package Mouse::Meta::Attribute;
use strict;
use warnings;
require overload;
use Carp 'confess';
use Scalar::Util ();
sub new {
my ($class, $name, %options) = @_;
$options{name} = $name;
$options{init_arg} = $name
unless exists $options{init_arg};
$options{is} ||= '';
bless \%options, $class;
}
sub name { $_[0]->{name} }
sub associated_class { $_[0]->{associated_class} }
sub _is_metadata { $_[0]->{is} }
sub is_required { $_[0]->{required} }
sub default { $_[0]->{default} }
sub is_lazy { $_[0]->{lazy} }
sub is_lazy_build { $_[0]->{lazy_build} }
sub predicate { $_[0]->{predicate} }
sub clearer { $_[0]->{clearer} }
sub handles { $_[0]->{handles} }
sub is_weak_ref { $_[0]->{weak_ref} }
sub init_arg { $_[0]->{init_arg} }
sub type_constraint { $_[0]->{type_constraint} }
sub trigger { $_[0]->{trigger} }
sub builder { $_[0]->{builder} }
sub should_auto_deref { $_[0]->{auto_deref} }
sub should_coerce { $_[0]->{should_coerce} }
sub find_type_constraint { $_[0]->{find_type_constraint} }
sub has_default { exists $_[0]->{default} }
sub has_predicate { exists $_[0]->{predicate} }
sub has_clearer { exists $_[0]->{clearer} }
sub has_handles { exists $_[0]->{handles} }
sub has_type_constraint { exists $_[0]->{type_constraint} }
sub has_trigger { exists $_[0]->{trigger} }
sub has_builder { exists $_[0]->{builder} }
sub _create_args {
$_[0]->{_create_args} = $_[1] if @_ > 1;
$_[0]->{_create_args}
}
sub inlined_name {
my $self = shift;
my $name = $self->name;
my $key = "'" . $name . "'";
return $key;
}
sub generate_accessor {
my $attribute = shift;
my $name = $attribute->name;
my $default = $attribute->default;
my $constraint = $attribute->find_type_constraint;
my $builder = $attribute->builder;
my $trigger = $attribute->trigger;
my $is_weak = $attribute->is_weak_ref;
my $should_deref = $attribute->should_auto_deref;
my $should_coerce = $attribute->should_coerce;
my $self = '$_[0]';
my $key = $attribute->inlined_name;
my $accessor = "sub {\n";
if ($attribute->_is_metadata eq 'rw') {
$accessor .= 'if (@_ >= 2) {' . "\n";
my $value = '$_[1]';
if ($constraint) {
$accessor .= 'my $val = ';
if ($should_coerce) {
$accessor .= 'Mouse::Util::TypeConstraints->typecast_constraints("'.$attribute->associated_class->name.'", $attribute->{find_type_constraint}, $attribute->{type_constraint}, '.$value.');';
} else {
$accessor .= $value.';';
}
$accessor .= 'local $_ = $val;';
$accessor .= '
unless ($constraint->()) {
$attribute->verify_type_constraint_error($name, $_, $attribute->type_constraint);
}' . "\n";
$value = '$val';
}
# if there's nothing left to do for the attribute we can return during
# this setter
$accessor .= 'return ' if !$is_weak && !$trigger && !$should_deref;
$accessor .= $self.'->{'.$key.'} = '.$value.';' . "\n";
if ($is_weak) {
$accessor .= 'Scalar::Util::weaken('.$self.'->{'.$key.'}) if ref('.$self.'->{'.$key.'});' . "\n";
}
if ($trigger) {
$accessor .= '$trigger->('.$self.', '.$value.', $attribute);' . "\n";
}
$accessor .= "}\n";
}
else {
$accessor .= 'confess "Cannot assign a value to a read-only accessor" if scalar(@_) >= 2;' . "\n";
}
if ($attribute->is_lazy) {
$accessor .= $self.'->{'.$key.'} = ';
$accessor .= $attribute->has_builder
? $self.'->$builder'
: ref($default) eq 'CODE'
? '$default->('.$self.')'
