Interface Command

ratis-shell/src/main/java/org/apache/ratis/shell/cli/Command.java:35–128

An interface for all the commands that can be run from a shell.

 * An interface for all the commands that can be run from a shell.
 */
public interface Command extends Comparable<Command>, Closeable {

  /**
   * Gets the command name as input from the shell.
   *
   * @return the command name
   */
  String getCommandName();

  @Override
  default int compareTo(Command that) {
    return this.getCommandName().compareTo(that.getCommandName());
  }

  /**
   * @return the supported {@link Options} of the command
   */
  default Options getOptions() {
    return new Options();
  }

  /**
   * If a command has sub-commands, the first argument should be the sub-command's name,
   * all arguments and options will be parsed for the sub-command.
   *
   * @return whether this command has sub-commands
   */
  default boolean hasSubCommand() {
    return Optional.ofNullable(getSubCommands()).filter(subs -> !subs.isEmpty()).isPresent();
  }

  /**
   * @return a map from sub-command names to sub-command instances
   */
  default Map<String, Command> getSubCommands() {
    return Collections.emptyMap();
  }

  /**
   * Parses and validates the arguments.
   *
   * @param args the arguments for the command, excluding the command name
   * @return the parsed command line object
   * @throws IllegalArgumentException when arguments are not valid
   */
  default CommandLine parseAndValidateArgs(String... args) throws IllegalArgumentException {
    CommandLine cmdline;
    Options opts = getOptions();
    CommandLineParser parser = new DefaultParser();
    try {
      cmdline = parser.parse(opts, args);
    } catch (ParseException e) {
      throw new IllegalArgumentException(
          String.format("Failed to parse args for %s: %s", getCommandName(), e.getMessage()), e);
    }
    validateArgs(cmdline);
    return cmdline;
  }