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. */
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ 02110-1301, USA. */
#include <config.h>
+#include "hash.h"
+#include "error.h"
#include <assert.h>
+#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
+#include "algorithm.h"
#include "alloc.h"
-#include "hash.h"
+#include <stdbool.h>
+#include "misc.h"
#include "str.h"
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+
/* Note for constructing hash functions:
You can store the hash values in the records, then compare hash
\f
/* Prime numbers and hash functions. */
-static int hsh_prime_tab[] =
+/* Returns smallest power of 2 greater than X. */
+static size_t
+next_power_of_2 (size_t x)
{
- 13, 31, 47, 67, 131, 257, 521, 1031, 2053, 4099, 8209, 16411,
- 32771, 65537, 131101, 262147, 524309, 1048583, 2097169, 4194319,
- 8388617, 16777259, 33554467, 67108879, 134217757, 268435459,
- 536870923, 1073741827, INT_MAX,
-};
-
-/* Returns pointer into hsh_prime_tab[], pointing to the first prime
- in the table greater than X. */
-int *
-hsh_next_prime (int x)
+ assert (x != 0);
+
+ for (;;)
+ {
+ /* Turn off rightmost 1-bit in x. */
+ size_t y = x & (x - 1);
+
+ /* If y is 0 then x only had a single 1-bit. */
+ if (y == 0)
+ return 2 * x;
+
+ /* Otherwise turn off the next. */
+ x = y;
+ }
+}
+
+/* Fowler-Noll-Vo hash constants, for 32-bit word sizes. */
+#define FNV_32_PRIME 16777619u
+#define FNV_32_BASIS 2166136261u
+
+/* Fowler-Noll-Vo 32-bit hash, for bytes. */
+unsigned
+hsh_hash_bytes (const void *buf_, size_t size)
{
- int *p;
+ const unsigned char *buf = buf_;
+ unsigned hash;
- assert (x >= 0);
+ assert (buf != NULL);
- for (p = hsh_prime_tab; *p < x; p++)
- ;
+ hash = FNV_32_BASIS;
+ while (size-- > 0)
+ hash = (hash * FNV_32_PRIME) ^ *buf++;
+
+ return hash;
+}
+
+/* Fowler-Noll-Vo 32-bit hash, for strings. */
+unsigned
+hsh_hash_string (const char *s_)
+{
+ const unsigned char *s = s_;
+ unsigned hash;
- assert (*p != INT_MAX);
+ assert (s != NULL);
- return p;
+ hash = FNV_32_BASIS;
+ while (*s != '\0')
+ hash = (hash * FNV_32_PRIME) ^ *s++;
+
+ return hash;
}
-/* P.J. Weinberger's hash function, recommended by the Red Dragon
- Book. Hashes the d-string between S1 and S2. Returns unbounded
- nonnegative result. */
-int
-hashpjw_d (const char *s1, const char *s2)
+/* Fowler-Noll-Vo 32-bit hash, for case-insensitive strings. */
+unsigned
+hsh_hash_case_string (const char *s_)
{
- const char *p;
- unsigned g, h;
+ const unsigned char *s = s_;
+ unsigned hash;
- for (h = 0, p = s1; p < s2; p++)
- {
- h = (h << 4) + *(unsigned char *) p;
- g = h & 0xf0000000;
- h ^= (g >> 24) | g;
- }
- return abs ((int) h);
+ assert (s != NULL);
+
+ hash = FNV_32_BASIS;
+ while (*s != '\0')
+ hash = (hash * FNV_32_PRIME) ^ toupper (*s++);
+
+ return hash;
}
-/* Alternate entry point for hashpjw_d() that takes an s-string. */
-int
-hashpjw (const char *s)
+/* Hash for ints. */
+unsigned
+hsh_hash_int (int i)
{
- return hashpjw_d (s, &s[strlen (s)]);
+ return hsh_hash_bytes (&i, sizeof i);
+}
+
+/* Hash for double. */
+unsigned
+hsh_hash_double (double d)
+{
+ if (!isnan (d))
+ return hsh_hash_bytes (&d, sizeof d);
+ else
+ return 0;
}
\f
-/*hash tables. */
+/* Hash tables. */
+
+/* Hash table. */
+struct hsh_table
+ {
+ size_t used; /* Number of filled entries. */
+ size_t size; /* Number of entries (a power of 2). */
+ void **entries; /* Hash table proper. */
+
+ void *aux; /* Auxiliary data for comparison functions. */
+ hsh_compare_func *compare;
+ hsh_hash_func *hash;
+ hsh_free_func *free;
+
+#ifndef NDEBUG
+ /* Set to false if hsh_data() or hsh_sort() has been called,
+ so that most hsh_*() functions may no longer be called. */
+ bool hash_ordered;
+#endif
+ };
/* Creates a hash table with at least M entries. COMPARE is a
