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-rw-r--r--ext/sqlite/libsqlite/src/hash.c356
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diff --git a/ext/sqlite/libsqlite/src/hash.c b/ext/sqlite/libsqlite/src/hash.c
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-/*
-** 2001 September 22
-**
-** The author disclaims copyright to this source code. In place of
-** a legal notice, here is a blessing:
-**
-** May you do good and not evil.
-** May you find forgiveness for yourself and forgive others.
-** May you share freely, never taking more than you give.
-**
-*************************************************************************
-** This is the implementation of generic hash-tables
-** used in SQLite.
-**
-** $Id$
-*/
-#include "sqliteInt.h"
-#include <assert.h>
-
-/* Turn bulk memory into a hash table object by initializing the
-** fields of the Hash structure.
-**
-** "new" is a pointer to the hash table that is to be initialized.
-** keyClass is one of the constants SQLITE_HASH_INT, SQLITE_HASH_POINTER,
-** SQLITE_HASH_BINARY, or SQLITE_HASH_STRING. The value of keyClass
-** determines what kind of key the hash table will use. "copyKey" is
-** true if the hash table should make its own private copy of keys and
-** false if it should just use the supplied pointer. CopyKey only makes
-** sense for SQLITE_HASH_STRING and SQLITE_HASH_BINARY and is ignored
-** for other key classes.
-*/
-void sqliteHashInit(Hash *new, int keyClass, int copyKey){
- assert( new!=0 );
- assert( keyClass>=SQLITE_HASH_INT && keyClass<=SQLITE_HASH_BINARY );
- new->keyClass = keyClass;
- new->copyKey = copyKey &&
- (keyClass==SQLITE_HASH_STRING || keyClass==SQLITE_HASH_BINARY);
- new->first = 0;
- new->count = 0;
- new->htsize = 0;
- new->ht = 0;
-}
-
-/* Remove all entries from a hash table. Reclaim all memory.
-** Call this routine to delete a hash table or to reset a hash table
-** to the empty state.
-*/
-void sqliteHashClear(Hash *pH){
- HashElem *elem; /* For looping over all elements of the table */
-
- assert( pH!=0 );
- elem = pH->first;
- pH->first = 0;
- if( pH->ht ) sqliteFree(pH->ht);
- pH->ht = 0;
- pH->htsize = 0;
- while( elem ){
- HashElem *next_elem = elem->next;
- if( pH->copyKey && elem->pKey ){
- sqliteFree(elem->pKey);
- }
- sqliteFree(elem);
- elem = next_elem;
- }
- pH->count = 0;
-}
-
-/*
-** Hash and comparison functions when the mode is SQLITE_HASH_INT
-*/
-static int intHash(const void *pKey, int nKey){
- return nKey ^ (nKey<<8) ^ (nKey>>8);
-}
-static int intCompare(const void *pKey1, int n1, const void *pKey2, int n2){
- return n2 - n1;
-}
-
-#if 0 /* NOT USED */
-/*
-** Hash and comparison functions when the mode is SQLITE_HASH_POINTER
-*/
-static int ptrHash(const void *pKey, int nKey){
- uptr x = Addr(pKey);
- return x ^ (x<<8) ^ (x>>8);
-}
-static int ptrCompare(const void *pKey1, int n1, const void *pKey2, int n2){
- if( pKey1==pKey2 ) return 0;
- if( pKey1<pKey2 ) return -1;
- return 1;
-}
-#endif
-
-/*
-** Hash and comparison functions when the mode is SQLITE_HASH_STRING
-*/
-static int strHash(const void *pKey, int nKey){
- return sqliteHashNoCase((const char*)pKey, nKey);
-}
-static int strCompare(const void *pKey1, int n1, const void *pKey2, int n2){
- if( n1!=n2 ) return n2-n1;
- return sqliteStrNICmp((const char*)pKey1,(const char*)pKey2,n1);
-}
-
-/*
-** Hash and comparison functions when the mode is SQLITE_HASH_BINARY
-*/
-static int binHash(const void *pKey, int nKey){
- int h = 0;
- const char *z = (const char *)pKey;
- while( nKey-- > 0 ){
- h = (h<<3) ^ h ^ *(z++);
- }
- return h & 0x7fffffff;
-}
-static int binCompare(const void *pKey1, int n1, const void *pKey2, int n2){
- if( n1!=n2 ) return n2-n1;
- return memcmp(pKey1,pKey2,n1);
-}
-
-/*
-** Return a pointer to the appropriate hash function given the key class.
