/*
 * 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.fory.format.encoder;

import java.util.AbstractList;
import java.util.RandomAccess;
import org.apache.fory.annotation.Internal;
import org.apache.fory.format.row.binary.BinaryArray;

@Internal
public abstract class LazyArray<E> extends AbstractList<E> implements RandomAccess {
  private final BinaryArray array;
  private final Object[] storage;

  public LazyArray(final BinaryArray array) {
    this.array = array;
    storage = new Object[array.numElements()];
  }

  protected BinaryArray array() {
    return array;
  }

  @Override
  public int size() {
    return array.numElements();
  }

  @SuppressWarnings("unchecked")
  @Override
  public E get(final int index) {
    Object value = storage[index];
    if (value == null) {
      storage[index] = value = deserialize(index);
    }
    return (E) value;
  }

  protected abstract Object deserialize(int index);
}
