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package Package::Util::Lite;
our $DATE = '2019-01-06'; # DATE
our $VERSION = '0.001'; # VERSION
use strict 'subs', 'vars';
use warnings;
require Exporter;
our @ISA = qw(Exporter);
our @EXPORT_OK = qw(
                       package_exists
                       list_subpackages
               );
sub package_exists {
    no strict 'refs';
    my $pkg = shift;
    # opt
    #return unless $pkg =~ /\A\w+(::\w+)*\z/;
    if ($pkg =~ s/::(\w+)\z//) {
        return !!${$pkg . "::"}{$1 . "::"};
    } else {
        return !!$::{$pkg . "::"};
    }
}
sub list_subpackages {
    my ($pkg, $recursive, $cur_res, $ref_mem) = @_;
    return () unless !length($pkg) || package_exists($pkg);
    # this is used to avoid deep recursion. for example (the only one?) %:: and
    # %main:: point to the same thing.
    $ref_mem ||= {};
    my $symtbl = \%{$pkg . "::"};
    return () if $ref_mem->{"$symtbl"}++;
    my $res = $cur_res || [];
    for (sort keys %$symtbl) {
        next unless s/::$//;
        my $name = (length($pkg) ? "$pkg\::" : "" ) . $_;
        push @$res, $name;
        list_subpackages($name, 1, $res, $ref_mem) if $recursive;
    }
    @$res;
}
1;
# ABSTRACT: Package-related utilities
__END__
HideShow 91 lines of Pod
=pod
=encoding UTF-8
=head1 NAME
Package::Util::Lite - Package-related utilities
=head1 VERSION
This document describes version 0.001 of Package::Util::Lite (from Perl distribution Package-Util-Lite), released on 2019-01-06.
=head1 SYNOPSIS
 use Package::Util::Lite qw(
     package_exists
     list_subpackages
 );
 print "Package Foo::Bar exists" if package_exists("Foo::Bar");
 my @subpkg    = list_subpackages("Foo::Bar");
 my @allsubpkg = list_subpackages("Foo::Bar", 1); # recursive
=head1 DESCRIPTION
This module provides package-related utilities. You should check
L<Package::Stash> first, then here.
=head1 FUNCTIONS
=head2 package_exists
Usage:
 package_exists($name) => bool
Return true if package "exists". By "exists", it means that the package has been
defined by C<package> statement or some entries have been created in the symbol
table (e.g. C<$Foo::var = 1;> will make the C<Foo> package "exist").
This function can be used e.g. for checking before aliasing one package to
another. Or to casually check whether a module has been loaded.
=head2 list_subpackages($name[, $recursive]) => @res
List subpackages, e.g.:
 (
     "Foo::Bar::Baz",
     "Foo::Bar::Qux",
     ...
 )
If $recursive is true, will also list subpackages of subpackages, and so on.
=head1 FAQ
=head1 HOMEPAGE
Please visit the project's homepage at L<https://metacpan.org/release/Package-Util-Lite>.
=head1 SOURCE
Source repository is at L<https://github.com/perlancar/perl-Package-Util-Lite>.
=head1 BUGS
Please report any bugs or feature requests on the bugtracker website L<https://rt.cpan.org/Public/Dist/Display.html?Name=Package-Util-Lite>
When submitting a bug or request, please include a test-file or a
patch to an existing test-file that illustrates the bug or desired
feature.
=head1 SEE ALSO
L<Package::Stash>
=head1 AUTHOR
perlancar <perlancar@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2019 by perlancar@cpan.org.
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