/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.beam.runners.flink.translation.functions;

import org.apache.flink.api.common.functions.MapFunction;

/**
 * A map function that outputs the input element without any change.
 *
 * @param <T> Input element type.
 */
public class FlinkIdentityFunction<T> implements MapFunction<T, T> {

  private static final FlinkIdentityFunction<?> INSTANCE = new FlinkIdentityFunction<>();

  @SuppressWarnings("unchecked")
  public static <T> FlinkIdentityFunction<T> of() {
    return (FlinkIdentityFunction) INSTANCE;
  }

  private FlinkIdentityFunction() {}

  @Override
  public T map(T value) {
    return value;
  }
}