: '$default';
$accessor .= ' if !exists '.$self.'->{'.$key.'};' . "\n";
}
if ($should_deref) {
my $type_constraint = $attribute->type_constraint;
if (!ref($type_constraint) && $type_constraint eq 'ArrayRef') {
$accessor .= 'if (wantarray) {
return @{ '.$self.'->{'.$key.'} || [] };
}';
}
else {
$accessor .= 'if (wantarray) {
return %{ '.$self.'->{'.$key.'} || {} };
}';
}
}
$accessor .= 'return '.$self.'->{'.$key.'};
}';
my $sub = eval $accessor;
confess $@ if $@;
return $sub;
}
sub generate_predicate {
my $attribute = shift;
my $key = $attribute->inlined_name;
my $predicate = 'sub { exists($_[0]->{'.$key.'}) }';
my $sub = eval $predicate;
confess $@ if $@;
return $sub;
}
sub generate_clearer {
my $attribute = shift;
my $key = $attribute->inlined_name;
my $clearer = 'sub { delete($_[0]->{'.$key.'}) }';
my $sub = eval $clearer;
confess $@ if $@;
return $sub;
}
sub generate_handles {
my $attribute = shift;
my $reader = $attribute->name;
my %handles = $attribute->_canonicalize_handles($attribute->handles);
my %method_map;
for my $local_method (keys %handles) {
my $remote_method = $handles{$local_method};
my $method = 'sub {
my $self = shift;
$self->'.$reader.'->'.$remote_method.'(@_)
}';
$method_map{$local_method} = eval $method;
confess $@ if $@;
}
return \%method_map;
}
sub create {
my ($self, $class, $name, %args) = @_;
$args{name} = $name;
$args{associated_class} = $class;
%args = $self->canonicalize_args($name, %args);
$self->validate_args($name, \%args);
$args{should_coerce} = delete $args{coerce}
if exists $args{coerce};
if (exists $args{isa}) {
my $type_constraint = delete $args{isa};
$type_constraint =~ s/\s//g;
my @type_constraints = split /\|/, $type_constraint;
my $code;
my $optimized_constraints = Mouse::Util::TypeConstraints->optimized_constraints;
if (@type_constraints == 1) {
$code = $optimized_constraints->{$type_constraints[0]} ||
sub { Scalar::Util::blessed($_) && $_->isa($type_constraints[0]) };
$args{type_constraint} = $type_constraints[0];
} else {
my @code_list = map {
my $type = $_;
$optimized_constraints->{$type} ||
sub { Scalar::Util::blessed($_) && $_->isa($type) }
} @type_constraints;
$code = sub {
for my $code (@code_list) {
return 1 if $code->();
}
return 0;
};
$args{type_constraint} = \@type_constraints;
}
$args{find_type_constraint} = $code;
}
my $attribute = $self->new($name, %args);
$attribute->_create_args(\%args);
$class->add_attribute($attribute);
# install an accessor
if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
my $accessor = $attribute->generate_accessor;
$class->add_method($name => $accessor);
}
for my $method (qw/predicate clearer/) {
my $predicate = "has_$method";
if ($attribute->$predicate) {
my $generator = "generate_$method";
my $coderef = $attribute->$generator;
$class->add_method($attribute->$method => $coderef);
}
}
if ($attribute->has_handles) {
my $method_map = $attribute->generate_handles;
for my $method_name (keys %$method_map) {
$class->add_method($method_name => $method_map->{$method_name});
}
}
return $attribute;
}
sub canonicalize_args {
my $self = shift;
my $name = shift;
my %args = @_;
if ($args{lazy_build}) {
$args{lazy} = 1;
$args{required} = 1;
$args{builder} = "_build_${name}"
if !exists($args{builder});
if ($name =~ /^_/) {
$args{clearer} = "_clear${name}" if !exists($args{clearer});
$args{predicate} = "_has${name}" if !exists($args{predicate});
}
else {
$args{clearer} = "clear_${name}" if !exists($args{clearer});
$args{predicate} = "has_${name}" if !exists($args{predicate});
}
}
return %args;
}
sub validate_args {
my $self = shift;
my $name = shift;
my $args = shift;
confess "You can not use lazy_build and default for the same attribute ($name)"
if $args->{lazy_build} && exists $args->{default};
confess "You cannot have lazy attribute ($name) without specifying a default value for it"
if $args->{lazy}
&& !exists($args->{default})
&& !exists($args->{builder});
confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
if ref($args->{default})
&& ref($args->{default}) ne 'CODE';
confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
if $args->{auto_deref} && !exists($args->{isa});
confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
if $args->{auto_deref}
