Sort.java

/*
 * Copyright (C) 2008 The Android Open Source Project
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */

package com.badlogic.gdx.utils;

import java.util.Comparator;

/**
 * Provides methods to sort arrays of objects. Sorting requires working memory and this class allows that memory to be
 * reused to avoid allocation. The sorting is otherwise identical to the Arrays.sort methods (uses timsort).<br>
 * <br>
 * Note that sorting primitive arrays with the Arrays.sort methods does not allocate memory (unless sorting large arrays
 * of char, short, or byte).
 * 
 * @author Nathan Sweet
 */
public class Sort {
	static private Sort instance;

	private TimSort timSort;
	private ComparableTimSort comparableTimSort;

	public <T> void sort(Array<T> a) {
		if (comparableTimSort == null)
			comparableTimSort = new ComparableTimSort();
		comparableTimSort.doSort(a.items, 0, a.size);
	}

	public <T> void sort(T[] a) {
		if (comparableTimSort == null)
			comparableTimSort = new ComparableTimSort();
		comparableTimSort.doSort(a, 0, a.length);
	}

	public <T> void sort(T[] a, int fromIndex, int toIndex) {
		if (comparableTimSort == null)
			comparableTimSort = new ComparableTimSort();
		comparableTimSort.doSort(a, fromIndex, toIndex);
	}

	public <T> void sort(Array<T> a, Comparator<T> c) {
		if (timSort == null)
			timSort = new TimSort();
		timSort.doSort(a.items, c, 0, a.size);
	}

	public <T> void sort(T[] a, Comparator<T> c) {
		if (timSort == null)
			timSort = new TimSort();
		timSort.doSort(a, c, 0, a.length);
	}

	public <T> void sort(T[] a, Comparator<T> c, int fromIndex, int toIndex) {
		if (timSort == null)
			timSort = new TimSort();
		timSort.doSort(a, c, fromIndex, toIndex);
	}

	/** Returns a Sort instance for convenience. Multiple threads must not use this instance at the same time. */
	static public Sort instance() {
		if (instance == null)
			instance = new Sort();
		return instance;
	}
}