content: /*
   * 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.sdk.transforms;
  
  import java.io.Serializable;
  import org.apache.beam.sdk.util.SerializableUtils;
  
  /** Useful {@link SerializableFunction} overrides. */
  public class SerializableFunctions {
    public static <InT, OutT extends Serializable> SerializableFunction<InT, OutT> clonesOf(
        final OutT base) {
      return input -> SerializableUtils.clone(base);
    }
  
    private static class Identity<T> implements SerializableFunction<T, T> {
      @Override
      public T apply(T input) {
        return input;
      }
    }
  
    private static class Constant<InT, OutT> implements SerializableFunction<InT, OutT> {
      OutT value;
  
      Constant(OutT value) {
        this.value = value;
      }
  
      @Override
      public OutT apply(InT input) {
        return value;
      }
    }
  
    public static <T> SerializableFunction<T, T> identity() {
      return new Identity<>();
    }
  
    public static <InT, OutT> SerializableFunction<InT, OutT> constant(OutT value) {
      return new Constant<>(value);
    }
  }
  