org.eclipse.jdt.internal.compiler.util.SimpleSet Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2000, 2009 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.util;
/**
* A simple lookup table is a non-synchronized Hashtable, whose keys
* and values are Objects. It also uses linear probing to resolve collisions
* rather than a linked list of hash table entries.
*/
public final class SimpleSet implements Cloneable {
// to avoid using Enumerations, walk the individual values skipping nulls
public Object[] values;
public int elementSize; // number of elements in the table
public int threshold;
public SimpleSet() {
this(13);
}
public SimpleSet(int size) {
if (size < 3) size = 3;
this.elementSize = 0;
this.threshold = size + 1; // size is the expected number of elements
this.values = new Object[2 * size + 1];
}
public Object add(Object object) {
int length = this.values.length;
int index = (object.hashCode() & 0x7FFFFFFF) % length;
Object current;
while ((current = this.values[index]) != null) {
if (current.equals(object)) return this.values[index] = object;
if (++index == length) index = 0;
}
this.values[index] = object;
// assumes the threshold is never equal to the size of the table
if (++this.elementSize > this.threshold) rehash();
return object;
}
public Object addIfNotIncluded(Object object) {
int length = this.values.length;
int index = (object.hashCode() & 0x7FFFFFFF) % length;
Object current;
while ((current = this.values[index]) != null) {
if (current.equals(object)) return null; // already existed
if (++index == length) index = 0;
}
this.values[index] = object;
// assumes the threshold is never equal to the size of the table
if (++this.elementSize > this.threshold) rehash();
return object;
}
public void asArray(Object[] copy) {
if (this.elementSize != copy.length)
throw new IllegalArgumentException();
int index = this.elementSize;
for (int i = 0, l = this.values.length; i < l && index > 0; i++)
if (this.values[i] != null)
copy[--index] = this.values[i];
}
public void clear() {
for (int i = this.values.length; --i >= 0;)
this.values[i] = null;
this.elementSize = 0;
}
public Object clone() throws CloneNotSupportedException {
SimpleSet result = (SimpleSet) super.clone();
result.elementSize = this.elementSize;
result.threshold = this.threshold;
int length = this.values.length;
result.values = new Object[length];
System.arraycopy(this.values, 0, result.values, 0, length);
return result;
}
public boolean includes(Object object) {
int length = this.values.length;
int index = (object.hashCode() & 0x7FFFFFFF) % length;
Object current;
while ((current = this.values[index]) != null) {
if (current.equals(object)) return true;
if (++index == length) index = 0;
}
return false;
}
public Object remove(Object object) {
int length = this.values.length;
int index = (object.hashCode() & 0x7FFFFFFF) % length;
Object current;
while ((current = this.values[index]) != null) {
if (current.equals(object)) {
this.elementSize--;
Object oldValue = this.values[index];
this.values[index] = null;
if (this.values[index + 1 == length ? 0 : index + 1] != null)
rehash(); // only needed if a possible collision existed
return oldValue;
}
if (++index == length) index = 0;
}
return null;
}
private void rehash() {
SimpleSet newSet = new SimpleSet(this.elementSize * 2); // double the number of expected elements
Object current;
for (int i = this.values.length; --i >= 0;)
if ((current = this.values[i]) != null)
newSet.add(current);
this.values = newSet.values;
this.elementSize = newSet.elementSize;
this.threshold = newSet.threshold;
}
public String toString() {
String s = ""; //$NON-NLS-1$
Object object;
for (int i = 0, l = this.values.length; i < l; i++)
if ((object = this.values[i]) != null)
s += object.toString() + "\n"; //$NON-NLS-1$
return s;
}
}