function that compares two entries and returns 0 if they are
identical, nonzero otherwise; HASH returns a nonnegative hash value
for an entry; FREE destroys an entry. */
struct hsh_table *
-hsh_create (int m,
- int (*compare) (const void *, const void *, void *param),
- unsigned (*hash) (const void *, void *param),
- void (*free) (void *, void *param),
- void *param)
+hsh_create (int size, hsh_compare_func *compare, hsh_hash_func *hash,
+ hsh_free_func *free, void *aux)
{
- struct hsh_table *h = xmalloc (sizeof *h);
+ struct hsh_table *h;
int i;
- h->n = 0;
- h->mp = hsh_next_prime (m);
- h->m = *h->mp++;
- h->table = xmalloc (sizeof *h->table * h->m);
- for (i = 0; i < h->m; i++)
- h->table[i] = NULL;
- h->param = param;
+ assert (compare != NULL);
+ assert (hash != NULL);
+
+ h = xmalloc (sizeof *h);
+ h->used = 0;
+ if (size < 4)
+ size = 4;
+ h->size = next_power_of_2 (size);
+ h->entries = xmalloc (sizeof *h->entries * h->size);
+ for (i = 0; i < h->size; i++)
+ h->entries[i] = NULL;
+ h->aux = aux;
h->compare = compare;
h->hash = hash;
h->free = free;
+#ifndef NDEBUG
+ h->hash_ordered = true;
+#endif
return h;
}
{
int i;
+ assert (h != NULL);
if (h->free)
- for (i = 0; i < h->m; i++)
- h->free (h->table[i], h->param);
+ for (i = 0; i < h->size; i++)
+ if (h->entries[i] != NULL)
+ h->free (h->entries[i], h->aux);
- if (h->m >= 128)
- {
- free (h->table);
- h->mp = hsh_next_prime (31);
- h->m = *h->mp++;
- h->table = xmalloc (sizeof *h->table * h->m);
- }
+ for (i = 0; i < h->size; i++)
+ h->entries[i] = NULL;
+
+ h->used = 0;
- for (i = 0; i < h->m; i++)
- h->table[i] = NULL;
+#ifndef NDEBUG
+ h->hash_ordered = true;
+#endif
}
/* Destroys table H and all its contents. */
{
int i;
- if (h == NULL)
- return;
- if (h->free)
- for (i = 0; i < h->m; i++)
- {
- void *p = h->table[i];
- if (p)
- h->free (p, h->param);
- }
- free (h->table);
- free (h);
+ if (h != NULL)
+ {
+ if (h->free)
+ for (i = 0; i < h->size; i++)
+ if (h->entries[i] != NULL)
+ h->free (h->entries[i], h->aux);
+ free (h->entries);
+ free (h);
+ }
}
-/* Increases the capacity of H. */
-void
-hsh_rehash (struct hsh_table *h)
+/* Locates an entry matching TARGET. Returns a pointer to the
+ entry, or a null pointer on failure. */
+static inline unsigned
+locate_matching_entry (struct hsh_table *h, const void *target)
{
- void **begin = h->table;
- void **end = &h->table[h->m];
- void **table_p;
+ unsigned i = h->hash (target, h->aux);
+
+ assert (h->hash_ordered);
+ for (;;)
+ {
+ void *entry;
+ i &= h->size - 1;
+ entry = h->entries[i];
+ if (entry == NULL || !h->compare (entry, target, h->aux))
+ return i;
+ i--;
+ }
+}
+
+/* Changes the capacity of H to NEW_SIZE, which must be a
+ positive power of 2 at least as large as the number of
+ elements in H. */
+static void
+rehash (struct hsh_table *h, size_t new_size)
+{
+ void **begin, **end, **table_p;
int i;
- h->m = *h->mp++;
- h->table = xmalloc (sizeof *h->table * h->m);
- for (i = 0; i < h->m; i++)
- h->table[i] = NULL;
- for (table_p = begin; table_p < end; table_p++)
+ assert (h != NULL);
+ assert (new_size >= h->used);
+
+ /* Verify that NEW_SIZE is a positive power of 2. */
+ assert (new_size > 0 && (new_size & (new_size - 1)) == 0);
+
+ begin = h->entries;
+ end = begin + h->size;
+
+ h->size = new_size;
+ h->entries = xmalloc (sizeof *h->entries * h->size);
+ for (i = 0; i < h->size; i++)
+ h->entries[i] = NULL;
+ for (table_p = begin; table_p < end; table_p++)
{
- void **entry;
-
- if (*table_p == NULL)
- continue;
- entry = &h->table[h->hash (*table_p, h->param) % h->m];
- while (*entry)
- if (--entry < h->table)
- entry = &h->table[h->m - 1];
- *entry = *table_p;
+ void *entry = *table_p;
+ if (entry != NULL)
+ h->entries[locate_matching_entry (h, entry)] = entry;
}
