Annotation of embedaddon/php/ext/sqlite/libsqlite/src/hash.c, revision 1.1
1.1 ! misho 1: /*
! 2: ** 2001 September 22
! 3: **
! 4: ** The author disclaims copyright to this source code. In place of
! 5: ** a legal notice, here is a blessing:
! 6: **
! 7: ** May you do good and not evil.
! 8: ** May you find forgiveness for yourself and forgive others.
! 9: ** May you share freely, never taking more than you give.
! 10: **
! 11: *************************************************************************
! 12: ** This is the implementation of generic hash-tables
! 13: ** used in SQLite.
! 14: **
! 15: ** $Id: hash.c 195361 2005-09-07 15:11:33Z iliaa $
! 16: */
! 17: #include "sqliteInt.h"
! 18: #include <assert.h>
! 19:
! 20: /* Turn bulk memory into a hash table object by initializing the
! 21: ** fields of the Hash structure.
! 22: **
! 23: ** "new" is a pointer to the hash table that is to be initialized.
! 24: ** keyClass is one of the constants SQLITE_HASH_INT, SQLITE_HASH_POINTER,
! 25: ** SQLITE_HASH_BINARY, or SQLITE_HASH_STRING. The value of keyClass
! 26: ** determines what kind of key the hash table will use. "copyKey" is
! 27: ** true if the hash table should make its own private copy of keys and
! 28: ** false if it should just use the supplied pointer. CopyKey only makes
! 29: ** sense for SQLITE_HASH_STRING and SQLITE_HASH_BINARY and is ignored
! 30: ** for other key classes.
! 31: */
! 32: void sqliteHashInit(Hash *new, int keyClass, int copyKey){
! 33: assert( new!=0 );
! 34: assert( keyClass>=SQLITE_HASH_INT && keyClass<=SQLITE_HASH_BINARY );
! 35: new->keyClass = keyClass;
! 36: new->copyKey = copyKey &&
! 37: (keyClass==SQLITE_HASH_STRING || keyClass==SQLITE_HASH_BINARY);
! 38: new->first = 0;
! 39: new->count = 0;
! 40: new->htsize = 0;
! 41: new->ht = 0;
! 42: }
! 43:
! 44: /* Remove all entries from a hash table. Reclaim all memory.
! 45: ** Call this routine to delete a hash table or to reset a hash table
! 46: ** to the empty state.
! 47: */
! 48: void sqliteHashClear(Hash *pH){
! 49: HashElem *elem; /* For looping over all elements of the table */
! 50:
! 51: assert( pH!=0 );
! 52: elem = pH->first;
! 53: pH->first = 0;
! 54: if( pH->ht ) sqliteFree(pH->ht);
! 55: pH->ht = 0;
! 56: pH->htsize = 0;
! 57: while( elem ){
! 58: HashElem *next_elem = elem->next;
! 59: if( pH->copyKey && elem->pKey ){
! 60: sqliteFree(elem->pKey);
! 61: }
! 62: sqliteFree(elem);
! 63: elem = next_elem;
! 64: }
! 65: pH->count = 0;
! 66: }
! 67:
! 68: /*
! 69: ** Hash and comparison functions when the mode is SQLITE_HASH_INT
! 70: */
! 71: static int intHash(const void *pKey, int nKey){
! 72: return nKey ^ (nKey<<8) ^ (nKey>>8);
! 73: }
! 74: static int intCompare(const void *pKey1, int n1, const void *pKey2, int n2){
! 75: return n2 - n1;
! 76: }
! 77:
! 78: #if 0 /* NOT USED */
! 79: /*
! 80: ** Hash and comparison functions when the mode is SQLITE_HASH_POINTER
! 81: */
! 82: static int ptrHash(const void *pKey, int nKey){
! 83: uptr x = Addr(pKey);
