/*
* 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.values;
import java.util.Map;
import org.apache.beam.sdk.Pipeline;
/**
* The interface for things that might be input to a
* {@link org.apache.beam.sdk.transforms.PTransform}.
*/
public interface PInput {
/**
* Returns the owning {@link Pipeline} of this {@link PInput}.
*/
Pipeline getPipeline();
/**
* Expands this {@link PInput} into a list of its component output
* {@link PValue PValues}.
*
* <ul>
* <li>A {@link PValue} expands to itself.</li>
* <li>A tuple or list of {@link PValue PValues} (such as
* {@link PCollectionTuple} or {@link PCollectionList})
* expands to its component {@code PValue PValues}.</li>
* </ul>
*
* <p>Not intended to be invoked directly by user code.
*/
Map<TupleTag<?>, PValue> expand();
}