/*
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* Copyright (C) 2019 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.server.wifi.util;
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import android.util.ArrayMap;
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import java.lang.reflect.Array;
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import java.util.Iterator;
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import java.util.Map;
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/**
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* Counts occurrences of keys of type K, where K is a custom key class. This is most commonly used
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* for counting occurrences of composite keys.
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* @param <K> Custom key type K must override {@link Object#hashCode()},
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* {@link Object#equals(Object)}, and {@link Object#toString()}. These methods can be auto-generated
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* by IntelliJ by right clicking inside your class and clicking "Generate...".
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*/
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public class ObjectCounter<K> implements Iterable<Map.Entry<K, Integer>> {
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private ArrayMap<K, Integer> mCounter;
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public ObjectCounter() {
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mCounter = new ArrayMap<>();
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}
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/**
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* Removes all keys and counts from this counter.
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*/
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public void clear() {
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mCounter.clear();
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}
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/**
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* Returns the number of keys in this counter.
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*/
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public int size() {
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return mCounter.size();
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}
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/**
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* Gets the number of occurrences of a key
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*/
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public int getCount(K key) {
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return mCounter.getOrDefault(key, 0);
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}
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/**
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* Increments the count of a key by 1.
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*/
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public void increment(K key) {
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add(key, 1);
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}
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/**
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* Increments the count of a key by <code>count</code>.
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*/
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public void add(K key, int count) {
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int curCount = getCount(key);
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mCounter.put(key, curCount + count);
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}
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/**
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* Returns a string representation of this counter object suitable for dump(). Note that the
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* type K must have an overridden implementation of {@link Object#toString()}.
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*/
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@Override
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public String toString() {
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return mCounter.toString();
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}
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/**
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* Iterates over all (key, count) pairs.
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*/
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@Override
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public Iterator<Map.Entry<K, Integer>> iterator() {
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return mCounter.entrySet().iterator();
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}
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/**
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* Converter function that converts a single (key, count) pair to a Protobuf object.
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* @param <I> The type of the key.
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* @param <O> The type of the Protobuf output.
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*/
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public interface ProtobufConverter<I, O> {
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/**
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* Converter function that converts a single (key, count) pair to a Protobuf object.
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* @param key the key that we are counting occurrences for
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* @param count the number of occurrences for this key
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* @return the Protobuf output
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*/
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O convert(I key, int count);
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}
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/**
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* Converts this object to a custom Protobuf representation.
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* @param protoClass the class object for the Protobuf type.
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* @param converter a conversion function.
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* @param <T> the type of the Protobuf output.
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* @return an array of Protobuf representation of buckets generated by the converter function.
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*/
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public <T> T[] toProto(Class<T> protoClass, ProtobufConverter<K, T> converter) {
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@SuppressWarnings("unchecked")
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T[] output = (T[]) Array.newInstance(protoClass, size());
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int i = 0;
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for (Map.Entry<K, Integer> entry : this) {
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output[i] = converter.convert(entry.getKey(), entry.getValue());
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i++;
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}
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return output;
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}
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}
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