/* 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 */
} G_GNUC_FLAG_ENUM 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 */
#define G_BSEARCH_UPPER_POWER2(n)       ((n) ? 1 << g_bit_storage ((n) - 1) : 0)
#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)
{
  size_t distance = (size_t) (((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;
  g_assert (distance <= UINT_MAX);

  return (unsigned int) 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__ */
