use strict;
use warnings;
package Moose::Meta::Attribute;
our $VERSION = '2.2011';

use B ();
use Scalar::Util 'blessed';
use List::Util 1.33 'any';
use Try::Tiny;
use overload     ();

use Moose::Deprecated;
use Moose::Meta::Method::Accessor;
use Moose::Meta::Method::Delegation;
use Moose::Util 'throw_exception';
use Moose::Util::TypeConstraints ();
use Class::MOP::MiniTrait;

use parent 'Class::MOP::Attribute', 'Moose::Meta::Mixin::AttributeCore';

use Carp 'confess';

Class::MOP::MiniTrait::apply(__PACKAGE__, 'Moose::Meta::Object::Trait');

__PACKAGE__->meta->add_attribute('traits' => (
    reader    => 'applied_traits',
    predicate => 'has_applied_traits',
    Class::MOP::_definition_context(),
));

__PACKAGE__->meta->add_attribute('role_attribute' => (
    reader    => 'role_attribute',
    predicate => 'has_role_attribute',
    Class::MOP::_definition_context(),
));

# we need to have a ->does method in here to
# more easily support traits, and the introspection
# of those traits. We extend the does check to look
# for metatrait aliases.
sub does {
    my ($self, $role_name) = @_;
    my $name = try {
        Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
    };
    return 0 if !defined($name); # failed to load class
    return $self->Moose::Object::does($name);
}

sub _inline_throw_exception {
    my ( $self, $exception_type, $throw_args ) = @_;
    return 'die Module::Runtime::use_module("Moose::Exception::' . $exception_type . '")->new(' . ($throw_args || '') . ')';
}

sub new {
    my ($class, $name, %options) = @_;
    $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS

    delete $options{__hack_no_process_options};

    my %attrs =
        ( map { $_ => 1 }
          grep { defined }
          map { $_->init_arg() }
          $class->meta()->get_all_attributes()
        );

    my @bad = sort grep { ! $attrs{$_} }  keys %options;

    if (@bad)
    {
        my $s = @bad > 1 ? 's' : '';
        my $list = join "', '", @bad;

        my $package = $options{definition_context}{package};
        my $context = $options{definition_context}{context}
                   || 'attribute constructor';
        my $type = $options{definition_context}{type} || 'class';

        my $location = '';
        if (defined($package)) {
            $location = " in ";
            $location .= "$type " if $type;
            $location .= $package;
        }

        Carp::cluck "Found unknown argument$s '$list' in the $context for '$name'$location";
    }

    return $class->SUPER::new($name, %options);
}

sub interpolate_class_and_new {
    my $class = shift;
    my $name  = shift;

    throw_exception( MustPassEvenNumberOfAttributeOptions => attribute_name => $name,
                                                             options        => \@_
                   )
        if @_ % 2 == 1;

    my %args = @_;

    my ( $new_class, @traits ) = $class->interpolate_class(\%args);
    $new_class->new($name, %args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
}

sub interpolate_class {
    my ($class, $options) = @_;

    $class = ref($class) || $class;

    if ( my $metaclass_name = delete $options->{metaclass} ) {
        my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );

        if ( $class ne $new_class ) {
            if ( $new_class->can("interpolate_class") ) {
                return $new_class->interpolate_class($options);
            } else {
                $class = $new_class;
            }
        }
    }

    my @traits;

    if (my $traits = $options->{traits}) {
        my $i = 0;
        my $has_foreign_options = 0;

        while ($i < @$traits) {
            my $trait = $traits->[$i++];
            next if ref($trait); # options to a trait we discarded

            $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
                  || $trait;

            next if $class->does($trait);

            push @traits, $trait;

            # are there options?
            if ($traits->[$i] && ref($traits->[$i])) {
                $has_foreign_options = 1
                    if any { $_ ne '-alias' && $_ ne '-excludes' } keys %{ $traits->[$i] };

                push @traits, $traits->[$i++];
            }
        }

        if (@traits) {
            my %options = (
                superclasses => [ $class ],
                roles        => [ @traits ],
            );

            if ($has_foreign_options) {
                $options{weaken} = 0;
            }
            else {
                $options{cache} = 1;
            }

            my $anon_class = Moose::Meta::Class->create_anon_class(%options);
            $class = $anon_class->name;
        }
    }

    return ( wantarray ? ( $class, @traits ) : $class );
}

# ...

# method-generating options shouldn't be overridden
sub illegal_options_for_inheritance {
    qw(reader writer accessor clearer predicate)
}

# NOTE/TODO
# This method *must* be able to handle
# Class::MOP::Attribute instances as
# well. Yes, I know that is wrong, but
# apparently we didn't realize it was
# doing that and now we have some code
# which is dependent on it. The real
# solution of course is to push this
# feature back up into Class::MOP::Attribute
# but I not right now, I am too lazy.
# However if you are reading this and
# looking for something to do,.. please
# be my guest.
# - stevan
sub clone_and_inherit_options {
    my ($self, %options) = @_;

    # NOTE:
    # we may want to extends a Class::MOP::Attribute
    # in which case we need to be able to use the
    # core set of legal options that have always
    # been here. But we allows Moose::Meta::Attribute
    # instances to changes them.
    # - SL
    my @illegal_options = $self->can('illegal_options_for_inheritance')
        ? $self->illegal_options_for_inheritance
        : ();

    my @found_illegal_options = grep { exists $options{$_} && exists $self->{$_} ? $_ : undef } @illegal_options;
    (scalar @found_illegal_options == 0)
        || throw_exception( IllegalInheritedOptions => illegal_options => \@found_illegal_options,
                                                       params          => \%options
                          );

    $self->_process_isa_option( $self->name, \%options );
    $self->_process_does_option( $self->name, \%options );

