FastQSorts the [l,r] partition (inclusive) of the specfied array of Rows, using the comparator. : Array Sort Search « Collections « Java Tutorial

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/* Copyright (c) 1995-2000, The Hypersonic SQL Group.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the Hypersonic SQL Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Hypersonic SQL Group.
 *
 *
 * For work added by the HSQL Development Group:
 *
 * Copyright (c) 2001-2009, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * FastQSorts the [l,r] partition (inclusive) of the specfied array of Rows,
 * using the comparator.
 * 
 * Modified from the original method in Hypersonic with the addition of the
 * comparator. (fredt@users)
 * 
 * @author Thomas Mueller (Hypersonic SQL Group)
 * @version 1.7.2
 * @since 1.7.2
 */
public class Sort {

  public static final void sort(Object[] w, ObjectComparator comparator, int l, int r) {

    int i;
    int j;
    Object p;

    if (l > r) {
      return;
    }

    while (r - l > 10) {
      i = (r + l) >>> 1;

      if (comparator.compare(w[l], w[r]) > 0) {
        swap(w, l, r);
      }

      if (comparator.compare(w[i], w[l]) < 0) {
        swap(w, l, i);
      } else if (comparator.compare(w[i], w[r]) > 0) {
        swap(w, i, r);
      }

      j = r - 1;

      swap(w, i, j);

      p = w[j];
      i = l;

      while (true) {
        while (comparator.compare(w[++i], p) < 0) {
          ;
        }

        while (comparator.compare(w[--j], p) > 0) {
          ;
        }

        if (i >= j) {
          break;
        }

        swap(w, i, j);
      }

      swap(w, i, r - 1);
      sort(w, comparator, l, i - 1);

      l = i + 1;
    }

    for (i = l + 1; i <= r; i++) {
      Object t = w[i];

      for (j = i - 1; j >= l && comparator.compare(w[j], t) > 0; j--) {
        w[j + 1] = w[j];
      }

      w[j + 1] = t;
    }
  }

  /**
   * Swaps the a'th and b'th elements of the specified Row array.
   */
  private static void swap(Object[] w, int a, int b) {

    Object t = w[a];

    w[a] = w[b];
    w[b] = t;
  }
}

interface ObjectComparator {
  int compare(Object a, Object b);
}