soot.toolkits.scalar.BinaryIdentitySet Maven / Gradle / Ivy
package soot.toolkits.scalar;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 2007 Eric Bodden
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 2.1 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
/**
* An optimized kind of {@link IdentityHashSet} that only holds two objects. (Allows for faster comparison.)
*
* @author Eric Bodden
*/
public class BinaryIdentitySet {
protected final T o1;
protected final T o2;
protected final int hashCode;
public BinaryIdentitySet(T o1, T o2) {
this.o1 = o1;
this.o2 = o2;
this.hashCode = computeHashCode();
}
@Override
public int hashCode() {
return hashCode;
}
/**
* {@inheritDoc}
*/
private int computeHashCode() {
int result = 1;
// must be commutative
result += System.identityHashCode(o1);
result += System.identityHashCode(o2);
return result;
}
/**
* {@inheritDoc}
*/
@SuppressWarnings("unchecked")
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final BinaryIdentitySet other = (BinaryIdentitySet) obj;
// must be commutative
if (o1 != other.o1 && o1 != other.o2) {
return false;
}
if (o2 != other.o2 && o2 != other.o1) {
return false;
}
return true;
}
public T getO1() {
return o1;
}
public T getO2() {
return o2;
}
public String toString() {
return "IdentityPair " + o1 + "," + o2;
}
}