/* GBSearchArray - Binary Searchable Array implementation

 * Copyright (C) 2000-2003 Tim Janik

 *

 * This software is provided "as is"; redistribution and modification

 * is permitted, provided that the following disclaimer is retained.

 *

 * This software 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.

 * In no event shall the authors 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.

 */

#ifndef __G_BSEARCH_ARRAY_H__

#define __G_BSEARCH_ARRAY_H__

#include <glib.h>

#include <string.h>

G_BEGIN_DECLS   /* c++ guards */

/* this implementation is intended to be usable in third-party code

 * simply by pasting the contents of this file. as such, the

 * implementation needs to be self-contained within this file.

 */

/* convenience macro to avoid signed overflow for value comparisons */

#define G_BSEARCH_ARRAY_CMP(v1,v2) ((v1) > (v2) ? +1 : (v1) == (v2) ? 0 : -1)

/* --- typedefs --- */

typedef gint  (*GBSearchCompareFunc) (gconstpointer bsearch_node1, /* key */

                                      gconstpointer bsearch_node2);

typedef enum

{

  G_BSEARCH_ARRAY_ALIGN_POWER2  = 1 << 0, /* align memory to power2 sizes */

  G_BSEARCH_ARRAY_AUTO_SHRINK  = 1 << 1   /* shrink array upon removal */

} GBSearchArrayFlags;

/* --- structures --- */

typedef struct

{

  guint               sizeof_node;

  GBSearchCompareFunc cmp_nodes;

  guint               flags;

} GBSearchConfig;

typedef union

{

  guint    n_nodes;

  /*< private >*/

  gpointer alignment_dummy1;

  glong    alignment_dummy2;

  gdouble  alignment_dummy3;

} GBSearchArray;

/* --- public API --- */

static inline GBSearchArray*    g_bsearch_array_create    (const GBSearchConfig *bconfig);

static inline gpointer          g_bsearch_array_get_nth   (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig,

                                                           guint                 nth);

static inline guint             g_bsearch_array_get_index (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig,

                                                           gconstpointer         node_in_array);

static inline GBSearchArray*    g_bsearch_array_remove    (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig,

                                                           guint                 index_);

/* provide uninitialized space at index for node insertion */

static inline GBSearchArray*    g_bsearch_array_grow      (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig,

                                                           guint                 index);

/* insert key_node into array if it does not exist, otherwise do nothing */

static inline GBSearchArray*    g_bsearch_array_insert    (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig,

                                                           gconstpointer         key_node);

/* insert key_node into array if it does not exist,

 * otherwise replace the existing node's contents with key_node

 */

static inline GBSearchArray*    g_bsearch_array_replace   (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig,

                                                           gconstpointer         key_node);

static inline void              g_bsearch_array_free      (GBSearchArray        *barray,

                                                           const GBSearchConfig *bconfig);

#define g_bsearch_array_get_n_nodes(barray)     (((GBSearchArray*) (barray))->n_nodes)

/* g_bsearch_array_lookup():

 * return NULL or exact match node

 */

#define g_bsearch_array_lookup(barray, bconfig, key_node)       \

    g_bsearch_array_lookup_fuzzy ((barray), (bconfig), (key_node), 0)

/* g_bsearch_array_lookup_sibling():

 * return NULL for barray->n_nodes==0, otherwise return the

 * exact match node, or, if there's no such node, return the

 * node last visited, which is pretty close to an exact match

 * (will be one off into either direction).

 */

#define g_bsearch_array_lookup_sibling(barray, bconfig, key_node)       \

    g_bsearch_array_lookup_fuzzy ((barray), (bconfig), (key_node), 1)

/* g_bsearch_array_lookup_insertion():

 * return NULL for barray->n_nodes==0 or exact match, otherwise

 * return the node where key_node should be inserted (may be one

 * after end, i.e. g_bsearch_array_get_index(result) <= barray->n_nodes).

