1*4520Snw141292 2*4520Snw141292 #pragma ident "%Z%%M% %I% %E% SMI" 3*4520Snw141292 4*4520Snw141292 /* 5*4520Snw141292 ** 2001 September 22 6*4520Snw141292 ** 7*4520Snw141292 ** The author disclaims copyright to this source code. In place of 8*4520Snw141292 ** a legal notice, here is a blessing: 9*4520Snw141292 ** 10*4520Snw141292 ** May you do good and not evil. 11*4520Snw141292 ** May you find forgiveness for yourself and forgive others. 12*4520Snw141292 ** May you share freely, never taking more than you give. 13*4520Snw141292 ** 14*4520Snw141292 ************************************************************************* 15*4520Snw141292 ** This is the header file for the generic hash-table implemenation 16*4520Snw141292 ** used in SQLite. 17*4520Snw141292 ** 18*4520Snw141292 ** $Id: hash.h,v 1.6 2004/01/08 02:17:33 drh Exp $ 19*4520Snw141292 */ 20*4520Snw141292 #ifndef _SQLITE_HASH_H_ 21*4520Snw141292 #define _SQLITE_HASH_H_ 22*4520Snw141292 23*4520Snw141292 /* Forward declarations of structures. */ 24*4520Snw141292 typedef struct Hash Hash; 25*4520Snw141292 typedef struct HashElem HashElem; 26*4520Snw141292 27*4520Snw141292 /* A complete hash table is an instance of the following structure. 28*4520Snw141292 ** The internals of this structure are intended to be opaque -- client 29*4520Snw141292 ** code should not attempt to access or modify the fields of this structure 30*4520Snw141292 ** directly. Change this structure only by using the routines below. 31*4520Snw141292 ** However, many of the "procedures" and "functions" for modifying and 32*4520Snw141292 ** accessing this structure are really macros, so we can't really make 33*4520Snw141292 ** this structure opaque. 34*4520Snw141292 */ 35*4520Snw141292 struct Hash { 36*4520Snw141292 char keyClass; /* SQLITE_HASH_INT, _POINTER, _STRING, _BINARY */ 37*4520Snw141292 char copyKey; /* True if copy of key made on insert */ 38*4520Snw141292 int count; /* Number of entries in this table */ 39*4520Snw141292 HashElem *first; /* The first element of the array */ 40*4520Snw141292 int htsize; /* Number of buckets in the hash table */ 41*4520Snw141292 struct _ht { /* the hash table */ 42*4520Snw141292 int count; /* Number of entries with this hash */ 43*4520Snw141292 HashElem *chain; /* Pointer to first entry with this hash */ 44*4520Snw141292 } *ht; 45*4520Snw141292 }; 46*4520Snw141292 47*4520Snw141292 /* Each element in the hash table is an instance of the following 48*4520Snw141292 ** structure. All elements are stored on a single doubly-linked list. 49*4520Snw141292 ** 50*4520Snw141292 ** Again, this structure is intended to be opaque, but it can't really 51*4520Snw141292 ** be opaque because it is used by macros. 52*4520Snw141292 */ 53*4520Snw141292 struct HashElem { 54*4520Snw141292 HashElem *next, *prev; /* Next and previous elements in the table */ 55*4520Snw141292 void *data; /* Data associated with this element */ 56*4520Snw141292 void *pKey; int nKey; /* Key associated with this element */ 57*4520Snw141292 }; 58*4520Snw141292 59*4520Snw141292 /* 60*4520Snw141292 ** There are 4 different modes of operation for a hash table: 61*4520Snw141292 ** 62*4520Snw141292 ** SQLITE_HASH_INT nKey is used as the key and pKey is ignored. 63*4520Snw141292 ** 64*4520Snw141292 ** SQLITE_HASH_POINTER pKey is used as the key and nKey is ignored. 65*4520Snw141292 ** 66*4520Snw141292 ** SQLITE_HASH_STRING pKey points to a string that is nKey bytes long 67*4520Snw141292 ** (including the null-terminator, if any). Case 68*4520Snw141292 ** is ignored in comparisons. 69*4520Snw141292 ** 70*4520Snw141292 ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long. 71*4520Snw141292 ** memcmp() is used to compare keys. 72*4520Snw141292 ** 73*4520Snw141292 ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY 74*4520Snw141292 ** if the copyKey parameter to HashInit is 1. 75*4520Snw141292 */ 76*4520Snw141292 #define SQLITE_HASH_INT 1 77*4520Snw141292 /* #define SQLITE_HASH_POINTER 2 // NOT USED */ 78*4520Snw141292 #define SQLITE_HASH_STRING 3 79*4520Snw141292 #define SQLITE_HASH_BINARY 4 80*4520Snw141292 81*4520Snw141292 /* 82*4520Snw141292 ** Access routines. To delete, insert a NULL pointer. 83*4520Snw141292 */ 84*4520Snw141292 void sqliteHashInit(Hash*, int keytype, int copyKey); 85*4520Snw141292 void *sqliteHashInsert(Hash*, const void *pKey, int nKey, void *pData); 86*4520Snw141292 void *sqliteHashFind(const Hash*, const void *pKey, int nKey); 87*4520Snw141292 void sqliteHashClear(Hash*); 88*4520Snw141292 89*4520Snw141292 /* 90*4520Snw141292 ** Macros for looping over all elements of a hash table. The idiom is 91*4520Snw141292 ** like this: 92*4520Snw141292 ** 93*4520Snw141292 ** Hash h; 94*4520Snw141292 ** HashElem *p; 95*4520Snw141292 ** ... 96*4520Snw141292 ** for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){ 97*4520Snw141292 ** SomeStructure *pData = sqliteHashData(p); 98*4520Snw141292 ** // do something with pData 99*4520Snw141292 ** } 100*4520Snw141292 */ 101*4520Snw141292 #define sqliteHashFirst(H) ((H)->first) 102*4520Snw141292 #define sqliteHashNext(E) ((E)->next) 103*4520Snw141292 #define sqliteHashData(E) ((E)->data) 104*4520Snw141292 #define sqliteHashKey(E) ((E)->pKey) 105*4520Snw141292 #define sqliteHashKeysize(E) ((E)->nKey) 106*4520Snw141292 107*4520Snw141292 /* 108*4520Snw141292 ** Number of entries in a hash table 109*4520Snw141292 */ 110*4520Snw141292 #define sqliteHashCount(H) ((H)->count) 111*4520Snw141292 112*4520Snw141292 #endif /* _SQLITE_HASH_H_ */ 113