Copyright (c) 2000, 2006 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, 2006 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.core.internal.registry;

import java.io.*;

Hashtable of {String --> int }
/**
 * Hashtable of {String --> int }
 */
public final class HashtableOfStringAndInt implements Cloneable {
	public static final int MISSING_ELEMENT = Integer.MIN_VALUE;

	// to avoid using Enumerations, walk the individual tables skipping nulls
	private String keyTable[];
	private int valueTable[];

	private int elementSize; // number of elements in the table
	private int threshold;
	private static final float GROWTH_FACTOR = 1.33f;

	public HashtableOfStringAndInt() {
		this(13);
	}

	public HashtableOfStringAndInt(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 String[extraRoom];
		this.valueTable = new int[extraRoom];
	}

	@Override
	public Object clone() throws CloneNotSupportedException {
		throw new CloneNotSupportedException();
		//		HashtableOfStringAndInt result = (HashtableOfStringAndInt) super.clone();
		//		result.elementSize = this.elementSize;
		//		result.threshold = this.threshold;
		//
		//		int length = this.keyTable.length;
		//		result.keyTable = new char[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(String key) {
		int index = (key.hashCode() & 0x7FFFFFFF) % valueTable.length;
		int keyLength = key.length();
		String currentKey;
		while ((currentKey = keyTable[index]) != null) {
			if (currentKey.length() == keyLength && currentKey.equals(key))
				return true;
			index = (index + 1) % keyTable.length;
		}
		return false;
	}

	public int get(String key) {
		int index = (key.hashCode() & 0x7FFFFFFF) % valueTable.length;
		int keyLength = key.length();
		String currentKey;
		while ((currentKey = keyTable[index]) != null) {
			if (currentKey.length() == keyLength && currentKey.equals(key))
				return valueTable[index];
			index = (index + 1) % keyTable.length;
		}
		return MISSING_ELEMENT;
	}

	public int put(String key, int value) {
		int index = (key.hashCode() & 0x7FFFFFFF) % valueTable.length;
		int keyLength = key.length();
		String currentKey;
		while ((currentKey = keyTable[index]) != null) {
			if (currentKey.length() == keyLength && currentKey.equals(key))
				return valueTable[index] = value;
			index = (index + 1) % keyTable.length;
		}
		keyTable[index] = key;
		valueTable[index] = value;

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

	public int removeKey(String key) {
		int index = (key.hashCode() & 0x7FFFFFFF) % valueTable.length;
		int keyLength = key.length();
		String currentKey;
		while ((currentKey = keyTable[index]) != null) {
			if (currentKey.length() == keyLength && currentKey.equals(key)) {
				int value = valueTable[index];
				elementSize--;
				keyTable[index] = null;
				valueTable[index] = MISSING_ELEMENT;
				rehash();
				return value;
			}
			index = (index + 1) % keyTable.length;
		}
		return MISSING_ELEMENT;
	}

	private void rehash() {
		HashtableOfStringAndInt newHashtable = new HashtableOfStringAndInt((int) (elementSize * GROWTH_FACTOR));
		String currentKey;
		for (int i = keyTable.length; --i >= 0;)
			if ((currentKey = keyTable[i]) != null)
				newHashtable.put(currentKey, valueTable[i]);

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

	public int size() {
		return elementSize;
	}

	@Override
	public String toString() {
		String s = ""; //$NON-NLS-1$
		int object;
		for (int i = 0, length = valueTable.length; i < length; i++)
			if ((object = valueTable[i]) != MISSING_ELEMENT)
				s += new String(keyTable[i]) + " -> " + object + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
		return s;
	}

	public int[] getValues() {
		int keyTableLength = keyTable.length;
		int[] result = new int[size()];
		int j = 0;
		for (int i = 0; i < keyTableLength; i++) {
			if (keyTable[i] != null)
				result[j++] = valueTable[i];
		}
		return result;
	}

	public void save(DataOutputStream out) throws IOException {
		out.writeInt(elementSize);
		int tableSize = keyTable.length;
		out.writeInt(tableSize);
		out.writeInt(threshold);
		for (int i = 0; i < tableSize; i++) {
			writeStringOrNull(keyTable[i], out);
			out.writeInt(valueTable[i]);
		}
	}

	
Filtered save: outputs only elements with values not in the excluded list.
/**
	 * Filtered save: outputs only elements with values not in the excluded list.
	 */
	public void save(DataOutputStream out, RegistryObjectManager objectManager) throws IOException {
		HashtableOfStringAndInt filteredHashtable = new HashtableOfStringAndInt((int) (elementSize * GROWTH_FACTOR));
		String currentKey;
		for (int i = keyTable.length; --i >= 0;)
			if ((currentKey = keyTable[i]) != null && objectManager.shouldPersist(valueTable[i]))
				filteredHashtable.put(currentKey, valueTable[i]);
		filteredHashtable.save(out);
	}

	public void load(DataInputStream in) throws IOException {
		elementSize = in.readInt();
		int tableSize = in.readInt();
		threshold = in.readInt();
		boolean fastMode = true;
		if (((double) tableSize / elementSize) < GROWTH_FACTOR) {
			keyTable = new String[(int) (elementSize * GROWTH_FACTOR)];
			valueTable = new int[(int) (elementSize * GROWTH_FACTOR)];
			elementSize = 0;
			fastMode = false;
		} else {
			keyTable = new String[tableSize];
			valueTable = new int[tableSize];
		}
		for (int i = 0; i < tableSize; i++) {
			String key = readStringOrNull(in);
			int value = in.readInt();
			if (fastMode) {
				keyTable[i] = key;
				valueTable[i] = value;
			} else {
				if (key != null)
					put(key, value);
			}
		}
	}

	private static final byte NULL = 0;
	private static final byte OBJECT = 1;

	private void writeStringOrNull(String string, DataOutputStream out) throws IOException {
		if (string == null)
			out.writeByte(NULL);
		else {
			out.writeByte(OBJECT);
			out.writeUTF(string);
		}
	}

	private String readStringOrNull(DataInputStream in) throws IOException {
		byte type = in.readByte();
		if (type == NULL)
			return null;
		return in.readUTF();
	}

}