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Jodd Core tools and huge number of utilities.
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// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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package jodd.util;

/**
 * Abstract binary search. It is more abstract then {@link jodd.util.BinarySearch}.
 */
public abstract class BinarySearchBase {

	/**
	 * Compares element at index position with the target.
	 */
	protected abstract int compare(int index);

	// ---------------------------------------------------------------- find

	/**
	 * Finds index of given element in inclusive index range. Returns negative
	 * value if element is not found.
	 */
	public int find(int low, int high) {
		while (low <= high) {
			int mid = (low + high) >>> 1;
			int delta = compare(mid);

			if (delta < 0) {
				low = mid + 1;
			} else if (delta > 0) {
				high = mid - 1;
			} else {
				return mid;
			}
		}
		// not found
		return -(low + 1);
	}

	// ---------------------------------------------------------------- first

	/**
	 * Finds very first index of given element in inclusive index range. Returns negative
	 * value if element is not found.
	 */
	public int findFirst(int low, int high) {

		int ndx = -1;
		while (low <= high) {
			int mid = (low + high) >>> 1;
			int delta = compare(mid);

			if (delta < 0) {
				low = mid + 1;
			} else {
				if (delta == 0) {
					ndx = mid;
				}
				high = mid - 1;
			}
		}

		if (ndx == -1) {
			return -(low + 1);
		}

		return ndx;
	}

	// ---------------------------------------------------------------- last

	/**
	 * Finds very last index of given element in inclusive index range. Returns negative
	 * value if element is not found.
	 */
	public int findLast(int low, int high) {
		int ndx = -1;
		while (low <= high) {
			int mid = (low + high) >>> 1;
			int delta = compare(mid);

			if (delta > 0) {
				high = mid - 1;
			} else {
				if (delta == 0) {
					ndx = mid;
				}
				low = mid + 1;
			}
		}

		if (ndx == -1) {
			return -(low + 1);
		}

		return ndx;
	}

}