rev 6218 : imported patch smallset

   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.Set;

  66 
  67 /**
  68  * A set of at most two elements.
  69  *
  70  * @author Eric Bruneton
  71  */
  72 class SmallSet<E> extends AbstractSet<E> implements Iterator<E> {
  73 
  74     // if e1 is null, e2 must be null; otherwise e2 must be different from e1
  75 
  76     E e1, e2;
  77 
  78     static final <T> Set<T> emptySet() {
  79         return new SmallSet<T>(null, null);
  80     }
  81 
  82     SmallSet(final E e1, final E e2) {
  83         this.e1 = e1;
  84         this.e2 = e2;
  85     }
  86 
  87     // -------------------------------------------------------------------------
  88     // Implementation of inherited abstract methods
  89     // -------------------------------------------------------------------------
  90 
  91     @Override
  92     public Iterator<E> iterator() {
  93         return new SmallSet<E>(e1, e2);
  94     }
  95 
  96     @Override
  97     public int size() {
  98         return e1 == null ? 0 : (e2 == null ? 1 : 2);
  99     }
 100 
 101     // -------------------------------------------------------------------------
 102     // Implementation of the Iterator interface
 103     // -------------------------------------------------------------------------
 104 
 105     public boolean hasNext() {
 106         return e1 != null;
 107     }
 108 
 109     public E next() {
 110         if (e1 == null) {
 111             throw new NoSuchElementException();
 112         }
 113         E e = e1;
 114         e1 = e2;
 115         e2 = null;
 116         return e;
 117     }
 118 
 119     public void remove() {
 120     }
 121 
 122     // -------------------------------------------------------------------------
 123     // Utility methods
 124     // -------------------------------------------------------------------------
 125 
 126     Set<E> union(final SmallSet<E> s) {
 127         if ((s.e1 == e1 && s.e2 == e2) || (s.e1 == e2 && s.e2 == e1)) {
 128             return this; // if the two sets are equal, return this
 129         }
 130         if (s.e1 == null) {
 131             return this; // if s is empty, return this
 132         }
 133         if (e1 == null) {
 134             return s; // if this is empty, return s
 135         }
 136         if (s.e2 == null) { // s contains exactly one element
 137             if (e2 == null) {
 138                 return new SmallSet<E>(e1, s.e1); // necessarily e1 != s.e1
 139             } else if (s.e1 == e1 || s.e1 == e2) { // s is included in this
 140                 return this;
 141             }
 142         }
 143         if (e2 == null) { // this contains exactly one element
 144             // if (s.e2 == null) { // cannot happen
 145             // return new SmallSet(e1, s.e1); // necessarily e1 != s.e1
 146             // } else
 147             if (e1 == s.e1 || e1 == s.e2) { // this in included in s
 148                 return s;
 149             }
 150         }
 151         // here we know that there are at least 3 distinct elements
 152         HashSet<E> r = new HashSet<E>(4);
 153         r.add(e1);
 154         if (e2 != null) {
 155             r.add(e2);
 156         }
 157         r.add(s.e1);
 158         if (s.e2 != null) {
 159             r.add(s.e2);
 160         }
 161         return r;











 162     }
 163 }
--- EOF ---