man-db/gl/lib/gl_hash_map.c

/* Map data type implemented by a hash table.
   Copyright (C) 2006, 2008-2024 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2018.

   This program 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 3 of the License, or
   (at your option) any later version.

   This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include "gl_hash_map.h"

#include <stdint.h> /* for uintptr_t, SIZE_MAX */
#include <stdlib.h>

#include "xsize.h"

/* --------------------------- gl_map_t Data Type --------------------------- */

#include "gl_anyhash1.h"

/* Concrete list node implementation, valid for this file only.  */
struct gl_list_node_impl
{
  struct gl_hash_entry h;           /* hash table entry fields; must be first */
  const void *key;
  const void *value;
};
typedef struct gl_list_node_impl * gl_list_node_t;

/* Concrete gl_map_impl type, valid for this file only.  */
struct gl_map_impl
{
  struct gl_map_impl_base base;
  gl_mapkey_hashcode_fn hashcode_fn;
  /* A hash table: managed as an array of collision lists.  */
  struct gl_hash_entry **table;
  size_t table_size;
  /* Number of hash table entries.  */
  size_t count;
};

#define CONTAINER_T gl_map_t
#define CONTAINER_COUNT(map) (map)->count
#include "gl_anyhash2.h"

/* --------------------------- gl_map_t Data Type --------------------------- */

static gl_map_t
gl_hash_nx_create_empty (gl_map_implementation_t implementation,
                         gl_mapkey_equals_fn equals_fn,
                         gl_mapkey_hashcode_fn hashcode_fn,
                         gl_mapkey_dispose_fn kdispose_fn,
                         gl_mapvalue_dispose_fn vdispose_fn)
{
  struct gl_map_impl *map =
    (struct gl_map_impl *) malloc (sizeof (struct gl_map_impl));

  if (map == NULL)
    return NULL;

  map->base.vtable = implementation;
  map->base.equals_fn = equals_fn;
  map->base.kdispose_fn = kdispose_fn;
  map->base.vdispose_fn = vdispose_fn;
  map->hashcode_fn = hashcode_fn;
  map->table_size = 11;
  map->table =
    (gl_hash_entry_t *) calloc (map->table_size, sizeof (gl_hash_entry_t));
  if (map->table == NULL)
    goto fail;
  map->count = 0;

  return map;

 fail:
  free (map);
  return NULL;
}

static size_t _GL_ATTRIBUTE_PURE
gl_hash_size (gl_map_t map)
{
  return map->count;
}

static bool _GL_ATTRIBUTE_PURE
gl_hash_search (gl_map_t map, const void *key, const void **valuep)
{
  size_t hashcode =
    (map->hashcode_fn != NULL
     ? map->hashcode_fn (key)
     : (size_t)(uintptr_t) key);
  size_t bucket = hashcode % map->table_size;
  gl_mapkey_equals_fn equals = map->base.equals_fn;

  /* Look for a match in the hash bucket.  */
  gl_list_node_t node;

  for (node = (gl_list_node_t) map->table[bucket];
       node != NULL;
       node = (gl_list_node_t) node->h.hash_next)
    if (node->h.hashcode == hashcode
        && (equals != NULL
            ? equals (key, node->key)
            : key == node->key))
      {
        *valuep = node->value;
        return true;
      }
  return false;
}

static int
gl_hash_nx_getput (gl_map_t map, const void *key, const void *value,
                   const void **oldvaluep)
{
  size_t hashcode =
    (map->hashcode_fn != NULL
     ? map->hashcode_fn (key)
     : (size_t)(uintptr_t) key);
  size_t bucket = hashcode % map->table_size;
  gl_mapkey_equals_fn equals = map->base.equals_fn;

  /* Look for a match in the hash bucket.  */
  {
    gl_list_node_t node;

    for (node = (gl_list_node_t) map->table[bucket];
         node != NULL;
         node = (gl_list_node_t) node->h.hash_next)
      if (node->h.hashcode == hashcode
          && (equals != NULL
              ? equals (key, node->key)
              : key == node->key))
        {
          *oldvaluep = node->value;
          node->value = value;
          return 0;
        }
  }

  /* Allocate a new node.  */
  gl_list_node_t node =
    (struct gl_list_node_impl *) malloc (sizeof (struct gl_list_node_impl));

  if (node == NULL)
    return -1;

  node->key = key;
  node->value = value;
  node->h.hashcode = hashcode;

