PrimitiveArray.java

/**
 * Bobo Browse Engine - High performance faceted/parametric search implementation
 * that handles various types of semi-structured data.  Written in Java.
 *
 * Copyright (C) 2005-2006  John Wang
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * To contact the project administrators for the bobo-browse project,
 * please go to https://sourceforge.net/projects/bobo-browse/, or
 * send mail to owner@browseengine.com.
 */

package com.browseengine.bobo.docidset;

import java.io.Serializable;
import java.lang.reflect.Array;

public abstract class PrimitiveArray<T> implements Serializable {
  private static final long serialVersionUID = 4564518164881690599L;

  protected Object _array;

  protected int _count;

  protected int _growth;

  protected int _len;

  private static final int DEFAULT_SIZE = 1000;

  protected abstract Object buildArray(int len);

  protected PrimitiveArray(int len) {
    super();
    if (len <= 0)
      throw new IllegalArgumentException("len must be greater than 0: " + len);
    _array = buildArray(len);
    _count = 0;
    _growth = 10;
    _len = len;
  }

  protected PrimitiveArray() {
    this(DEFAULT_SIZE);
  }

  public void clear() {
    _count = 0;
    _growth = 10;
  }

  protected synchronized void expand() {
    expand(_len + 100);
  }

  protected synchronized void expand(int idx) {
    if (idx <= _len)
      return;
    int oldLen = _len;
    _len = idx + _growth;
    Object newArray = buildArray(_len);
    System.arraycopy(_array, 0, newArray, 0, oldLen);
    _growth += _len;
    _array = newArray;
  }

  public synchronized void ensureCapacity(int idx) {
    expand(idx);
  }

  public int size() {
    return _count;
  }

  /**
   * called to shrink the array size to the current # of elements to save
   * memory.
   *
   */
  public synchronized void seal() {
    if (_len > _count) {
      Object newArray = buildArray(_count);
      System.arraycopy(_array, 0, newArray, 0, _count);
      _array = newArray;
      _len = _count;
    }
    _growth = 10;
  }

  public synchronized T[] toArray(T[] array) {
    System.arraycopy(_array, 0, array, 0, _count);
    return array;
  }

  public synchronized Object toArray() {
    Object array = buildArray(_count);
    System.arraycopy(_array, 0, array, 0, _count);
    return array;
  }

  @SuppressWarnings("unchecked")
  @Override
  public PrimitiveArray<T> clone() {
    PrimitiveArray<T> obj;
    try {
      obj = this.getClass().newInstance();
      obj._count = _count;
      obj._growth = _growth;
      obj._len = _len;

      Object newArray = buildArray(_len);
      System.arraycopy(_array, 0, newArray, 0, _count);
      obj._array = newArray;
      return obj;
    } catch (Exception e) {
      throw new RuntimeException(e.getMessage());
    }
  }

  @Override
  public String toString() {
    StringBuffer buffer = new StringBuffer("[");
    for (int i = 0; i < _count; ++i) {
      if (i != 0) {
        buffer.append(", ");
      }
      buffer.append(Array.get(_array, i));
    }
    buffer.append(']');

    return buffer.toString();
  }

  public int length() {
    return _len;
  }
}