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.extensions.sql.impl.transform.agg;
  
  import org.apache.beam.sdk.coders.CannotProvideCoderException;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.coders.CoderRegistry;
  import org.apache.beam.sdk.transforms.Combine;
  import org.apache.beam.sdk.transforms.Count;
  
  /**
   * Returns the count of TRUE values for expression. Returns 0 if there are zero input rows, or if
   * expression evaluates to FALSE or NULL for all rows.
   */
  public class CountIf {
    private CountIf() {}
  
    public static Combine.CombineFn<Boolean, ?, Long> combineFn() {
      return new CountIfFn();
    }
  
    public static class CountIfFn extends Combine.CombineFn<Boolean, long[], Long> {
      private final Combine.CombineFn<Boolean, long[], Long> countFn =
          (Combine.CombineFn<Boolean, long[], Long>) Count.<Boolean>combineFn();
  
      @Override
      public long[] createAccumulator() {
        return countFn.createAccumulator();
      }
  
      @Override
      public long[] addInput(long[] accumulator, Boolean input) {
        if (Boolean.TRUE.equals(input)) {
          countFn.addInput(accumulator, input);
        }
        return accumulator;
      }
  
      @Override
      public long[] mergeAccumulators(Iterable<long[]> accumulators) {
        return countFn.mergeAccumulators(accumulators);
      }
  
      @Override
      public Long extractOutput(long[] accumulator) {
        return countFn.extractOutput(accumulator);
      }
  
      @Override
      public Coder<long[]> getAccumulatorCoder(CoderRegistry registry, Coder<Boolean> inputCoder)
          throws CannotProvideCoderException {
        return countFn.getAccumulatorCoder(registry, inputCoder);
      }
    }
  }
  