public boolean prepare()

in shell/core/src/main/java/org/apache/karaf/shell/impl/action/command/DefaultActionPreparator.java [60:246]


    public boolean prepare(Action action, Session session, List<Object> params) throws Exception {

        Command command = action.getClass().getAnnotation(Command.class);
        Map<Option, Field> options = new HashMap<>();
        Map<Argument, Field> arguments = new HashMap<>();
        List<Argument> orderedArguments = new ArrayList<>();

        for (Class<?> type = action.getClass(); type != null; type = type.getSuperclass()) {
            for (Field field : type.getDeclaredFields()) {
                Option option = field.getAnnotation(Option.class);
                if (option != null) {
                    options.put(option, field);
                }

                Argument argument = field.getAnnotation(Argument.class);
                if (argument != null) {
                    argument = replaceDefaultArgument(field, argument);
                    arguments.put(argument, field);
                    int index = argument.index();
                    while (orderedArguments.size() <= index) {
                        orderedArguments.add(null);
                    }
                    if (orderedArguments.get(index) != null) {
                        throw new IllegalArgumentException("Duplicate argument index: " + index + " on Action " + action.getClass().getName());
                    }
                    orderedArguments.set(index, argument);
                }
            }
        }
        assertIndexesAreCorrect(action.getClass(), orderedArguments);

        String commandErrorSt = COLOR_RED + "Error executing command " + command.scope() + ":" + INTENSITY_BOLD + command.name() + INTENSITY_NORMAL + COLOR_DEFAULT + ": ";
        for (Object param : params) {
            if (HelpOption.HELP.name().equals(param.toString())) {
                int termWidth = session.getTerminal() != null ? session.getTerminal().getWidth() : 80;
                termWidth = termWidth == 0 ? 80 : termWidth;
                boolean globalScope = NameScoping.isGlobalScope(session, command.scope());
                printUsage(action, options, arguments, System.out, globalScope, termWidth);
                return false;
            }
        }
        
        // Populate
        Map<Option, Object> optionValues = new HashMap<>();
        Map<Argument, Object> argumentValues = new HashMap<>();
        boolean processOptions = true;
        int argIndex = 0;
        for (Iterator<Object> it = params.iterator(); it.hasNext(); ) {
            Object param = it.next();

            String paramValue = null;
            if (param instanceof String) {
                paramValue = (String)param;
            }
            if (param instanceof Token) {
                paramValue = param.toString();
            }

            if (processOptions
                    && paramValue != null
                    && paramValue.startsWith("-")) {
                boolean isKeyValuePair = paramValue.indexOf('=') != -1;
                String name;
                Object value = null;
                if (isKeyValuePair) {
                    name = paramValue.substring(0, paramValue.indexOf('='));
                    value = paramValue.substring(paramValue.indexOf('=') + 1);
                } else {
                    name = paramValue;
                }
                Option option = null;
                for (Option opt : options.keySet()) {
                    if (name.equals(opt.name()) || Arrays.asList(opt.aliases()).contains(name)) {
                        option = opt;
                        break;
                    }
                }
                if (option == null) {
                    throw new CommandException(commandErrorSt
                                + "undefined option " + INTENSITY_BOLD + paramValue + INTENSITY_NORMAL + "\n"
                                + "Try <command> --help' for more information.",
                                        "Undefined option: " + paramValue);
                }
                Field field = options.get(option);
                if (value == null && (field.getType() == boolean.class || field.getType() == Boolean.class)) {
                    value = Boolean.TRUE;
                }
                if (value == null && it.hasNext()) {
                    value = it.next();
                }
                if (value == null) {
                        throw new CommandException(commandErrorSt
                                + "missing value for option " + INTENSITY_BOLD + paramValue + INTENSITY_NORMAL,
                                "Missing value for option: " + paramValue
                        );
                }
                if (option.multiValued()) {
                    @SuppressWarnings("unchecked")
                    List<Object> l = (List<Object>) optionValues.get(option);
                    if (l == null) {
                        l = new ArrayList<>();
                        optionValues.put(option, l);
                    }
                    l.add(value);
                } else {
                    optionValues.put(option, value);
                }
            } else {
                processOptions = false;
                if (argIndex >= orderedArguments.size()) {
                        throw new CommandException(commandErrorSt +
                                "too many arguments specified",
                                "Too many arguments specified"
                        );
                }
                Argument argument = orderedArguments.get(argIndex);
                if (!argument.multiValued()) {
                    argIndex++;
                }
                if (argument.multiValued()) {
                    @SuppressWarnings("unchecked")
                    List<Object> l = (List<Object>) argumentValues.get(argument);
                    if (l == null) {
                        l = new ArrayList<>();
                        argumentValues.put(argument, l);
                    }
                    l.add(param);
                } else {
                    argumentValues.put(argument, param);
                }
            }
        }
        // Check required arguments / options
        for (Option option : options.keySet()) {
            if (option.required() && optionValues.get(option) == null) {
                    throw new CommandException(commandErrorSt +
                            "option " + INTENSITY_BOLD + option.name() + INTENSITY_NORMAL + " is required",
                            "Option " + option.name() + " is required"
                    );
            }
        }
        for (Argument argument : orderedArguments) {
            if (argument.required() && argumentValues.get(argument) == null) {
                    throw new CommandException(commandErrorSt +
                            "argument " + INTENSITY_BOLD + argument.name() + INTENSITY_NORMAL + " is required",
                            "Argument " + argument.name() + " is required"
                    );
            }
        }
            
        // Convert and inject values
        for (Map.Entry<Option, Object> entry : optionValues.entrySet()) {
            Field field = options.get(entry.getKey());
            Object value;
            try {
                value = convert(action, entry.getValue(), field.getGenericType());
            } catch (Exception e) {
                    throw new CommandException(commandErrorSt +
                            "unable to convert option " + INTENSITY_BOLD + entry.getKey().name() + INTENSITY_NORMAL + " with value '"
                            + entry.getValue() + "' to type " + new GenericType(field.getGenericType()).toString(),
                            "Unable to convert option " + entry.getKey().name() + " with value '"
                                    + entry.getValue() + "' to type " + new GenericType(field.getGenericType()).toString(),
                            e
                    );
            }
            field.setAccessible(true);
            field.set(action, value);
        }
        for (Map.Entry<Argument, Object> entry : argumentValues.entrySet()) {
            Field field = arguments.get(entry.getKey());
            Object value;
            try {
                value = convert(action, entry.getValue(), field.getGenericType());
            } catch (Exception e) {
                    throw new CommandException(commandErrorSt +
                            "unable to convert argument " + INTENSITY_BOLD + entry.getKey().name() + INTENSITY_NORMAL + " with value '"
                            + entry.getValue() + "' to type " + new GenericType(field.getGenericType()).toString(),
                            "Unable to convert argument " + entry.getKey().name() + " with value '"
                                    + entry.getValue() + "' to type " + new GenericType(field.getGenericType()).toString(),
                            e
                    );
            }
            field.setAccessible(true);
            field.set(action, value);
        }
        return true;
    }