| /* |
| * 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. |
| */ |
| package org.apache.cassandra.utils; |
| |
| import java.util.List; |
| |
| import com.google.common.collect.Ordering; |
| |
| import net.nicoulaj.compilecommand.annotations.Inline; |
| |
| public abstract class AsymmetricOrdering<T1, T2> extends Ordering<T1> |
| { |
| |
| public abstract int compareAsymmetric(T1 left, T2 right); |
| |
| public static enum Op |
| { |
| // maximum index < key; -1 if no such key. == CEIL - 1 |
| LOWER, |
| |
| // maximum index <= key; -1 if no such key. == HIGHER + 1 |
| FLOOR, |
| |
| // minimum index >= key; size() if no such key. == LOWER + 1 |
| CEIL, |
| |
| // minimum index > key; size() if no such key. == FLOOR - 1 |
| HIGHER |
| } |
| |
| /** |
| * @param searchIn sorted list to look in |
| * @param searchFor key to find |
| */ |
| public int binarySearchAsymmetric(List<? extends T1> searchIn, T2 searchFor, Op op) |
| { |
| final int strictnessOfLessThan = strictnessOfLessThan(op); |
| int lb = -1; |
| int ub = searchIn.size(); |
| // a[-1] ^= -infinity |
| // a[search.size()] ^= +infinity |
| |
| while (lb + 1 < ub) |
| { |
| int m = (lb + ub) / 2; |
| int c = compareAsymmetric(searchIn.get(m), searchFor); |
| |
| if (c < strictnessOfLessThan) lb = m; |
| else ub = m; |
| } |
| |
| return selectBoundary(op, lb, ub); |
| } |
| |
| @Inline |
| // this value, used as the right operand to a less than operator for the result |
| // of a compare() makes its behaviour either strict (<) or not strict (<=). |
| // a value of 1 is not strict, whereas 0 is strict |
| private static int strictnessOfLessThan(Op op) |
| { |
| switch (op) |
| { |
| case FLOOR: case HIGHER: |
| |
| // { a[lb] <= v ^ a[ub] > v } |
| return 1; |
| |
| // { a[m] > v ==> a[ub] > v ==> a[lb] <= v ^ a[ub] > v } |
| // { a[m] <= v ==> a[lb] <= v ==> a[lb] <= v ^ a[ub] > v } |
| |
| case CEIL: case LOWER: |
| |
| // { a[lb] < v ^ a[ub] >= v } |
| |
| return 0; |
| |
| // { a[m] >= v ==> a[ub] >= v ==> a[lb] < v ^ a[ub] >= v } |
| // { a[m] < v ==> a[lb] < v ==> a[lb] < v ^ a[ub] >= v } |
| } |
| throw new IllegalStateException(); |
| } |
| |
| @Inline |
| private static int selectBoundary(Op op, int lb, int ub) |
| { |
| switch (op) |
| { |
| case CEIL: |
| // { a[lb] < v ^ a[ub] >= v } |
| case HIGHER: |
| // { a[lb] <= v ^ a[ub] > v } |
| return ub; |
| case FLOOR: |
| // { a[lb] <= v ^ a[ub] > v } |
| case LOWER: |
| // { a[lb] < v ^ a[ub] >= v } |
| return lb; |
| } |
| throw new IllegalStateException(); |
| } |
| |
| private class Reversed extends AsymmetricOrdering<T1, T2> |
| { |
| public int compareAsymmetric(T1 left, T2 right) |
| { |
| return -AsymmetricOrdering.this.compareAsymmetric(left, right); |
| } |
| |
| public int compare(T1 left, T1 right) |
| { |
| return AsymmetricOrdering.this.compare(right, left); |
| } |
| |
| public AsymmetricOrdering<T1, T2> reverse() |
| { |
| return AsymmetricOrdering.this; |
| } |
| } |
| |
| public AsymmetricOrdering<T1, T2> reverse() |
| { |
| return new Reversed(); |
| } |
| } |