 */

#define g_bsearch_array_lookup_insertion(barray, bconfig, key_node)     \

    g_bsearch_array_lookup_fuzzy ((barray), (bconfig), (key_node), 2)

/* --- implementation --- */

/* helper macro to cut down realloc()s */

#ifdef  DISABLE_MEM_POOLS

#define G_BSEARCH_UPPER_POWER2(n)       (n)

#else   /* !DISABLE_MEM_POOLS */

#define G_BSEARCH_UPPER_POWER2(n)       ((n) ? 1 << g_bit_storage ((n) - 1) : 0)

#endif  /* !DISABLE_MEM_POOLS */

#define G_BSEARCH_ARRAY_NODES(barray)    (((guint8*) (barray)) + sizeof (GBSearchArray))

static inline GBSearchArray*

g_bsearch_array_create (const GBSearchConfig *bconfig)

{

  GBSearchArray *barray;

  guint size;

  g_return_val_if_fail (bconfig != NULL, NULL);

  size = sizeof (GBSearchArray) + bconfig->sizeof_node;

  if (bconfig->flags & G_BSEARCH_ARRAY_ALIGN_POWER2)

    size = G_BSEARCH_UPPER_POWER2 (size);

  barray = (GBSearchArray *) g_malloc (size);

  memset (barray, 0, sizeof (GBSearchArray));

  return barray;

}

static inline gpointer

g_bsearch_array_lookup_fuzzy (GBSearchArray             *barray,

                              const GBSearchConfig      *bconfig,

                              gconstpointer              key_node,

                              const guint                sibling_or_after);

static inline gpointer

g_bsearch_array_lookup_fuzzy (GBSearchArray        *barray,

                              const GBSearchConfig *bconfig,

                              gconstpointer         key_node,

                              const guint           sibling_or_after)

{

  GBSearchCompareFunc cmp_nodes = bconfig->cmp_nodes;

  guint8 *check = NULL, *nodes = G_BSEARCH_ARRAY_NODES (barray);

  guint n_nodes = barray->n_nodes, offs = 0;

  guint sizeof_node = bconfig->sizeof_node;

  gint cmp = 0;

  while (offs < n_nodes)

    {

      guint i = (offs + n_nodes) >> 1;

      check = nodes + i * sizeof_node;

      cmp = cmp_nodes (key_node, check);

      if (cmp == 0)

        return sibling_or_after > 1 ? NULL : check;

      else if (cmp < 0)

        n_nodes = i;

      else /* (cmp > 0) */

        offs = i + 1;

    }

  /* check is last mismatch, cmp > 0 indicates greater key */

  return G_LIKELY (!sibling_or_after) ? NULL : (sibling_or_after > 1 && cmp > 0) ? check + sizeof_node : check;

}

static inline gpointer

g_bsearch_array_get_nth (GBSearchArray        *barray,

                         const GBSearchConfig *bconfig,

                         guint                 nth)

{

  return (G_LIKELY (nth < barray->n_nodes) ?

          G_BSEARCH_ARRAY_NODES (barray) + nth * bconfig->sizeof_node :

          NULL);

}

static inline guint

g_bsearch_array_get_index (GBSearchArray        *barray,

                           const GBSearchConfig *bconfig,

                           gconstpointer         node_in_array)

{

  guint distance = ((guint8*) node_in_array) - G_BSEARCH_ARRAY_NODES (barray);

  g_return_val_if_fail (node_in_array != NULL, barray->n_nodes);

  distance /= bconfig->sizeof_node;

  return MIN (distance, barray->n_nodes + 1); /* may return one after end */

}

static inline GBSearchArray*

g_bsearch_array_grow (GBSearchArray        *barray,

                      const GBSearchConfig *bconfig,

                      guint                 index_)