-**
-** The C syntax in this function definition may be unfamilar to some
-** programmers, so we provide the following additional explanation:
-**
-** The name of the function is "hashFunction". The function takes a
-** single parameter "keyClass". The return value of hashFunction()
-** is a pointer to another function. Specifically, the return value
-** of hashFunction() is a pointer to a function that takes two parameters
-** with types "const void*" and "int" and returns an "int".
-*/
-static int (*hashFunction(int keyClass))(const void*,int){
- switch( keyClass ){
- case SQLITE_HASH_INT: return &intHash;
- /* case SQLITE_HASH_POINTER: return &ptrHash; // NOT USED */
- case SQLITE_HASH_STRING: return &strHash;
- case SQLITE_HASH_BINARY: return &binHash;;
- default: break;
- }
- return 0;
-}
-
-/*
-** Return a pointer to the appropriate hash function given the key class.
-**
-** For help in interpreted the obscure C code in the function definition,
-** see the header comment on the previous function.
-*/
-static int (*compareFunction(int keyClass))(const void*,int,const void*,int){
- switch( keyClass ){
- case SQLITE_HASH_INT: return &intCompare;
- /* case SQLITE_HASH_POINTER: return &ptrCompare; // NOT USED */
- case SQLITE_HASH_STRING: return &strCompare;
- case SQLITE_HASH_BINARY: return &binCompare;
- default: break;
- }
- return 0;
-}
-
-
-/* Resize the hash table so that it cantains "new_size" buckets.
-** "new_size" must be a power of 2. The hash table might fail
-** to resize if sqliteMalloc() fails.
-*/
-static void rehash(Hash *pH, int new_size){
- struct _ht *new_ht; /* The new hash table */
- HashElem *elem, *next_elem; /* For looping over existing elements */
- HashElem *x; /* Element being copied to new hash table */
- int (*xHash)(const void*,int); /* The hash function */
-
- assert( (new_size & (new_size-1))==0 );
- new_ht = (struct _ht *)sqliteMalloc( new_size*sizeof(struct _ht) );
- if( new_ht==0 ) return;
- if( pH->ht ) sqliteFree(pH->ht);
- pH->ht = new_ht;
- pH->htsize = new_size;
- xHash = hashFunction(pH->keyClass);
- for(elem=pH->first, pH->first=0; elem; elem = next_elem){
- int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1);
- next_elem = elem->next;
- x = new_ht[h].chain;
- if( x ){
- elem->next = x;
- elem->prev = x->prev;
- if( x->prev ) x->prev->next = elem;
- else pH->first = elem;
- x->prev = elem;
- }else{
- elem->next = pH->first;
- if( pH->first ) pH->first->prev = elem;
- elem->prev = 0;
- pH->first = elem;
- }
- new_ht[h].chain = elem;
- new_ht[h].count++;
- }
-}
-
-/* This function (for internal use only) locates an element in an
-** hash table that matches the given key. The hash for this key has
-** already been computed and is passed as the 4th parameter.
-*/
-static HashElem *findElementGivenHash(
- const Hash *pH, /* The pH to be searched */
- const void *pKey, /* The key we are searching for */
- int nKey,
- int h /* The hash for this key. */
-){
- HashElem *elem; /* Used to loop thru the element list */
- int count; /* Number of elements left to test */
- int (*xCompare)(const void*,int,const void*,int); /* comparison function */
-
- if( pH->ht ){
- elem = pH->ht[h].chain;
- count = pH->ht[h].count;
- xCompare = compareFunction(pH->keyClass);
- while( count-- && elem ){
- if( (*xCompare)(elem->pKey,elem->nKey,pKey,nKey)==0 ){
- return elem;
- }
- elem = elem->next;
- }
- }
- return 0;
-}
-
-/* Remove a single entry from the hash table given a pointer to that
-** element and a hash on the element's key.
