org.sonar.duplications.index.DataUtils Maven / Gradle / Ivy
/*
* SonarQube
* Copyright (C) 2009-2017 SonarSource SA
* mailto:info AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.sonar.duplications.index;
public final class DataUtils {
public interface Sortable {
/**
* @return the number of elements.
*/
int size();
/**
* Swaps elements in positions i and j.
*/
void swap(int i, int j);
/**
* @return true if element in position i less than in position j.
*/
boolean isLess(int i, int j);
}
/**
* Value for search must be stored in position {@link Sortable#size() size}.
*/
public static int binarySearch(Sortable data) {
int value = data.size();
int lower = 0;
int upper = data.size();
while (lower < upper) {
int mid = (lower + upper) >> 1;
if (data.isLess(mid, value)) {
lower = mid + 1;
} else {
upper = mid;
}
}
return lower;
}
public static void sort(Sortable data) {
quickSort(data, 0, data.size() - 1);
}
private static void bubbleSort(Sortable data, int left, int right) {
for (int i = right; i > left; i--) {
for (int j = left; j < i; j++) {
if (data.isLess(j + 1, j)) {
data.swap(j, j + 1);
}
}
}
}
private static int partition(Sortable data, int i, int j) {
// can be selected randomly
int pivot = i + (j - i) / 2;
while (i <= j) {
while (data.isLess(i, pivot)) {
i++;
}
while (data.isLess(pivot, j)) {
j--;
}
if (i <= j) {
data.swap(i, j);
if (i == pivot) {
pivot = j;
} else if (j == pivot) {
pivot = i;
}
i++;
j--;
}
}
return i;
}
private static void quickSort(Sortable data, int low, int high) {
if (high - low < 5) {
bubbleSort(data, low, high);
return;
}
int i = partition(data, low, high);
if (low < i - 1) {
quickSort(data, low, i - 1);
}
if (i < high) {
quickSort(data, i, high);
}
}
private DataUtils() {
}
}