/*
* Copyright (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com
* The software in this package is published under the terms of the CPAL v1.0
* license, a copy of which has been included with this distribution in the
* LICENSE.txt file.
*/
package org.mule.runtime.core.util.collection;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import java.util.Map;
import java.util.Set;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;
/**
* {@link Collector} which returns an {@link ImmutableMap}
*
* @param <T> the generic type of input elements
* @param <K> the output map's key type
* @param <V> the output map's values type
* @since 4.0
*/
public class ImmutableMapCollector<T, K, V> implements Collector<T, ImmutableMap.Builder<K, V>, Map<K, V>> {
private final Function<T, K> keyMapper;
private final Function<T, V> valueMapper;
/**
* Creates a new instance
*
* @param keyMapper a mapping function to produce keys
* @param valueMapper a mapping function to produce values
*/
public ImmutableMapCollector(Function<T, K> keyMapper, Function<T, V> valueMapper) {
this.keyMapper = keyMapper;
this.valueMapper = valueMapper;
}
@Override
public Supplier<ImmutableMap.Builder<K, V>> supplier() {
return ImmutableMap::builder;
}
@Override
public BiConsumer<ImmutableMap.Builder<K, V>, T> accumulator() {
return (builder, value) -> builder.put(keyMapper.apply(value), valueMapper.apply(value));
}
@Override
public BinaryOperator<ImmutableMap.Builder<K, V>> combiner() {
return (left, right) -> left.putAll(right.build());
}
@Override
public Function<ImmutableMap.Builder<K, V>, Map<K, V>> finisher() {
return ImmutableMap.Builder::build;
}
@Override
public Set<Characteristics> characteristics() {
return ImmutableSet.of();
}
}