scouter.org.objectweb.asm.tree.analysis.SmallSet Maven / Gradle / Ivy
/***
* ASM: a very small and fast Java bytecode manipulation framework
* Copyright (c) 2000-2011 INRIA, France Telecom
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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package scouter.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
*/
class SmallSet extends AbstractSet implements Iterator {
// if e1 is null, e2 must be null; otherwise e2 must be different from e1
E e1, e2;
static final Set emptySet() {
return new SmallSet(null, null);
}
SmallSet(final E e1, final E e2) {
this.e1 = e1;
this.e2 = e2;
}
// -------------------------------------------------------------------------
// Implementation of inherited abstract methods
// -------------------------------------------------------------------------
@Override
public Iterator iterator() {
return new SmallSet(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 union(final SmallSet 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(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 r = new HashSet(4);
r.add(e1);
if (e2 != null) {
r.add(e2);
}
r.add(s.e1);
if (s.e2 != null) {
r.add(s.e2);
}
return r;
}
}