- /**
- * Contains current and default value of an option.
- *
- * @param <T>
- * The type of the option
- * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
- */
- public static interface Option<T> {
-
- /**
- * Returns the default value of the option.
- *
- * @return The default value of the option
- */
- public T getDefault();
-
- /**
- * Returns the current value of the option. If the current value is not
- * set (usually {@code null}), the default value is returned.
- *
- * @return The current value of the option
- */
- public T get();
-
- /**
- * Returns the real value of the option. This will also return an unset
- * value (usually {@code null})!
- *
- * @return The real value of the option
- */
- public T getReal();
-
- /**
- * Sets the current value of the option.
- *
- * @param value
- * The new value of the option
- */
- public void set(T value);
-
- }
-
- /**
- * Interface for objects that want to be notified when an option changes its
- * value.
- *
- * @param <T>
- * The type of the option
- * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
- */
- public static interface OptionWatcher<T> {
-
- /**
- * Notifies an object that an option has been changed.
- *
- * @param option
- * The option that has changed
- * @param oldValue
- * The old value of the option
- * @param newValue
- * The new value of the option
- */
- public void optionChanged(Option<T> option, T oldValue, T newValue);
-
- }
-
- /**
- * Basic implementation of an {@link Option} that notifies an
- * {@link OptionWatcher} if the value changes.
- *
- * @param <T>
- * The type of the option
- * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
- */
- public static class DefaultOption<T> implements Option<T> {
-
- /** The default value. */
- private final T defaultValue;
-
- /** The current value. */
- private T value;
-
- /** The option watcher. */
- private final List<OptionWatcher<T>> optionWatchers = new ArrayList<OptionWatcher<T>>();
-
- /**
- * Creates a new default option.
- *
- * @param defaultValue
- * The default value of the option
- * @param optionWatchers
- * The option watchers
- */
- public DefaultOption(T defaultValue, OptionWatcher<T>... optionWatchers) {
- this.defaultValue = defaultValue;
- this.optionWatchers.addAll(Arrays.asList(optionWatchers));
- }
-
- /**
- * {@inheritDoc}
- */
- @Override
- public T getDefault() {
- return defaultValue;
- }
-
- /**
- * {@inheritDoc}
- */
- @Override
- public T get() {
- return (value != null) ? value : defaultValue;
- }
-
- /**
- * Returns the real value of the option. This will also return an unset
- * value (usually {@code null})!
- *
- * @return The real value of the option
- */
- @Override
- public T getReal() {
- return value;
- }
-
- /**
- * {@inheritDoc}
- */
- @Override
- public void set(T value) {
- T oldValue = this.value;
- this.value = value;
- if (!get().equals(oldValue)) {
- for (OptionWatcher<T> optionWatcher : optionWatchers) {
- optionWatcher.optionChanged(this, oldValue, get());
- }
- }
- }
-
- }
-