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.gandiva.evaluator;
  
  import org.apache.arrow.vector.BaseVariableWidthVector;
  
  /**
   * This class provides the functionality to expand output vectors using a callback mechanism from
   * gandiva.
   */
  public class VectorExpander {
    private final BaseVariableWidthVector[] vectors;
  
    public VectorExpander(BaseVariableWidthVector[] vectors) {
      this.vectors = vectors;
    }
  
    /** Result of vector expansion. */
    public static class ExpandResult {
      public long address;
      public long capacity;
  
      public ExpandResult(long address, long capacity) {
        this.address = address;
        this.capacity = capacity;
      }
    }
  
    /**
     * Expand vector at specified index. This is used as a back call from jni, and is only relevant
     * for variable width vectors.
     *
     * @param index index of buffer in the list passed to jni.
     * @param toCapacity the size to which the buffer should be expanded to.
     * @return address and size of the buffer after expansion.
     */
    public ExpandResult expandOutputVectorAtIndex(int index, long toCapacity) {
      if (index >= vectors.length || vectors[index] == null) {
        throw new IllegalArgumentException("invalid index " + index);
      }
  
      BaseVariableWidthVector vector = vectors[index];
      while (vector.getDataBuffer().capacity() < toCapacity) {
        vector.reallocDataBuffer();
      }
      return new ExpandResult(
          vector.getDataBuffer().memoryAddress(), vector.getDataBuffer().capacity());
    }
  }
  