/* x-hash.c - basic hash tables

   Copyright (c) 2002 Apple Computer, Inc. All rights reserved.

   Permission is hereby granted, free of charge, to any person
   obtaining a copy of this software and associated documentation files
   (the "Software"), to deal in the Software without restriction,
   including without limitation the rights to use, copy, modify, merge,
   publish, distribute, sublicense, and/or sell copies of the Software,
   and to permit persons to whom the Software is furnished to do so,
   subject to the following conditions:

   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT.  IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT
   HOLDER(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   DEALINGS IN THE SOFTWARE.

   Except as contained in this notice, the name(s) of the above
   copyright holders shall not be used in advertising or otherwise to
   promote the sale, use or other dealings in this Software without
   prior written authorization. */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include "x-hash.h"
#include "x-list.h"
#include <stdlib.h>
#include <assert.h>

struct x_hash_table_struct {
    unsigned int bucket_index;
    unsigned int total_keys;
    x_list **buckets;

    x_hash_fun *hash_key;
    x_compare_fun *compare_keys;
    x_destroy_fun *destroy_key;
    x_destroy_fun *destroy_value;
};

#define ITEM_NEW(k, v) X_PFX (list_prepend) ((x_list *) (k), v)
#define ITEM_FREE(i) X_PFX (list_free_1) (i)
#define ITEM_KEY(i) ((void *) (i)->next)
#define ITEM_VALUE(i) ((i)->data)

#define SPLIT_THRESHOLD_FACTOR 2

/* http://planetmath.org/?op=getobj&from=objects&name=GoodHashTablePrimes */
static const unsigned int bucket_sizes[] = {
    29, 53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593, 49157,
    98317, 196613, 393241, 786433, 1572869, 3145739, 6291469, 12582917,
    25165843, 50331653, 100663319, 201326611, 402653189, 805306457,
    1610612741
};

#define N_BUCKET_SIZES (sizeof (bucket_sizes) / sizeof (bucket_sizes[0]))

static inline unsigned int
hash_table_total_buckets (x_hash_table *h)
{
    return bucket_sizes[h->bucket_index];
}

static inline void
hash_table_destroy_item (x_hash_table *h, void *k, void *v)
{
    if (h->destroy_key != 0)
        (*h->destroy_key) (k);

    if (h->destroy_value != 0)
        (*h->destroy_value) (v);
}

static inline size_t
hash_table_hash_key (x_hash_table *h, void *k)
{
    if (h->hash_key != 0)
        return (*h->hash_key) (k);
    else
        return (size_t) k;
}

static inline int
hash_table_compare_keys (x_hash_table *h, void *k1, void *k2)
{
    if (h->compare_keys == 0)
        return k1 == k2;
    else
        return (*h->compare_keys) (k1, k2) == 0;
}

static void
hash_table_split (x_hash_table *h)
{
    x_list **new, **old;
    x_list *node, *item, *next;
    int new_size, old_size;
    size_t b;
    int i;

    if (h->bucket_index == N_BUCKET_SIZES - 1)
        return;

    old_size = hash_table_total_buckets (h);
    old = h->buckets;

    h->bucket_index++;

    new_size = hash_table_total_buckets (h);
    new = calloc (new_size, sizeof (x_list *));

    if (new == 0)
    {
        h->bucket_index--;
        return;
    }

    for (i = 0; i < old_size; i++)
    {
        for (node = old[i]; node != 0; node = next)
        {
            next = node->next;
            item = node->data;

            b = hash_table_hash_key (h, ITEM_KEY (item)) % new_size;

            node->next = new[b];
            new[b] = node;
        }
    }

    h->buckets = new;
    free (old);
}

X_EXTERN x_hash_table *
X_PFX (hash_table_new) (x_hash_fun *hash,
                        x_compare_fun *compare,
                        x_destroy_fun *key_destroy,
                        x_destroy_fun *value_destroy)
{
    x_hash_table *h;

    h = calloc (1, sizeof (x_hash_table));
    if (h == 0)
        return 0;

    h->bucket_index = 0;
    h->buckets = calloc (hash_table_total_buckets (h), sizeof (x_list *));

    if (h->buckets == 0)
    {
        free (h);
        return 0;
    }
    
    h->hash_key = hash;
    h->compare_keys = compare;
    h->destroy_key = key_destroy;
    h->destroy_value = value_destroy;

