soot.util.IdentityHashSet Maven / Gradle / Ivy
/* Soot - a J*va Optimization Framework
* Copyright (C) 2004 Ondrej Lhotak
*
* This library 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 library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
package soot.util;
import java.util.AbstractSet;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.Set;
/**
* Implements a hashset with comparison over identity.
* @author Eric Bodden
*/
public class IdentityHashSet extends AbstractSet implements Set {
protected IdentityHashMap delegate;
/**
* Creates a new, empty IdentityHashSet.
*/
@SuppressWarnings("unchecked")
public IdentityHashSet() {
delegate = new IdentityHashMap();
}
/**
* {@inheritDoc}
*/
public int size() {
return delegate.size();
}
/**
* {@inheritDoc}
*/
public boolean contains(Object o) {
return delegate.containsKey(o);
}
/**
* {@inheritDoc}
*/
public Iterator iterator() {
return delegate.keySet().iterator();
}
/**
* {@inheritDoc}
*/
public boolean add(E o) {
return delegate.put(o, o)==null;
}
/**
* {@inheritDoc}
*/
public boolean remove(Object o) {
return delegate.remove(o)!=null;
}
/**
* {@inheritDoc}
*/
public void clear() {
delegate.entrySet().clear();
}
/*
* Equality based on identity.
*/
public int hashCode() {
final int PRIME = 31;
int result = 1;
result = PRIME * result + ((delegate == null) ? 0 : delegate.hashCode());
return result;
}
/*
* Hash code based on identity.
*/
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
final IdentityHashSet other = (IdentityHashSet) obj;
if (delegate == null) {
if (other.delegate != null)
return false;
} else if (!delegate.equals(other.delegate))
return false;
return true;
}
/**
* {@inheritDoc}
*/
public String toString() {
return delegate.keySet().toString();
}
}