Copyright (c) 2000, 2009 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.core.util;

HashSet of Object[]
/**
 * HashSet of Object[]
 */
public final class HashSetOfArray implements Cloneable {

	// to avoid using Enumerations, walk the individual tables skipping nulls
	public Object[][] set;

	public int elementSize; // number of elements in the table
	int threshold;

	public HashSetOfArray() {
		this(13);
	}

	public HashSetOfArray(int size) {

		this.elementSize = 0;
		this.threshold = size; // size represents the expected number of elements
		int extraRoom = (int) (size * 1.75f);
		if (this.threshold == extraRoom)
			extraRoom++;
		this.set = new Object[extraRoom][];
	}

	@Override
	public Object clone() throws CloneNotSupportedException {
		HashSetOfArray result = (HashSetOfArray) super.clone();
		result.elementSize = this.elementSize;
		result.threshold = this.threshold;

		int length = this.set.length;
		result.set = new Object[length][];
		System.arraycopy(this.set, 0, result.set, 0, length);

		return result;
	}

	public boolean contains(Object[] array) {
		int length = this.set.length;
		int index = hashCode(array) % length;
		int arrayLength = array.length;
		Object[] currentArray;
		while ((currentArray = this.set[index]) != null) {
			if (currentArray.length == arrayLength && Util.equalArraysOrNull(currentArray, array))
				return true;
			if (++index == length) {
				index = 0;
			}
		}
		return false;
	}

	private int hashCode(Object[] element) {
		return hashCode(element, element.length);
	}

	private int hashCode(Object[] element, int length) {
		int hash = 0;
		for (int i = length-1; i >= 0; i--)
			hash = Util.combineHashCodes(hash, element[i].hashCode());
		return hash & 0x7FFFFFFF;
	}

	public Object add(Object[] array) {
		int length = this.set.length;
		int index = hashCode(array) % length;
		int arrayLength = array.length;
		Object[] currentArray;
		while ((currentArray = this.set[index]) != null) {
			if (currentArray.length == arrayLength && Util.equalArraysOrNull(currentArray, array))
				return this.set[index] = array;
			if (++index == length) {
				index = 0;
			}
		}
		this.set[index] = array;

		// assumes the threshold is never equal to the size of the table
		if (++this.elementSize > this.threshold)
			rehash();
		return array;
	}

	public Object remove(Object[] array) {
		int length = this.set.length;
		int index = hashCode(array) % length;
		int arrayLength = array.length;
		Object[] currentArray;
		while ((currentArray = this.set[index]) != null) {
			if (currentArray.length == arrayLength && Util.equalArraysOrNull(currentArray, array)) {
				Object existing = this.set[index];
				this.elementSize--;
				this.set[index] = null;
				rehash();
				return existing;
			}
			if (++index == length) {
				index = 0;
			}
		}
		return null;
	}

	private void rehash() {

		HashSetOfArray newHashSet = new HashSetOfArray(this.elementSize * 2);		// double the number of expected elements
		Object[] currentArray;
		for (int i = this.set.length; --i >= 0;)
			if ((currentArray = this.set[i]) != null)
				newHashSet.add(currentArray);

		this.set = newHashSet.set;
		this.threshold = newHashSet.threshold;
	}

	public int size() {
		return this.elementSize;
	}

	@Override
	public String toString() {
		StringBuffer buffer = new StringBuffer();
		Object[] element;
		for (int i = 0, length = this.set.length; i < length; i++)
			if ((element = this.set[i]) != null) {
				buffer.append('{');
				for (int j = 0, length2 = element.length; j < length2; j++) {
					buffer.append(element[j]);
					if (j != length2-1)
						buffer.append(", "); //$NON-NLS-1$
				}
				buffer.append("}");  //$NON-NLS-1$
				if (i != length-1)
					buffer.append('\n');
			}
		return buffer.toString();
	}
}