! 84: return x ^ (x<<8) ^ (x>>8);
! 85: }
! 86: static int ptrCompare(const void *pKey1, int n1, const void *pKey2, int n2){
! 87: if( pKey1==pKey2 ) return 0;
! 88: if( pKey1<pKey2 ) return -1;
! 89: return 1;
! 90: }
! 91: #endif
! 92:
! 93: /*
! 94: ** Hash and comparison functions when the mode is SQLITE_HASH_STRING
! 95: */
! 96: static int strHash(const void *pKey, int nKey){
! 97: return sqliteHashNoCase((const char*)pKey, nKey);
! 98: }
! 99: static int strCompare(const void *pKey1, int n1, const void *pKey2, int n2){
! 100: if( n1!=n2 ) return n2-n1;
! 101: return sqliteStrNICmp((const char*)pKey1,(const char*)pKey2,n1);
! 102: }
! 103:
! 104: /*
! 105: ** Hash and comparison functions when the mode is SQLITE_HASH_BINARY
! 106: */
! 107: static int binHash(const void *pKey, int nKey){
! 108: int h = 0;
! 109: const char *z = (const char *)pKey;
! 110: while( nKey-- > 0 ){
! 111: h = (h<<3) ^ h ^ *(z++);
! 112: }
! 113: return h & 0x7fffffff;
! 114: }
! 115: static int binCompare(const void *pKey1, int n1, const void *pKey2, int n2){
! 116: if( n1!=n2 ) return n2-n1;
! 117: return memcmp(pKey1,pKey2,n1);
! 118: }
! 119:
! 120: /*
! 121: ** Return a pointer to the appropriate hash function given the key class.
! 122: **
! 123: ** The C syntax in this function definition may be unfamilar to some
! 124: ** programmers, so we provide the following additional explanation:
! 125: **
! 126: ** The name of the function is "hashFunction". The function takes a
! 127: ** single parameter "keyClass". The return value of hashFunction()
! 128: ** is a pointer to another function. Specifically, the return value
! 129: ** of hashFunction() is a pointer to a function that takes two parameters
! 130: ** with types "const void*" and "int" and returns an "int".
! 131: */
! 132: static int (*hashFunction(int keyClass))(const void*,int){
! 133: switch( keyClass ){
! 134: case SQLITE_HASH_INT: return &intHash;
! 135: /* case SQLITE_HASH_POINTER: return &ptrHash; // NOT USED */
! 136: case SQLITE_HASH_STRING: return &strHash;
! 137: case SQLITE_HASH_BINARY: return &binHash;;
! 138: default: break;
! 139: }
! 140: return 0;
! 141: }
! 142:
! 143: /*
! 144: ** Return a pointer to the appropriate hash function given the key class.
! 145: **
! 146: ** For help in interpreted the obscure C code in the function definition,
! 147: ** see the header comment on the previous function.
! 148: */
! 149: static int (*compareFunction(int keyClass))(const void*,int,const void*,int){
! 150: switch( keyClass ){
! 151: case SQLITE_HASH_INT: return &intCompare;
! 152: /* case SQLITE_HASH_POINTER: return &ptrCompare; // NOT USED */
! 153: case SQLITE_HASH_STRING: return &strCompare;
! 154: case SQLITE_HASH_BINARY: return &binCompare;
! 155: default: break;
! 156: }
! 157: return 0;
! 158: }
! 159:
! 160:
! 161: /* Resize the hash table so that it cantains "new_size" buckets.
! 162: ** "new_size" must be a power of 2. The hash table might fail
! 163: ** to resize if sqliteMalloc() fails.
