Copyright (c) 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) 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.core.internal.registry;

Essentially a map String -> String[] for small number of keys.
For Maps containing a small number of objects hashing often reduces performance.
This implementation uses two parallel arrays, one for keys, one for
values, and grows them as necessary.
/**
 * Essentially a map String -> String[] for small number of keys.
 *
 * For Maps containing a small number of objects hashing often reduces performance.
 * This implementation uses two parallel arrays, one for keys, one for
 * values, and grows them as necessary.
 */
public class DirectMap {

	final private float growthFactor;

	private String[] keyArray;
	private String[][] valueArray;
	private int size;

	public DirectMap(int initialSize, float growthFactor) {
		if (initialSize < 1)
			throw new IllegalArgumentException();
		if (growthFactor <= 0)
			throw new IllegalArgumentException();
		this.growthFactor = growthFactor;
		keyArray = new String[initialSize];
		valueArray = new String[initialSize][];
		size = 0;
	}

	public synchronized void put(String key, String[] value) {
		if (key == null)
			throw new IllegalArgumentException();
		int id = findKey(key);
		if (id != -1)
			throw new IllegalArgumentException();

		if (size >= keyArray.length) { // need to resize
			int newSize = recalcSize(keyArray.length);
			if (newSize <= size)
				newSize = size + 1;

			String[] newKeyArray = new String[newSize];
			System.arraycopy(keyArray, 0, newKeyArray, 0, keyArray.length);
			keyArray = newKeyArray;

			String[][] newValueArray = new String[newSize][];
			System.arraycopy(valueArray, 0, newValueArray, 0, valueArray.length);
			valueArray = newValueArray;
		}
		keyArray[size] = key;
		valueArray[size] = value;
		size++;
	}

	public synchronized boolean containsKey(String key) {
		if (key == null)
			throw new IllegalArgumentException();
		return (findKey(key) != -1);
	}

	public synchronized String[] get(String key) {
		if (key == null)
			throw new IllegalArgumentException();
		int id = findKey(key);
		if (id == -1)
			return null;
		return valueArray[id];
	}

	/* package */String[] getKeys() {
		return keyArray;
	}

	/* package */String[][] getValues() {
		return valueArray;
	}

	/* package */int getSzie() {
		return size;
	}

	private int recalcSize(int currentSize) {
		return (int) (currentSize * (1.0f + growthFactor));
	}

	private int findKey(String key) {
		for (int i = 0; i < keyArray.length; i++) {
			if (keyArray[i] == null)
				continue;
			if (keyArray[i].equals(key))
				return i;
		}
		return -1;
	}
}