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