2 * Copyright (c) 1988, 1989, 1990, 1993
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4 * Copyright (c) 1988, 1989 by Adam de Boor
5 * Copyright (c) 1989 by Berkeley Softworks
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39 * @(#)hash.c 8.1 (Berkeley) 6/6/93
40 * $FreeBSD: src/usr.bin/make/hash.c,v 1.24 2005/02/01 10:50:35 harti Exp $
41 * $DragonFly: src/usr.bin/make/hash.c,v 1.17 2005/05/05 09:06:23 okumoto Exp $
46 * This module contains routines to manipulate a hash table.
47 * See hash.h for a definition of the structure of the hash
48 * table. Hash tables grow automatically as the amount of
49 * information increases.
60 * Forward references to local procedures that are used before they're
63 static void RebuildTable(Hash_Table *);
66 * The following defines the ratio of # entries to # buckets
67 * at which we rebuild the table to make it larger.
70 #define rebuildLimit 8
73 *---------------------------------------------------------
77 * Set up the hash table t with a given number of buckets, or a
78 * reasonable default if the number requested is less than or
79 * equal to zero. Hash tables will grow in size as needed.
86 * Memory is allocated for the initial bucket area.
88 *---------------------------------------------------------
91 Hash_InitTable(Hash_Table *t, int numBuckets)
94 struct Hash_Entry **hp;
97 * Round up the size to a power of two.
102 for (i = 2; i < numBuckets; i <<= 1)
108 t->bucketPtr = hp = emalloc(sizeof(*hp) * i);
114 *---------------------------------------------------------
116 * Hash_DeleteTable --
118 * This routine removes everything from a hash table
119 * and frees up the memory space it occupied (except for
120 * the space in the Hash_Table structure).
126 * Lots of memory is freed up.
128 *---------------------------------------------------------
131 Hash_DeleteTable(Hash_Table *t)
133 struct Hash_Entry **hp, *h, *nexth = NULL;
136 for (hp = t->bucketPtr, i = t->size; --i >= 0;) {
137 for (h = *hp++; h != NULL; h = nexth) {
145 * Set up the hash table to cause memory faults on any future access
146 * attempts until re-initialization.
152 *---------------------------------------------------------
156 * Searches a hash table for an entry corresponding to key.
159 * The return value is a pointer to the entry for key,
160 * if key was present in the table. If key was not
161 * present, NULL is returned.
166 *---------------------------------------------------------
169 Hash_FindEntry(const Hash_Table *t, const char *key)
175 for (h = 0, p = key; *p;)
176 h = (h << 5) - h + *p++;
178 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next)
179 if (e->namehash == h && strcmp(e->name, p) == 0)
185 *---------------------------------------------------------
187 * Hash_CreateEntry --
189 * Searches a hash table for an entry corresponding to
190 * key. If no entry is found, then one is created.
193 * The return value is a pointer to the entry. If *newPtr
194 * isn't NULL, then *newPtr is filled in with TRUE if a
195 * new entry was created, and FALSE if an entry already existed
196 * with the given key.
199 * Memory may be allocated, and the hash buckets may be modified.
200 *---------------------------------------------------------
203 Hash_CreateEntry(Hash_Table *t, const char *key, Boolean *newPtr)
209 struct Hash_Entry **hp;
212 * Hash the key. As a side effect, save the length (strlen) of the
213 * key in case we need to create the entry.
215 for (h = 0, p = key; *p;)
216 h = (h << 5) - h + *p++;
219 for (e = t->bucketPtr[h & t->mask]; e != NULL; e = e->next) {
220 if (e->namehash == h && strcmp(e->name, p) == 0) {
228 * The desired entry isn't there. Before allocating a new entry,
229 * expand the table if necessary (and this changes the resulting
232 if (t->numEntries >= rebuildLimit * t->size)
234 e = emalloc(sizeof(*e) + keylen);
235 hp = &t->bucketPtr[h & t->mask];
238 e->clientData = NULL;
249 *---------------------------------------------------------
251 * Hash_DeleteEntry --
253 * Delete the given hash table entry and free memory associated with
260 * Hash chain that entry lives in is modified and memory is freed.
262 *---------------------------------------------------------
265 Hash_DeleteEntry(Hash_Table *t, Hash_Entry *e)
271 for (hp = &t->bucketPtr[e->namehash & t->mask];
272 (p = *hp) != NULL; hp = &p->next) {
280 write(STDERR_FILENO, "bad call to Hash_DeleteEntry\n", 29);
285 *---------------------------------------------------------
288 * This procedure sets things up for a complete search
289 * of all entries recorded in the hash table.
292 * The return value is the address of the first entry in
293 * the hash table, or NULL if the table is empty.
296 * The information in searchPtr is initialized so that successive
297 * calls to Hash_Next will return successive HashEntry's
300 *---------------------------------------------------------
303 Hash_EnumFirst(const Hash_Table *t, Hash_Search *searchPtr)
306 searchPtr->tablePtr = t;
307 searchPtr->nextIndex = 0;
308 searchPtr->hashEntryPtr = NULL;
309 return (Hash_EnumNext(searchPtr));
313 *---------------------------------------------------------
316 * This procedure returns successive entries in the hash table.
319 * The return value is a pointer to the next HashEntry
320 * in the table, or NULL when the end of the table is
324 * The information in searchPtr is modified to advance to the
327 *---------------------------------------------------------
330 Hash_EnumNext(Hash_Search *searchPtr)
333 const Hash_Table *t = searchPtr->tablePtr;
336 * The hashEntryPtr field points to the most recently returned
337 * entry, or is NULL if we are starting up. If not NULL, we have
338 * to start at the next one in the chain.
340 e = searchPtr->hashEntryPtr;
344 * If the chain ran out, or if we are starting up, we need to
345 * find the next nonempty chain.
348 if (searchPtr->nextIndex >= t->size)
350 e = t->bucketPtr[searchPtr->nextIndex++];
352 searchPtr->hashEntryPtr = e;
357 *---------------------------------------------------------
360 * This local routine makes a new hash table that
361 * is larger than the old one.
367 * The entire hash table is moved, so any bucket numbers
368 * from the old table are invalid.
370 *---------------------------------------------------------
373 RebuildTable(Hash_Table *t)
375 Hash_Entry *e, *next = NULL, **hp, **xp;
380 oldhp = t->bucketPtr;
381 oldsize = i = t->size;
384 t->mask = mask = i - 1;
385 t->bucketPtr = hp = emalloc(sizeof(*hp) * i);
388 for (hp = oldhp, i = oldsize; --i >= 0;) {
389 for (e = *hp++; e != NULL; e = next) {
391 xp = &t->bucketPtr[e->namehash & mask];