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/*
 * Copyright 2015 Igor Maznitsa.
 *
 * Licensed 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 com.igormaznitsa.meta.common.utils;

import com.igormaznitsa.meta.annotation.Weight;
import java.lang.reflect.Array;
import com.igormaznitsa.meta.annotation.MayContainNull;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.ThreadSafe;

/**
 * Set of auxiliary methods to process arrays.
 *
 * @since 1.0
 */
@ThreadSafe
public final class ArrayUtils {

  /**
   * Empty object array.
   *
   * @since 1.0.2
   */
  public static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
  /**
   * Empty string array.
   *
   * @since 1.0.2
   */
  public static final String[] EMPTY_STRING_ARRAY = new String[0];
  /**
   * Empty byte array.
   *
   * @since 1.0.2
   */
  public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
  /**
   * Empty char array.
   *
   * @since 1.0.2
   */
  public static final char[] EMPTY_CHAR_ARRAY = new char[0];
  /**
   * Empty short array.
   *
   * @since 1.0.2
   */
  public static final short[] EMPTY_SHORT_ARRAY = new short[0];
  /**
   * Empty boolean array.
   *
   * @since 1.0.2
   */
  public static final boolean[] EMPTY_BOOL_ARRAY = new boolean[0];
  /**
   * Empty int array.
   *
   * @since 1.0.2
   */
  public static final int[] EMPTY_INT_ARRAY = new int[0];
  /**
   * Empty long array.
   *
   * @since 1.0.2
   */
  public static final long[] EMPTY_LONG_ARRAY = new long[0];

  private ArrayUtils() {
  }

  /**
   * Join arrays provided as parameters, all arrays must be the same type, null values allowed.
   *
   * @param  type of array
   * @param arrays array of arrays to be joined
   * @return all joined arrays as single array
   * @since 1.0
   */
  @Nonnull
  @MayContainNull
  @Weight(Weight.Unit.NORMAL)
  public static  T[] joinArrays(@MayContainNull final T[]... arrays) {
    int commonLength = 0;
    for (final T[] array : arrays) {
      if (array != null) {
        commonLength += array.length;
      }
    }
    @SuppressWarnings("unchecked")
    final T[] result = (T[]) Array.newInstance(arrays.getClass().getComponentType().getComponentType(), commonLength);
    int position = 0;
    for (final T[] array : arrays) {
      if (array != null) {
        System.arraycopy(array, 0, result, position, array.length);
        position += array.length;
      }
    }
    return result;
  }

}