| /******************************************************************************* |
| * Copyright (c) 2010, 2012 Oracle. All rights reserved. |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Public License v1.0, which accompanies this distribution |
| * and is available at http://www.eclipse.org/legal/epl-v10.html. |
| * |
| * Contributors: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.common.utility; |
| |
| import java.io.Serializable; |
| |
| /** |
| * Interface for a container for holding a <code>boolean</code> that cannot be |
| * changed by clients. |
| * <p> |
| * Provisional API: This interface is part of an interim API that is still |
| * under development and expected to change significantly before reaching |
| * stability. It is available at this early stage to solicit feedback from |
| * pioneering adopters on the understanding that any code that uses this API |
| * will almost certainly be broken (repeatedly) as the API evolves. |
| */ |
| public interface BooleanReference { |
| |
| /** |
| * Return the current <code>boolean</code> value. |
| */ |
| boolean getValue(); |
| |
| /** |
| * Return whether the current <code>boolean</code> value is equal to the |
| * specified value. |
| */ |
| boolean is(boolean value); |
| |
| /** |
| * Return whether the current <code>boolean</code> value is not equal to |
| * the specified value. |
| */ |
| boolean isNot(boolean value); |
| |
| /** |
| * Return whether the current <code>boolean</code> value is |
| * <code>true</code>. |
| */ |
| boolean isTrue(); |
| |
| /** |
| * Return whether the current <code>boolean</code> value is |
| * <code>false</code>. |
| */ |
| boolean isFalse(); |
| |
| |
| /** |
| * Convenience method. |
| */ |
| final class Value { |
| public static BooleanReference of(boolean value) { |
| return value ? True.instance() : False.instance(); |
| } |
| } |
| |
| |
| /** |
| * Singleton implementation of the read-only boolean reference interface |
| * whose value is always <code>true</code>. |
| */ |
| final class True |
| implements BooleanReference, Serializable |
| { |
| public static final BooleanReference INSTANCE = new True(); |
| |
| public static BooleanReference instance() { |
| return INSTANCE; |
| } |
| |
| // ensure single instance |
| private True() { |
| super(); |
| } |
| |
| public boolean getValue() { |
| return true; |
| } |
| |
| public boolean is(boolean value) { |
| return value; |
| } |
| |
| public boolean isNot(boolean value) { |
| return ! value; |
| } |
| |
| public boolean isTrue() { |
| return true; |
| } |
| |
| public boolean isFalse() { |
| return false; |
| } |
| |
| @Override |
| public String toString() { |
| return "[true]"; //$NON-NLS-1$ |
| } |
| |
| private static final long serialVersionUID = 1L; |
| private Object readResolve() { |
| // replace this object with the singleton |
| return INSTANCE; |
| } |
| } |
| |
| |
| /** |
| * Singleton implementation of the read-only boolean reference interface |
| * whose value is always <code>false</code>. |
| */ |
| final class False |
| implements BooleanReference, Serializable |
| { |
| public static final BooleanReference INSTANCE = new False(); |
| |
| public static BooleanReference instance() { |
| return INSTANCE; |
| } |
| |
| // ensure single instance |
| private False() { |
| super(); |
| } |
| |
| public boolean getValue() { |
| return false; |
| } |
| |
| public boolean is(boolean value) { |
| return ! value; |
| } |
| |
| public boolean isNot(boolean value) { |
| return value; |
| } |
| |
| public boolean isTrue() { |
| return false; |
| } |
| |
| public boolean isFalse() { |
| return false; |
| } |
| |
| @Override |
| public String toString() { |
| return "[false]"; //$NON-NLS-1$ |
| } |
| |
| private static final long serialVersionUID = 1L; |
| private Object readResolve() { |
| // replace this object with the singleton |
| return INSTANCE; |
| } |
| } |
| } |