+/* hash.c -- hash table maintenance
+ Copyright (C) 1995 Free Software Foundation, Inc.
+ Written by Greg McGary <gkm@gnu.ai.mit.edu>
+
+ 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 2, 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, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+*/
+
+#include <config.h>
+#include <stdio.h>
+#include "hash.h"
+#include "error.h"
+#include "system.h"
+#include "xalloc.h"
+
+static void hash_rehash __P((struct hash_table* ht));
+static unsigned long round_up_2 __P((unsigned long rough));
+
+/* Implement double hashing with open addressing. The table size is
+ always a power of two. The secondary (`increment') hash function
+ is forced to return an odd-value, in order to be relatively prime
+ to the table size. This guarantees that the increment can
+ potentially hit every slot in the table during collision
+ resolution. */
+
+void *hash_deleted_item = &hash_deleted_item;
+
+/* Force the table size to be a power of two, possibly rounding up the
+ given size. */
+
+void
+hash_init (struct hash_table* ht, unsigned long size,
+ hash_func_t hash_1, hash_func_t hash_2, hash_cmp_func_t hash_cmp)
+{
+ ht->ht_size = round_up_2 (size);
+ if (ht->ht_size > (128 * 1024)) /* prevent size from getting out of hand */
+ ht->ht_size /= 2;
+ ht->ht_vec = (void**) CALLOC (struct token *, ht->ht_size);
+ if (ht->ht_vec == 0)
+ error (1, 0, _("can't allocate %ld bytes for hash table: memory exhausted"),
+ ht->ht_size * sizeof(struct token *));
+ ht->ht_capacity = ht->ht_size * 15 / 16; /* 93.75% loading factor */
+ ht->ht_fill = 0;
+ ht->ht_collisions = 0;
+ ht->ht_lookups = 0;
+ ht->ht_rehashes = 0;
+ ht->ht_hash_1 = hash_1;
+ ht->ht_hash_2 = hash_2;
+ ht->ht_compare = hash_cmp;
+}
+
+/* Load an array of items into `ht'. */
+
+void
+hash_load (struct hash_table* ht, void *item_table, unsigned long cardinality, unsigned long size)
+{
+ char *items = (char *) item_table;
+ while (cardinality--)
+ {
+ hash_insert (ht, items);
+ items += size;
+ }
+}
+
+/* Returns the address of the table slot matching `key'. If `key' is
+ not found, return the address of an empty slot suitable for
+ inserting `key'. The caller is responsible for incrementing
+ ht_fill on insertion. */
+
+void **
+hash_find_slot (struct hash_table* ht, void const *key)
+{
+ void **slot;
+ void **deleted_slot = 0;
+ unsigned int hash_2 = 0;
+ unsigned int hash_1 = (*ht->ht_hash_1) (key);
+
+ ht->ht_lookups++;
+ for (;;)
+ {
+ hash_1 %= ht->ht_size;
+ slot = &ht->ht_vec[hash_1];
+
+ if (*slot == 0)
+ return slot;
+ if (*slot == hash_deleted_item)
+ {
+ if (deleted_slot == 0)
+ deleted_slot = slot;
+ }
+ else
+ {
+ if (key == *slot)
+ return slot;
+ if ((*ht->ht_compare) (key, *slot) == 0)
+ return slot;
+ ht->ht_collisions++;
+ }
+ if (!hash_2)
+ hash_2 = (*ht->ht_hash_2) (key) | 1;
+ hash_1 += hash_2;
+ }
+}
+
+void *
+hash_find_item (struct hash_table* ht, void const *key)
+{
+ void **slot = hash_find_slot (ht, key);
+ return ((HASH_VACANT (*slot)) ? 0 : *slot);
+}
+
+void *
+hash_insert (struct hash_table* ht, void *item)
+{
+ void **slot = hash_find_slot (ht, item);
+ return hash_insert_at (ht, item, slot);
+}
+
+void *
+hash_insert_at (struct hash_table* ht, void *item, void const *slot)
+{
+ void *old_item = *(void **) slot;