    # NOTE:
    # this doesn't apply to Class::MOP::Attributes,
    # so we can ignore it for them.
    # - SL
    if ($self->can('interpolate_class')) {
        ( $options{metaclass}, my @traits ) = $self->interpolate_class(\%options);

        my %seen;
        my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
        $options{traits} = \@all_traits if @all_traits;
    }

    # This method can be called on a CMOP::Attribute object, so we need to
    # make sure we can call this method.
    $self->_process_lazy_build_option( $self->name, \%options )
        if $self->can('_process_lazy_build_option');

    $self->clone(%options);
}

sub clone {
    my ( $self, %params ) = @_;

    my $class = delete $params{metaclass} || ref $self;

    my ( @init, @non_init );

    foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
        push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
    }

    my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );

    my $name = delete $new_params{name};

    my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );

    foreach my $attr ( @non_init ) {
        $attr->set_value($clone, $attr->get_value($self));
    }

    return $clone;
}

sub _process_options {
    my ( $class, $name, $options ) = @_;

    $class->_process_is_option( $name, $options );
    $class->_process_isa_option( $name, $options );
    $class->_process_does_option( $name, $options );
    $class->_process_coerce_option( $name, $options );
    $class->_process_trigger_option( $name, $options );
    $class->_process_auto_deref_option( $name, $options );
    $class->_process_lazy_build_option( $name, $options );
    $class->_process_lazy_option( $name, $options );
    $class->_process_required_option( $name, $options );
}

sub _process_is_option {
    my ( $class, $name, $options ) = @_;

    return unless $options->{is};

    ### -------------------------
    ## is => ro, writer => _foo    # turns into (reader => foo, writer => _foo) as before
    ## is => rw, writer => _foo    # turns into (reader => foo, writer => _foo)
    ## is => rw, accessor => _foo  # turns into (accessor => _foo)
    ## is => ro, accessor => _foo  # error, accesor is rw
    ### -------------------------

    if ( $options->{is} eq 'ro' ) {
        throw_exception("AccessorMustReadWrite" => attribute_name => $name,
                                                   params         => $options,
                       )
            if exists $options->{accessor};
        $options->{reader} ||= $name;
    }
    elsif ( $options->{is} eq 'rw' ) {
        if ( ! $options->{accessor} ) {
            if ( $options->{writer}) {
                $options->{reader} ||= $name;
            }
            else {
                $options->{accessor} = $name;
            }
        }
    }
    elsif ( $options->{is} eq 'bare' ) {
        return;
        # do nothing, but don't complain (later) about missing methods
    }
    else {
        throw_exception( InvalidValueForIs => attribute_name => $name,
                                              params         => $options,
                       );
    }
}

sub _process_isa_option {
    my ( $class, $name, $options ) = @_;

    return unless exists $options->{isa};

    if ( exists $options->{does} ) {
        if ( try { $options->{isa}->can('does') } ) {
            ( $options->{isa}->does( $options->{does} ) )
                || throw_exception( IsaDoesNotDoTheRole => attribute_name => $name,
                                                           params         => $options,
                                  );
        }
        else {
            throw_exception( IsaLacksDoesMethod => attribute_name => $name,
                                                   params         => $options,
                           );
        }
    }

    # allow for anon-subtypes here ...
    #
    # There are a _lot_ of methods that we expect from TC objects, but
    # checking for a specific parent class via ->isa is gross, so we'll check
    # for at least one method.
    if ( blessed( $options->{isa} )
        && $options->{isa}->can('has_coercion') ) {

        $options->{type_constraint} = $options->{isa};
    }
    else {
        $options->{type_constraint}
            = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint(
            $options->{isa},
            { package_defined_in => $options->{definition_context}->{package} }
        );
    }
}

sub _process_does_option {
    my ( $class, $name, $options ) = @_;

    return unless exists $options->{does} && ! exists $options->{isa};

    # allow for anon-subtypes here ...
    if ( blessed( $options->{does} )
        && $options->{does}->can('has_coercion') ) {

        $options->{type_constraint} = $options->{does};
    }
    else {
        $options->{type_constraint}
            = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
            $options->{does},
            { package_defined_in => $options->{definition_context}->{package} }
        );
    }
}

sub _process_coerce_option {
    my ( $class, $name, $options ) = @_;

    return unless $options->{coerce};

    ( exists $options->{type_constraint} )
        || throw_exception( CoercionNeedsTypeConstraint => attribute_name => $name,
                                                           params         => $options,
                          );

    throw_exception( CannotCoerceAWeakRef => attribute_name => $name,
                                             params         => $options,
                   )
        if $options->{weak_ref};

    unless ( $options->{type_constraint}->has_coercion ) {
        my $type = $options->{type_constraint}->name;

        throw_exception( CannotCoerceAttributeWhichHasNoCoercion => attribute_name => $name,
                                                                    type_name      => $type,
                                                                    params         => $options
                       );
    }
}

sub _process_trigger_option {
    my ( $class, $name, $options ) = @_;

    return unless exists $options->{trigger};

    ( 'CODE' eq ref $options->{trigger} )
        || throw_exception( TriggerMustBeACodeRef => attribute_name => $name,
                                                     params         => $options,
                          );
}

sub _process_auto_deref_option {
    my ( $class, $name, $options ) = @_;

    return unless $options->{auto_deref};

    ( exists $options->{type_constraint} )
        || throw_exception( CannotAutoDerefWithoutIsa => attribute_name => $name,
                                                         params         => $options,
                          );

    ( $options->{type_constraint}->is_a_type_of('ArrayRef')
      || $options->{type_constraint}->is_a_type_of('HashRef') )
        || throw_exception( AutoDeRefNeedsArrayRefOrHashRef => attribute_name => $name,
                                                               params         => $options,
                          );
}

sub _process_lazy_build_option {
    my ( $class, $name, $options ) = @_;

    return unless $options->{lazy_build};

    throw_exception( CannotUseLazyBuildAndDefaultSimultaneously => attribute_name => $name,
                                                                   params         => $options,
                   )
        if exists $options->{default};