free (begin);
+
+#ifndef NDEBUG
+ h->hash_ordered = true;
+#endif
}
-/* Static variables for hsh_sort(). */
-static void *hsh_param;
-static int (*hsh_compare) (const void *, const void *, void *param);
+/* A "algo_predicate_func" that returns nonzero if DATA points
+ to a non-null void. */
+static int
+not_null (const void *data_, void *aux UNUSED)
+{
+ void *const *data = data_;
+
+ return *data != NULL;
+}
-/* hsh_sort() helper function that ensures NULLs are sorted after the
- rest of the table. */
+/* Compacts hash table H and returns a pointer to its data. The
+ returned data consists of hsh_count(H) non-null pointers, in
+ no particular order, followed by a null pointer.
+
+ After calling this function, only hsh_destroy() and
+ hsh_count() should be applied to H. hsh_first() and
+ hsh_next() could also be used, but you're better off just
+ iterating through the returned array.
+
+ This function is intended for use in situations where data
+ processing occurs in two phases. In the first phase, data is
+ added, removed, and searched for within a hash table. In the
+ second phase, the contents of the hash table are output and
+ the hash property itself is no longer of interest.
+
+ Use hsh_sort() instead, if the second phase wants data in
+ sorted order. Use hsh_data_copy() or hsh_sort_copy() instead,
+ if the second phase still needs to search the hash table. */
+void *const *
+hsh_data (struct hsh_table *h)
+{
+ size_t n;
+
+ assert (h != NULL);
+ n = partition (h->entries, h->size, sizeof *h->entries, not_null, NULL);
+ assert (n == h->used);
+#ifndef NDEBUG
+ h->hash_ordered = false;
+#endif
+ return h->entries;
+}
+
+/* Dereferences void ** pointers and passes them to the hash
+ comparison function. */
static int
-internal_comparison_fn (const void *pa, const void *pb)
+comparison_helper (const void *a_, const void *b_, void *h_)
+{
+ void *const *a = a_;
+ void *const *b = b_;
+ struct hsh_table *h = h_;
+
+ assert(a);
+ assert(b);
+
+ return h->compare (*a, *b, h->aux);
+}
+
+/* Sorts hash table H based on hash comparison function. The
+ returned data consists of hsh_count(H) non-null pointers,
+ sorted in order of the hash comparison function, followed by a
+ null pointer.
+
+ After calling this function, only hsh_destroy() and
+ hsh_count() should be applied to H. hsh_first() and
+ hsh_next() could also be used, but you're better off just
+ iterating through the returned array.
+
+ This function is intended for use in situations where data
+ processing occurs in two phases. In the first phase, data is
+ added, removed, and searched for within a hash table. In the
+ second phase, the contents of the hash table are output and
+ the hash property itself is no longer of interest.
+
+ Use hsh_data() instead, if the second phase doesn't need the
+ data in any particular order. Use hsh_data_copy() or
+ hsh_sort_copy() instead, if the second phase still needs to
+ search the hash table. */
+void *const *
+hsh_sort (struct hsh_table *h)
{
- void *a = *(void **) pa;
- void *b = *(void **) pb;
- return a == NULL ? 1 : (b == NULL ? -1 : hsh_compare (a, b, hsh_param));
+ assert (h != NULL);
+
+ hsh_data (h);
+ sort (h->entries, h->used, sizeof *h->entries, comparison_helper, h);
+ return h->entries;
}
-/* Sorts hash table H based on function COMPARE. NULLs are sent to
- the end of the table. The resultant table is returned (it is
- guaranteed to be NULL-terminated). H should not be used again as a
- hash table until and unless hsh_clear() called. */
+/* Makes and returns a copy of the pointers to the data in H.
+ The returned data consists of hsh_count(H) non-null pointers,
+ in no particular order, followed by a null pointer. The hash
+ table is not modified. The caller is responsible for freeing
+ the allocated data.
