1/*
2 * Copyright 2013, Google Inc.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met:
8 *
9 *     * Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *     * Redistributions in binary form must reproduce the above
12 * copyright notice, this list of conditions and the following disclaimer
13 * in the documentation and/or other materials provided with the
14 * distribution.
15 *     * Neither the name of Google Inc. nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 */
31
32package org.jf.util;
33
34import java.util.Comparator;
35import java.util.List;
36
37public class LinearSearch {
38    /**
39     * Performs a linear search in a sorted list for key, starting at initialGuess
40     *
41     * @param list The sorted list to search
42     * @param comparator The comparator to use
43     * @param key The key to search for
44     * @param initialGuess An initial guess of the location.
45     * @return If found, the index of the item. If not found, -return + 1 is the index at which the item would be
46     *         inserted
47     */
48    public static <T> int linearSearch(List<? extends T> list, Comparator<T> comparator, T key, int initialGuess) {
49        int guess = initialGuess;
50        if (guess >= list.size()) {
51            guess = list.size()-1;
52        }
53        int comparison = comparator.compare(list.get(guess), key);
54        if (comparison == 0) {
55            return guess;
56        }
57        if (comparison < 0) {
58            guess++;
59            while (guess < list.size()) {
60                comparison = comparator.compare(list.get(guess), key);
61                if (comparison == 0) {
62                    return guess;
63                }
64                if (comparison > 0) {
65                    return -(guess+1);
66                }
67                guess++;
68            }
69            return -(list.size()+1);
70        } else {
71            guess--;
72            while (guess >= 0) {
73                comparison = comparator.compare(list.get(guess), key);
74                if (comparison == 0) {
75                    return guess;
76                }
77                if (comparison < 0) {
78                    return -(guess+2);
79                }
80                guess--;
81            }
82            return -1;
83        }
84    }
85}
86