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NonMutatingAggregationProcedure.java
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NonMutatingAggregationProcedure.java
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/*
* Copyright (c) 2020 Goldman Sachs and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v. 1.0 which accompany this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package org.eclipse.collections.impl.block.procedure;
import org.eclipse.collections.api.block.function.Function;
import org.eclipse.collections.api.block.function.Function0;
import org.eclipse.collections.api.block.function.Function2;
import org.eclipse.collections.api.block.procedure.Procedure;
import org.eclipse.collections.api.map.MutableMapIterable;
/**
* This procedure is used to apply an aggregate function like sum on a grouped set of data. The values in the
* grouping must be immutable using this procedure. An example would be using an Integer which is immutable
* vs. an AtomicInteger which is not.
*/
public final class NonMutatingAggregationProcedure<T, K, V> implements Procedure<T>
{
private static final long serialVersionUID = 1L;
private final MutableMapIterable<K, V> map;
private final Function<? super T, ? extends K> groupBy;
private final Function0<? extends V> zeroValueFactory;
private final Function2<? super V, ? super T, ? extends V> nonMutatingAggregator;
public NonMutatingAggregationProcedure(
MutableMapIterable<K, V> map,
Function<? super T, ? extends K> groupBy,
Function0<? extends V> zeroValueFactory,
Function2<? super V, ? super T, ? extends V> nonMutatingAggregator)
{
this.map = map;
this.groupBy = groupBy;
this.zeroValueFactory = zeroValueFactory;
this.nonMutatingAggregator = nonMutatingAggregator;
}
@Override
public void value(T each)
{
K key = this.groupBy.valueOf(each);
this.map.updateValueWith(key, this.zeroValueFactory, this.nonMutatingAggregator, each);
}
}