+
+ If you don't need to search or modify the hash table, then
+ hsh_data() is a more efficient choice. */
void **
-hsh_sort (struct hsh_table *h,
- int (*compare) (const void *, const void *, void *param))
+hsh_data_copy (struct hsh_table *h)
{
-#if GLOBAL_DEBUGGING
- static int reentrant;
- if (reentrant)
- abort ();
- reentrant++;
-#endif
- hsh_param = h->param;
- hsh_compare = compare ? compare : h->compare;
- qsort (h->table, h->m, sizeof *h->table, internal_comparison_fn);
-#if GLOBAL_DEBUGGING
- reentrant--;
-#endif
- return h->table;
+ void **copy;
+
+ assert (h != NULL);
+ copy = xmalloc ((h->used + 1) * sizeof *copy);
+ copy_if (h->entries, h->size, sizeof *h->entries, copy, not_null, NULL);
+ copy[h->used] = NULL;
+ return copy;
+}
+
+/* Makes and returns a copy of the pointers to the data in H.
+ The returned data consists of hsh_count(H) non-null pointers,
+ sorted in order of the hash comparison function, followed by a
+ null pointer. The hash table is not modified. The caller is
+ responsible for freeing the allocated data.
+
+ If you don't need to search or modify the hash table, then
+ hsh_sort() is a more efficient choice. */
+void **
+hsh_sort_copy (struct hsh_table *h)
+{
+ void **copy;
+
+ assert (h != NULL);
+ copy = hsh_data_copy (h);
+ sort (copy, h->used, sizeof *copy, comparison_helper, h);
+ return copy;
}
\f
/* Hash entries. */
-/* Searches hash table H for TARGET. If found, returns a pointer to a
- pointer to that entry; otherwise returns a pointer to a NULL entry
- which _must_ be used to insert a new entry having the same key
- data. */
+/* Searches hash table H for TARGET. If found, returns a pointer
+ to a pointer to that entry; otherwise returns a pointer to a
+ NULL entry which *must* be used to insert a new entry having
+ the same key data. */
inline void **
hsh_probe (struct hsh_table *h, const void *target)
+{
+ unsigned i;
+
+ assert (h != NULL);
+ assert (target != NULL);
+ assert (h->hash_ordered);
+
+ if (h->used > h->size / 2)
+ rehash (h, h->size * 2);
+ i = locate_matching_entry (h, target);
+ if (h->entries[i] == NULL)
+ h->used++;
+ return &h->entries[i];
+}
+
+/* Searches hash table H for TARGET. If not found, inserts
+ TARGET and returns a null pointer. If found, returns the
+ match, without replacing it in the table. */
+void *
+hsh_insert (struct hsh_table *h, void *target)
{
void **entry;
- /* Order of these statements is important! */
- if (h->n > h->m / 2)
- hsh_rehash (h);
- entry = &h->table[h->hash (target, h->param) % h->m];
+ assert (h != NULL);
+ assert (target != NULL);
- while (*entry)
+ entry = hsh_probe (h, target);
+ if (*entry == NULL)
{
- if (!h->compare (*entry, target, h->param))
- return entry;
-
- if (--entry < h->table)
- entry = &h->table[h->m - 1];
+ *entry = target;
+ return NULL;
}
- h->n++;
- return entry;
+ else
+ return *entry;
}
-/* Returns the entry in hash table H that matches TARGET, NULL if
- there is none. */
+/* Searches hash table H for TARGET. If not found, inserts
+ TARGET and returns a null pointer. If found, returns the
+ match, after replacing it in the table by TARGET. */
+void *
+hsh_replace (struct hsh_table *h, void *target)
+{
+ void **entry = hsh_probe (h, target);
+ void *old = *entry;
+ *entry = target;
+ return old;
+}
+
+/* Returns the entry in hash table H that matches TARGET, or NULL
+ if there is none. */
void *
hsh_find (struct hsh_table *h, const void *target)
{
- void **entry = &h->table[h->hash (target, h->param) % h->m];
+ return h->entries[locate_matching_entry (h, target)];
+}
+
+/* Deletes the entry in hash table H that matches TARGET.
+ Returns nonzero if an entry was deleted.
- while (*entry)
+ Uses Knuth's Algorithm 6.4R (Deletion with linear probing).
