+++ /dev/null
-package org.apache.lucene.util;
-
-/**
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You 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.
- */
-
-/**
- * This class was inspired by CGLIB, but provides a better
- * QuickSort algorithm without additional InsertionSort
- * at the end.
- * To use, subclass and override the four abstract methods
- * which compare and modify your data.
- * Allows custom swap so that two arrays can be sorted
- * at the same time.
- * @lucene.internal
- */
-public abstract class SorterTemplate {
-
- private static final int MERGESORT_THRESHOLD = 12;
- private static final int QUICKSORT_THRESHOLD = 7;
-
- /** Implement this method, that swaps slots {@code i} and {@code j} in your data */
- protected abstract void swap(int i, int j);
-
- /** Compares slots {@code i} and {@code j} of you data.
- * Should be implemented like <code><em>valueOf(i)</em>.compareTo(<em>valueOf(j)</em>)</code> */
- protected abstract int compare(int i, int j);
-
- /** Implement this method, that stores the value of slot {@code i} as pivot value */
- protected abstract void setPivot(int i);
-
- /** Implements the compare function for the previously stored pivot value.
- * Should be implemented like <code>pivot.compareTo(<em>valueOf(j)</em>)</code> */
- protected abstract int comparePivot(int j);
-
- /** Sorts via stable in-place InsertionSort algorithm
- *(ideal for small collections which are mostly presorted). */
- public final void insertionSort(int lo, int hi) {
- for (int i = lo + 1 ; i <= hi; i++) {
- for (int j = i; j > lo; j--) {
- if (compare(j - 1, j) > 0) {
- swap(j - 1, j);
- } else {
- break;
- }
- }
- }
- }
-
- /** Sorts via in-place, but unstable, QuickSort algorithm.
- * For small collections falls back to {@link #insertionSort(int,int)}. */
- public final void quickSort(final int lo, final int hi) {
- if (hi <= lo) return;
- // from Integer's Javadocs: ceil(log2(x)) = 32 - numberOfLeadingZeros(x - 1)
- quickSort(lo, hi, (Integer.SIZE - Integer.numberOfLeadingZeros(hi - lo)) << 1);
- }
-
- private void quickSort(int lo, int hi, int maxDepth) {
- // fall back to insertion when array has short length
- final int diff = hi - lo;
- if (diff <= QUICKSORT_THRESHOLD) {
- insertionSort(lo, hi);
- return;
- }
-
- // fall back to merge sort when recursion depth gets too big
- if (--maxDepth == 0) {
- mergeSort(lo, hi);
- return;
- }
-
- final int mid = lo + (diff >>> 1);
-
- if (compare(lo, mid) > 0) {
- swap(lo, mid);
- }
-
- if (compare(mid, hi) > 0) {
- swap(mid, hi);
- if (compare(lo, mid) > 0) {
- swap(lo, mid);
- }
- }
-
- int left = lo + 1;
- int right = hi - 1;
-
- setPivot(mid);
- for (;;) {
- while (comparePivot(right) < 0)
- --right;
-
- while (left < right && comparePivot(left) >= 0)
- ++left;
-
- if (left < right) {
- swap(left, right);
- --right;
- } else {
- break;
- }
- }
-
- quickSort(lo, left, maxDepth);
- quickSort(left + 1, hi, maxDepth);
- }
-
- /** Sorts via stable in-place MergeSort algorithm
- * For small collections falls back to {@link #insertionSort(int,int)}. */
- public final void mergeSort(int lo, int hi) {
- final int diff = hi - lo;
- if (diff <= MERGESORT_THRESHOLD) {
- insertionSort(lo, hi);
- return;
- }
-
- final int mid = lo + (diff >>> 1);
-
- mergeSort(lo, mid);
- mergeSort(mid, hi);
- merge(lo, mid, hi, mid - lo, hi - mid);
- }
-
- private void merge(int lo, int pivot, int hi, int len1, int len2) {
- if (len1 == 0 || len2 == 0) {
- return;
- }
- if (len1 + len2 == 2) {
- if (compare(pivot, lo) < 0) {
- swap(pivot, lo);
- }
- return;
- }
- int first_cut, second_cut;
- int len11, len22;
- if (len1 > len2) {
- len11 = len1 >>> 1;
- first_cut = lo + len11;
- second_cut = lower(pivot, hi, first_cut);
- len22 = second_cut - pivot;
- } else {
- len22 = len2 >>> 1;
- second_cut = pivot + len22;
- first_cut = upper(lo, pivot, second_cut);
- len11 = first_cut - lo;
- }
- rotate(first_cut, pivot, second_cut);
- final int new_mid = first_cut + len22;
- merge(lo, first_cut, new_mid, len11, len22);
- merge(new_mid, second_cut, hi, len1 - len11, len2 - len22);
- }
-
- private void rotate(int lo, int mid, int hi) {
- int lot = lo;
- int hit = mid - 1;
- while (lot < hit) {
- swap(lot++, hit--);
- }
- lot = mid; hit = hi - 1;
- while (lot < hit) {
- swap(lot++, hit--);
- }
- lot = lo; hit = hi - 1;
- while (lot < hit) {
- swap(lot++, hit--);
- }
- }
-
- private int lower(int lo, int hi, int val) {
- int len = hi - lo;
- while (len > 0) {
- final int half = len >>> 1,
- mid = lo + half;
- if (compare(mid, val) < 0) {
- lo = mid + 1;
- len = len - half -1;
- } else {
- len = half;
- }
- }
- return lo;
- }
-
- private int upper(int lo, int hi, int val) {
- int len = hi - lo;
- while (len > 0) {
- final int half = len >>> 1,
- mid = lo + half;
- if (compare(val, mid) < 0) {
- len = half;
- } else {
- lo = mid + 1;
- len = len - half -1;
- }
- }
- return lo;
- }
-
-}
fnp / pylucene.git / blobdiff