001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * The contents of this file are subject to the terms of either the GNU
007: * General Public License Version 2 only ("GPL") or the Common
008: * Development and Distribution License("CDDL") (collectively, the
009: * "License"). You may not use this file except in compliance with the
010: * License. You can obtain a copy of the License at
011: * http://www.netbeans.org/cddl-gplv2.html
012: * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
013: * specific language governing permissions and limitations under the
014: * License. When distributing the software, include this License Header
015: * Notice in each file and include the License file at
016: * nbbuild/licenses/CDDL-GPL-2-CP. Sun designates this
017: * particular file as subject to the "Classpath" exception as provided
018: * by Sun in the GPL Version 2 section of the License file that
019: * accompanied this code. If applicable, add the following below the
020: * License Header, with the fields enclosed by brackets [] replaced by
021: * your own identifying information:
022: * "Portions Copyrighted [year] [name of copyright owner]"
023: *
024: * Contributor(s):
025: *
026: * The Original Software is NetBeans. The Initial Developer of the Original
027: * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
028: * Microsystems, Inc. All Rights Reserved.
029: *
030: * If you wish your version of this file to be governed by only the CDDL
031: * or only the GPL Version 2, indicate your decision by adding
032: * "[Contributor] elects to include this software in this distribution
033: * under the [CDDL or GPL Version 2] license." If you do not indicate a
034: * single choice of license, a recipient has the option to distribute
035: * your version of this file under either the CDDL, the GPL Version 2 or
036: * to extend the choice of license to its licensees as provided above.
037: * However, if you add GPL Version 2 code and therefore, elected the GPL
038: * Version 2 license, then the option applies only if the new code is
039: * made subject to such option by the copyright holder.
040: */
041:
042: package org.openide.util;
043:
044: import java.io.Serializable;
045:
046: /**
047: * A union type which can contain one of two kinds of objects.
048: * {@link Object#equals} and {@link Object#hashCode} treat this as a container,
049: * not identical to the contained object, but the identity is based on the contained
050: * object. The union is serialiable if its contained object is.
051: * {@link Object#toString} delegates to the contained object.
052: * @author Jesse Glick
053: * @since org.openide.util 7.1
054: */
055: public abstract class Union2<First, Second> implements Cloneable,
056: Serializable {
057:
058: private static final long serialVersionUID = 1L;
059:
060: Union2() {
061: }
062:
063: /**
064: * Retrieve the union member of the first type.
065: * @return the object of the first type
066: * @throws IllegalArgumentException if the union really contains the second type
067: */
068: public abstract First first() throws IllegalArgumentException;
069:
070: /**
071: * Retrieve the union member of the second type.
072: * @return the object of the second type
073: * @throws IllegalArgumentException if the union really contains the first type
074: */
075: public abstract Second second() throws IllegalArgumentException;
076:
077: /**
078: * Check if the union contains the first type.
079: * @return true if it contains the first type, false if it contains the second type
080: */
081: public abstract boolean hasFirst();
082:
083: /**
084: * Check if the union contains the second type.
085: * @return true if it contains the second type, false if it contains the first type
086: */
087: public abstract boolean hasSecond();
088:
089: @Override
090: public abstract Union2<First, Second> clone();
091:
092: /**
093: * Construct a union based on the first type.
094: * @param first an object of the first type
095: * @return a union containing that object
096: */
097: public static <First, Second> Union2<First, Second> createFirst(
098: First first) {
099: return new Union2First<First, Second>(first);
100: }
101:
102: /**
103: * Construct a union based on the second type.
104: * @param second an object of the second type
105: * @return a union containing that object
106: */
107: public static <First, Second> Union2<First, Second> createSecond(
108: Second second) {
109: return new Union2Second<First, Second>(second);
110: }
111:
112: private static final class Union2First<First, Second> extends
113: Union2<First, Second> {
114:
115: private static final long serialVersionUID = 1L;
116:
117: private final First first;
118:
119: public Union2First(First first) {
120: this .first = first;
121: }
122:
123: @Override
124: public First first() throws IllegalArgumentException {
125: return first;
126: }
127:
128: @Override
129: public Second second() throws IllegalArgumentException {
130: throw new IllegalArgumentException();
131: }
132:
133: @Override
134: public boolean hasFirst() {
135: return true;
136: }
137:
138: @Override
139: public boolean hasSecond() {
140: return false;
141: }
142:
143: @Override
144: public String toString() {
145: return String.valueOf(first);
146: }
147:
148: @Override
149: public boolean equals(Object obj) {
150: return (obj instanceof Union2First)
151: && first.equals(((Union2First) obj).first);
152: }
153:
154: @Override
155: public int hashCode() {
156: return first.hashCode();
157: }
158:
159: @Override
160: public Union2<First, Second> clone() {
161: return createFirst(first);
162: }
163:
164: }
165:
166: private static final class Union2Second<First, Second> extends
167: Union2<First, Second> {
168:
169: private static final long serialVersionUID = 1L;
170:
171: private final Second second;
172:
173: public Union2Second(Second second) {
174: this .second = second;
175: }
176:
177: @Override
178: public First first() throws IllegalArgumentException {
179: throw new IllegalArgumentException();
180: }
181:
182: @Override
183: public Second second() throws IllegalArgumentException {
184: return second;
185: }
186:
187: @Override
188: public boolean hasFirst() {
189: return false;
190: }
191:
192: @Override
193: public boolean hasSecond() {
194: return true;
195: }
196:
197: @Override
198: public String toString() {
199: return String.valueOf(second);
200: }
201:
202: @Override
203: public boolean equals(Object obj) {
204: return (obj instanceof Union2Second)
205: && second.equals(((Union2Second) obj).second);
206: }
207:
208: @Override
209: public int hashCode() {
210: return second.hashCode();
211: }
212:
213: @Override
214: public Union2<First, Second> clone() {
215: return createSecond(second);
216: }
217:
218: }
219:
220: }
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