    $options->{lazy} = 1;
    $options->{builder} ||= "_build_${name}";

    if ( $name =~ /^_/ ) {
        $options->{clearer}   ||= "_clear${name}";
        $options->{predicate} ||= "_has${name}";
    }
    else {
        $options->{clearer}   ||= "clear_${name}";
        $options->{predicate} ||= "has_${name}";
    }
}

sub _process_lazy_option {
    my ( $class, $name, $options ) = @_;

    return unless $options->{lazy};

    ( exists $options->{default} || defined $options->{builder} )
        || throw_exception( LazyAttributeNeedsADefault => params         => $options,
                                                          attribute_name => $name,
                          );
}

sub _process_required_option {
    my ( $class, $name, $options ) = @_;

    if (
        $options->{required}
        && !(
            ( !exists $options->{init_arg} || defined $options->{init_arg} )
            || exists $options->{default}
            || defined $options->{builder}
        )
        ) {
        throw_exception( RequiredAttributeNeedsADefault => params         => $options,
                                                           attribute_name => $name,
                       );
    }
}

sub initialize_instance_slot {
    my ($self, $meta_instance, $instance, $params) = @_;
    my $init_arg = $self->init_arg();
    # try to fetch the init arg from the %params ...

    my $val;
    my $value_is_set;
    if ( defined($init_arg) and exists $params->{$init_arg}) {
        $val = $params->{$init_arg};
        $value_is_set = 1;
    }
    else {
        # skip it if it's lazy
        return if $self->is_lazy;
        # and die if it's required and doesn't have a default value
        my $class_name = blessed( $instance );
        throw_exception(
            'AttributeIsRequired',
            attribute_name => $self->name,
            ( defined $init_arg ? ( attribute_init_arg => $init_arg ) : () ),
            class_name => $class_name,
            params     => $params,
            )
            if $self->is_required
            && !$self->has_default
            && !$self->has_builder;

        # if nothing was in the %params, we can use the
        # attribute's default value (if it has one)
        if ($self->has_default) {
            $val = $self->default($instance);
            $value_is_set = 1;
        }
        elsif ($self->has_builder) {
            $val = $self->_call_builder($instance);
            $value_is_set = 1;
        }
    }

    return unless $value_is_set;

    $val = $self->_coerce_and_verify( $val, $instance );

    $self->set_initial_value($instance, $val);

    if ( ref $val && $self->is_weak_ref ) {
        $self->_weaken_value($instance);
    }
}

sub _call_builder {
    my ( $self, $instance ) = @_;

    my $builder = $self->builder();

    return $instance->$builder()
        if $instance->can( $self->builder );

    throw_exception( BuilderDoesNotExist => instance  => $instance,
                                            attribute => $self,
                   );
}

## Slot management

sub _make_initializer_writer_callback {
    my $self = shift;
    my ($meta_instance, $instance, $slot_name) = @_;
    my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
    return sub {
        $old_callback->($self->_coerce_and_verify($_[0], $instance));
    };
}

sub set_value {
    my ($self, $instance, @args) = @_;
    my $value = $args[0];

    my $class_name = blessed( $instance );
    if ($self->is_required and not @args) {
        throw_exception(
            'AttributeIsRequired',
            attribute_name => $self->name,
            (
                defined $self->init_arg
                ? ( attribute_init_arg => $self->init_arg )
                : ()
            ),
            class_name => $class_name,
        );
    }

    $value = $self->_coerce_and_verify( $value, $instance );

    my @old;
    if ( $self->has_trigger && $self->has_value($instance) ) {
        @old = $self->get_value($instance, 'for trigger');
    }

    $self->SUPER::set_value($instance, $value);

    if ( ref $value && $self->is_weak_ref ) {
        $self->_weaken_value($instance);
    }

    if ($self->has_trigger) {
        $self->trigger->($instance, $value, @old);
    }
}

sub _inline_set_value {
    my $self = shift;
    my ($instance, $value, $tc, $coercion, $message, $for_constructor) = @_;

    my $old     = '@old';
    my $copy    = '$val';
    $tc       ||= '$type_constraint';
    $coercion ||= '$type_coercion';
    $message  ||= '$type_message';

    my @code;
    if ($self->_writer_value_needs_copy) {
        push @code, $self->_inline_copy_value($value, $copy);
        $value = $copy;
    }

    # constructors already handle required checks
    push @code, $self->_inline_check_required
        unless $for_constructor;

    push @code, $self->_inline_tc_code($value, $tc, $coercion, $message);

    # constructors do triggers all at once at the end
    push @code, $self->_inline_get_old_value_for_trigger($instance, $old)
        unless $for_constructor;

    push @code, (
        $self->SUPER::_inline_set_value($instance, $value),
        $self->_inline_weaken_value($instance, $value),
    );

    # constructors do triggers all at once at the end
    push @code, $self->_inline_trigger($instance, $value, $old)
        unless $for_constructor;

    return @code;
}

sub _writer_value_needs_copy {
    my $self = shift;
    return $self->should_coerce;
}

sub _inline_copy_value {
    my $self = shift;
    my ($value, $copy) = @_;

    return 'my ' . $copy . ' = ' . $value . ';'
}

sub _inline_check_required {
    my $self = shift;

    return unless $self->is_required;

    my $throw_params = sprintf( <<'EOF', quotemeta( $self->name ) );
attribute_name => "%s",
class_name     => $class_name,
EOF
    $throw_params .= sprintf(
        'attribute_init_arg => "%s",',
        quotemeta( $self->init_arg )
    ) if defined $self->init_arg;

    my $throw = $self->_inline_throw_exception(
        'AttributeIsRequired',
        $throw_params
    );

