/*

 * Copyright © 2012  Google, Inc.

 *

 *  This is part of HarfBuzz, a text shaping library.

 *

 * Permission is hereby granted, without written agreement and without

 * license or royalty fees, to use, copy, modify, and distribute this

 * software and its documentation for any purpose, provided that the

 * above copyright notice and the following two paragraphs appear in

 * all copies of this software.

 *

 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR

 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES

 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN

 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH

 * DAMAGE.

 *

 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,

 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS

 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO

 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

 *

 * Google Author(s): Behdad Esfahbod

 */

#include "hb-private.hh"

#include "hb-shaper-private.hh"

#include "hb-atomic-private.hh"

static const hb_shaper_pair_t all_shapers[] = {

#define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape},

#include "hb-shaper-list.hh"

#undef HB_SHAPER_IMPLEMENT

};

/* Thread-safe, lock-free, shapers */

static const hb_shaper_pair_t *static_shapers;

#ifdef HB_USE_ATEXIT

static

void free_static_shapers (void)

{

  if (unlikely (static_shapers != all_shapers))

    free ((void *) static_shapers);

}

#endif

const hb_shaper_pair_t *

_hb_shapers_get (void)

{

retry:

  hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);

  if (unlikely (!shapers))

  {

    char *env = getenv ("HB_SHAPER_LIST");

    if (!env || !*env) {

      (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);

      return (const hb_shaper_pair_t *) all_shapers;

    }

    /* Not found; allocate one. */

    shapers = (hb_shaper_pair_t *) calloc (1, sizeof (all_shapers));

    if (unlikely (!shapers)) {

      (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);

      return (const hb_shaper_pair_t *) all_shapers;

    }

    memcpy (shapers, all_shapers, sizeof (all_shapers));

     /* Reorder shaper list to prefer requested shapers. */

    unsigned int i = 0;

    char *end, *p = env;

    for (;;) {

      end = strchr (p, ',');

      if (!end)

	end = p + strlen (p);

      for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)

	if (end - p == (int) strlen (shapers[j].name) &&

	    0 == strncmp (shapers[j].name, p, end - p))

	{

	  /* Reorder this shaper to position i */

	 struct hb_shaper_pair_t t = shapers[j];

	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));

	 shapers[i] = t;

	 i++;

	}

      if (!*end)

	break;

      else

	p = end + 1;

    }

    if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {

      free (shapers);

      goto retry;

    }

#ifdef HB_USE_ATEXIT

    atexit (free_static_shapers); /* First person registers atexit() callback. */

#endif

  }

  return shapers;

}