[1] | 1 | package de.ugoe.cs.util.console;
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| 2 |
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| 3 | import java.security.InvalidParameterException;
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| 4 | import java.util.ArrayList;
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| 5 | import java.util.List;
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| 6 |
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| 7 | /**
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| 8 | * <p>
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| 9 | * Executes commands. The commands have to implement the {@link Command}
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| 10 | * interface and be in packages registered using addCommandPackage().
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| 11 | * Additionally, default commands are implemented in the
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| 12 | * de.ugoe.cs.util.console.defaultcommands package.
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| 13 | * </p>
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| 14 | * <p>
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[175] | 15 | * This class is implemented as a <i>Singleton</i>.
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[1] | 16 | * </p>
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| 17 | *
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| 18 | * @author Steffen Herbold
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[175] | 19 | * @version 1.0
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[1] | 20 | */
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| 21 | public class CommandExecuter {
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| 22 |
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| 23 | /**
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| 24 | * <p>
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| 25 | * Handle of the CommandExecuter instance.
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| 26 | * </p>
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| 27 | */
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| 28 | private final static CommandExecuter theInstance = new CommandExecuter();
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| 29 |
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| 30 | /**
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| 31 | * <p>
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| 32 | * Prefix of all command classes.
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| 33 | * </p>
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| 34 | */
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| 35 | private static final String cmdPrefix = "CMD";
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[175] | 36 |
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[1] | 37 | /**
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| 38 | * <p>
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| 39 | * Name of the package for default commands.
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| 40 | * </p>
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| 41 | */
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| 42 | private static final String defaultPackage = "de.ugoe.cs.util.console.defaultcommands";
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| 43 |
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| 44 | /**
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| 45 | * <p>
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| 46 | * List of packages in which commands may be defined. The exec methods trys
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| 47 | * to load command from these packages in the order they have been added.
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| 48 | * </p>
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| 49 | * <p>
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[175] | 50 | * The de.ugoe.cs.util.console.defaultcommands package has always lowest
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| 51 | * priority, unless it is specifically added.
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[1] | 52 | * </p>
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| 53 | */
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| 54 | private List<String> commandPackageList;
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| 55 |
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| 56 | /**
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| 57 | * <p>
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| 58 | * Returns the instance of CommandExecuter. If no instances exists yet, a
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| 59 | * new one is created.
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| 60 | * </p>
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| 61 | *
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| 62 | * @return the instance of CommandExecuter
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| 63 | */
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| 64 | public static synchronized CommandExecuter getInstance() {
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| 65 | return theInstance;
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| 66 | }
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| 67 |
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| 68 | /**
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| 69 | * <p>
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| 70 | * Creates a new CommandExecuter. Private to prevent multiple instances
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| 71 | * (Singleton).
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| 72 | * </p>
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| 73 | */
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| 74 | private CommandExecuter() {
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| 75 | commandPackageList = new ArrayList<String>();
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| 76 | }
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| 77 |
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| 78 | /**
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| 79 | * <p>
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[175] | 80 | * Adds a package that will be used by {@link #exec(String)} to load command
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| 81 | * from.
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[1] | 82 | * </p>
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| 83 | *
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| 84 | * @param pkg
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| 85 | * package where commands are located
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| 86 | */
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| 87 | public void addCommandPackage(String pkg) {
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| 88 | commandPackageList.add(pkg);
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| 89 | }
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| 90 |
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| 91 | /**
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| 92 | * <p>
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| 93 | * Executes the command defined by string. A command has the following form
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| 94 | * (mix of EBNF and natural language):
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| 95 | * </p>
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| 96 | * <code>
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| 97 | * <command> := <commandname><whitespace>{<parameter>}<br>
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| 98 | * <commandname> := String without whitespaces. Has to be a valid Java class name<br>
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| 99 | * <parameter> := <string>|<stringarray><br>
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| 100 | * <string> := <stringwithoutwhitespaces>|<stringwithwhitespaces>
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| 101 | * <stringwithoutwhitespaces> := a string without whitespaces<br>
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| 102 | * <stringwithoutwhitespaces> := a string, that can have whitespaces, but must be in double quotes<br>
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| 103 | * <stringarray> := "["<string>{<whitespace><string>"]"
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| 104 | * </code>
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| 105 | *
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| 106 | * @param command
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| 107 | * the command as a string
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| 108 | */
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| 109 | public void exec(String command) {
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[186] | 110 | Console.commandNotification(command);
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[1] | 111 | Command cmd = null;
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| 112 | CommandParser parser = new CommandParser();
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| 113 | parser.parse(command);
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| 114 | for (int i = 0; cmd == null && i < commandPackageList.size(); i++) {
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[175] | 115 | cmd = loadCMD(commandPackageList.get(i) + "." + cmdPrefix
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| 116 | + parser.getCommandName());
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[1] | 117 | }
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| 118 | if (cmd == null) { // check if command is available as default command
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[175] | 119 | cmd = loadCMD(defaultPackage + "." + cmdPrefix
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| 120 | + parser.getCommandName());
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[1] | 121 | }
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| 122 | if (cmd == null) {
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| 123 | Console.println("Unknown command");
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| 124 | } else {
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| 125 | try {
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| 126 | cmd.run(parser.getParameters());
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| 127 | } catch (InvalidParameterException e) {
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| 128 | cmd.help();
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| 129 | }
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| 130 | }
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| 131 | }
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| 132 |
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| 133 | /**
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[175] | 134 | * <p>
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[1] | 135 | * Helper method that loads a class and tries to cast it to {@link Command}.
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[175] | 136 | * </p>
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[1] | 137 | *
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[175] | 138 | * @param className
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| 139 | * qualified name of the class (including package name)
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| 140 | * @return if class is available and implement {@link Command} and instance
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| 141 | * of the class, null otherwise
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[1] | 142 | */
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| 143 | private Command loadCMD(String className) {
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| 144 | Command cmd = null;
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| 145 | try {
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| 146 | Class<?> cmdClass = Class.forName(className);
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| 147 | cmd = (Command) cmdClass.newInstance();
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| 148 | } catch (NoClassDefFoundError e) {
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| 149 | String[] splitResult = e.getMessage().split("CMD");
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[175] | 150 | String correctName = splitResult[splitResult.length - 1].replace(
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| 151 | ")", "");
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[244] | 152 | Console.println("Did you mean " + correctName + "?");
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[1] | 153 | } catch (ClassNotFoundException e) {
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| 154 | } catch (IllegalAccessException e) {
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| 155 | } catch (InstantiationException e) {
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| 156 | } catch (ClassCastException e) {
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| 157 | Console.traceln(className + "found, but does not implement Command");
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| 158 | }
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| 159 | return cmd;
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| 160 | }
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| 161 | }
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