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 org.apache.beam.sdk.transforms.Contextful.Fn;
  import org.apache.beam.sdk.transforms.WithFailures.ExceptionElement;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * A {@code PTransform} that adds exception handling to {@link MapKeys} and {@link MapValues} using
   * {@link MapElements.MapWithFailures}.
   */
  class SimpleMapWithFailures<InputT, OutputT, FailureT>
      extends PTransform<PCollection<InputT>, WithFailures.Result<PCollection<OutputT>, FailureT>> {
  
    private final transient TypeDescriptor<OutputT> outputType;
    private final Contextful<Fn<InputT, OutputT>> fn;
    private final transient TypeDescriptor<FailureT> failureType;
    private final @Nullable ProcessFunction<ExceptionElement<InputT>, FailureT> exceptionHandler;
    private final String transformName;
  
    SimpleMapWithFailures(
        String transformName,
        Contextful<Fn<InputT, OutputT>> fn,
        TypeDescriptor<OutputT> outputType,
        @Nullable ProcessFunction<ExceptionElement<InputT>, FailureT> exceptionHandler,
        TypeDescriptor<FailureT> failureType) {
      this.transformName = transformName;
      this.fn = fn;
      this.outputType = outputType;
      this.exceptionHandler = exceptionHandler;
      this.failureType = failureType;
    }
  
    @Override
    public WithFailures.Result<PCollection<OutputT>, FailureT> expand(PCollection<InputT> input) {
      if (exceptionHandler == null) {
        throw new NullPointerException(".exceptionsVia() is required");
      }
      return input.apply(
          transformName,
          MapElements.into(outputType)
              .via(fn)
              .exceptionsInto(failureType)
              .exceptionsVia(exceptionHandler));
    }
  
    /**
     * Returns a {@code PTransform} that catches exceptions raised while mapping elements, passing the
     * raised exception instance and the input element being processed through the given {@code
     * exceptionHandler} and emitting the result to a failure collection.
     */
    public SimpleMapWithFailures<InputT, OutputT, FailureT> exceptionsVia(
        ProcessFunction<ExceptionElement<InputT>, FailureT> exceptionHandler) {
      return new SimpleMapWithFailures<>(
          transformName, fn, outputType, exceptionHandler, failureType);
    }
  }
  