List the packages currently installed in a dict::

        {'<package_name>': '<version>'}

    CLI Example:

    .. code-block:: bash

        salt '*' pkg.list_pkgs

def list_pkgs(versions_as_list=False, **kwargs):
    '''
    List the packages currently installed in a dict::

        {'<package_name>': '<version>'}

    CLI Example:

    .. code-block:: bash

        salt '*' pkg.list_pkgs
    '''
    versions_as_list = salt.utils.data.is_true(versions_as_list)
    # not yet implemented or not applicable
    if any([salt.utils.data.is_true(kwargs.get(x))
            for x in ('removed', 'purge_desired')]):
        return {}

    if 'pkg.list_pkgs' in __context__:
        if versions_as_list:
            return __context__['pkg.list_pkgs']
        else:
            ret = copy.deepcopy(__context__['pkg.list_pkgs'])
            __salt__['pkg_resource.stringify'](ret)
            return ret

    ret = {}
    cmd = 'info --json=v1 --installed'
    package_info = salt.utils.json.loads(_call_brew(cmd)['stdout'])

    for package in package_info:
        # Brew allows multiple versions of the same package to be installed.
        # Salt allows for this, so it must be accounted for.
        versions = [v['version'] for v in package['installed']]
        # Brew allows for aliasing of packages, all of which will be
        # installable from a Salt call, so all names must be accounted for.
        names = package['aliases'] + [package['name'], package['full_name']]
        # Create a list of tuples containing all possible combinations of
        # names and versions, because all are valid.
        combinations = [(n, v) for n in names for v in versions]

        for name, version in combinations:
            __salt__['pkg_resource.add_pkg'](ret, name, version)

    # Grab packages from brew cask, if available.
    # Brew Cask doesn't provide a JSON interface, must be parsed the old way.
    try:
        cask_cmd = 'cask list --versions'
        out = _call_brew(cask_cmd)['stdout']

        for line in out.splitlines():
            try:
                name_and_versions = line.split(' ')
                name = '/'.join(('caskroom/cask', name_and_versions[0]))
                installed_versions = name_and_versions[1:]
                key_func = functools.cmp_to_key(salt.utils.versions.version_cmp)
                newest_version = sorted(installed_versions, key=key_func).pop()
            except ValueError:
                continue
            __salt__['pkg_resource.add_pkg'](ret, name, newest_version)
    except CommandExecutionError:
        pass

    __salt__['pkg_resource.sort_pkglist'](ret)
    __context__['pkg.list_pkgs'] = copy.deepcopy(ret)
    if not versions_as_list:
        __salt__['pkg_resource.stringify'](ret)
    return ret