- /**
- * 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 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();
-
- /**
- * Validates the given value. Note that {@code null} is always a valid
- * value!
- *
- * @param value
- * The value to validate
- * @return {@code true} if this option does not have a validator, or the
- * validator validates this object, {@code false} otherwise
- */
- public boolean validate(T value);
-
- /**
- * Sets the current value of the option.
- *
- * @param value
- * The new value of the option
- * @throws IllegalArgumentException
- * if the value is not valid for this option
- */
- public void set(T value) throws IllegalArgumentException;
-
- }
-
- /**
- * Basic implementation of an {@link Option}.
- *
- * @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 volatile T value;
-
- /** The validator. */
- private Predicate<T> validator;
-
- /**
- * Creates a new default option.
- *
- * @param defaultValue
- * The default value of the option
- */
- public DefaultOption(T defaultValue) {
- this(defaultValue, null);
- }
-
- /**
- * Creates a new default option.
- *
- * @param defaultValue
- * The default value of the option
- * @param validator
- * The validator for value validation (may be {@code null})
- */
- public DefaultOption(T defaultValue, Predicate<T> validator) {
- this.defaultValue = defaultValue;
- this.validator = validator;
- }
-
- /**
- * {@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 boolean validate(T value) {
- return (validator == null) || (value == null) || validator.apply(value);
- }
-
- /**
- * {@inheritDoc}
- */
- @Override
- public void set(T value) {
- if ((value != null) && (validator != null) && (!validator.apply(value))) {
- throw new IllegalArgumentException("New Value (" + value + ") could not be validated.");
- }
- T oldValue = this.value;
- this.value = value;
- }
-
- }
-