File Coverage

blib/lib/Check/ISA.pm

Criterion	Covered	Total	%
statement	59	60	98.3
branch	22	24	91.6
condition	21	24	87.5
subroutine	14	14	100.0
pod	5	6	83.3
total	121	128	94.5

package Check::ISA;

use strict;
use warnings;

use Scalar::Util qw(blessed);

use Sub::Exporter -setup => {
	exports => [qw(obj obj_does inv inv_does obj_can inv_can)],
	groups => {
		default => [qw(obj obj_does inv)],
	},
};

use constant CAN_HAS_DOES => not not UNIVERSAL->can("DOES");
use warnings::register;

our $VERSION = "0.08";

sub extract_io {
    my $glob = shift;

    # handle the case of a string like "STDIN"
    # STDIN->print is actually:
    #   const(PV "STDIN") sM/BARE
    #   method_named(PV "print")
    # so we need to lookup the glob
    if ( defined($glob) and !ref($glob) and length($glob) ) {
        no strict 'refs';
        $glob = \*{$glob};
    }

    # extract the IO
    if ( ref($glob) eq 'GLOB' ) {
        if ( defined ( my $io = *{$glob}{IO} ) ) {
            require IO::Handle;
            return $io;
        }
    }

    return;
}

sub obj ($;$); # predeclare, it's recursive

sub obj ($;$) {
    my ($object_or_filehandle, $class) = @_;

    my $object = blessed($object_or_filehandle)
        ? $object_or_filehandle
        : extract_io($object_or_filehandle) || return;

    if ( defined $class ) {
        $object->isa($class);
    } else {
        return 1; # return $object? what if it's overloaded?
    }
}

sub obj_does ($;$) {
    my ($object_or_filehandle, $class_or_role) = @_;

    my $object = blessed($object_or_filehandle)
        ? $object_or_filehandle
        : extract_io($object_or_filehandle) || return;

    if (defined $class_or_role) {
        if (CAN_HAS_DOES) {
            # we can be faster in 5.10
            $object->DOES($class_or_role);
        } else {
            my $method = $object->can("DOES") || "isa";
            $object->$method($class_or_role);
        }
    } else {
        return 1; # return $object? what if it's overloaded?
    }
}

sub inv ($;$) {
    my ( $inv, $class_or_role ) = @_;

    if (blessed($inv)) {
        return obj_does($inv, $class_or_role);
    } else {
        # we check just for scalar keys on the stash because:
        # sub Foo::Bar::gorch {}
        # Foo->can("isa") # true
        # Bar->can("isa") # false
        # this means that 'Foo' is a valid invocant, but Bar is not

        if (!ref($inv)
            and
            defined $inv
            and
            length($inv)
            and
            do { no strict 'refs'; scalar keys %{$inv . "::"} }
            ) {
            # it's considered a class name as far as gv_fetchmethod is concerned
            # even if the class def is empty
            if (defined $class_or_role) {
                if (CAN_HAS_DOES) {
                    # we can be faster in 5.10
                    $inv->DOES($class_or_role);
                } else {
                    my $method = $inv->can("DOES") || "isa";
                    $inv->$method($class_or_role);
                }
            } else {
                return 1; # $inv is always true, so not a problem, but that would be inconsistent
            }
        } else {
            return;
        }
    }
}

sub obj_can ($;$) {
    my ( $obj, $method ) = @_;
    (blessed($obj) ? $obj : extract_io($obj) || return)->can($method);
}

sub inv_can ($;$) {
    my ( $inv, $method ) = @_;
    obj_can($inv, $method) || inv($inv) && $inv->can($method);
}

__PACKAGE__

__END__