-*/
-static void removeElementGivenHash(
- Hash *pH, /* The pH containing "elem" */
- HashElem* elem, /* The element to be removed from the pH */
- int h /* Hash value for the element */
-){
- if( elem->prev ){
- elem->prev->next = elem->next;
- }else{
- pH->first = elem->next;
- }
- if( elem->next ){
- elem->next->prev = elem->prev;
- }
- if( pH->ht[h].chain==elem ){
- pH->ht[h].chain = elem->next;
- }
- pH->ht[h].count--;
- if( pH->ht[h].count<=0 ){
- pH->ht[h].chain = 0;
- }
- if( pH->copyKey && elem->pKey ){
- sqliteFree(elem->pKey);
- }
- sqliteFree( elem );
- pH->count--;
-}
-
-/* Attempt to locate an element of the hash table pH with a key
-** that matches pKey,nKey. Return the data for this element if it is
-** found, or NULL if there is no match.
-*/
-void *sqliteHashFind(const Hash *pH, const void *pKey, int nKey){
- int h; /* A hash on key */
- HashElem *elem; /* The element that matches key */
- int (*xHash)(const void*,int); /* The hash function */
-
- if( pH==0 || pH->ht==0 ) return 0;
- xHash = hashFunction(pH->keyClass);
- assert( xHash!=0 );
- h = (*xHash)(pKey,nKey);
- assert( (pH->htsize & (pH->htsize-1))==0 );
- elem = findElementGivenHash(pH,pKey,nKey, h & (pH->htsize-1));
- return elem ? elem->data : 0;
-}
-
-/* Insert an element into the hash table pH. The key is pKey,nKey
-** and the data is "data".
-**
-** If no element exists with a matching key, then a new
-** element is created. A copy of the key is made if the copyKey
-** flag is set. NULL is returned.
-**
-** If another element already exists with the same key, then the
-** new data replaces the old data and the old data is returned.
-** The key is not copied in this instance. If a malloc fails, then
-** the new data is returned and the hash table is unchanged.
-**
-** If the "data" parameter to this function is NULL, then the
-** element corresponding to "key" is removed from the hash table.
-*/
-void *sqliteHashInsert(Hash *pH, const void *pKey, int nKey, void *data){
- int hraw; /* Raw hash value of the key */
- int h; /* the hash of the key modulo hash table size */
- HashElem *elem; /* Used to loop thru the element list */
- HashElem *new_elem; /* New element added to the pH */
- int (*xHash)(const void*,int); /* The hash function */
-
- assert( pH!=0 );
- xHash = hashFunction(pH->keyClass);
- assert( xHash!=0 );
- hraw = (*xHash)(pKey, nKey);
- assert( (pH->htsize & (pH->htsize-1))==0 );
- h = hraw & (pH->htsize-1);
- elem = findElementGivenHash(pH,pKey,nKey,h);
- if( elem ){
- void *old_data = elem->data;
- if( data==0 ){
- removeElementGivenHash(pH,elem,h);
- }else{
- elem->data = data;
- }
- return old_data;
- }
- if( data==0 ) return 0;
- new_elem = (HashElem*)sqliteMalloc( sizeof(HashElem) );
- if( new_elem==0 ) return data;
- if( pH->copyKey && pKey!=0 ){
- new_elem->pKey = sqliteMallocRaw( nKey );
- if( new_elem->pKey==0 ){
- sqliteFree(new_elem);
- return data;
- }
- memcpy((void*)new_elem->pKey, pKey, nKey);
- }else{
- new_elem->pKey = (void*)pKey;
- }
- new_elem->nKey = nKey;
- pH->count++;
- if( pH->htsize==0 ) rehash(pH,8);
- if( pH->htsize==0 ){
- pH->count = 0;
- sqliteFree(new_elem);
- return data;
- }
- if( pH->count > pH->htsize ){
- rehash(pH,pH->htsize*2);
- }
- assert( (pH->htsize & (pH->htsize-1))==0 );
- h = hraw & (pH->htsize-1);
- elem = pH->ht[h].chain;
- if( elem ){
- new_elem->next = elem;
- new_elem->prev = elem->prev;
- if( elem->prev ){ elem->prev->next = new_elem; }
- else { pH->first = new_elem; }
- elem->prev = new_elem;
- }else{
- new_elem->next = pH->first;
- new_elem->prev = 0;
- if( pH->first ){ pH->first->prev = new_elem; }
- pH->first = new_elem;
- }
- pH->ht[h].count++;
- pH->ht[h].chain = new_elem;
- new_elem->data = data;
- return 0;
-}
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