+ if (HASH_VACANT (old_item))
+ {
+ ht->ht_fill++;
+ old_item = item;
+ }
+ *(void const **) slot = item;
+ if (ht->ht_fill >= ht->ht_capacity)
+ hash_rehash (ht);
+ return old_item;
+}
+
+void *
+hash_delete (struct hash_table* ht, void const *item)
+{
+ void **slot = hash_find_slot (ht, item);
+ return hash_delete_at (ht, slot);
+}
+
+void *
+hash_delete_at (struct hash_table* ht, void const *slot)
+{
+ void *item = *(void **) slot;
+ if (!HASH_VACANT (item))
+ {
+ *(void const **) slot = hash_deleted_item;
+ ht->ht_fill--;
+ return item;
+ }
+ else
+ return 0;
+}
+
+void
+hash_free_items (struct hash_table* ht)
+{
+ void **vec = ht->ht_vec;
+ void **end = &vec[ht->ht_size];
+ for (; vec < end; vec++)
+ {
+ void *item = *vec;
+ if (!HASH_VACANT (item))
+ free (item);
+ *vec = 0;
+ }
+ ht->ht_fill = 0;
+}
+
+void
+hash_delete_items (struct hash_table* ht)
+{
+ void **vec = ht->ht_vec;
+ void **end = &vec[ht->ht_size];
+ for (; vec < end; vec++)
+ *vec = 0;
+ ht->ht_fill = 0;
+ ht->ht_collisions = 0;
+ ht->ht_lookups = 0;
+ ht->ht_rehashes = 0;
+}
+
+void
+hash_free (struct hash_table* ht, int free_items)
+{
+ if (free_items)
+ hash_free_items (ht);
+ free (ht->ht_vec);
+ ht->ht_vec = 0;
+ ht->ht_fill = 0;
+ ht->ht_capacity = 0;
+}
+
+void
+hash_map (struct hash_table *ht, hash_map_func_t map)
+{
+ void **slot;
+ void **end = &ht->ht_vec[ht->ht_size];
+
+ for (slot = ht->ht_vec; slot < end; slot++)
+ {
+ if (!HASH_VACANT (*slot))
+ (*map) (*slot);
+ }
+}
+
+/* Double the size of the hash table in the event of overflow... */
+
+static void
+hash_rehash (struct hash_table* ht)
+{
+ unsigned long old_ht_size = ht->ht_size;
+ void **old_vec = ht->ht_vec;
+ void **ovp;
+ void **slot;
+
+ ht->ht_size *= 2;
+ ht->ht_rehashes++;
+ ht->ht_capacity = ht->ht_size - (ht->ht_size >> 4);
+ ht->ht_vec = (void **) CALLOC (struct token *, ht->ht_size);
+
+ for (ovp = old_vec; ovp < &old_vec[old_ht_size]; ovp++)
+ {
+ if (*ovp == 0)
+ continue;
+ slot = hash_find_slot (ht, *ovp);
+ *slot = *ovp;
+ }
+ free (old_vec);
+}
+
+void
+hash_print_stats (struct hash_table *ht, FILE *out_FILE)
+{
+ fprintf (out_FILE, _("Load=%ld/%ld=%.0f%%, "), ht->ht_fill, ht->ht_size,
+ 100.0 * (double) ht->ht_fill / (double) ht->ht_size);
+ fprintf (out_FILE, _("Rehash=%d, "), ht->ht_rehashes);
+ fprintf (out_FILE, _("Collisions=%ld/%ld=%.0f%%"), ht->ht_collisions, ht->ht_lookups,
+ (ht->ht_lookups
+ ? (100.0 * (double) ht->ht_collisions / (double) ht->ht_lookups)
+ : 0));
+}
+
+/* Dump all items into a NULL-terminated vector. Use the
+ user-supplied vector, or malloc one. */
+
+void**
+hash_dump (struct hash_table *ht, void **vector_0, qsort_cmp_t compare)
+{
+ void **vector;
+ void **slot;
+ void **end = &ht->ht_vec[ht->ht_size];
+
+ if (vector_0 == 0)
+ vector_0 = MALLOC (void *, ht->ht_fill + 1);
+ vector = vector_0;
+
+ for (slot = ht->ht_vec; slot < end; slot++)
+ if (!HASH_VACANT (*slot))
+ *vector++ = *slot;
+ *vector = 0;
+
+ if (compare)
+ qsort (vector_0, ht->ht_fill, sizeof (void *), compare);
+ return vector_0;
+}
+
+/* Round a given number up to the nearest power of 2. */
+
+static unsigned long
+round_up_2 (unsigned long rough)
+{
+ int round;
+
+ round = 1;
+ while (rough)
+ {
+ round <<= 1;
+ rough >>= 1;
+ }
+ return round;
+}
projects / bison.git / commitdiff
