1 /* 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /* 26 * This file is available under and governed by the GNU General Public 27 * License version 2 only, as published by the Free Software Foundation. 28 * However, the following notice accompanied the original version of this 29 * file: 30 * 31 * ASM: a very small and fast Java bytecode manipulation framework 32 * Copyright (c) 2000-2011 INRIA, France Telecom 33 * All rights reserved. 34 * 35 * Redistribution and use in source and binary forms, with or without 36 * modification, are permitted provided that the following conditions 37 * are met: 38 * 1. Redistributions of source code must retain the above copyright 39 * notice, this list of conditions and the following disclaimer. 40 * 2. Redistributions in binary form must reproduce the above copyright 41 * notice, this list of conditions and the following disclaimer in the 42 * documentation and/or other materials provided with the distribution. 43 * 3. Neither the name of the copyright holders nor the names of its 44 * contributors may be used to endorse or promote products derived from 45 * this software without specific prior written permission. 46 * 47 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 48 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 50 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 51 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 52 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 53 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 54 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 55 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 56 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 57 * THE POSSIBILITY OF SUCH DAMAGE. 58 */ 59 package jdk.internal.org.objectweb.asm.tree.analysis; 60 61 import java.util.AbstractSet; 62 import java.util.HashSet; 63 import java.util.Iterator; 64 import java.util.NoSuchElementException; 65 import java.util.Objects; 66 import java.util.Set; 67 import java.util.function.Block; 68 69 /** 70 * A set of at most two elements. 71 * 72 * @author Eric Bruneton 73 */ 74 class SmallSet<E> extends AbstractSet<E> implements Iterator<E> { 75 76 // if e1 is null, e2 must be null; otherwise e2 must be different from e1 77 78 E e1, e2; 79 80 static final <T> Set<T> emptySet() { 81 return new SmallSet<T>(null, null); 82 } 83 84 SmallSet(final E e1, final E e2) { 85 this.e1 = e1; 86 this.e2 = e2; 87 } 88 89 // ------------------------------------------------------------------------- 90 // Implementation of inherited abstract methods 91 // ------------------------------------------------------------------------- 92 93 @Override 94 public Iterator<E> iterator() { 95 return new SmallSet<E>(e1, e2); 96 } 97 98 @Override 99 public int size() { 100 return e1 == null ? 0 : (e2 == null ? 1 : 2); 101 } 102 103 // ------------------------------------------------------------------------- 104 // Implementation of the Iterator interface 105 // ------------------------------------------------------------------------- 106 107 public boolean hasNext() { 108 return e1 != null; 109 } 110 111 public E next() { 112 if (e1 == null) { 113 throw new NoSuchElementException(); 114 } 115 E e = e1; 116 e1 = e2; 117 e2 = null; 118 return e; 119 } 120 121 public void remove() { 122 } 123 124 // ------------------------------------------------------------------------- 125 // Utility methods 126 // ------------------------------------------------------------------------- 127 128 Set<E> union(final SmallSet<E> s) { 129 if ((s.e1 == e1 && s.e2 == e2) || (s.e1 == e2 && s.e2 == e1)) { 130 return this; // if the two sets are equal, return this 131 } 132 if (s.e1 == null) { 133 return this; // if s is empty, return this 134 } 135 if (e1 == null) { 136 return s; // if this is empty, return s 137 } 138 if (s.e2 == null) { // s contains exactly one element 139 if (e2 == null) { 140 return new SmallSet<E>(e1, s.e1); // necessarily e1 != s.e1 141 } else if (s.e1 == e1 || s.e1 == e2) { // s is included in this 142 return this; 143 } 144 } 145 if (e2 == null) { // this contains exactly one element 146 // if (s.e2 == null) { // cannot happen 147 // return new SmallSet(e1, s.e1); // necessarily e1 != s.e1 148 // } else 149 if (e1 == s.e1 || e1 == s.e2) { // this in included in s 150 return s; 151 } 152 } 153 // here we know that there are at least 3 distinct elements 154 HashSet<E> r = new HashSet<E>(4); 155 r.add(e1); 156 if (e2 != null) { 157 r.add(e2); 158 } 159 r.add(s.e1); 160 if (s.e2 != null) { 161 r.add(s.e2); 162 } 163 return r; 164 } 165 166 @Override 167 public void forEach(Block<? super E> block) { 168 Objects.requireNonNull(block); 169 if (e1 != null) { 170 block.accept(e1); 171 if (e2 != null) { 172 block.accept(e2); 173 } 174 } 175 } 176 }