How to use the west.cmake function in west

if cache_file is None:
        log.wrn('No build directory (--build-dir) or CMake cache '
                '(--cache-file) given or found; output will be limited')
        cache = None
    else:
        try:
            cache = cmake.CMakeCache(cache_file)
        except Exception:
            log.die('Cannot load cache {}.'.format(cache_file))

    # If we have a build directory, try to ensure build artifacts are
    # up to date. If that doesn't work, still try to print information
    # on a best-effort basis.
    if build_dir and not args.skip_rebuild:
        try:
            cmake.run_build(build_dir)
        except CalledProcessError:
            msg = 'Failed re-building application; cannot load context. '
            if args.build_dir:
                msg += 'Is {} the right --build-dir?'.format(args.build_dir)
            else:
                msg += textwrap.dedent('''\
                Use --build-dir (-d) to specify a build directory; the one
                used was {}.'''.format(build_dir))
            log.die('\n'.join(textwrap.wrap(msg, initial_indent='',
                                            subsequent_indent=INDENT,
                                            break_on_hyphens=False)))

    if cache is None:
        _dump_no_context_info(command, args)
        if not args.runner:
            return

def do_run_common(command, args, runner_args, cached_runner_var):
    if args.context:
        _dump_context(command, args, runner_args, cached_runner_var)
        return

    command_name = command.name
    build_dir = _build_dir(args)

    if not args.skip_rebuild:
        try:
            cmake.run_build(build_dir)
        except CalledProcessError:
            if args.build_dir:
                log.die('cannot run {}, build in {} failed'.format(
                    command_name, args.build_dir))
            else:
                log.die('cannot run {}; no --build-dir given and build in '
                        'current directory {} failed'.format(command_name,
                                                             build_dir))

    # Runner creation, phase 1.
    #
    # Get the default runner name from the cache, allowing a command
    # line override. Get the ZephyrBinaryRunner class by name, and
    # make sure it supports the command.

    cache_file = path.join(build_dir, args.cmake_cache or cmake.DEFAULT_CACHE)

def _update_cache(self):
        try:
            self.cmake_cache = cmake.CMakeCache.from_build_dir(self.build_dir)
        except FileNotFoundError:
            pass

def _update_cache(self):
        try:
            self.cmake_cache = cmake.CMakeCache.from_build_dir(self.build_dir)
        except FileNotFoundError:
            pass

# options to set the source and binary directories.
        #
        # However, it's the only known way to set that directory and
        # run CMake from the current working directory. This is
        # important because users expect invocations like this to Just
        # Work:
        #
        # west build -- -DOVERLAY_CONFIG=relative-path.conf
        final_cmake_args = ['-B{}'.format(self.build_dir),
                            '-H{}'.format(self.source_dir),
                            '-G{}'.format(DEFAULT_CMAKE_GENERATOR)]
        if self.args.board:
            final_cmake_args.append('-DBOARD={}'.format(self.args.board))
        if cmake_opts:
            final_cmake_args.extend(cmake_opts)
        cmake.run_cmake(final_cmake_args)

def _dump_context(command, args, runner_args, cached_runner_var):
    build_dir = _build_dir(args, die_if_none=False)

    # Try to figure out the CMake cache file based on the build
    # directory or an explicit argument.
    if build_dir is not None:
        cache_file = path.abspath(
            path.join(build_dir, args.cmake_cache or cmake.DEFAULT_CACHE))
    elif args.cmake_cache:
        cache_file = path.abspath(args.cmake_cache)
    else:
        cache_file = None

    # Load the cache itself, if possible.
    if cache_file is None:
        log.wrn('No build directory (--build-dir) or CMake cache '
                '(--cache-file) given or found; output will be limited')
        cache = None
    else:
        try:
            cache = cmake.CMakeCache(cache_file)
        except Exception:
            log.die('Cannot load cache {}.'.format(cache_file))

def is_zephyr_build(path):
    '''Return true if and only if `path` appears to be a valid Zephyr
    build directory.

    "Valid" means the given path is a directory which contains a CMake
    cache with a 'ZEPHYR_TOOLCHAIN_VARIANT' key.
    '''
    try:
        cache = cmake.CMakeCache.from_build_dir(path)
    except FileNotFoundError:
        cache = {}

    if 'ZEPHYR_TOOLCHAIN_VARIANT' in cache:
        log.dbg('{} is a zephyr build directory'.format(path),
                level=log.VERBOSE_EXTREME)
        return True
    else:
        log.dbg('{} is NOT a valid zephyr build directory'.format(path),
                level=log.VERBOSE_EXTREME)
        return False

def _dump_context(command, args, runner_args, cached_runner_var):
    build_dir = _build_dir(args, die_if_none=False)

    # Try to figure out the CMake cache file based on the build
    # directory or an explicit argument.
    if build_dir is not None:
        cache_file = path.abspath(
            path.join(build_dir, args.cmake_cache or cmake.DEFAULT_CACHE))
    elif args.cmake_cache:
        cache_file = path.abspath(args.cmake_cache)
    else:
        cache_file = None

    # Load the cache itself, if possible.
    if cache_file is None:
        log.wrn('No build directory (--build-dir) or CMake cache '
                '(--cmake-cache) given or found; output will be limited')
        cache = None
    else:
        try:
            cache = cmake.CMakeCache(cache_file)
        except Exception:
            log.die('Cannot load cache {}.'.format(cache_file))