    return sprintf( <<'EOF', $throw );
if ( @_ < 2 ) {
    %s;
}
EOF
}

sub _inline_tc_code {
    my $self = shift;
    my ($value, $tc, $coercion, $message, $is_lazy) = @_;
    return (
        $self->_inline_check_coercion(
            $value, $tc, $coercion, $is_lazy,
        ),
        $self->_inline_check_constraint(
            $value, $tc, $message, $is_lazy,
        ),
    );
}

sub _inline_check_coercion {
    my $self = shift;
    my ($value, $tc, $coercion) = @_;

    return unless $self->should_coerce && $self->type_constraint->has_coercion;

    if ( $self->type_constraint->can_be_inlined ) {
        return (
            'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
                $value . ' = ' . $coercion . '->(' . $value . ');',
            '}',
        );
    }
    else {
        return (
            'if (!' . $tc . '->(' . $value . ')) {',
                $value . ' = ' . $coercion . '->(' . $value . ');',
            '}',
        );
    }
}

sub _inline_check_constraint {
    my $self = shift;
    my ($value, $tc, $message) = @_;

    return unless $self->has_type_constraint;

    my $attr_name = quotemeta($self->name);

    if ( $self->type_constraint->can_be_inlined ) {
        return (
            'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
                'my $msg = do { local $_ = ' . $value . '; '
                . $message . '->(' . $value . ');'
                . '};'.
                $self->_inline_throw_exception( ValidationFailedForInlineTypeConstraint =>
                                                'type_constraint_message => $msg , '.
                                                'class_name              => $class_name, '.
                                                'attribute_name          => "'.$attr_name.'",'.
                                                'value                   => '.$value
                ).';',
            '}',
        );
    }
    else {
        return (
            'if (!' . $tc . '->(' . $value . ')) {',
                'my $msg = do { local $_ = ' . $value . '; '
                . $message . '->(' . $value . ');'
                . '};'.
                $self->_inline_throw_exception( ValidationFailedForInlineTypeConstraint =>
                                                'type_constraint_message => $msg , '.
                                                'class_name              => $class_name, '.
                                                'attribute_name          => "'.$attr_name.'",'.
                                                'value                   => '.$value
                ).';',
            '}',
        );
    }
}

sub _inline_get_old_value_for_trigger {
    my $self = shift;
    my ($instance, $old) = @_;

    return unless $self->has_trigger;

    return (
        'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
            '? ' . $self->_inline_instance_get($instance),
            ': ();',
    );
}

sub _inline_weaken_value {
    my $self = shift;
    my ($instance, $value) = @_;

    return unless $self->is_weak_ref;

    my $mi = $self->associated_class->get_meta_instance;
    return (
        $mi->inline_weaken_slot_value($instance, $self->name),
            'if ref ' . $value . ';',
    );
}

sub _inline_trigger {
    my $self = shift;
    my ($instance, $value, $old) = @_;

    return unless $self->has_trigger;

    return '$trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
}

sub _eval_environment {
    my $self = shift;

    my $env = { };

    $env->{'$trigger'} = \($self->trigger)
        if $self->has_trigger;
    $env->{'$attr_default'} = \($self->default)
        if $self->has_default;

    if ($self->has_type_constraint) {
        my $tc_obj = $self->type_constraint;

        $env->{'$type_constraint'} = \(
            $tc_obj->_compiled_type_constraint
        ) unless $tc_obj->can_be_inlined;
        # these two could probably get inlined versions too
        $env->{'$type_coercion'} = \(
            $tc_obj->coercion->_compiled_type_coercion
        ) if $tc_obj->has_coercion;
        $env->{'$type_message'} = \(
            $tc_obj->has_message ? $tc_obj->message : $tc_obj->_default_message
        );

        $env = { %$env, %{ $tc_obj->inline_environment } };
    }

    $env->{'$class_name'} = \($self->associated_class->name);

    # XXX ugh, fix these
    $env->{'$attr'} = \$self
        if $self->has_initializer && $self->is_lazy;
    # pretty sure this is only going to be closed over if you use a custom
    # error class at this point, but we should still get rid of this
    # at some point
    $env->{'$meta'} = \($self->associated_class);

    return $env;
}

sub _weaken_value {
    my ( $self, $instance ) = @_;

    my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
        ->get_meta_instance;

    $meta_instance->weaken_slot_value( $instance, $self->name );
}

sub get_value {
    my ($self, $instance, $for_trigger) = @_;

    if ($self->is_lazy) {
        unless ($self->has_value($instance)) {
            my $value;
            if ($self->has_default) {
                $value = $self->default($instance);
            } elsif ( $self->has_builder ) {
                $value = $self->_call_builder($instance);
            }

            $value = $self->_coerce_and_verify( $value, $instance );

            $self->set_initial_value($instance, $value);

            if ( ref $value && $self->is_weak_ref ) {
                $self->_weaken_value($instance);
            }
        }
    }

    if ( $self->should_auto_deref && ! $for_trigger ) {

        my $type_constraint = $self->type_constraint;

        if ($type_constraint->is_a_type_of('ArrayRef')) {
            my $rv = $self->SUPER::get_value($instance);
            return unless defined $rv;
            return wantarray ? @{ $rv } : $rv;
        }
        elsif ($type_constraint->is_a_type_of('HashRef')) {
            my $rv = $self->SUPER::get_value($instance);
            return unless defined $rv;
            return wantarray ? %{ $rv } : $rv;
        }
        else {
            throw_exception( CannotAutoDereferenceTypeConstraint => type_name => $type_constraint->name,
                                                                    instance  => $instance,
                                                                    attribute => $self
                           );
        }

