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+/*
+Copyright (C) 2003 David Bateman
+
+This file is part of Octave.
+
+Octave is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+Octave 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 General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+Code stolen in large part from Python's, listobject.c, which itself had
+no license header. However, thanks to Tim Peters for the parts of the
+code I ripped-off.
+
+As required in the Python license the short description of the changes
+made are
+
+* convert the sorting code in listobject.cc into a generic class, 
+  replacing PyObject* with the type of the class T.
+
+The Python license is
+
+  PSF LICENSE AGREEMENT FOR PYTHON 2.3
+  --------------------------------------
+
+  1. This LICENSE AGREEMENT is between the Python Software Foundation
+  ("PSF"), and the Individual or Organization ("Licensee") accessing and
+  otherwise using Python 2.3 software in source or binary form and its
+  associated documentation.
+
+  2. Subject to the terms and conditions of this License Agreement, PSF
+  hereby grants Licensee a nonexclusive, royalty-free, world-wide
+  license to reproduce, analyze, test, perform and/or display publicly,
+  prepare derivative works, distribute, and otherwise use Python 2.3
+  alone or in any derivative version, provided, however, that PSF's
+  License Agreement and PSF's notice of copyright, i.e., "Copyright (c)
+  2001, 2002, 2003 Python Software Foundation; All Rights Reserved" are
+  retained in Python 2.3 alone or in any derivative version prepared by
+  Licensee.
+
+  3. In the event Licensee prepares a derivative work that is based on
+  or incorporates Python 2.3 or any part thereof, and wants to make
+  the derivative work available to others as provided herein, then
+  Licensee hereby agrees to include in any such work a brief summary of
+  the changes made to Python 2.3.
+
+  4. PSF is making Python 2.3 available to Licensee on an "AS IS"
+  basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
+  IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
+  DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
+  FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON 2.3 WILL NOT
+  INFRINGE ANY THIRD PARTY RIGHTS.
+
+  5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
+  2.3 FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
+  A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON 2.3,
+  OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
+
+  6. This License Agreement will automatically terminate upon a material
+  breach of its terms and conditions.
+
+  7. Nothing in this License Agreement shall be deemed to create any
+  relationship of agency, partnership, or joint venture between PSF and
+  Licensee.  This License Agreement does not grant permission to use PSF
+  trademarks or trade name in a trademark sense to endorse or promote
+  products or services of Licensee, or any third party.
+
+  8. By copying, installing or otherwise using Python 2.3, Licensee
+  agrees to be bound by the terms and conditions of this License
+  Agreement.
+*/
+
+#if !defined (octave_sort_h)
+#define octave_sort_h 1
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "oct-obj.h"
+#include "lo-mappers.h"
+#include "quit.h"
+
+/* The maximum number of entries in a MergeState's pending-runs stack.
+ * This is enough to sort arrays of size up to about
+ *     32 * phi ** MAX_MERGE_PENDING
+ * where phi ~= 1.618.  85 is ridiculously large enough, good for an array
+ * with 2**64 elements.
+ */
+#define MAX_MERGE_PENDING 85
+
+/* When we get into galloping mode, we stay there until both runs win less
+ * often than MIN_GALLOP consecutive times.  See listsort.txt for more info.
+ */
+#define MIN_GALLOP 7
+
+/* Avoid malloc for small temp arrays. */
+#define MERGESTATE_TEMP_SIZE 1024
+
+template <class T>
+class
+octave_sort
+{
+ public:
+  octave_sort (void);
+
+  octave_sort (bool (*comp) (T, T));
+  
+  ~octave_sort (void) { merge_freemem ( ); }
+
+  void sort (T *v, int elements);
+
+ private:
+  /* One MergeState exists on the stack per invocation of mergesort.  It's just
+   * a convenient way to pass state around among the helper functions.
+   *
+   * DGB: This isn't needed with mergesort in a class, but it doesn't slow
+   *      things up, and it is likely to make my life easier for any potential
+   *      backporting of changes in the Python code.
+   */
+  
+  struct s_slice 
+  {
+    T *base;
+    int len;
+  };
+  
+  typedef struct s_MergeState 
+  {
+    /* This controls when we get *into* galloping mode.  It's initialized
+     * to MIN_GALLOP.  merge_lo and merge_hi tend to nudge it higher for
+     * random data, and lower for highly structured data.
+     */
+    int min_gallop;
+
+    /* 'a' is temp storage to help with merges.  It contains room for
+     * alloced entries.
+     */
+    T *a;	/* may point to temparray below */
+    int alloced;
+    
+    /* A stack of n pending runs yet to be merged.  Run #i starts at
+     * address base[i] and extends for len[i] elements.  It's always
+     * true (so long as the indices are in bounds) that
+     *
+     *     pending[i].base + pending[i].len == pending[i+1].base
+     *
+     * so we could cut the storage for this, but it's a minor amount,
+     * and keeping all the info explicit simplifies the code.
+     */
+    int n;
+    struct s_slice pending[MAX_MERGE_PENDING];
+  } MergeState;
+
+  bool (*compare)(T, T);
+  
+  MergeState ms;
+  
+  void reverse_slice (T *lo, T *hi);
+  
+  void binarysort (T *lo, T *hi, T *start);
+    
+  int count_run(T *lo, T *hi, int *descending);
+
+  int gallop_left(T key, T *a, int n, int hint);
+
+  int gallop_right(T key, T *a, int n, int hint);
+
+  void merge_init(void);
+
+  void merge_freemem(void);
+
+  int merge_getmem(int need);
+
+  int merge_lo(T *pa, int na, T *pb, int nb);
+
+  int merge_hi(T *pa, int na, T *pb, int nb);
+
+  int merge_at(int i);
+
+  int merge_collapse(void);
+
+  int merge_force_collapse(void);
+
+  int merge_compute_minrun(int n);
+};
+
+#endif
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; End: ***
+*/