/* hash - hashing table processing.
- Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
+
+ Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2006, 2007 Free
+ Software Foundation, Inc.
+
Written by Jim Meyering, 1992.
- This program is free software; you can redistribute it and/or modify
+ 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.
+ 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
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. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* A generic hash table package. */
/* Define USE_OBSTACK to 1 if you want the allocator to use obstacks instead
of malloc. If you change USE_OBSTACK, you have to recompile! */
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
-#if HAVE_STDLIB_H
-# include <stdlib.h>
-#endif
-#if HAVE_STDBOOL_H
-# include <stdbool.h>
-#else
-typedef enum {false = 0, true = 1} bool;
-#endif
-#include <stdio.h>
-#include <assert.h>
+#include <config.h>
-#ifndef HAVE_DECL_FREE
-"this configure-time declaration test was not run"
-#endif
-#if !HAVE_DECL_FREE
-void free ();
-#endif
+#include "hash.h"
+#include "xalloc.h"
-#ifndef HAVE_DECL_MALLOC
-"this configure-time declaration test was not run"
-#endif
-#if !HAVE_DECL_MALLOC
-char *malloc ();
-#endif
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
#if USE_OBSTACK
# include "obstack.h"
# endif
#endif
-#include "hash.h"
+#ifndef SIZE_MAX
+# define SIZE_MAX ((size_t) -1)
+#endif
+
+struct hash_table
+ {
+ /* The array of buckets starts at BUCKET and extends to BUCKET_LIMIT-1,
+ for a possibility of N_BUCKETS. Among those, N_BUCKETS_USED buckets
+ are not empty, there are N_ENTRIES active entries in the table. */
+ struct hash_entry *bucket;
+ struct hash_entry const *bucket_limit;
+ size_t n_buckets;
+ size_t n_buckets_used;
+ size_t n_entries;
+
+ /* Tuning arguments, kept in a physicaly separate structure. */
+ const Hash_tuning *tuning;
+
+ /* Three functions are given to `hash_initialize', see the documentation
+ block for this function. In a word, HASHER randomizes a user entry
+ into a number up from 0 up to some maximum minus 1; COMPARATOR returns
+ true if two user entries compare equally; and DATA_FREER is the cleanup
+ function for a user entry. */
+ Hash_hasher hasher;
+ Hash_comparator comparator;
+ Hash_data_freer data_freer;
+
+ /* A linked list of freed struct hash_entry structs. */
+ struct hash_entry *free_entry_list;
+
+#if USE_OBSTACK
+ /* Whenever obstacks are used, it is possible to allocate all overflowed
+ entries into a single stack, so they all can be freed in a single
+ operation. It is not clear if the speedup is worth the trouble. */
+ struct obstack entry_stack;
+#endif
+ };
/* A hash table contains many internal entries, each holding a pointer to
some user provided data (also called a user entry). An entry indistinctly
number of buckets (used plus unused), or the maximum number of slots, are
the same quantity. */
-unsigned
+size_t
hash_get_n_buckets (const Hash_table *table)
{
return table->n_buckets;
/* Return the number of slots in use (non-empty buckets). */
-unsigned
+size_t
hash_get_n_buckets_used (const Hash_table *table)
{
return table->n_buckets_used;
/* Return the number of active entries. */
-unsigned
+size_t
hash_get_n_entries (const Hash_table *table)
{
return table->n_entries;
/* Return the length of the longest chain (bucket). */
-unsigned
+size_t
hash_get_max_bucket_length (const Hash_table *table)
{
- struct hash_entry *bucket;
- unsigned max_bucket_length = 0;
+ struct hash_entry const *bucket;
+ size_t max_bucket_length = 0;
for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
{
if (bucket->data)
{
- struct hash_entry *cursor = bucket;
- unsigned bucket_length = 1;
+ struct hash_entry const *cursor = bucket;
+ size_t bucket_length = 1;
while (cursor = cursor->next, cursor)
bucket_length++;
bool
hash_table_ok (const Hash_table *table)
{
- struct hash_entry *bucket;
- unsigned n_buckets_used = 0;
- unsigned n_entries = 0;
+ struct hash_entry const *bucket;
+ size_t n_buckets_used = 0;
+ size_t n_entries = 0;
for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
{
if (bucket->data)
{
- struct hash_entry *cursor = bucket;
+ struct hash_entry const *cursor = bucket;
/* Count bucket head. */
n_buckets_used++;
void