    }
    else {

        return $self->SUPER::get_value($instance);
    }
}

sub _inline_get_value {
    my $self = shift;
    my ($instance, $tc, $coercion, $message) = @_;

    my $slot_access = $self->_inline_instance_get($instance);
    $tc           ||= '$type_constraint';
    $coercion     ||= '$type_coercion';
    $message      ||= '$type_message';

    return (
        $self->_inline_check_lazy($instance, $tc, $coercion, $message),
        $self->_inline_return_auto_deref($slot_access),
    );
}

sub _inline_check_lazy {
    my $self = shift;
    my ($instance, $tc, $coercion, $message) = @_;

    return unless $self->is_lazy;

    my $slot_exists = $self->_inline_instance_has($instance);

    return (
        'if (!' . $slot_exists . ') {',
            $self->_inline_init_from_default($instance, '$default', $tc, $coercion, $message, 'lazy'),
        '}',
    );
}

sub _inline_init_from_default {
    my $self = shift;
    my ($instance, $default, $tc, $coercion, $message, $for_lazy) = @_;

    if (!($self->has_default || $self->has_builder)) {
        throw_exception( LazyAttributeNeedsADefault => attribute => $self );
    }

    return (
        $self->_inline_generate_default($instance, $default),
        # intentionally not using _inline_tc_code, since that can be overridden
        # to do things like possibly only do member tc checks, which isn't
        # appropriate for checking the result of a default
        $self->has_type_constraint
            ? ($self->_inline_check_coercion($default, $tc, $coercion, $for_lazy),
               $self->_inline_check_constraint($default, $tc, $message, $for_lazy))
            : (),
        $self->_inline_init_slot($instance, $default),
        $self->_inline_weaken_value($instance, $default),
    );
}

sub _inline_generate_default {
    my $self = shift;
    my ($instance, $default) = @_;

    if ($self->has_default) {
        my $source = 'my ' . $default . ' = $attr_default';
        $source .= '->(' . $instance . ')'
            if $self->is_default_a_coderef;
        return $source . ';';
    }
    elsif ($self->has_builder) {
        my $builder = B::perlstring($self->builder);
        my $builder_str = quotemeta($self->builder);
        my $attr_name_str = quotemeta($self->name);
        return (
            'my ' . $default . ';',
            'if (my $builder = ' . $instance . '->can(' . $builder . ')) {',
                $default . ' = ' . $instance . '->$builder;',
            '}',
            'else {',
                'my $class = ref(' . $instance . ') || ' . $instance . ';',
                $self->_inline_throw_exception(
                    BuilderMethodNotSupportedForInlineAttribute =>
                    'class_name     => $class,'.
                    'attribute_name => "'.$attr_name_str.'",'.
                    'instance       => '.$instance.','.
                    'builder        => "'.$builder_str.'"'
                ) . ';',
            '}',
        );
    }
    else {
        confess(
            "Can't generate a default for " . $self->name
          . " since no default or builder was specified"
        );
    }
}

sub _inline_init_slot {
    my $self = shift;
    my ($inv, $value) = @_;

    if ($self->has_initializer) {
        return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
    }
    else {
        return $self->_inline_instance_set($inv, $value) . ';';
    }
}

sub _inline_return_auto_deref {
    my $self = shift;

    return 'return ' . $self->_auto_deref(@_) . ';';
}

sub _auto_deref {
    my $self = shift;
    my ($ref_value) = @_;

    return $ref_value unless $self->should_auto_deref;

    my $type_constraint = $self->type_constraint;

    my $sigil;
    if ($type_constraint->is_a_type_of('ArrayRef')) {
        $sigil = '@';
    }
    elsif ($type_constraint->is_a_type_of('HashRef')) {
        $sigil = '%';
    }
    else {
        confess(
            'Can not auto de-reference the type constraint \''
          . $type_constraint->name
          . '\''
        );
    }

    return 'wantarray '
             . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
             . ': (' . $ref_value . ')';
}

## installing accessors

sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }

sub install_accessors {
    my $self = shift;
    $self->SUPER::install_accessors(@_);
    $self->install_delegation if $self->has_handles;
    return;
}

sub _check_associated_methods {
    my $self = shift;
    unless (
        @{ $self->associated_methods }
        || ($self->_is_metadata || '') eq 'bare'
    ) {
        Carp::cluck(
            'Attribute (' . $self->name . ') of class '
            . $self->associated_class->name
            . ' has no associated methods'
            . ' (did you mean to provide an "is" argument?)'
            . "\n"
        )
    }
}

sub _process_accessors {
    my $self = shift;
    my ($type, $accessor, $generate_as_inline_methods) = @_;

    $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
    my $method = $self->associated_class->get_method($accessor);

    if (   $method
        && $method->isa('Class::MOP::Method::Accessor') ) {

        # This is a special case that is very unlikely to occur outside of the
        # Moose bootstrapping process. We do not want to warn if the method
        # we're about to replace is for this same attribute, _and_ we're
        # replacing a non-inline method with an inlined version.
        #
        # This would never occur in normal user code because Moose inlines all
        # accessors. However, Moose metaclasses are instances of
        # Class::MOP::Class, which _does not_ inline accessors by
        # default. However, in Class::MOP & Moose.pm, we iterate over all of
        # our internal metaclasses and make them immutable after they're fully
        # defined. This ends up replacing the attribute accessors.
        unless ( $method->associated_attribute->name eq $self->name
            && ( $generate_as_inline_methods && !$method->is_inline ) ) {

            my $other_attr = $method->associated_attribute;

            my $msg = sprintf(
                'You are overwriting a %s (%s) for the %s attribute',
                $method->accessor_type,
                $accessor,
                $other_attr->name,
            );

            if ( my $method_context = $method->definition_context ) {
                $msg .= sprintf(
                    ' (defined at %s line %s)',
                    $method_context->{file},
                    $method_context->{line},
                    )
                    if defined $method_context->{file}
                    && $method_context->{line};
            }

