| /******************************************************************************* |
| * Copyright (c) 2000, 2004 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.core.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 = values.length; |
| int index = (object.hashCode() & 0x7FFFFFFF) % length; |
| Object current; |
| while ((current = values[index]) != null) { |
| if (current.equals(object)) return values[index] = object; |
| if (++index == length) index = 0; |
| } |
| values[index] = object; |
| |
| // assumes the threshold is never equal to the size of the table |
| if (++elementSize > threshold) rehash(); |
| return object; |
| } |
| |
| 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 = values.length; |
| int index = (object.hashCode() & 0x7FFFFFFF) % length; |
| Object current; |
| while ((current = values[index]) != null) { |
| if (current.equals(object)) return true; |
| if (++index == length) index = 0; |
| } |
| return false; |
| } |
| |
| public Object remove(Object object) { |
| int length = values.length; |
| int index = (object.hashCode() & 0x7FFFFFFF) % length; |
| Object current; |
| while ((current = values[index]) != null) { |
| if (current.equals(object)) { |
| elementSize--; |
| Object oldValue = values[index]; |
| values[index] = null; |
| if (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(elementSize * 2); // double the number of expected elements |
| Object current; |
| for (int i = values.length; --i >= 0;) |
| if ((current = 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 = values.length; i < l; i++) |
| if ((object = values[i]) != null) |
| s += object.toString() + "\n"; //$NON-NLS-1$ |
| return s; |
| } |
| } |