hash_print_statistics (const Hash_table *table, FILE *stream)
{
- unsigned n_entries = hash_get_n_entries (table);
- unsigned n_buckets = hash_get_n_buckets (table);
- unsigned n_buckets_used = hash_get_n_buckets_used (table);
- unsigned max_bucket_length = hash_get_max_bucket_length (table);
-
- fprintf (stream, "# entries: %u\n", n_entries);
- fprintf (stream, "# buckets: %u\n", n_buckets);
- fprintf (stream, "# buckets used: %u (%.2f%%)\n", n_buckets_used,
+ size_t n_entries = hash_get_n_entries (table);
+ size_t n_buckets = hash_get_n_buckets (table);
+ size_t n_buckets_used = hash_get_n_buckets_used (table);
+ size_t max_bucket_length = hash_get_max_bucket_length (table);
+
+ fprintf (stream, "# entries: %lu\n", (unsigned long int) n_entries);
+ fprintf (stream, "# buckets: %lu\n", (unsigned long int) n_buckets);
+ fprintf (stream, "# buckets used: %lu (%.2f%%)\n",
+ (unsigned long int) n_buckets_used,
(100.0 * n_buckets_used) / n_buckets);
- fprintf (stream, "max bucket length: %u\n", max_bucket_length);
+ fprintf (stream, "max bucket length: %lu\n",
+ (unsigned long int) max_bucket_length);
}
/* If ENTRY matches an entry already in the hash table, return the
void *
hash_lookup (const Hash_table *table, const void *entry)
{
- struct hash_entry *bucket
+ struct hash_entry const *bucket
= table->bucket + table->hasher (entry, table->n_buckets);
- struct hash_entry *cursor;
+ struct hash_entry const *cursor;
- assert (bucket < table->bucket_limit);
+ if (! (bucket < table->bucket_limit))
+ abort ();
if (bucket->data == NULL)
return NULL;
void *
hash_get_first (const Hash_table *table)
{
- struct hash_entry *bucket;
+ struct hash_entry const *bucket;
if (table->n_entries == 0)
return NULL;
- for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
- if (bucket->data)
+ for (bucket = table->bucket; ; bucket++)
+ if (! (bucket < table->bucket_limit))
+ abort ();
+ else if (bucket->data)
return bucket->data;
-
- assert (0);
- return NULL;
}
/* Return the user data for the entry following ENTRY, where ENTRY has been
void *
hash_get_next (const Hash_table *table, const void *entry)
{
- struct hash_entry *bucket
+ struct hash_entry const *bucket
= table->bucket + table->hasher (entry, table->n_buckets);
- struct hash_entry *cursor;
+ struct hash_entry const *cursor;
- assert (bucket < table->bucket_limit);
+ if (! (bucket < table->bucket_limit))
+ abort ();
/* Find next entry in the same bucket. */
for (cursor = bucket; cursor; cursor = cursor->next)
return the number of pointers copied. Do not copy more than BUFFER_SIZE
pointers. */
-unsigned
+size_t
hash_get_entries (const Hash_table *table, void **buffer,
- unsigned buffer_size)
+ size_t buffer_size)
{
- unsigned counter = 0;
- struct hash_entry *bucket;
- struct hash_entry *cursor;
+ size_t counter = 0;
+ struct hash_entry const *bucket;
+ struct hash_entry const *cursor;
for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
{
as received. The walking continue for as long as the PROCESSOR function
returns nonzero. When it returns zero, the walking is interrupted. */
-unsigned
+size_t
hash_do_for_each (const Hash_table *table, Hash_processor processor,
void *processor_data)
{
- unsigned counter = 0;
- struct hash_entry *bucket;
- struct hash_entry *cursor;
+ size_t counter = 0;
+ struct hash_entry const *bucket;
+ struct hash_entry const *cursor;
for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
{
algorithms tend to be domain-specific, so what's good for [diffutils'] io.c
may not be good for your application." */
-unsigned
-hash_string (const char *string, unsigned n_buckets)
+size_t
+hash_string (const char *string, size_t n_buckets)
{
-# ifndef CHAR_BIT
-# define CHAR_BIT 8
-# endif
# define ROTATE_LEFT(Value, Shift) \
- ((Value) << (Shift) | (Value) >> ((sizeof (unsigned) * CHAR_BIT) - (Shift)))
+ ((Value) << (Shift) | (Value) >> ((sizeof (size_t) * CHAR_BIT) - (Shift)))
# define HASH_ONE_CHAR(Value, Byte) \
((Byte) + ROTATE_LEFT (Value, 7))
- unsigned value = 0;
+ size_t value = 0;
+ unsigned char ch;
- for (; *string; string++)
- value = HASH_ONE_CHAR (value, *(const unsigned char *) string);
+ for (; (ch = *string); string++)
+ value = HASH_ONE_CHAR (value, ch);
return value % n_buckets;
# undef ROTATE_LEFT
very old Cyber `snoop', itself written in typical Greg Mansfield style.