            $msg .= sprintf(
                ' with a new %s method for the %s attribute',
                $type,
                $self->name,
            );

            if ( my $self_context = $self->definition_context ) {
                $msg .= sprintf(
                    ' (defined at %s line %s)',
                    $self_context->{file},
                    $self_context->{line},
                    )
                    if defined $self_context->{file}
                    && $self_context->{line};
            }

            Carp::cluck($msg);
        }
    }

    if (
           $method
        && !$method->is_stub
        && !$method->isa('Class::MOP::Method::Accessor')
        && (  !$self->definition_context
            || $method->package_name eq $self->definition_context->{package} )
        ) {

        Carp::cluck(
            "You are overwriting a locally defined method ($accessor) with "
                . "an accessor" );
    }

    if (  !$self->associated_class->has_method($accessor)
        && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {

        Carp::cluck(
            "You are overwriting a locally defined function ($accessor) with "
                . "an accessor" );
    }

    $self->SUPER::_process_accessors(@_);
}

sub remove_accessors {
    my $self = shift;
    $self->SUPER::remove_accessors(@_);
    $self->remove_delegation if $self->has_handles;
    return;
}

sub install_delegation {
    my $self = shift;

    # NOTE:
    # Here we canonicalize the 'handles' option
    # this will sort out any details and always
    # return an hash of methods which we want
    # to delegate to, see that method for details
    my %handles = $self->_canonicalize_handles;

    # install the delegation ...
    my $associated_class = $self->associated_class;
    my $class_name = $associated_class->name;

    foreach my $handle ( sort keys %handles ) {
        my $method_to_call = $handles{$handle};
        my $name           = "${class_name}::${handle}";

        if ( my $method = $associated_class->get_method($handle) ) {
            throw_exception(
                CannotDelegateLocalMethodIsPresent => attribute => $self,
                method                             => $method,
            ) unless $method->is_stub;
        }

        # NOTE:
        # handles is not allowed to delegate
        # any of these methods, as they will
        # override the ones in your class, which
        # is almost certainly not what you want.

        # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
        #cluck("Not delegating method '$handle' because it is a core method") and
        next
            if $class_name->isa("Moose::Object")
            and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);

        my $method = $self->_make_delegation_method($handle, $method_to_call);

        $self->associated_class->add_method($method->name, $method);
        $self->associate_method($method);
    }
}

sub remove_delegation {
    my $self = shift;
    my %handles = $self->_canonicalize_handles;
    my $associated_class = $self->associated_class;
    foreach my $handle (keys %handles) {
        next unless any { $handle eq $_ }
                    map { $_->name }
                    @{ $self->associated_methods };
        $self->associated_class->remove_method($handle);
    }
}

# private methods to help delegation ...

sub _canonicalize_handles {
    my $self    = shift;
    my $handles = $self->handles;
    if (my $handle_type = ref($handles)) {
        if ($handle_type eq 'HASH') {
            return %{$handles};
        }
        elsif ($handle_type eq 'ARRAY') {
            return map { $_ => $_ } @{$handles};
        }
        elsif ($handle_type eq 'Regexp') {
            ($self->has_type_constraint)
                || throw_exception( CannotDelegateWithoutIsa => attribute => $self );
            return map  { ($_ => $_) }
                   grep { /$handles/ } $self->_get_delegate_method_list;
        }
        elsif ($handle_type eq 'CODE') {
            return $handles->($self, $self->_find_delegate_metaclass);
        }
        elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
            return map { $_ => $_ } @{ $handles->methods };
        }
        elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
            $handles = $handles->role;
        }
        else {
            throw_exception( UnableToCanonicalizeHandles => attribute => $self,
                                                            handles   => $handles
                           );
        }
    }

    Moose::Util::_load_user_class($handles);
    my $role_meta = Class::MOP::class_of($handles);

    (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
        || throw_exception( UnableToCanonicalizeNonRolePackage => attribute => $self,
                                                                  handles   => $handles
                          );

    return map { $_ => $_ }
        map { $_->name }
        grep { !$_->isa('Class::MOP::Method::Meta') } (
        $role_meta->_get_local_methods,
        $role_meta->get_required_method_list,
        );
}

sub _get_delegate_method_list {
    my $self = shift;
    my $meta = $self->_find_delegate_metaclass;
    if ($meta->isa('Class::MOP::Class')) {
        return map  { $_->name }  # NOTE: !never! delegate &meta
               grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
                    $meta->get_all_methods;
    }
    elsif ($meta->isa('Moose::Meta::Role')) {
        return $meta->get_method_list;
    }
    else {
        throw_exception( UnableToRecognizeDelegateMetaclass => attribute          => $self,
                                                               delegate_metaclass => $meta
                       );
    }
}

sub _find_delegate_metaclass {
    my $self = shift;
    my $class = $self->_isa_metadata;
    my $role = $self->_does_metadata;

    if ( $class ) {
        # make sure isa is actually a class
        unless ( $self->type_constraint->isa("Moose::Meta::TypeConstraint::Class") ) {
            throw_exception( DelegationToATypeWhichIsNotAClass => attribute => $self );
        }

        # make sure the class is loaded
        unless ( Moose::Util::_is_package_loaded($class) ) {
            throw_exception( DelegationToAClassWhichIsNotLoaded => attribute  => $self,
                                                                   class_name => $class
                           );
        }
        # we might be dealing with a non-Moose class,
        # and need to make our own metaclass. if there's
        # already a metaclass, it will be returned
        return Class::MOP::Class->initialize($class);
    }
    elsif ( $role ) {
        unless ( Moose::Util::_is_package_loaded($role) ) {
            throw_exception( DelegationToARoleWhichIsNotLoaded => attribute => $self,
                                                                  role_name => $role
                           );
        }

        return Class::MOP::class_of($role);
    }
    else {
        throw_exception( CannotFindDelegateMetaclass => attribute => $self );
    }
}

sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }

sub _make_delegation_method {
    my ( $self, $handle_name, $method_to_call ) = @_;

    my @curried_arguments;