  /* Add node to the hash table.  */
  node->h.hash_next = map->table[bucket];
  map->table[bucket] = &node->h;

  /* Add node to the map.  */
  map->count++;

  hash_resize_after_add (map);

  return 1;
}

static bool
gl_hash_getremove (gl_map_t map, const void *key, const void **oldvaluep)
{
  size_t hashcode =
    (map->hashcode_fn != NULL
     ? map->hashcode_fn (key)
     : (size_t)(uintptr_t) key);
  size_t bucket = hashcode % map->table_size;
  gl_mapkey_equals_fn equals = map->base.equals_fn;

  /* Look for the first match in the hash bucket.  */
  gl_list_node_t *nodep;

  for (nodep = (gl_list_node_t *) &map->table[bucket];
       *nodep != NULL;
       nodep = (gl_list_node_t *) &(*nodep)->h.hash_next)
    {
      gl_list_node_t node = *nodep;
      if (node->h.hashcode == hashcode
          && (equals != NULL
              ? equals (key, node->key)
              : key == node->key))
        {
          *oldvaluep = node->value;

          /* Remove node from the hash table.  */
          *nodep = (gl_list_node_t) node->h.hash_next;

          /* Remove node from the map.  */
          map->count--;

          if (map->base.kdispose_fn != NULL)
            map->base.kdispose_fn (node->key);
          free (node);
          return true;
        }
    }

  return false;
}

static void
gl_hash_free (gl_map_t map)
{
  if (map->count > 0)
    {
      gl_mapkey_dispose_fn kdispose = map->base.kdispose_fn;
      gl_mapvalue_dispose_fn vdispose = map->base.vdispose_fn;
      struct gl_hash_entry **table = map->table;
      size_t i;

      for (i = map->table_size; i > 0; )
        {
          gl_hash_entry_t node = table[--i];

          while (node != NULL)
            {
              gl_hash_entry_t next = node->hash_next;

              /* Free the entry.  */
              if (vdispose != NULL)
                vdispose (((gl_list_node_t) node)->value);
              if (kdispose != NULL)
                kdispose (((gl_list_node_t) node)->key);
              free (node);

              node = next;
            }
        }
    }

  free (map->table);
  free (map);
}

/* ---------------------- gl_map_iterator_t Data Type ---------------------- */

/* Here we iterate through the hash buckets.  Therefore the order in which the
   pairs are returned is unpredictable.  */

static gl_map_iterator_t
gl_hash_iterator (gl_map_t map)
{
  gl_map_iterator_t result;

  result.vtable = map->base.vtable;
  result.map = map;
  result.p = NULL;         /* runs through the nodes of a bucket */
  result.i = 0;            /* index of the bucket that p points into + 1 */
  result.j = map->table_size;
#if defined GCC_LINT || defined lint
  result.q = NULL;
  result.count = 0;
#endif

  return result;
}

static bool
gl_hash_iterator_next (gl_map_iterator_t *iterator,
                       const void **keyp, const void **valuep)
{
  if (iterator->p != NULL)
    {
      /* We're traversing a bucket.  */
      gl_list_node_t node = (gl_list_node_t) iterator->p;
      *keyp = node->key;
      *valuep = node->value;
      iterator->p = (gl_list_node_t) node->h.hash_next;
      return true;
    }
  else
    {
      /* Find the next bucket that is not empty.  */
      size_t j = iterator->j;
      size_t i = iterator->i;

      if (i < j)
        {
          gl_hash_entry_t *table = iterator->map->table;
          do
            {
              gl_list_node_t node = (gl_list_node_t) table[i++];
              if (node != NULL)
                {
                  *keyp = node->key;
                  *valuep = node->value;
                  iterator->p = (gl_list_node_t) node->h.hash_next;
                  iterator->i = i;
                  return true;
                }
            }
          while (i < j);
        }
      /* Here iterator->p is still NULL, and i == j.  */
      iterator->i = j;
      return false;
    }
}

static void
gl_hash_iterator_free (gl_map_iterator_t *iterator)
{
}


const struct gl_map_implementation gl_hash_map_implementation =
  {
    gl_hash_nx_create_empty,
    gl_hash_size,
    gl_hash_search,
    gl_hash_nx_getput,
    gl_hash_getremove,
    gl_hash_free,
    gl_hash_iterator,
    gl_hash_iterator_next,
    gl_hash_iterator_free
  };