(By the way, what happened to this excellent man? Is he still alive?) */
-unsigned
-hash_string (const char *string, unsigned n_buckets)
+size_t
+hash_string (const char *string, size_t n_buckets)
{
- unsigned value = 0;
+ size_t value = 0;
+ unsigned char ch;
- while (*string)
- value = ((value * 31 + (int) *(const unsigned char *) string++)
- % n_buckets);
+ for (; (ch = *string); string++)
+ value = (value * 31 + ch) % n_buckets;
return value;
}
number at least equal to 11. */
static bool
-is_prime (unsigned long candidate)
+is_prime (size_t candidate)
{
- unsigned long divisor = 3;
- unsigned long square = divisor * divisor;
+ size_t divisor = 3;
+ size_t square = divisor * divisor;
while (square < candidate && (candidate % divisor))
{
/* Round a given CANDIDATE number up to the nearest prime, and return that
prime. Primes lower than 10 are merely skipped. */
-static unsigned long
-next_prime (unsigned long candidate)
+static size_t
+next_prime (size_t candidate)
{
/* Skip small primes. */
if (candidate < 10)
{
const Hash_tuning *tuning = table->tuning;
- if (tuning->growth_threshold > 0.0
- && tuning->growth_threshold < 1.0
- && tuning->growth_factor > 1.0
- && tuning->shrink_threshold >= 0.0
- && tuning->shrink_threshold < 1.0
- && tuning->shrink_factor > tuning->shrink_threshold
- && tuning->shrink_factor <= 1.0
- && tuning->shrink_threshold < tuning->growth_threshold)
+ /* Be a bit stricter than mathematics would require, so that
+ rounding errors in size calculations do not cause allocations to
+ fail to grow or shrink as they should. The smallest allocation
+ is 11 (due to next_prime's algorithm), so an epsilon of 0.1
+ should be good enough. */
+ float epsilon = 0.1f;
+
+ if (epsilon < tuning->growth_threshold
+ && tuning->growth_threshold < 1 - epsilon
+ && 1 + epsilon < tuning->growth_factor
+ && 0 <= tuning->shrink_threshold
+ && tuning->shrink_threshold + epsilon < tuning->shrink_factor
+ && tuning->shrink_factor <= 1
+ && tuning->shrink_threshold + epsilon < tuning->growth_threshold)
return true;
table->tuning = &default_tuning;
values. */
Hash_table *
-hash_initialize (unsigned candidate, const Hash_tuning *tuning,
+hash_initialize (size_t candidate, const Hash_tuning *tuning,
Hash_hasher hasher, Hash_comparator comparator,
Hash_data_freer data_freer)
{
Hash_table *table;
- struct hash_entry *bucket;
if (hasher == NULL || comparator == NULL)
return NULL;
- table = (Hash_table *) malloc (sizeof (Hash_table));
+ table = malloc (sizeof *table);
if (table == NULL)
return NULL;
if the user provides invalid tuning options, we silently revert to
using the defaults, and ignore further request to change the tuning
options. */
- free (table);
- return NULL;
+ goto fail;
}
- table->n_buckets
- = next_prime (tuning->is_n_buckets ? candidate
- : (unsigned) (candidate / tuning->growth_threshold));
-
- table->bucket = (struct hash_entry *)
- malloc (table->n_buckets * sizeof (struct hash_entry));
- if (table->bucket == NULL)
+ if (!tuning->is_n_buckets)
{
- free (table);
- return NULL;
+ float new_candidate = candidate / tuning->growth_threshold;
+ if (SIZE_MAX <= new_candidate)
+ goto fail;
+ candidate = new_candidate;
}
- table->bucket_limit = table->bucket + table->n_buckets;
- for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
- {
- bucket->data = NULL;
- bucket->next = NULL;
- }
+ if (xalloc_oversized (candidate, sizeof *table->bucket))
+ goto fail;
+ table->n_buckets = next_prime (candidate);
+ if (xalloc_oversized (table->n_buckets, sizeof *table->bucket))
+ goto fail;
+
+ table->bucket = calloc (table->n_buckets, sizeof *table->bucket);
+ if (table->bucket == NULL)
+ goto fail;
+ table->bucket_limit = table->bucket + table->n_buckets;
table->n_buckets_used = 0;
table->n_entries = 0;
obstack_init (&table->entry_stack);
#endif
return table;
+
+ fail:
+ free (table);
+ return NULL;
}
/* Make all buckets empty, placing any chained entries on the free list.