    ($method_to_call, @curried_arguments) = @$method_to_call
        if 'ARRAY' eq ref($method_to_call);

    return $self->delegation_metaclass->new(
        name               => $handle_name,
        package_name       => $self->associated_class->name,
        attribute          => $self,
        delegate_to_method => $method_to_call,
        curried_arguments  => \@curried_arguments,
    );
}

sub _coerce_and_verify {
    my $self     = shift;
    my $val      = shift;
    my $instance = shift;

    return $val unless $self->has_type_constraint;

    $val = $self->type_constraint->coerce($val)
        if $self->should_coerce && $self->type_constraint->has_coercion;

    $self->verify_against_type_constraint($val, instance => $instance);

    return $val;
}

sub verify_against_type_constraint {
    my $self = shift;
    my $val  = shift;

    return 1 if !$self->has_type_constraint;

    my $type_constraint = $self->type_constraint;

    $type_constraint->check($val)
        || throw_exception( ValidationFailedForTypeConstraint => type      => $type_constraint,
                                                                 value     => $val,
                                                                 attribute => $self,
                          );
}

package  # hide from PAUSE
    Moose::Meta::Attribute::Custom::Moose;

sub register_implementation { 'Moose::Meta::Attribute' }
1;

# ABSTRACT: The Moose attribute metaclass

__END__

=pod

=encoding UTF-8

=head1 NAME

Moose::Meta::Attribute - The Moose attribute metaclass

=head1 VERSION

version 2.2011

=head1 DESCRIPTION

This class is a subclass of L<Class::MOP::Attribute> that provides
additional Moose-specific functionality.

To really understand this class, you will need to start with the
L<Class::MOP::Attribute> documentation. This class can be understood
as a set of additional features on top of the basic feature provided
by that parent class.

=head1 INHERITANCE

C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.

=head1 METHODS

Many of the documented below override methods in
L<Class::MOP::Attribute> and add Moose specific features.

=head2 Creation

=over 4

=item B<< Moose::Meta::Attribute->new($name, %options) >>

This method overrides the L<Class::MOP::Attribute> constructor.

Many of the options below are described in more detail in the
L<Moose::Manual::Attributes> document.

It adds the following options to the constructor:

=over 8

=item * is => 'ro', 'rw', 'bare'

This provides a shorthand for specifying the C<reader>, C<writer>, or
C<accessor> names. If the attribute is read-only ('ro') then it will
have a C<reader> method with the same attribute as the name.

If it is read-write ('rw') then it will have an C<accessor> method
with the same name. If you provide an explicit C<writer> for a
read-write attribute, then you will have a C<reader> with the same
name as the attribute, and a C<writer> with the name you provided.

Use 'bare' when you are deliberately not installing any methods
(accessor, reader, etc.) associated with this attribute; otherwise,
Moose will issue a warning when this attribute is added to a
metaclass.

=item * isa => $type

This option accepts a type. The type can be a string, which should be
a type name. If the type name is unknown, it is assumed to be a class
name.

This option can also accept a L<Moose::Meta::TypeConstraint> object.

If you I<also> provide a C<does> option, then your C<isa> option must
be a class name, and that class must do the role specified with
C<does>.

=item * does => $role

This is short-hand for saying that the attribute's type must be an
object which does the named role.

=item * coerce => $bool

This option is only valid for objects with a type constraint
(C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
this attribute is set.

You cannot make both this and the C<weak_ref> option true.

=item * trigger => $sub

This option accepts a subroutine reference, which will be called after
the attribute is set.

=item * required => $bool

An attribute which is required must be provided to the constructor. An
attribute which is required can also have a C<default> or C<builder>,
which will satisfy its required-ness.

A required attribute must have a C<default>, C<builder> or a
non-C<undef> C<init_arg>

=item * lazy => $bool

A lazy attribute must have a C<default> or C<builder>. When an
attribute is lazy, the default value will not be calculated until the
attribute is read.

=item * weak_ref => $bool

If this is true, the attribute's value will be stored as a weak
reference.

=item * documentation

An arbitrary string that can be retrieved later by calling C<<
$attr->documentation >>.

=item * auto_deref => $bool

B<Note that in cases where you want this feature you are often better served
by using a L<Moose::Meta::Attribute::Native> trait instead>.

If this is true, then the reader will dereference the value when it is
called. The attribute must have a type constraint which defines the
attribute as an array or hash reference.

=item * lazy_build => $bool

B<Note that use of this feature is strongly discouraged.> Some documentation
used to encourage use of this feature as a best practice, but we have changed
our minds.

Setting this to true makes the attribute lazy and provides a number of
default methods.

  has 'size' => (
      is         => 'ro',
      lazy_build => 1,
  );

is equivalent to this:

  has 'size' => (
      is        => 'ro',
      lazy      => 1,
      builder   => '_build_size',
      clearer   => 'clear_size',
      predicate => 'has_size',
  );

If your attribute name starts with an underscore (C<_>), then the clearer
and predicate will as well:

  has '_size' => (
      is         => 'ro',
      lazy_build => 1,
  );

becomes:

  has '_size' => (
      is        => 'ro',
      lazy      => 1,
      builder   => '_build__size',
      clearer   => '_clear_size',
      predicate => '_has_size',
  );

Note the doubled underscore in the builder name. Internally, Moose
simply prepends the attribute name with "_build_" to come up with the
builder name.

=item * role_attribute => $role_attribute

If provided, this should be a L<Moose::Meta::Role::Attribute> object.

=back

=item B<< $attr->clone(%options) >>

This creates a new attribute based on attribute being cloned. You must
supply a C<name> option to provide a new name for the attribute.

