alluxio.cli.Command.java Source code

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/*
 * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
 * (the "License"). You may not use this work except in compliance with the License, which is
 * available at www.apache.org/licenses/LICENSE-2.0
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied, as more fully set forth in the License.
 *
 * See the NOTICE file distributed with this work for information regarding copyright ownership.
 */

package alluxio.cli;

import alluxio.exception.AlluxioException;
import alluxio.exception.status.InvalidArgumentException;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;

import java.io.IOException;

/**
 * An interface for all the commands that can be run from a shell.
 */
public interface Command {

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

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

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

    /**
     * Checks if the arguments are valid or throw InvalidArgumentException.
     *
     * @param cl the parsed command line for the arguments
     * @throws InvalidArgumentException when arguments are not valid
     */
    default void validateArgs(CommandLine cl) throws InvalidArgumentException {
    }

    /**
     * Runs the command.
     *
     * @param cl the parsed command line for the arguments
     * @return the result of running the command
     */
    int run(CommandLine cl) throws AlluxioException, IOException;

    /**
     * @return the usage information of the command
     */
    String getUsage();

    /**
     * @return the description information of the command
     */
    String getDescription();
}