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.arrow.algorithm.sort;
  
  import org.apache.arrow.util.Preconditions;
  import org.apache.arrow.vector.IntVector;
  import org.apache.arrow.vector.ValueVector;
  
  /**
   * An out-of-place sorter for vectors of arbitrary type, with time complexity O(n*log(n)). Since it
   * does not make any assumptions about the memory layout of the vector, its performance can be
   * sub-optimal. So if another sorter is applicable ({@link FixedWidthInPlaceVectorSorter}), it
   * should be used in preference.
   *
   * @param <V> vector type.
   */
  public class GeneralOutOfPlaceVectorSorter<V extends ValueVector>
      implements OutOfPlaceVectorSorter<V> {
  
    @Override
    public void sortOutOfPlace(V srcVector, V dstVector, VectorValueComparator<V> comparator) {
      comparator.attachVector(srcVector);
  
      // check vector capacity
      Preconditions.checkArgument(
          dstVector.getValueCapacity() >= srcVector.getValueCount(),
          "Not enough capacity for the target vector. " + "Expected capacity %s, actual capacity %s",
          srcVector.getValueCount(),
          dstVector.getValueCapacity());
  
      // sort value indices
      try (IntVector sortedIndices = new IntVector("", srcVector.getAllocator())) {
        sortedIndices.allocateNew(srcVector.getValueCount());
        sortedIndices.setValueCount(srcVector.getValueCount());
  
        IndexSorter<V> indexSorter = new IndexSorter<>();
        indexSorter.sort(srcVector, sortedIndices, comparator);
  
        // copy sorted values to the output vector
        for (int dstIndex = 0; dstIndex < sortedIndices.getValueCount(); dstIndex++) {
          int srcIndex = sortedIndices.get(dstIndex);
  
          dstVector.copyFromSafe(srcIndex, dstIndex, srcVector);
        }
      }
    }
  }
  