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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* The Original Code is Mozilla Communicator client code, released
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1998
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* the Initial Developer. All Rights Reserved.
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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* ***** END LICENSE BLOCK ***** */
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* PR hash table package.
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#include "jsutil.h" /* Added by JSIFY */
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#include "jshash.h" /* Added by JSIFY */
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/* Compute the number of buckets in ht */
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#define NBUCKETS(ht) JS_BIT(JS_HASH_BITS - (ht)->shift)
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/* The smallest table has 16 buckets */
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#define MINBUCKETSLOG2 4
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#define MINBUCKETS JS_BIT(MINBUCKETSLOG2)
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/* Compute the maximum entries given n buckets that we will tolerate, ~90% */
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#define OVERLOADED(n) ((n) - ((n) >> 3))
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/* Compute the number of entries below which we shrink the table by half */
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#define UNDERLOADED(n) (((n) > MINBUCKETS) ? ((n) >> 2) : 0)
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** Stubs for default hash allocator ops.
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DefaultAllocTable(void *pool, size_t size)
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DefaultFreeTable(void *pool, void *item)
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DefaultAllocEntry(void *pool, const void *key)
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return (JSHashEntry*) malloc(sizeof(JSHashEntry));
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DefaultFreeEntry(void *pool, JSHashEntry *he, uintN flag)
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if (flag == HT_FREE_ENTRY)
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static JSHashAllocOps defaultHashAllocOps = {
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DefaultAllocTable, DefaultFreeTable,
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DefaultAllocEntry, DefaultFreeEntry
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JS_PUBLIC_API(JSHashTable *)
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JS_NewHashTable(uint32 n, JSHashFunction keyHash,
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JSHashComparator keyCompare, JSHashComparator valueCompare,
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JSHashAllocOps *allocOps, void *allocPriv)
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if (n <= MINBUCKETS) {
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n = JS_CeilingLog2(n);
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if (!allocOps) allocOps = &defaultHashAllocOps;
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ht = (JSHashTable*) allocOps->allocTable(allocPriv, sizeof *ht);
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memset(ht, 0, sizeof *ht);
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ht->shift = JS_HASH_BITS - n;
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nb = n * sizeof(JSHashEntry *);
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ht->buckets = (JSHashEntry**) allocOps->allocTable(allocPriv, nb);
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allocOps->freeTable(allocPriv, ht);
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memset(ht->buckets, 0, nb);
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ht->keyHash = keyHash;
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ht->keyCompare = keyCompare;
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ht->valueCompare = valueCompare;
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ht->allocOps = allocOps;
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ht->allocPriv = allocPriv;
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JS_HashTableDestroy(JSHashTable *ht)
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JSHashEntry *he, **hep;
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JSHashAllocOps *allocOps = ht->allocOps;
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void *allocPriv = ht->allocPriv;
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for (i = 0; i < n; i++) {
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hep = &ht->buckets[i];
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while ((he = *hep) != NULL) {
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allocOps->freeEntry(allocPriv, he, HT_FREE_ENTRY);
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memset(ht->buckets, 0xDB, n * sizeof ht->buckets[0]);
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allocOps->freeTable(allocPriv, ht->buckets);
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memset(ht, 0xDB, sizeof *ht);
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allocOps->freeTable(allocPriv, ht);
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** Multiplicative hash, from Knuth 6.4.
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JS_PUBLIC_API(JSHashEntry **)
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JS_HashTableRawLookup(JSHashTable *ht, JSHashNumber keyHash, const void *key)
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JSHashEntry *he, **hep, **hep0;
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h = keyHash * JS_GOLDEN_RATIO;
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hep = hep0 = &ht->buckets[h];
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while ((he = *hep) != NULL) {
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if (he->keyHash == keyHash && ht->keyCompare(key, he->key)) {
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/* Move to front of chain if not already there */
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JS_PUBLIC_API(JSHashEntry *)
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JS_HashTableRawAdd(JSHashTable *ht, JSHashEntry **hep,
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JSHashNumber keyHash, const void *key, void *value)
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JSHashEntry *he, *next, **oldbuckets;
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/* Grow the table if it is overloaded */
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if (ht->nentries >= OVERLOADED(n)) {
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oldbuckets = ht->buckets;
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nb = 2 * n * sizeof(JSHashEntry *);
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ht->buckets = (JSHashEntry**)
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ht->allocOps->allocTable(ht->allocPriv, nb);
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ht->buckets = oldbuckets;
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memset(ht->buckets, 0, nb);
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for (i = 0; i < n; i++) {
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for (he = oldbuckets[i]; he; he = next) {
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hep = JS_HashTableRawLookup(ht, he->keyHash, he->key);
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JS_ASSERT(*hep == NULL);
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memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
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ht->allocOps->freeTable(ht->allocPriv, oldbuckets);
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hep = JS_HashTableRawLookup(ht, keyHash, key);
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/* Make a new key value entry */
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he = ht->allocOps->allocEntry(ht->allocPriv, key);
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he->keyHash = keyHash;
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JS_PUBLIC_API(JSHashEntry *)
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JS_HashTableAdd(JSHashTable *ht, const void *key, void *value)
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JSHashNumber keyHash;
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JSHashEntry *he, **hep;