hash_clear (Hash_table *table)
{
struct hash_entry *bucket;
- struct hash_entry *cursor;
for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
{
if (bucket->data)
{
+ struct hash_entry *cursor;
+ struct hash_entry *next;
+
/* Free the bucket overflow. */
- for (cursor = bucket->next; cursor; cursor = cursor->next)
+ for (cursor = bucket->next; cursor; cursor = next)
{
if (table->data_freer)
(*table->data_freer) (cursor->data);
cursor->data = NULL;
+ next = cursor->next;
/* Relinking is done one entry at a time, as it is to be expected
that overflows are either rare or short. */
cursor->next = table->free_entry_list;
else
{
#if USE_OBSTACK
- new = (struct hash_entry *)
- obstack_alloc (&table->entry_stack, sizeof (struct hash_entry));
+ new = obstack_alloc (&table->entry_stack, sizeof *new);
#else
- new = (struct hash_entry *) malloc (sizeof (struct hash_entry));
+ new = malloc (sizeof *new);
#endif
}
= table->bucket + table->hasher (entry, table->n_buckets);
struct hash_entry *cursor;
- assert (bucket < table->bucket_limit);
+ if (! (bucket < table->bucket_limit))
+ abort ();
+
*bucket_head = bucket;
/* Test for empty bucket. */
exact number of buckets desired. */
bool
-hash_rehash (Hash_table *table, unsigned candidate)
+hash_rehash (Hash_table *table, size_t candidate)
{
Hash_table *new_table;
struct hash_entry *bucket;
= (new_table->bucket
+ new_table->hasher (data, new_table->n_buckets));
- assert (new_bucket < new_table->bucket_limit);
+ if (! (new_bucket < new_table->bucket_limit))
+ abort ();
+
next = cursor->next;
if (new_bucket->data)
void *data;
struct hash_entry *bucket;
- assert (entry); /* cannot insert a NULL entry */
+ /* The caller cannot insert a NULL entry. */
+ if (! entry)
+ abort ();
/* If there's a matching entry already in the table, return that. */
if ((data = hash_find_entry (table, entry, &bucket, false)) != NULL)
> table->tuning->growth_threshold * table->n_buckets)
{
const Hash_tuning *tuning = table->tuning;
- unsigned candidate
- = (unsigned) (tuning->is_n_buckets
- ? (table->n_buckets * tuning->growth_factor)
- : (table->n_buckets * tuning->growth_factor
- * tuning->growth_threshold));
+ float candidate =
+ (tuning->is_n_buckets
+ ? (table->n_buckets * tuning->growth_factor)
+ : (table->n_buckets * tuning->growth_factor
+ * tuning->growth_threshold));
+
+ if (SIZE_MAX <= candidate)
+ return NULL;
/* If the rehash fails, arrange to return NULL. */
if (!hash_rehash (table, candidate))
< table->tuning->shrink_threshold * table->n_buckets)
{
const Hash_tuning *tuning = table->tuning;
- unsigned candidate
- = (unsigned) (tuning->is_n_buckets
- ? table->n_buckets * tuning->shrink_factor
- : (table->n_buckets * tuning->shrink_factor
- * tuning->growth_threshold));
+ size_t candidate =
+ (tuning->is_n_buckets
+ ? table->n_buckets * tuning->shrink_factor
+ : (table->n_buckets * tuning->shrink_factor
+ * tuning->growth_threshold));
hash_rehash (table, candidate);
}
void
hash_print (const Hash_table *table)
{
- struct hash_entry *bucket;
+ struct hash_entry const *bucket;
for (bucket = table->bucket; bucket < table->bucket_limit; bucket++)
{
struct hash_entry *cursor;
if (bucket)
- printf ("%d:\n", slot);
+ printf ("%lu:\n", (unsigned long int) (bucket - table->bucket));
for (cursor = bucket; cursor; cursor = cursor->next)
{
- char *s = (char *) cursor->data;
+ char const *s = cursor->data;
/* FIXME */
- printf (" %s\n", s);
+ if (s)
+ printf (" %s\n", s);
}
}
}
projects / gnulib.git / blobdiff