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 header file for the generic hash-table implemenation 13 ** used in SQLite. We've modified it slightly to serve as a standalone 14 ** hash table implementation for the full-text indexing module. 15 ** 16 */ 17 #ifndef _FTS2_HASH_H_ 18 #define _FTS2_HASH_H_ 19 20 /* Forward declarations of structures. */ 21 typedef struct fts2Hash fts2Hash; 22 typedef struct fts2HashElem fts2HashElem; 23 24 /* A complete hash table is an instance of the following structure. 25 ** The internals of this structure are intended to be opaque -- client 26 ** code should not attempt to access or modify the fields of this structure 27 ** directly. Change this structure only by using the routines below. 28 ** However, many of the "procedures" and "functions" for modifying and 29 ** accessing this structure are really macros, so we can't really make 30 ** this structure opaque. 31 */ 32 struct fts2Hash { 33 char keyClass; /* HASH_INT, _POINTER, _STRING, _BINARY */ 34 char copyKey; /* True if copy of key made on insert */ 35 int count; /* Number of entries in this table */ 36 fts2HashElem *first; /* The first element of the array */ 37 int htsize; /* Number of buckets in the hash table */ 38 struct _fts2ht { /* the hash table */ 39 int count; /* Number of entries with this hash */ 40 fts2HashElem *chain; /* Pointer to first entry with this hash */ 41 } *ht; 42 }; 43 44 /* Each element in the hash table is an instance of the following 45 ** structure. All elements are stored on a single doubly-linked list. 46 ** 47 ** Again, this structure is intended to be opaque, but it can't really 48 ** be opaque because it is used by macros. 49 */ 50 struct fts2HashElem { 51 fts2HashElem *next, *prev; /* Next and previous elements in the table */ 52 void *data; /* Data associated with this element */ 53 void *pKey; int nKey; /* Key associated with this element */ 54 }; 55 56 /* 57 ** There are 2 different modes of operation for a hash table: 58 ** 59 ** FTS2_HASH_STRING pKey points to a string that is nKey bytes long 60 ** (including the null-terminator, if any). Case 61 ** is respected in comparisons. 62 ** 63 ** FTS2_HASH_BINARY pKey points to binary data nKey bytes long. 64 ** memcmp() is used to compare keys. 65 ** 66 ** A copy of the key is made if the copyKey parameter to fts2HashInit is 1. 67 */ 68 #define FTS2_HASH_STRING 1 69 #define FTS2_HASH_BINARY 2 70 71 /* 72 ** Access routines. To delete, insert a NULL pointer. 73 */ 74 void sqlite3Fts2HashInit(fts2Hash*, int keytype, int copyKey); 75 void *sqlite3Fts2HashInsert(fts2Hash*, const void *pKey, int nKey, void *pData); 76 void *sqlite3Fts2HashFind(const fts2Hash*, const void *pKey, int nKey); 77 void sqlite3Fts2HashClear(fts2Hash*); 78 79 /* 80 ** Shorthand for the functions above 81 */ 82 #define fts2HashInit sqlite3Fts2HashInit 83 #define fts2HashInsert sqlite3Fts2HashInsert 84 #define fts2HashFind sqlite3Fts2HashFind 85 #define fts2HashClear sqlite3Fts2HashClear 86 87 /* 88 ** Macros for looping over all elements of a hash table. The idiom is 89 ** like this: 90 ** 91 ** fts2Hash h; 92 ** fts2HashElem *p; 93 ** ... 94 ** for(p=fts2HashFirst(&h); p; p=fts2HashNext(p)){ 95 ** SomeStructure *pData = fts2HashData(p); 96 ** // do something with pData 97 ** } 98 */ 99 #define fts2HashFirst(H) ((H)->first) 100 #define fts2HashNext(E) ((E)->next) 101 #define fts2HashData(E) ((E)->data) 102 #define fts2HashKey(E) ((E)->pKey) 103 #define fts2HashKeysize(E) ((E)->nKey) 104 105 /* 106 ** Number of entries in a hash table 107 */ 108 #define fts2HashCount(H) ((H)->count) 109 110 #endif /* _FTS2_HASH_H_ */ 111
