pluggably merge methods variant table methods can
gain role composition.
=head1 AUTHOR
Yuval Kogman E<lt>nothingmuch@woobling.orgE<gt>
Florian Ragwitz E<lt>rafl@debian.orgE<gt>
=head1 COPYRIGHT
Copyright (c) 2008 Yuval Kogman. All rights reserved
This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
=cut
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