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.util;
  
  import java.util.Collection;
  import java.util.Collections;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.transforms.windowing.GlobalWindow;
  import org.apache.beam.sdk.transforms.windowing.IncompatibleWindowException;
  import org.apache.beam.sdk.transforms.windowing.NonMergingWindowFn;
  import org.apache.beam.sdk.transforms.windowing.WindowFn;
  import org.apache.beam.sdk.transforms.windowing.WindowMappingFn;
  
  /**
   * A {@link WindowFn} for use during tests that returns the input window for calls to {@link
   * WindowFn#getSideInputWindow(BoundedWindow)}.
   */
  public class IdentitySideInputWindowFn extends NonMergingWindowFn<Integer, BoundedWindow> {
    @Override
    public Collection<BoundedWindow> assignWindows(WindowFn<Integer, BoundedWindow>.AssignContext c)
        throws Exception {
      return Collections.singleton(c.window());
    }
  
    @Override
    public boolean isCompatible(WindowFn<?, ?> other) {
      return true;
    }
  
    @Override
    public void verifyCompatibility(WindowFn<?, ?> other) throws IncompatibleWindowException {}
  
    @Override
    public Coder<BoundedWindow> windowCoder() {
      // not used
      return (Coder) GlobalWindow.Coder.INSTANCE;
    }
  
    @Override
    public WindowMappingFn<BoundedWindow> getDefaultWindowMappingFn() {
      return new WindowMappingFn<BoundedWindow>() {
        @Override
        public BoundedWindow getSideInputWindow(BoundedWindow window) {
          return window;
        }
      };
    }
  }
  