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;

Hashtable of {Object[] --> Object }
/**
 * Hashtable of {Object[] --> Object }
 */
public final class HashtableOfArrayToObject implements Cloneable {

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

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

	public HashtableOfArrayToObject() {
		this(13);
	}

	public HashtableOfArrayToObject(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.keyTable = new Object[extraRoom][];
		this.valueTable = new Object[extraRoom];
	}

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

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

		length = this.valueTable.length;
		result.valueTable = new Object[length];
		System.arraycopy(this.valueTable, 0, result.valueTable, 0, length);
		return result;
	}

	public boolean containsKey(Object[] key) {
		int length = this.keyTable.length;
		int index = hashCode(key) % length;
		int keyLength = key.length;
		Object[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && Util.equalArraysOrNull(currentKey, key))
				return true;
			if (++index == length) {
				index = 0;
			}
		}
		return false;
	}

	public Object get(Object[] key) {
		int length = this.keyTable.length;
		int index = hashCode(key) % length;
		int keyLength = key.length;
		Object[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && Util.equalArraysOrNull(currentKey, key))
				return this.valueTable[index];
			if (++index == length) {
				index = 0;
			}
		}
		return null;
	}

	public int getIndex(Object[] key) {
		int length = this.keyTable.length;
		int index = hashCode(key) % length;
		int keyLength = key.length;
		Object[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && Util.equalArraysOrNull(currentKey, key))
				return index;
			if (++index == length) {
				index = 0;
			}
		}
		return -1;
	}
	
	public Object[] getKey(Object[] key, int keyLength) {
		int length = this.keyTable.length;
		int index = hashCode(key, keyLength) % length;
		Object[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && Util.equalArrays(currentKey, key, keyLength))
				return currentKey;
			if (++index == length) {
				index = 0;
			}
		}
		return null;
	}

	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 put(Object[] key, Object value) {
		int length = this.keyTable.length;
		int index = hashCode(key) % length;
		int keyLength = key.length;
		Object[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && Util.equalArraysOrNull(currentKey, key))
				return this.valueTable[index] = value;
			if (++index == length) {
				index = 0;
			}
		}
		this.keyTable[index] = key;
		this.valueTable[index] = value;

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

	public Object removeKey(Object[] key) {
		int length = this.keyTable.length;
		int index = hashCode(key) % length;
		int keyLength = key.length;
		Object[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && Util.equalArraysOrNull(currentKey, key)) {
				Object value = this.valueTable[index];
				this.elementSize--;
				this.keyTable[index] = null;
				this.valueTable[index] = null;
				rehash();
				return value;
			}
			if (++index == length) {
				index = 0;
			}
		}
		return null;
	}

	private void rehash() {

		HashtableOfArrayToObject newHashtable = new HashtableOfArrayToObject(this.elementSize * 2);		// double the number of expected elements
		Object[] currentKey;
		for (int i = this.keyTable.length; --i >= 0;)
			if ((currentKey = this.keyTable[i]) != null)
				newHashtable.put(currentKey, this.valueTable[i]);

		this.keyTable = newHashtable.keyTable;
		this.valueTable = newHashtable.valueTable;
		this.threshold = newHashtable.threshold;
	}

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

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