    return h;
}

X_EXTERN void
X_PFX (hash_table_free) (x_hash_table *h)
{
    int n, i;
    x_list *node, *item;

    assert (h != NULL);

    n = hash_table_total_buckets (h);

    for (i = 0; i < n; i++)
    {
        for (node = h->buckets[i]; node != 0; node = node->next)
        {
            item = node->data;
            hash_table_destroy_item (h, ITEM_KEY (item), ITEM_VALUE (item));
            ITEM_FREE (item);
        }
        X_PFX (list_free) (h->buckets[i]);
    }

    free (h->buckets);
    free (h);
}

X_EXTERN unsigned int
X_PFX (hash_table_size) (x_hash_table *h)
{
    assert (h != NULL);

    return h->total_keys;
}

static void
hash_table_modify (x_hash_table *h, void *k, void *v, int replace)
{
    size_t hash_value;
    x_list *node, *item;

    assert (h != NULL);

    hash_value = hash_table_hash_key (h, k);

    for (node = h->buckets[hash_value % hash_table_total_buckets (h)];
         node != 0; node = node->next)
    {
        item = node->data;

        if (hash_table_compare_keys (h, ITEM_KEY (item), k))
        {
            if (replace)
            {
                hash_table_destroy_item (h, ITEM_KEY (item),
                                         ITEM_VALUE (item));
                item->next = k;
                ITEM_VALUE (item) = v;
            }
            else
            {
                hash_table_destroy_item (h, k, ITEM_VALUE (item));
                ITEM_VALUE (item) = v;
            }
            return;
        }
    }

    /* Key isn't already in the table. Insert it. */

    if (h->total_keys + 1
        > hash_table_total_buckets (h) * SPLIT_THRESHOLD_FACTOR)
    {
        hash_table_split (h);
    }

    hash_value = hash_value % hash_table_total_buckets (h);
    h->buckets[hash_value] = X_PFX (list_prepend) (h->buckets[hash_value],
                                                   ITEM_NEW (k, v));
    h->total_keys++;
}

X_EXTERN void
X_PFX (hash_table_insert) (x_hash_table *h, void *k, void *v)
{
    hash_table_modify (h, k, v, 0);
}

X_EXTERN void
X_PFX (hash_table_replace) (x_hash_table *h, void *k, void *v)
{
    hash_table_modify (h, k, v, 1);
}

X_EXTERN void
X_PFX (hash_table_remove) (x_hash_table *h, void *k)
{
    size_t hash_value;
    x_list **ptr, *item;

    assert (h != NULL);

    hash_value = hash_table_hash_key (h, k);

    for (ptr = &h->buckets[hash_value % hash_table_total_buckets (h)];
         *ptr != 0; ptr = &((*ptr)->next))
    {
        item = (*ptr)->data;

        if (hash_table_compare_keys (h, ITEM_KEY (item), k))
        {
            hash_table_destroy_item (h, ITEM_KEY (item), ITEM_VALUE (item));
            ITEM_FREE (item);
            item = *ptr;
            *ptr = item->next;
            X_PFX (list_free_1) (item);
            h->total_keys--;
            return;
        }
    }
}

X_EXTERN void *
X_PFX (hash_table_lookup) (x_hash_table *h, void *k, void **k_ret)
{
    size_t hash_value;
    x_list *node, *item;

    assert (h != NULL);

    hash_value = hash_table_hash_key (h, k);

    for (node = h->buckets[hash_value % hash_table_total_buckets (h)];
         node != 0; node = node->next)
    {
        item = node->data;

        if (hash_table_compare_keys (h, ITEM_KEY (item), k))
        {
            if (k_ret != 0)
            *k_ret = ITEM_KEY (item);

            return ITEM_VALUE (item);
        }
    }

    if (k_ret != 0)
        *k_ret = 0;

    return 0;
}

X_EXTERN void
X_PFX (hash_table_foreach) (x_hash_table *h,
                            x_hash_foreach_fun *fun, void *data)
{
    int i, n;
    x_list *node, *item;

    assert (h != NULL);

    n = hash_table_total_buckets (h);

    for (i = 0; i < n; i++)
    {
        for (node = h->buckets[i]; node != 0; node = node->next)
        {
            item = node->data;
            (*fun) (ITEM_KEY (item), ITEM_VALUE (item), data);
        }
    }
}