The C<%options> can only specify options handled by
L<Class::MOP::Attribute>.

=back

=head2 Value management

=over 4

=item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>

This method is used internally to initialize the attribute's slot in
the object C<$instance>.

This overrides the L<Class::MOP::Attribute> method to handle lazy
attributes, weak references, and type constraints.

=item B<get_value>

=item B<set_value>

  eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
  if($@) {
    print "Oops: $@\n";
  }

I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>

Before setting the value, a check is made on the type constraint of
the attribute, if it has one, to see if the value passes it. If the
value fails to pass, the set operation dies.

Any coercion to convert values is done before checking the type constraint.

To check a value against a type constraint before setting it, fetch the
attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Company_Subtypes>
for an example.

=back

=head2 Attribute Accessor generation

=over 4

=item B<< $attr->install_accessors >>

This method overrides the parent to also install delegation methods.

If, after installing all methods, the attribute object has no associated
methods, it throws an error unless C<< is => 'bare' >> was passed to the
attribute constructor.  (Trying to add an attribute that has no associated
methods is almost always an error.)

=item B<< $attr->remove_accessors >>

This method overrides the parent to also remove delegation methods.

=item B<< $attr->inline_set($instance_var, $value_var) >>

This method return a code snippet suitable for inlining the relevant
operation. It expect strings containing variable names to be used in the
inlining, like C<'$self'> or C<'$_[1]'>.

=item B<< $attr->install_delegation >>

This method adds its delegation methods to the attribute's associated
class, if it has any to add.

=item B<< $attr->remove_delegation >>

This method remove its delegation methods from the attribute's
associated class.

=item B<< $attr->accessor_metaclass >>

Returns the accessor metaclass name, which defaults to
L<Moose::Meta::Method::Accessor>.

=item B<< $attr->delegation_metaclass >>

Returns the delegation metaclass name, which defaults to
L<Moose::Meta::Method::Delegation>.

=back

=head2 Additional Moose features

These methods are not found in the superclass. They support features
provided by Moose.

=over 4

=item B<< $attr->does($role) >>

This indicates whether the I<attribute itself> does the given
role. The role can be given as a full class name, or as a resolvable
trait name.

Note that this checks the attribute itself, not its type constraint,
so it is checking the attribute's metaclass and any traits applied to
the attribute.

=item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>

This is an alternate constructor that handles the C<metaclass> and
C<traits> options.

Effectively, this method is a factory that finds or creates the
appropriate class for the given C<metaclass> and/or C<traits>.

Once it has the appropriate class, it will call C<< $class->new($name,
%options) >> on that class.

=item B<< $attr->clone_and_inherit_options(%options) >>

This method supports the C<has '+foo'> feature. It does various bits
of processing on the supplied C<%options> before ultimately calling
the C<clone> method.

One of its main tasks is to make sure that the C<%options> provided
does not include the options returned by the
C<illegal_options_for_inheritance> method.

=item B<< $attr->illegal_options_for_inheritance >>

This returns a blacklist of options that can not be overridden in a
subclass's attribute definition.

This exists to allow a custom metaclass to change or add to the list
of options which can not be changed.

=item B<< $attr->type_constraint >>

Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
if it has one.

=item B<< $attr->has_type_constraint >>

Returns true if this attribute has a type constraint.

=item B<< $attr->verify_against_type_constraint($value) >>

Given a value, this method returns true if the value is valid for the
attribute's type constraint. If the value is not valid, it throws an
error.

=item B<< $attr->handles >>

This returns the value of the C<handles> option passed to the
constructor.

=item B<< $attr->has_handles >>

Returns true if this attribute performs delegation.

=item B<< $attr->is_weak_ref >>

Returns true if this attribute stores its value as a weak reference.

=item B<< $attr->is_required >>

Returns true if this attribute is required to have a value.

=item B<< $attr->is_lazy >>

Returns true if this attribute is lazy.

=item B<< $attr->is_lazy_build >>

Returns true if the C<lazy_build> option was true when passed to the
constructor.

=item B<< $attr->should_coerce >>

Returns true if the C<coerce> option passed to the constructor was
true.

=item B<< $attr->should_auto_deref >>

Returns true if the C<auto_deref> option passed to the constructor was
true.

=item B<< $attr->trigger >>

This is the subroutine reference that was in the C<trigger> option
passed to the constructor, if any.

=item B<< $attr->has_trigger >>

Returns true if this attribute has a trigger set.

=item B<< $attr->documentation >>

Returns the value that was in the C<documentation> option passed to
the constructor, if any.

=item B<< $attr->has_documentation >>

Returns true if this attribute has any documentation.

=item B<< $attr->role_attribute >>

Returns the L<Moose::Meta::Role::Attribute> object from which this attribute
was created, if any. This may return C<undef>.

=item B<< $attr->has_role_attribute >>

Returns true if this attribute has an associated role attribute.

=item B<< $attr->applied_traits >>

This returns an array reference of all the traits which were applied
to this attribute. If none were applied, this returns C<undef>.

=item B<< $attr->has_applied_traits >>

Returns true if this attribute has any traits applied.

=back

=head1 BUGS

See L<Moose/BUGS> for details on reporting bugs.

=head1 AUTHORS

=over 4

=item *

Stevan Little <stevan.little@iinteractive.com>

=item *

Dave Rolsky <autarch@urth.org>

=item *

Jesse Luehrs <doy@tozt.net>

=item *

Shawn M Moore <code@sartak.org>

=item *

יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>

=item *

Karen Etheridge <ether@cpan.org>

=item *

Florian Ragwitz <rafl@debian.org>

=item *

Hans Dieter Pearcey <hdp@weftsoar.net>

=item *

Chris Prather <chris@prather.org>

=item *

Matt S Trout <mst@shadowcat.co.uk>

=back

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2006 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
