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.asterix.runtime.runningaggregates.std;
  
  import java.io.DataOutput;
  
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IWindowAggregateEvaluator;
  import org.apache.hyracks.api.dataflow.value.IBinaryComparator;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.primitive.VoidPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  /**
   * Base evaluator implementation for ranking window functions:
   * {@code rank()}, {@code dense_rank()}, {@code percent_rank()}
   */
  public abstract class AbstractRankRunningAggregateEvaluator implements IWindowAggregateEvaluator {
  
      private final IScalarEvaluator[] args;
  
      private final ArrayBackedValueStorage[] argPrevValues;
  
      private final IPointable[] argCurrValues;
  
      private final boolean dense;
  
      protected final SourceLocation sourceLoc;
  
      private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
  
      private IBinaryComparator[] argComparators;
  
      protected boolean first;
  
      protected long rank;
  
      private long groupSize;
  
      AbstractRankRunningAggregateEvaluator(IScalarEvaluator[] args, boolean dense, SourceLocation sourceLoc) {
          this.args = args;
          this.dense = dense;
          this.sourceLoc = sourceLoc;
          argPrevValues = new ArrayBackedValueStorage[args.length];
          argCurrValues = new IPointable[args.length];
          for (int i = 0; i < args.length; i++) {
              argPrevValues[i] = new ArrayBackedValueStorage();
              argCurrValues[i] = VoidPointable.FACTORY.createPointable();
          }
      }
  
      @Override
      public void configure(IBinaryComparator[] orderComparators) {
          argComparators = orderComparators;
      }
  
      @Override
      public void init() throws HyracksDataException {
      }
  
      @Override
      public void initPartition(long partitionLength) {
          first = true;
      }
  
      @Override
      public void step(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
          resultStorage.reset();
          for (int i = 0; i < args.length; i++) {
              args[i].evaluate(tuple, argCurrValues[i]);
          }
  
          computeRank();
          computeResult(resultStorage.getDataOutput());
  
          result.set(resultStorage);
  
          for (int i = 0; i < args.length; i++) {
              argPrevValues[i].assign(argCurrValues[i]);
          }
          first = false;
      }
  
      protected abstract void computeResult(DataOutput out) throws HyracksDataException;
  
      private void computeRank() throws HyracksDataException {
          if (first) {
              rank = 1;
              groupSize = 1;
          } else if (sameGroup()) {
              groupSize++;
          } else {
              rank += dense ? 1 : groupSize;
              groupSize = 1;
          }
      }
  
      private boolean sameGroup() throws HyracksDataException {
          for (int i = 0; i < args.length; i++) {
              IPointable v1 = argPrevValues[i];
              IPointable v2 = argCurrValues[i];
              IBinaryComparator cmp = argComparators[i];
              if (cmp.compare(v1.getByteArray(), v1.getStartOffset(), v1.getLength(), v2.getByteArray(),
                      v2.getStartOffset(), v2.getLength()) != 0) {
                  return false;
              }
          }
          return true;
      }
  }
  