| /* |
| * 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.core.construction; |
| |
| import org.apache.beam.sdk.coders.CannotProvideCoderException; |
| import org.apache.beam.sdk.options.PipelineOptions; |
| import org.apache.beam.sdk.transforms.PTransform; |
| import org.apache.beam.sdk.transforms.display.DisplayData; |
| import org.apache.beam.sdk.values.PCollection; |
| import org.apache.beam.sdk.values.PInput; |
| import org.apache.beam.sdk.values.POutput; |
| |
| /** |
| * A base class for implementing {@link PTransform} overrides, which behave identically to the |
| * delegate transform but with overridden methods. Implementors are required to implement |
| * {@link #delegate()}, which returns the object to forward calls to, and {@link #expand(PInput)}. |
| */ |
| public abstract class ForwardingPTransform<InputT extends PInput, OutputT extends POutput> |
| extends PTransform<InputT, OutputT> { |
| protected abstract PTransform<InputT, OutputT> delegate(); |
| |
| @Override |
| public OutputT expand(InputT input) { |
| OutputT res = delegate().expand(input); |
| if (res instanceof PCollection) { |
| PCollection pc = (PCollection) res; |
| try { |
| pc.setCoder(delegate().getDefaultOutputCoder(input, pc)); |
| } catch (CannotProvideCoderException e) { |
| // Let coder inference happen later. |
| } |
| } |
| return res; |
| } |
| |
| @Override |
| public void validate(PipelineOptions options) { |
| delegate().validate(options); |
| } |
| |
| @Override |
| public String getName() { |
| return delegate().getName(); |
| } |
| |
| @Override |
| public void populateDisplayData(DisplayData.Builder builder) { |
| builder.delegate(delegate()); |
| } |
| } |