63 lines
1.8 KiB
Java
63 lines
1.8 KiB
Java
/*
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* Copyright 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.pump.util;
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import androidx.annotation.AnyThread;
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import androidx.annotation.NonNull;
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import androidx.annotation.Nullable;
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import java.util.List;
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@AnyThread
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public final class Collections {
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private Collections() { }
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@FunctionalInterface
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public interface LongKeyRetriever<T> {
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long getKey(@NonNull T value);
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}
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public static @Nullable <T> T find(@NonNull List<T> list, long key,
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@NonNull LongKeyRetriever<T> keyRetriever) {
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int index = binarySearch(list, key, keyRetriever);
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if (index >= 0) {
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return list.get(index);
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}
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return null;
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}
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public static <T> int binarySearch(@NonNull List<T> list, long key,
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@NonNull LongKeyRetriever<T> keyRetriever) {
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int lo = 0;
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int hi = list.size() - 1;
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while (lo <= hi) {
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int mid = lo + (hi - lo) / 2;
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long midKey = keyRetriever.getKey(list.get(mid));
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if (midKey < key) {
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lo = mid + 1;
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} else if (midKey > key) {
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hi = mid - 1;
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} else {
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return mid;
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}
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}
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return ~lo;
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}
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}
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