/*
* Copyright 2012 Goldman Sachs.
*
* 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.gs.collections.impl.block.procedure;
import com.gs.collections.api.block.function.Function;
import com.gs.collections.api.block.function.Function0;
import com.gs.collections.api.block.procedure.Procedure;
import com.gs.collections.api.block.procedure.Procedure2;
import com.gs.collections.api.map.MutableMap;
/**
* This procedure is used to apply an aggregate function like sum on a grouped set of data. The values in the
* grouping must be mutable using this procedure. An example would be using an AtomicInteger which can be mutated
* vs. an Integer which cannot.
*/
public final class MutatingAggregationProcedure<T, K, V> implements Procedure<T>
{
private static final long serialVersionUID = 1L;
private final MutableMap<K, V> map;
private final Function<? super T, ? extends K> groupBy;
private final Function0<? extends V> zeroValueFactory;
private final Procedure2<? super V, ? super T> mutatingAggregator;
public MutatingAggregationProcedure(MutableMap<K, V> map, Function<? super T, ? extends K> groupBy, Function0<? extends V> zeroValueFactory, Procedure2<? super V, ? super T> mutatingAggregator)
{
this.map = map;
this.groupBy = groupBy;
this.zeroValueFactory = zeroValueFactory;
this.mutatingAggregator = mutatingAggregator;
}
public void value(T each)
{
K key = this.groupBy.valueOf(each);
V value = this.map.getIfAbsentPut(key, this.zeroValueFactory);
this.mutatingAggregator.value(value, each);
}
}