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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
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 * modification, are permitted provided that the following conditions
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 *    notice, this list of conditions and the following disclaimer in the
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 *    this software without specific prior written permission.
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package jdk.internal.org.objectweb.asm.tree.analysis;

import java.util.AbstractSet;
import java.util.HashSet;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;

A set of at most two elements.
Author:Eric Bruneton
/** * A set of at most two elements. * * @author Eric Bruneton */
class SmallSet<E> extends AbstractSet<E> implements Iterator<E> { // if e1 is null, e2 must be null; otherwise e2 must be different from e1 E e1, e2; static final <T> Set<T> emptySet() { return new SmallSet<T>(null, null); } SmallSet(final E e1, final E e2) { this.e1 = e1; this.e2 = e2; } // ------------------------------------------------------------------------- // Implementation of inherited abstract methods // ------------------------------------------------------------------------- @Override public Iterator<E> iterator() { return new SmallSet<E>(e1, e2); } @Override public int size() { return e1 == null ? 0 : (e2 == null ? 1 : 2); } // ------------------------------------------------------------------------- // Implementation of the Iterator interface // ------------------------------------------------------------------------- public boolean hasNext() { return e1 != null; } public E next() { if (e1 == null) { throw new NoSuchElementException(); } E e = e1; e1 = e2; e2 = null; return e; } public void remove() { } // ------------------------------------------------------------------------- // Utility methods // ------------------------------------------------------------------------- Set<E> union(final SmallSet<E> s) { if ((s.e1 == e1 && s.e2 == e2) || (s.e1 == e2 && s.e2 == e1)) { return this; // if the two sets are equal, return this } if (s.e1 == null) { return this; // if s is empty, return this } if (e1 == null) { return s; // if this is empty, return s } if (s.e2 == null) { // s contains exactly one element if (e2 == null) { return new SmallSet<E>(e1, s.e1); // necessarily e1 != s.e1 } else if (s.e1 == e1 || s.e1 == e2) { // s is included in this return this; } } if (e2 == null) { // this contains exactly one element // if (s.e2 == null) { // cannot happen // return new SmallSet(e1, s.e1); // necessarily e1 != s.e1 // } else if (e1 == s.e1 || e1 == s.e2) { // this in included in s return s; } } // here we know that there are at least 3 distinct elements HashSet<E> r = new HashSet<E>(4); r.add(e1); if (e2 != null) { r.add(e2); } r.add(s.e1); if (s.e2 != null) { r.add(s.e2); } return r; } }