gen_compile_commands: move directory walk to a generator function

        log_level: A logging level to filter log output.

        directory: The work directory where the objects were built.

        output: Where to write the compile-commands JSON file.

        paths: The list of directories to handle to find .cmd files.

    """

    usage = 'Creates a compile_commands.json database from kernel .cmd files'

    parser = argparse.ArgumentParser(description=usage)

    return (args.log_level,

            os.path.abspath(args.directory),

            args.output)

            args.output,

            [args.directory])

def cmdfiles_in_dir(directory):

    """Generate the iterator of .cmd files found under the directory.

    Walk under the given directory, and yield every .cmd file found.

    Args:

        directory: The directory to search for .cmd files.

    Yields:

        The path to a .cmd file.

    """

    filename_matcher = re.compile(_FILENAME_PATTERN)

    for dirpath, _, filenames in os.walk(directory):

        for filename in filenames:

            if filename_matcher.match(filename):

                yield os.path.join(dirpath, filename)

def process_line(root_directory, command_prefix, file_path):

def main():

    """Walks through the directory and finds and parses .cmd files."""

    log_level, directory, output = parse_arguments()

    log_level, directory, output, paths = parse_arguments()

    level = getattr(logging, log_level)

    logging.basicConfig(format='%(levelname)s: %(message)s', level=level)

    filename_matcher = re.compile(_FILENAME_PATTERN)

    line_matcher = re.compile(_LINE_PATTERN)

    compile_commands = []

    for dirpath, _, filenames in os.walk(directory):

        for filename in filenames:

            if not filename_matcher.match(filename):

                continue

            filepath = os.path.join(dirpath, filename)

            with open(filepath, 'rt') as f:

    for path in paths:

        cmdfiles = cmdfiles_in_dir(path)

        for cmdfile in cmdfiles:

            with open(cmdfile, 'rt') as f:

                result = line_matcher.match(f.readline())

                if result:

                    try:

                        entry = process_line(directory,

                                             result.group(1), result.group(2))

                        entry = process_line(directory, result.group(1),

                                             result.group(2))

                        compile_commands.append(entry)

                    except ValueError as err:

                        logging.info('Could not add line from %s: %s',

                                     filepath, err)

                                     cmdfile, err)

    with open(output, 'wt') as f:

        json.dump(compile_commands, f, indent=2, sort_keys=True)