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/*
* SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
*
* SPDX-License-Identifier: EPL-2.0
*/
package tools.refinery.store.query.term;
import java.util.Comparator;
import java.util.Objects;
import java.util.SortedMap;
import java.util.TreeMap;
public class ExtremeValueAggregator<T> implements StatefulAggregator<T, T> {
private final Class<T> type;
private final T emptyResult;
private final Comparator<T> comparator;
public ExtremeValueAggregator(Class<T> type, T emptyResult) {
this(type, emptyResult, null);
}
public ExtremeValueAggregator(Class<T> type, T emptyResult, Comparator<T> comparator) {
this.type = type;
this.emptyResult = emptyResult;
this.comparator = comparator;
}
@Override
public Class<T> getResultType() {
return getInputType();
}
@Override
public Class<T> getInputType() {
return type;
}
@Override
public StatefulAggregate<T, T> createEmptyAggregate() {
return new Aggregate();
}
@Override
public T getEmptyResult() {
return emptyResult;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ExtremeValueAggregator<?> that = (ExtremeValueAggregator<?>) o;
return type.equals(that.type) && Objects.equals(emptyResult, that.emptyResult) && Objects.equals(comparator,
that.comparator);
}
@Override
public int hashCode() {
return Objects.hash(type, emptyResult, comparator);
}
private class Aggregate implements StatefulAggregate<T, T> {
private final SortedMap<T, Integer> values;
private Aggregate() {
values = new TreeMap<>(comparator);
}
private Aggregate(Aggregate other) {
values = new TreeMap<>(other.values);
}
@Override
public void add(T value) {
values.compute(value, (ignoredValue, currentCount) -> currentCount == null ? 1 : currentCount + 1);
}
@Override
public void remove(T value) {
values.compute(value, (theValue, currentCount) -> {
if (currentCount == null || currentCount <= 0) {
throw new IllegalStateException("Invalid count %d for value %s".formatted(currentCount, theValue));
}
return currentCount.equals(1) ? null : currentCount - 1;
});
}
@Override
public T getResult() {
return isEmpty() ? emptyResult : values.firstKey();
}
@Override
public boolean isEmpty() {
return values.isEmpty();
}
@Override
public StatefulAggregate<T, T> deepCopy() {
return new Aggregate(this);
}
@Override
public boolean contains(T value) {
return StatefulAggregate.super.contains(value);
}
}
}
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