! 164: */
! 165: static void rehash(Hash *pH, int new_size){
! 166: struct _ht *new_ht; /* The new hash table */
! 167: HashElem *elem, *next_elem; /* For looping over existing elements */
! 168: HashElem *x; /* Element being copied to new hash table */
! 169: int (*xHash)(const void*,int); /* The hash function */
! 170:
! 171: assert( (new_size & (new_size-1))==0 );
! 172: new_ht = (struct _ht *)sqliteMalloc( new_size*sizeof(struct _ht) );
! 173: if( new_ht==0 ) return;
! 174: if( pH->ht ) sqliteFree(pH->ht);
! 175: pH->ht = new_ht;
! 176: pH->htsize = new_size;
! 177: xHash = hashFunction(pH->keyClass);
! 178: for(elem=pH->first, pH->first=0; elem; elem = next_elem){
! 179: int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1);
! 180: next_elem = elem->next;
! 181: x = new_ht[h].chain;
! 182: if( x ){
! 183: elem->next = x;
! 184: elem->prev = x->prev;
! 185: if( x->prev ) x->prev->next = elem;
! 186: else pH->first = elem;
! 187: x->prev = elem;
! 188: }else{
! 189: elem->next = pH->first;
! 190: if( pH->first ) pH->first->prev = elem;
! 191: elem->prev = 0;
! 192: pH->first = elem;
! 193: }
! 194: new_ht[h].chain = elem;
! 195: new_ht[h].count++;
! 196: }
! 197: }
! 198:
! 199: /* This function (for internal use only) locates an element in an
! 200: ** hash table that matches the given key. The hash for this key has
! 201: ** already been computed and is passed as the 4th parameter.
! 202: */
! 203: static HashElem *findElementGivenHash(
! 204: const Hash *pH, /* The pH to be searched */
! 205: const void *pKey, /* The key we are searching for */
! 206: int nKey,
! 207: int h /* The hash for this key. */
! 208: ){
! 209: HashElem *elem; /* Used to loop thru the element list */
! 210: int count; /* Number of elements left to test */
! 211: int (*xCompare)(const void*,int,const void*,int); /* comparison function */
! 212:
! 213: if( pH->ht ){
! 214: elem = pH->ht[h].chain;
! 215: count = pH->ht[h].count;
! 216: xCompare = compareFunction(pH->keyClass);
! 217: while( count-- && elem ){
! 218: if( (*xCompare)(elem->pKey,elem->nKey,pKey,nKey)==0 ){
! 219: return elem;
! 220: }
! 221: elem = elem->next;
! 222: }
! 223: }
! 224: return 0;
! 225: }
! 226:
! 227: /* Remove a single entry from the hash table given a pointer to that
! 228: ** element and a hash on the element's key.
! 229: */
! 230: static void removeElementGivenHash(
! 231: Hash *pH, /* The pH containing "elem" */
! 232: HashElem* elem, /* The element to be removed from the pH */
! 233: int h /* Hash value for the element */
! 234: ){
! 235: if( elem->prev ){
! 236: elem->prev->next = elem->next;
! 237: }else{
! 238: pH->first = elem->next;
! 239: }
! 240: if( elem->next ){
! 241: elem->next->prev = elem->prev;
! 242: }
! 243: if( pH->ht[h].chain==elem ){
! 244: pH->ht[h].chain = elem->next;
! 245: }
! 246: pH->ht[h].count--;
! 247: if( pH->ht[h].count<=0 ){
! 248: pH->ht[h].chain = 0;
! 249: }
! 250: if( pH->copyKey && elem->pKey ){
! 251: sqliteFree(elem->pKey);
! 252: }
! 253: sqliteFree( elem );
! 254: pH->count--;
! 255: }
! 256:
! 257: /* Attempt to locate an element of the hash table pH with a key
! 258: ** that matches pKey,nKey. Return the data for this element if it is
! 259: ** found, or NULL if there is no match.
! 260: */
! 261: void *sqliteHashFind(const Hash *pH, const void *pKey, int nKey){
! 262: int h; /* A hash on key */
! 263: HashElem *elem; /* The element that matches key */
! 264: int (*xHash)(const void*,int); /* The hash function */
! 265:
! 266: if( pH==0 || pH->ht==0 ) return 0;
! 267: xHash = hashFunction(pH->keyClass);
! 268: assert( xHash!=0 );
! 269: h = (*xHash)(pKey,nKey);
! 270: assert( (pH->htsize & (pH->htsize-1))==0 );
! 271: elem = findElementGivenHash(pH,pKey,nKey, h & (pH->htsize-1));
! 272: return elem ? elem->data : 0;
! 273: }
! 274:
! 275: /* Insert an element into the hash table pH. The key is pKey,nKey
! 276: ** and the data is "data".
