htable.c

/* Copyright (c) 2011-2016, David Hauweele <david@hauweele.net>
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this
       list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER 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.
 */

#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>

#include "htable.h"

#define IDX(hash, size) hash & (size - 1)

struct entry {
  const void *key;
  void *data;

  struct entry *next;
};

struct htable {
  uint32_t (*hash)(const void *);
  bool (*compare)(const void *, const void *);
  void (*destroy)(void *);

  unsigned int nbuckets;

  struct entry *buckets[];
};

htable_t ht_create(unsigned int nbuckets,
                   uint32_t (*hash)(const void *),
                   bool (*compare)(const void *, const void *),
                   void (*destroy)(void *))
{
  struct htable *ht = malloc(sizeof(struct htable) +            \
                             sizeof(struct entry) * nbuckets);

  if(!ht)
    return NULL;
  memset(ht, 0, sizeof(struct htable) + sizeof(struct entry *) * nbuckets);

  ht->nbuckets = nbuckets;

  ht->hash    = hash;
  ht->compare = compare;
  ht->destroy = destroy;

  return ht;
}

/* also known as ht_insert_or_replace() */
/* FIXME: In future MAJOR version the name of this function
   must be replaced by ht_insert_or_replace() and ht_search()
   used as a synonym for ht_insert(ht, key, NULL) or even better
   provide a dedicated function to do so. */
void * ht_search(htable_t ht, const void *key, void *data)
{
  struct entry *entry;
  uint32_t index = IDX(ht->hash(key), ht->nbuckets);

  for(entry = ht->buckets[index] ; entry ; entry = entry->next) {
    if(ht->compare(entry->key, key)) {
      if(data) {
        ht->destroy(entry->data);
        entry->key  = key;
        entry->data = data;
      }

      return entry->data;
    }
  }

  if(data) {
    struct entry *new = malloc(sizeof(struct entry));

    new->key  = key;
    new->data = data;
    new->next = ht->buckets[index];

    ht->buckets[index] = new;

    return data;
  }

  return NULL;
}

void * ht_replace(htable_t ht, const void *key, void *data)
{
  struct entry *entry;
  uint32_t index = IDX(ht->hash(key), ht->nbuckets);

  for(entry = ht->buckets[index] ; entry ; entry = entry->next) {
    if(ht->compare(entry->key, key)) {
      if(data) {
        ht->destroy(entry->data);
        entry->key  = key;
        entry->data = data;
      }

      return entry->data;
    }
  }

  return NULL;
}


void * ht_insert(htable_t ht, const void *key, void *data)
{
  struct entry *entry;
  uint32_t index = IDX(ht->hash(key), ht->nbuckets);

  for(entry = ht->buckets[index] ; entry ; entry = entry->next) {
    if(ht->compare(entry->key, key))
      return entry->data;
  }

  if(data) {
    struct entry *new = malloc(sizeof(struct entry));

    new->key  = key;
    new->data = data;
    new->next = ht->buckets[index];

    ht->buckets[index] = new;

    return data;
  }

  return NULL;
}

/* FIXME: In a future MAJOR version, the name of this function
   should probably be replaced with something more appropriate. */
void * ht_lookup(htable_t ht, const void *key,
                 void * (*retrieve)(const void *, void *),
                 void *optarg)
{
  struct entry *entry;
  uint32_t index    = IDX(ht->hash(key), ht->nbuckets);

  for(entry = ht->buckets[index] ; entry ; entry = entry->next)
    if(ht->compare(entry->key, key))
      return entry->data;

  entry = malloc(sizeof(struct entry));
  entry->key  = key;
  entry->data = retrieve(key, optarg);
  entry->next = ht->buckets[index];

  ht->buckets[index] = entry;

  return entry->data;
}

void ht_walk(htable_t ht, void (*action)(void *, void *), void *data)
{
  unsigned int i;

  for(i = 0 ; i < ht->nbuckets ; i++) {
    struct entry *entry;

    for(entry = ht->buckets[i] ; entry ; entry = entry->next)
      action(entry->data, data);
  }
}

void ht_walk2(htable_t ht, void (*action)(const void *, void *, void *), void *data)
{
  unsigned int i;

  for(i = 0 ; i < ht->nbuckets ; i++) {
    struct entry *entry;

    for(entry = ht->buckets[i] ; entry ; entry = entry->next)
      action(entry->key, entry->data, data);
  }
}

void ht_delete(htable_t ht, const void *key)
{
  struct entry *entry;
  struct entry *prev = NULL;
  uint32_t index     = IDX(ht->hash(key), ht->nbuckets);

  for(entry = ht->buckets[index], prev = NULL ;
      entry ;
      prev = entry, entry = entry->next)
    if(ht->compare(entry->key, key))
      break;

  if(!entry)
    return;

  if(!prev)
    ht->buckets[index] = entry->next;
  else
    prev->next = entry->next;

  ht->destroy(entry->data);
  free(entry);
}

void ht_destroy(htable_t ht)
{
  unsigned int i;

  for(i = 0 ; i < ht->nbuckets ; i++) {
    struct entry *entry = ht->buckets[i];

    while(entry) {
      struct entry *f = entry;

      entry = entry->next;
      ht->destroy(f->data);
      free(f);
    }
  }

  free(ht);
}