&& $args->{isa} ne 'ArrayRef'
&& $args->{isa} ne 'HashRef';
if ($args->{trigger}) {
if (ref($args->{trigger}) eq 'HASH') {
Carp::carp "HASH-based form of trigger has been removed. Only the coderef form of triggers are now supported.";
}
confess "Trigger must be a CODE ref on attribute ($name)"
if ref($args->{trigger}) ne 'CODE';
}
return 1;
}
sub verify_against_type_constraint {
return 1 unless $_[0]->{type_constraint};
local $_ = $_[1];
return 1 if $_[0]->{find_type_constraint}->($_);
my $self = shift;
$self->verify_type_constraint_error($self->name, $_, $self->type_constraint);
}
sub verify_type_constraint_error {
my($self, $name, $value, $type) = @_;
$type = ref($type) eq 'ARRAY' ? join '|', @{ $type } : $type;
my $display = defined($_) ? overload::StrVal($_) : 'undef';
Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
}
sub coerce_constraint { ## my($self, $value) = @_;
my $type = $_[0]->{type_constraint}
or return $_[1];
return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $_[0]->find_type_constraint, $type, $_[1]);
}
sub _canonicalize_handles {
my $self = shift;
my $handles = shift;
if (ref($handles) eq 'HASH') {
return %$handles;
}
elsif (ref($handles) eq 'ARRAY') {
return map { $_ => $_ } @$handles;
}
else {
confess "Unable to canonicalize the 'handles' option with $handles";
}
}
sub clone_parent {
my $self = shift;
my $class = shift;
my $name = shift;
my %args = ($self->get_parent_args($class, $name), @_);
$self->create($class, $name, %args);
}
sub get_parent_args {
my $self = shift;
my $class = shift;
my $name = shift;
for my $super ($class->linearized_isa) {
my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
or next;
return %{ $super_attr->_create_args };
}
confess "Could not find an attribute by the name of '$name' to inherit from";
}
1;
__END__
=head1 NAME
Mouse::Meta::Attribute - attribute metaclass
=head1 METHODS
=head2 new %args -> Mouse::Meta::Attribute
Instantiates a new Mouse::Meta::Attribute. Does nothing else.
=head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
Creates a new attribute in OwnerClass. Accessors and helper methods are
installed. Some error checking is done.
=head2 name -> AttributeName
=head2 associated_class -> OwnerClass
=head2 is_required -> Bool
=head2 default -> Item
=head2 has_default -> Bool
=head2 is_lazy -> Bool
=head2 predicate -> MethodName | Undef
=head2 has_predicate -> Bool
=head2 clearer -> MethodName | Undef
=head2 has_clearer -> Bool
=head2 handles -> { LocalName => RemoteName }
=head2 has_handles -> Bool
=head2 is_weak_ref -> Bool
=head2 init_arg -> Str
=head2 type_constraint -> Str
=head2 has_type_constraint -> Bool
=head2 trigger => CODE | Undef
=head2 has_trigger -> Bool
=head2 builder => MethodName | Undef
=head2 has_builder -> Bool
=head2 is_lazy_build => Bool
=head2 should_auto_deref -> Bool
Informational methods.
=head2 generate_accessor -> CODE
Creates a new code reference for the attribute's accessor.
=head2 generate_predicate -> CODE
Creates a new code reference for the attribute's predicate.
=head2 generate_clearer -> CODE
Creates a new code reference for the attribute's clearer.
=head2 generate_handles -> { MethodName => CODE }
Creates a new code reference for each of the attribute's handles methods.
=head2 find_type_constraint -> CODE
Returns a code reference which can be used to check that a given value passes
this attribute's type constraint;
=head2 verify_against_type_constraint Item -> 1 | ERROR
Checks that the given value passes this attribute's type constraint. Returns 1
on success, otherwise C<confess>es.
=head2 canonicalize_args Name, %args -> %args
Canonicalizes some arguments to create. In particular, C<lazy_build> is
canonicalized into C<lazy>, C<builder>, etc.
=head2 validate_args Name, \%args -> 1 | ERROR
Checks that the arguments to create the attribute (ie those specified by
C<has>) are valid.
=head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
Creates a new attribute in OwnerClass, inheriting options from parent classes.
Accessors and helper methods are installed. Some error checking is done.
=head2 get_parent_args OwnerClass, AttributeName -> Hash
Returns the options that the parent class of C<OwnerClass> used for attribute
C<AttributeName>.
=cut