+ Because our load factor is at most 1/2, the average number of
+ moves that this algorithm makes should be at most 2 - ln 2 ~=
+ 1.65. */
+int
+hsh_delete (struct hsh_table *h, const void *target)
+{
+ unsigned i = locate_matching_entry (h, target);
+ if (h->entries[i] != NULL)
{
- if (!h->compare (*entry, target, h->param))
- return *entry;
- if (--entry < h->table)
- entry = &h->table[h->m - 1];
+ h->used--;
+ if (h->free != NULL)
+ h->free (h->entries[i], h->aux);
+
+ for (;;)
+ {
+ unsigned r;
+ ptrdiff_t j;
+
+ h->entries[i] = NULL;
+ j = i;
+ do
+ {
+ i = (i - 1) & (h->size - 1);
+ if (h->entries[i] == NULL)
+ return 1;
+
+ r = h->hash (h->entries[i], h->aux) & (h->size - 1);
+ }
+ while ((i <= r && r < j) || (r < j && j < i) || (j < i && i <= r));
+ h->entries[j] = h->entries[i];
+ }
}
- return NULL;
+ else
+ return 0;
+}
+\f
+/* Iteration. */
+
+/* Finds and returns an entry in TABLE, and initializes ITER for
+ use with hsh_next(). If TABLE is empty, returns a null
+ pointer. */
+void *
+hsh_first (struct hsh_table *h, struct hsh_iterator *iter)
+{
+ assert (h != NULL);
+ assert (iter != NULL);
+
+ iter->next = 0;
+ return hsh_next (h, iter);
}
-/* Iterates throught hash table TABLE with iterator ITER. Returns the
- next non-NULL entry in TABLE, or NULL after the last non-NULL
- entry. After NULL is returned, ITER is returned to a condition in
- which hsh_foreach() will return the first non-NULL entry if any on
- the next call. Do not add entries to TABLE between call to
- hsh_foreach() between NULL returns.
+/* Iterates through TABLE with iterator ITER. Returns the next
+ entry in TABLE, or a null pointer after the last entry.
- Before calling hsh_foreach with a particular iterator for the first
- time, you must initialize the iterator with a call to
- hsh_iterator_init. */
+ Entries are returned in an undefined order. Modifying TABLE
+ during iteration may cause some entries to be returned
+ multiple times or not at all. */
void *
-hsh_foreach (struct hsh_table *table, struct hsh_iterator *iter)
+hsh_next (struct hsh_table *h, struct hsh_iterator *iter)
{
- int i;
+ size_t i;
- if (!table)
- return NULL;
- if (!iter->init)
- {
- iter->init = 1;
- iter->next = 0;
- }
- for (i = iter->next; i < table->m; i++)
- if (table->table[i])
+ assert (h != NULL);
+ assert (iter != NULL);
+ assert (iter->next <= h->size);
+
+ for (i = iter->next; i < h->size; i++)
+ if (h->entries[i])
{
iter->next = i + 1;
- return table->table[i];
+ return h->entries[i];
}
- iter->init = 0;
+
+ iter->next = h->size;
return NULL;
}
+\f
+/* Returns the number of items in H. */
+size_t
+hsh_count (struct hsh_table *h)
+{
+ assert (h != NULL);
+
+ return h->used;
+}
+\f
+/* Debug helpers. */
#if GLOBAL_DEBUGGING
+#undef NDEBUG
+#include "error.h"
#include <stdio.h>
/* Displays contents of hash table H on stdout. */
void
hsh_dump (struct hsh_table *h)
{
- void **entry = h->table;
+ void **entry = h->entries;
int i;
printf (_("hash table:"));
- for (i = 0; i < h->m; i++)
+ for (i = 0; i < h->size; i++)
printf (" %p", *entry++);
printf ("\n");
}
to a NULL pointer. This function is used when it is known that the
entry to be inserted does not already exist in the table. */
void
-force_hsh_insert (struct hsh_table *h, void *p)
+hsh_force_insert (struct hsh_table *h, void *p)
{
void **pp = hsh_probe (h, p);
- if (*pp != NULL)
- assert (0);
+ assert (*pp == NULL);
*pp = p;
}
This function is for use when it is known that the entry being
searched for must exist in the table. */
void *
-force_hsh_find (struct hsh_table *h, const void *p)
+hsh_force_find (struct hsh_table *h, const void *target)
+{
+ void *found = hsh_find (h, target);
+ assert (found != NULL);
+ return found;
+}
+
+/* This wrapper for hsh_delete() verifies that an item really was
+ deleted. */
+void
+hsh_force_delete (struct hsh_table *h, const void *target)
{
- p = hsh_find (h, p);
- if (p == NULL)
- assert (0);
- return (void *) p;
+ int found = hsh_delete (h, target);
+ assert (found != 0);
}
#endif
projects / pspp-builds.git / blobdiff