{

  guint old_size = barray->n_nodes * bconfig->sizeof_node;

  guint new_size = old_size + bconfig->sizeof_node;

  guint8 *node;

  g_return_val_if_fail (index_ <= barray->n_nodes, NULL);

  if (G_UNLIKELY (bconfig->flags & G_BSEARCH_ARRAY_ALIGN_POWER2))

    {

      new_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + new_size);

      old_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + old_size);

      if (old_size != new_size)

        barray = (GBSearchArray *) g_realloc (barray, new_size);

    }

  else

    barray = (GBSearchArray *) g_realloc (barray, sizeof (GBSearchArray) + new_size);

  node = G_BSEARCH_ARRAY_NODES (barray) + index_ * bconfig->sizeof_node;

  memmove (node + bconfig->sizeof_node, node, (barray->n_nodes - index_) * bconfig->sizeof_node);

  barray->n_nodes += 1;

  return barray;

}

static inline GBSearchArray*

g_bsearch_array_insert (GBSearchArray        *barray,

                        const GBSearchConfig *bconfig,

                        gconstpointer         key_node)

{

  guint8 *node;

  if (G_UNLIKELY (!barray->n_nodes))

    {

      barray = g_bsearch_array_grow (barray, bconfig, 0);

      node = G_BSEARCH_ARRAY_NODES (barray);

    }

  else

    {

      node = (guint8 *) g_bsearch_array_lookup_insertion (barray, bconfig, key_node);

      if (G_LIKELY (node))

        {

          guint index_ = g_bsearch_array_get_index (barray, bconfig, node);

          /* grow and insert */

          barray = g_bsearch_array_grow (barray, bconfig, index_);

          node = G_BSEARCH_ARRAY_NODES (barray) + index_ * bconfig->sizeof_node;

        }

      else /* no insertion needed, node already there */

        return barray;

    }

  memcpy (node, key_node, bconfig->sizeof_node);

  return barray;

}

static inline GBSearchArray*

g_bsearch_array_replace (GBSearchArray        *barray,

                         const GBSearchConfig *bconfig,

                         gconstpointer         key_node)

{

  guint8 *node = (guint8 *) g_bsearch_array_lookup (barray, bconfig, key_node);

  if (G_LIKELY (node))  /* expected path */

    memcpy (node, key_node, bconfig->sizeof_node);

  else                  /* revert to insertion */

    barray = g_bsearch_array_insert (barray, bconfig, key_node);

  return barray;

}

static inline GBSearchArray*

g_bsearch_array_remove (GBSearchArray        *barray,

                        const GBSearchConfig *bconfig,

                        guint                 index_)

{

  guint8 *node;

  g_return_val_if_fail (index_ < barray->n_nodes, NULL);

  barray->n_nodes -= 1;

  node = G_BSEARCH_ARRAY_NODES (barray) + index_ * bconfig->sizeof_node;

  memmove (node, node + bconfig->sizeof_node, (barray->n_nodes - index_) * bconfig->sizeof_node);

  if (G_UNLIKELY (bconfig->flags & G_BSEARCH_ARRAY_AUTO_SHRINK))

    {

      guint new_size = barray->n_nodes * bconfig->sizeof_node;

      guint old_size = new_size + bconfig->sizeof_node;

      if (G_UNLIKELY (bconfig->flags & G_BSEARCH_ARRAY_ALIGN_POWER2))

        {

          new_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + new_size);

          old_size = G_BSEARCH_UPPER_POWER2 (sizeof (GBSearchArray) + old_size);

          if (old_size != new_size)

            barray = (GBSearchArray *) g_realloc (barray, new_size);

        }

      else

        barray = (GBSearchArray *) g_realloc (barray, sizeof (GBSearchArray) + new_size);

    }

  return barray;

}

static inline void

g_bsearch_array_free (GBSearchArray        *barray,

                      const GBSearchConfig *bconfig)

{

  g_return_if_fail (barray != NULL);

  g_free (barray);

}

G_END_DECLS     /* c++ guards */

#endif  /* !__G_BSEARCH_ARRAY_H__ */