Copyright (c) 2016 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) 2016 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.compiler.util;

import org.eclipse.jdt.core.compiler.CharOperation;
import org.eclipse.jdt.internal.compiler.lookup.ModuleBinding;

public final class HashtableOfModule {
	// to avoid using Enumerations, walk the individual tables skipping nulls
	public char[] keyTable[];
	public ModuleBinding valueTable[];

	public int elementSize; // number of elements in the table
	int threshold;
	public HashtableOfModule() {
		this(3); // usually not very large
	}
	public HashtableOfModule(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 char[extraRoom][];
		this.valueTable = new ModuleBinding[extraRoom];
	}
	public boolean containsKey(char[] key) {
		int length = this.keyTable.length,
				index = CharOperation.hashCode(key) % length;
		int keyLength = key.length;
		char[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && CharOperation.equals(currentKey, key))
				return true;
			if (++index == length) {
				index = 0;
			}
		}
		return false;
	}
	public ModuleBinding get(char[] key) {
		int length = this.keyTable.length,
				index = CharOperation.hashCode(key) % length;
		int keyLength = key.length;
		char[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && CharOperation.equals(currentKey, key))
				return this.valueTable[index];
			if (++index == length) {
				index = 0;
			}
		}
		return null;
	}
	public ModuleBinding put(char[] key, ModuleBinding value) {
		int length = this.keyTable.length,
				index = CharOperation.hashCode(key) % length;
		int keyLength = key.length;
		char[] currentKey;
		while ((currentKey = this.keyTable[index]) != null) {
			if (currentKey.length == keyLength && CharOperation.equals(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;
	}
	private void rehash() {
		HashtableOfModule newHashtable = new HashtableOfModule(this.elementSize * 2); // double the number of expected elements
		char[] 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() {
		String s = ""; //$NON-NLS-1$
		ModuleBinding pkg;
		for (int i = 0, length = this.valueTable.length; i < length; i++)
			if ((pkg = this.valueTable[i]) != null)
				s += pkg.toString() + "\n"; //$NON-NLS-1$
		return s;
	}
}