AsyncList.java

package org.opensha2.calc;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.util.concurrent.ListenableFuture;

import java.util.AbstractList;
import java.util.ArrayList;
import java.util.List;

/**
 * Convenience {@code List} implementation for {@code List}s of
 * {@code ListenableFuture}s of some type {@code <T>}. An {@code AsyncList} does
 * not permit {@code null} elements.
 *
 * @author Peter Powers
 */
final class AsyncList<T> extends AbstractList<ListenableFuture<T>> {

  private final List<ListenableFuture<T>> delegate;

  private AsyncList(int initialCapacity) {
    delegate = new ArrayList<>(initialCapacity);
  }

  /**
   * Creates a new {@code AsyncList} with an initial capacity of 256 elements.
   * @return a new {@code AsyncList}
   */
  static <T> AsyncList<T> create() {
    return new AsyncList<T>(256);
  }

  /**
   * Creates a new {@code AsyncList} with the specified initial capacity.
   * @return a new {@code AsyncList}
   */
  static <T> AsyncList<T> createWithCapacity(int initialCapacity) {
    return new AsyncList<T>(initialCapacity);
  }

  @Override
  public boolean add(ListenableFuture<T> future) {
    return delegate.add(checkNotNull(future));
  }

  @Override
  public ListenableFuture<T> get(int index) {
    return delegate.get(index);
  }

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

}