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keyHash = ht->keyHash(key);
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hep = JS_HashTableRawLookup(ht, keyHash, key);
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if ((he = *hep) != NULL) {
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/* Hit; see if values match */
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if (ht->valueCompare(he->value, value)) {
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/* key,value pair is already present in table */
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ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_VALUE);
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return JS_HashTableRawAdd(ht, hep, keyHash, key, value);
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JS_HashTableRawRemove(JSHashTable *ht, JSHashEntry **hep, JSHashEntry *he)
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JSHashEntry *next, **oldbuckets;
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ht->allocOps->freeEntry(ht->allocPriv, he, HT_FREE_ENTRY);
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/* Shrink table if it's underloaded */
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if (--ht->nentries < UNDERLOADED(n)) {
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oldbuckets = ht->buckets;
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nb = n * sizeof(JSHashEntry*) / 2;
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ht->buckets = (JSHashEntry**)
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ht->allocOps->allocTable(ht->allocPriv, nb);
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ht->buckets = oldbuckets;
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memset(ht->buckets, 0, nb);
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for (i = 0; i < n; i++) {
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for (he = oldbuckets[i]; he; he = next) {
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hep = JS_HashTableRawLookup(ht, he->keyHash, he->key);
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JS_ASSERT(*hep == NULL);
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memset(oldbuckets, 0xDB, n * sizeof oldbuckets[0]);
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ht->allocOps->freeTable(ht->allocPriv, oldbuckets);
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JS_PUBLIC_API(JSBool)
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JS_HashTableRemove(JSHashTable *ht, const void *key)
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JSHashNumber keyHash;
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JSHashEntry *he, **hep;
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keyHash = ht->keyHash(key);
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hep = JS_HashTableRawLookup(ht, keyHash, key);
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if ((he = *hep) == NULL)
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/* Hit; remove element */
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JS_HashTableRawRemove(ht, hep, he);
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JS_PUBLIC_API(void *)
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JS_HashTableLookup(JSHashTable *ht, const void *key)
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JSHashNumber keyHash;
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JSHashEntry *he, **hep;
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keyHash = ht->keyHash(key);
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hep = JS_HashTableRawLookup(ht, keyHash, key);
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if ((he = *hep) != NULL) {
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** Iterate over the entries in the hash table calling func for each
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** entry found. Stop if "f" says to (return value & JS_ENUMERATE_STOP).
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** Return a count of the number of elements scanned.
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JS_HashTableEnumerateEntries(JSHashTable *ht, JSHashEnumerator f, void *arg)
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JSHashEntry *he, **hep;
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JSHashEntry *todo = NULL;
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nbuckets = NBUCKETS(ht);
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for (i = 0; i < nbuckets; i++) {
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hep = &ht->buckets[i];
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while ((he = *hep) != NULL) {
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if (rv & (HT_ENUMERATE_REMOVE | HT_ENUMERATE_UNHASH)) {
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if (rv & HT_ENUMERATE_REMOVE) {
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if (rv & HT_ENUMERATE_STOP) {
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while ((he = *hep) != NULL) {
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JS_HashTableRawRemove(ht, hep, he);
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JS_HashTableDumpMeter(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
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double sqsum, mean, variance, sigma;
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uint32 nchains, nbuckets, nentries;
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uint32 i, n, maxChain, maxChainLen;
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nbuckets = NBUCKETS(ht);
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for (i = 0; i < nbuckets; i++) {
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for (n = 0; he; he = he->next)
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if (n > maxChainLen) {
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nentries = ht->nentries;
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mean = (double)nentries / nchains;
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variance = nchains * sqsum - nentries * nentries;
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if (variance < 0 || nchains == 1)
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variance /= nchains * (nchains - 1);
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sigma = sqrt(variance);
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fprintf(fp, "\nHash table statistics:\n");
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fprintf(fp, " number of lookups: %u\n", ht->nlookups);
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fprintf(fp, " number of entries: %u\n", ht->nentries);
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fprintf(fp, " number of grows: %u\n", ht->ngrows);
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fprintf(fp, " number of shrinks: %u\n", ht->nshrinks);
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fprintf(fp, " mean steps per hash: %g\n", (double)ht->nsteps
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fprintf(fp, "mean hash chain length: %g\n", mean);
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fprintf(fp, " standard deviation: %g\n", sigma);
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fprintf(fp, " max hash chain length: %u\n", maxChainLen);
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fprintf(fp, " max hash chain: [%u]\n", maxChain);
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for (he = ht->buckets[maxChain], i = 0; he; he = he->next, i++)
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if (dump(he, i, fp) != HT_ENUMERATE_NEXT)
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#endif /* HASHMETER */
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JS_HashTableDump(JSHashTable *ht, JSHashEnumerator dump, FILE *fp)
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count = JS_HashTableEnumerateEntries(ht, dump, fp);
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JS_HashTableDumpMeter(ht, dump, fp);
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JS_PUBLIC_API(JSHashNumber)
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JS_HashString(const void *key)
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const unsigned char *s;
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for (s = (const unsigned char *)key; *s; s++)
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h = (h >> (JS_HASH_BITS - 4)) ^ (h << 4) ^ *s;
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JS_CompareValues(const void *v1, const void *v2)