! 277: **
! 278: ** If no element exists with a matching key, then a new
! 279: ** element is created. A copy of the key is made if the copyKey
! 280: ** flag is set. NULL is returned.
! 281: **
! 282: ** If another element already exists with the same key, then the
! 283: ** new data replaces the old data and the old data is returned.
! 284: ** The key is not copied in this instance. If a malloc fails, then
! 285: ** the new data is returned and the hash table is unchanged.
! 286: **
! 287: ** If the "data" parameter to this function is NULL, then the
! 288: ** element corresponding to "key" is removed from the hash table.
! 289: */
! 290: void *sqliteHashInsert(Hash *pH, const void *pKey, int nKey, void *data){
! 291: int hraw; /* Raw hash value of the key */
! 292: int h; /* the hash of the key modulo hash table size */
! 293: HashElem *elem; /* Used to loop thru the element list */
! 294: HashElem *new_elem; /* New element added to the pH */
! 295: int (*xHash)(const void*,int); /* The hash function */
! 296:
! 297: assert( pH!=0 );
! 298: xHash = hashFunction(pH->keyClass);
! 299: assert( xHash!=0 );
! 300: hraw = (*xHash)(pKey, nKey);
! 301: assert( (pH->htsize & (pH->htsize-1))==0 );
! 302: h = hraw & (pH->htsize-1);
! 303: elem = findElementGivenHash(pH,pKey,nKey,h);
! 304: if( elem ){
! 305: void *old_data = elem->data;
! 306: if( data==0 ){
! 307: removeElementGivenHash(pH,elem,h);
! 308: }else{
! 309: elem->data = data;
! 310: }
! 311: return old_data;
! 312: }
! 313: if( data==0 ) return 0;
! 314: new_elem = (HashElem*)sqliteMalloc( sizeof(HashElem) );
! 315: if( new_elem==0 ) return data;
! 316: if( pH->copyKey && pKey!=0 ){
! 317: new_elem->pKey = sqliteMallocRaw( nKey );
! 318: if( new_elem->pKey==0 ){
! 319: sqliteFree(new_elem);
! 320: return data;
! 321: }
! 322: memcpy((void*)new_elem->pKey, pKey, nKey);
! 323: }else{
! 324: new_elem->pKey = (void*)pKey;
! 325: }
! 326: new_elem->nKey = nKey;
! 327: pH->count++;
! 328: if( pH->htsize==0 ) rehash(pH,8);
! 329: if( pH->htsize==0 ){
! 330: pH->count = 0;
! 331: sqliteFree(new_elem);
! 332: return data;
! 333: }
! 334: if( pH->count > pH->htsize ){
! 335: rehash(pH,pH->htsize*2);
! 336: }
! 337: assert( (pH->htsize & (pH->htsize-1))==0 );
! 338: h = hraw & (pH->htsize-1);
! 339: elem = pH->ht[h].chain;
! 340: if( elem ){
! 341: new_elem->next = elem;
! 342: new_elem->prev = elem->prev;
! 343: if( elem->prev ){ elem->prev->next = new_elem; }
! 344: else { pH->first = new_elem; }
! 345: elem->prev = new_elem;
! 346: }else{
! 347: new_elem->next = pH->first;
! 348: new_elem->prev = 0;
! 349: if( pH->first ){ pH->first->prev = new_elem; }
! 350: pH->first = new_elem;
! 351: }
! 352: pH->ht[h].count++;
! 353: pH->ht[h].chain = new_elem;
! 354: new_elem->data = data;
! 355: return 0;
! 356: }
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